NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) mission has successfully stowed the spacecraft’s Sample Return Capsule (SRC) and its abundant sample of asteroid Bennu. On Wednesday, Oct. 28, the mission team sent commands to the spacecraft, instructing it to close the capsule – marking the end of one of the most challenging phases of the mission.

“This achievement by OSIRIS-REx on behalf of NASA and the world has lifted our vision to the higher things we can achieve together, as teams and nations,” said NASA Administrator Jim Bridenstine. “Together a team comprising industry, academia and international partners, and a talented and diverse team of NASA employees with all types of expertise, has put us on course to vastly increase our collection on Earth of samples from space. Samples like this are going to transform what we know about our universe and ourselves, which is at the base of all NASA’s endeavors.”

The mission team spent two days working around the clock to carry out the stowage procedure, with preparations for the stowage event beginning last weekend. The process to stow the sample is unique compared to other spacecraft operations and required the team’s continuous oversight and input over the two-day period. For the spacecraft to proceed with each step in the stowage sequence, the team had to assess images and telemetry from the previous step to confirm the operation was successful and the spacecraft was ready to continue. Given that OSIRIS-REx is currently more than 205 million miles (330 million km) from Earth, this required the team to also work with a greater than 18.5-minute time delay for signals traveling in each direction.

Throughout the process, the OSIRIS-REx team continually assessed the Touch-And-Go Sample Acquisition Mechanism’s (TAGSAM) wrist alignment to ensure the collector head was being placed properly into the SRC. Additionally, the team inspected images to observe any material escaping from the collector head to confirm that no particles would hinder the stowage process. StowCam images of the stowage sequence show that a few particles escaped during the stowage procedure, but the team is confident that a plentiful amount of material remains inside of the head.

“Given the complexity of the process to place the sample collector head onto the capture ring, we expected that it would take a few attempts to get it in the perfect position,” said Rich Burns, OSIRIS-REx project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Fortunately, the head was captured on the first try, which allowed us to expeditiously execute the stow procedure.”

By the evening of Oct. 27, the spacecraft’s TAGSAM arm had placed the collector head into the SRC. The following morning, the OSIRIS-REx team verified that the collector head was thoroughly fastened into the capsule by performing a “backout check.” This sequence commanded the TAGSAM arm to attempt to back out of the capsule – which tugged on the collector head and ensured the latches are well secured.

“I want to thank the OSIRIS-REx team from the University of Arizona, NASA Goddard, Lockheed Martin, and their partners, and also especially the SCaN and Deep Space Network people at NASA and JPL, who worked tirelessly to get us the bandwidth we needed to achieve this milestone, early and while still hundreds of millions of miles away,” said Thomas Zurbuchen, NASA’s associate administrator for science at the agency’s headquarters in Washington. “What we have done is a real first for NASA, and we will benefit for decades by what we have been able to achieve at Bennu.”

On the afternoon of Oct. 28, following the backout check, the mission team sent commands to disconnect the two mechanical parts on the TAGSAM arm that connect the sampler head to the arm. The spacecraft first cut the tube that carried the nitrogen gas that stirred up the sample through the TAGSAM head during sample collection, and then separated the collector head from the TAGSAM arm itself.

That evening, the spacecraft completed the final step of the sample stowage process  –closing the SRC. To secure the capsule, the spacecraft closed the lid and then fastened two internal latches. As of late Oct. 28, the sample of Bennu is safely stored and ready for its journey to Earth.

“I’m very thankful that our team worked so hard to get this sample stowed as quickly as they did,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. “Now we can look forward to receiving the sample here on Earth and opening up that capsule.”

The stowage process, originally scheduled to begin in early November, was expedited after sample collection when the mission team received images that showed the spacecraft’s collector head overflowing with material. The images indicated that the spacecraft collected well over 2 ounces (60 grams) of Bennu’s surface material, and that some of these particles appeared to be slowly escaping from the head. A mylar flap designed to keep the sample inside the head appeared to be wedged open by some larger rocks. Now that the head is secure inside the SRC, pieces of the sample will no longer be lost.

The OSIRIS-REx team will now focus on preparing the spacecraft for the next phase of the mission – Earth Return Cruise. The departure window opens in March 2021 for OSIRIS-REx to begin its voyage home, and the spacecraft is targeting delivery of the SRC to Earth on Sep. 24, 2023.

Goddard provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Littleton built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

Yesterday, NASA’s OSIRIS-REx mission successfully placed the spacecraft’s sample collector head into its Sample Return Capsule (SRC). The first image shows the collector head hovering over the SRC after the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) arm moved it into the proper position for capture. The second image shows the collector head secured onto the capture ring in the SRC. Both images were captured by the StowCam camera.

Today, after the head was seated into the SRC’s capture ring, the spacecraft performed a “backout check,” which commanded the TAGSAM arm to back out of the capsule. This maneuver is designed to tug on the collector head and ensure that the latches – which keep the collector head in place – are well secured. Following the test, the mission team received telemetry confirming that the head is properly secured in the SRC.

Before the sampler head can be sealed into the SRC, two mechanical parts on the TAGSAM arm must first be disconnected – these are the tube that carried the nitrogen gas to the TAGSAM head during sample collection and the TAGSAM arm itself. Over the next several hours, the mission team will command the spacecraft to cut the tube and separate the collector head from the TAGSAM arm. Once the team confirms these activities have executed as planned, they will command the spacecraft to seal the SRC.

StowCam, a color imager, is one of three cameras comprising TAGCAMS (the Touch-and-Go Camera System), which is part of OSIRIS-REx’s guidance, navigation, and control system. TAGCAMS was designed, built and tested by Malin Space Science Systems; Lockheed Martin integrated TAGCAMS to the OSIRIS-REx spacecraft and operates TAGCAMS.

NASA’s OSIRIS-REx mission is ready to perform an early stow on Tuesday, Oct. 27, of the large sample it collected last week from the surface of the asteroid Bennu to protect and return as much of the sample as possible.

On Oct. 22, the OSIRIS-REx mission team received images that showed the spacecraft’s collector head overflowing with material collected from Bennu’s surface – well over the two-ounce (60-gram) mission requirement – and that some of these particles appeared to be slowly escaping from the collection head, called the Touch-And-Go Sample Acquisition Mechanism (TAGSAM).

A mylar flap on the TAGSAM allows material to easily enter the collector head, and should seal shut once the particles pass through. However, larger rocks that didn’t fully pass through the flap into the TAGSAM appear to have wedged this flap open, allowing bits of the sample to leak out.

Because the first sample collection event was so successful, NASA’s Science Mission Directorate has given the mission team the go-ahead to expedite sample stowage, originally scheduled for Nov. 2, in the spacecraft’s Sample Return Capsule (SRC) to minimize further sample loss.

“The abundance of material we collected from Bennu made it possible to expedite our decision to stow,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. “The team is now working around the clock to accelerate the stowage timeline, so that we can protect as much of this material as possible for return to Earth.”

Unlike other spacecraft operations where OSIRIS-REx autonomously runs through an entire sequence, stowing the sample is done in stages and requires the team’s oversight and input. The team will send the preliminary commands to the spacecraft to start the stow sequence and, once OSIRIS-REx completes each step in sequence, the spacecraft sends telemetry and images back to the team on Earth and waits for the team’s confirmation to proceed with the next step.

Signals currently take just over 18.5 minutes to travel between Earth and the spacecraft one-way, so each step of the sequence factors in about 37 minutes of communications transit time. Throughout the process, the mission team will continually assess the TAGSAM’s wrist alignment to ensure the collector head is properly placed in the SRC. A new imaging sequence also has been added to the process to observe the material escaping from the collector head and verify that no particles hinder the stowage process. The mission anticipates the entire stowage process will take multiple days, at the end of which the sample will be safely sealed in the SRC for the spacecraft’s journey back to Earth.

“I’m proud of the OSIRIS-REx team’s amazing work and success to this point,” said NASA’s Associate Administrator for Science Thomas Zurbuchen. “This mission is well positioned to return a historic and substantial sample of an asteroid to Earth, and they’ve been doing all the right things, on an expedited timetable, to protect that precious cargo.”

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

Two days after touching down on asteroid Bennu, NASA’s OSIRIS-REx mission team received on Thursday, Oct. 22, images that confirm the spacecraft has collected more than enough material to meet one of its main mission requirements – acquiring at least 2 ounces (60 grams) of the asteroid’s surface material.

 

The spacecraft captured images of the sample collector head as it moved through several different positions. In reviewing these images, the OSIRIS-REx team noticed both that the head appeared to be full of asteroid particles, and that some of these particles appeared to be escaping slowly from the sample collector, called the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) head. They suspect bits of material are passing through small gaps where a mylar flap – the collector’s “lid” – is slightly wedged open by larger rocks.

The team believes it has collected a sufficient sample and is on a path to stow the sample as quickly as possible. They came to this conclusion after comparing images of the empty collector head with Oct. 22 images of the TAGSAM head after the sample collection event.

“Bennu continues to surprise us with great science and also throwing a few curveballs,” said Thomas Zurbuchen, NASA’s associate administrator for science at the agency’s headquarters in Washington. “And although we may have to move more quickly to stow the sample, it’s not a bad problem to have. We are so excited to see what appears to be an abundant sample that will inspire science for decades beyond this historic moment.”

The images also show that any movement to the spacecraft and the TAGSAM instrument may lead to further sample loss. To preserve the remaining material, the mission team decided to forego the Sample Mass Measurement activity originally scheduled for Saturday, Oct. 24, and canceled a braking burn scheduled for Friday to minimize any acceleration to the spacecraft.

From here, the OSIRIS-Rex team will focus on stowing the sample in the Sample Return Capsule (SRC), where any loose material will be kept safe during the spacecraft’s journey back to Earth.

“We are working to keep up with our own success here, and my job is to safely return as large a sample of Bennu as possible,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona in Tucson. “The loss of mass is of concern to me, so I’m strongly encouraging the team to stow this precious sample as quickly as possible.”

The TAGSAM head performed the sampling event in optimal conditions. Newly available analyses show that the collector head was flush with Bennu’s surface when it made contact and when the nitrogen gas bottle was fired to stir surface material. It also penetrated several centimeters into the asteroid’s surface material. All data so far suggest that the collector head is holding much more than 2 ounces of regolith.

OSIRIS-REx remains in good health, and the mission team is finalizing a timeline for sample storage. An update will be provided once a decision is made on the sample storage timing and procedures.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

Captured on Oct. 20, 2020 during the OSIRIS-REx mission’s Touch-And-Go (TAG) sample collection event, this series of images shows the SamCam imager’s field of view as the NASA spacecraft approaches and touches down on asteroid Bennu’s surface, over 200 million miles (321 million km) away from Earth. The sampling event brought the spacecraft all the way down to sample site Nightingale, touching down within three feet (one meter) of the targeted location. The team on Earth received confirmation at 6:08 pm EDT that successful touchdown occurred. Preliminary data show the one-foot-wide (0.3-meter-wide) sampling head touched Bennu’s surface for approximately 6 seconds, after which the spacecraft performed a back-away burn.

 

The spacecraft’s sampling arm – called the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) – is visible in the lower part of the frame. The round head at the end of TAGSAM is the only part of OSIRIS-REx that contacted the surface during the sample collection event. In the middle of the image sequence, the sampling head positions itself to contact the asteroid’s surface head-on. Shortly after, the sampling head impacts site Nightingale and penetrates Bennu’s regolith. Upon initial contact, the TAGSAM head appears to crush some of the porous rocks underneath it. One second later, the spacecraft fires a nitrogen gas bottle, which mobilizes a substantial amount of the sample site’s material. Preliminary data show the spacecraft spent approximately 5 of the 6 seconds of contact collecting surface material, and the majority of sample collection occurred within the first 3 seconds.

 

The TAGSAM is designed to catch the agitated surface material, and the mission team will assess the amount of material collected through various spacecraft activities. After touchdown, the spacecraft fired its thrusters to back away from Bennu. As expected, this maneuver also disturbed the Nightingale site, and loose debris is visible near the end of the image sequence. Preliminary telemetry shows the spacecraft remains in good health. The spacecraft was traveling at 0.2 mph (10 cm/sec) when it contacted sample site Nightingale and then backed away at 0.9 mph (40 cm/sec).

 

These images were captured over approximately a five-minute period. The imaging sequence begins at about 82 feet (25 meters) above the surface, and runs through the back-away maneuver, with the last image in the sequence taken at approximately 43 feet (13 meters) in altitude – about 35 seconds after backing away. The sequence was created using 82 SamCam images, with 1.25 seconds between frames. For context, the images are oriented with Bennu’s west at the top.

NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) spacecraft unfurled its robotic arm Tuesday, and in a first for the agency, briefly touched an asteroid to collect dust and pebbles from the surface for delivery to Earth in 2023.

This well-preserved, ancient asteroid, known as Bennu, is currently more than 200 million miles (321 million kilometers) from Earth. Bennu offers scientists a window into the early solar system as it was first taking shape billions of years ago and flinging ingredients that could have helped seed life on Earth. If Tuesday’s sample collection event, known as “Touch-And-Go” (TAG), provided enough of a sample, mission teams will command the spacecraft to begin stowing the precious primordial cargo to begin its journey back to Earth in March 2021. Otherwise, they will prepare for another attempt in January.

“This amazing first for NASA demonstrates how an incredible team from across the country came together and persevered through incredible challenges to expand the boundaries of knowledge,” said NASA Administrator Jim Bridenstine. “Our industry, academic, and international partners have made it possible to hold a piece of the most ancient solar system in our hands.”

At 1:50 p.m. EDT, OSIRIS-REx fired its thrusters to nudge itself out of orbit around Bennu. It extended the shoulder, then elbow, then wrist of its 11-foot (3.35-meter) sampling arm, known as the Touch-And-Go Sample Acquisition Mechanism (TAGSAM), and transited across Bennu while descending about a half-mile (805 meters) toward the surface. After a four-hour descent, at an altitude of approximately 410 feet (125 meters), the spacecraft executed the “Checkpoint” burn, the first of two maneuvers to allow it to precisely target the sample collection site, known as “Nightingale.”

Ten minutes later, the spacecraft fired its thrusters for the second “Matchpoint” burn to slow its descent and match the asteroid’s rotation at the time of contact. It then continued a treacherous, 11-minute coast past a boulder the size of a two-story building, nicknamed “Mount Doom,” to touch down in a clear spot in a crater on Bennu’s northern hemisphere. The size of a small parking lot, the site Nightingale site is one of the few relatively clear spots on this unexpectedly boulder-covered space rock.

“This was an incredible feat – and today we’ve advanced both science and engineering and our prospects for future missions to study these mysterious ancient storytellers of the solar system,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate at the agency’s headquarters in Washington. “A piece of primordial rock that has witnessed our solar system’s entire history may now be ready to come home for generations of scientific discovery, and we can’t wait to see what comes next.”

“After over a decade of planning, the team is overjoyed at the success of today’s sampling attempt,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona in Tucson. “Even though we have some work ahead of us to determine the outcome of the event – the successful contact, the TAGSAM gas firing, and back-away from Bennu are major accomplishments for the team. I look forward to analyzing the data to determine the mass of sample collected.”

All spacecraft telemetry data indicates the TAG event executed as expected. However, it will take about a week for the OSIRIS-REx team to confirm how much sample the spacecraft collected.

Real-time data indicates the TAGSAM successfully contacted the surface and fired a burst of nitrogen gas. The gas should have stirred up dust and pebbles on Bennu’s surface, some of which should have been captured in the TAGSAM sample collection head. OSIRIS-REx engineers also confirmed that shortly after the spacecraft made contact with the surface, it fired its thrusters and safely backed away from Bennu.

“Today’s TAG maneuver was historic,” said Lori Glaze, Planetary Science Division director at NASA Headquarters in Washington. “The fact that we safely and successfully touched the surface of Bennu, in addition to all the other milestones this mission has already achieved, is a testament to the living spirit of exploration that continues to uncover the secrets of the solar system.”

“It’s hard to put into words how exciting it was to receive confirmation that the spacecraft successfully touched the surface and fired one of the gas bottles,” said Michael Moreau, OSIRIS-REx deputy project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The team can’t wait to receive the imagery from the TAG event late tonight and see how the surface of Bennu responded to the TAG event.”

The spacecraft carried out TAG autonomously, with pre-programmed instructions from engineers on Earth. Now, the OSIRIS-REx team will begin to assess whether the spacecraft grabbed any material, and, if so, how much; the goal is at least 60 grams, which is roughly equivalent to a full-size candy bar.

OSIRIS-REx engineers and scientists will use several techniques to identify and measure the sample remotely. First, they’ll compare images of the Nightingale site before and after TAG to see how much surface material moved around in response to the burst of gas.

“Our first indication of whether we were successful in collecting a sample will come on October 21 when we downlink the back-away movie from the spacecraft,” Moreau said. “If TAG made a significant disturbance of the surface, we likely collected a lot of material.”

Next, the team will try to determine the amount of sample collected. One method involves taking pictures of the TAGSAM head with a camera known as SamCam, which is devoted to documenting the sample-collection process and determining whether dust and rocks made it into the collector head. One indirect indication will be the amount of dust found around the sample collector head. OSIRIS-REx engineers also will attempt to snap photos that could, given the right lighting conditions, show the inside of the head so engineers can look for evidence of sample inside of it.

A couple of days after the SamCam images are analyzed, the spacecraft will attempt yet another method to measure the mass of the sample collected by determining the change in the spacecraft’s “moment of inertia,” a phrase that describes how mass is distributed and how it affects the rotation of the body around a central axis. This maneuver entails extending the TAGSAM arm out to the side of the spacecraft and slowly spinning the spacecraft about an axis perpendicular to the arm. This technique is analogous to a person spinning with one arm extended while holding a string with a ball attached to the end. The person can sense the mass of the ball by the tension in the string. Having performed this maneuver before TAG, and now after, engineers can measure the change in the mass of the collection head as a result of the sample inside.

“We will use the combination of data from TAG and the post-TAG images and mass measurement to assess our confidence that we have collected at least 60 grams of sample,” said Rich Burns, OSIRIS-REx project manager at Goddard. “If our confidence is high, we’ll make the decision to stow the sample on October 30.”

To store the sample, engineers will command the robotic arm to place the sample collector head into the Sample Return Capsule (SRC), located in the body of the spacecraft. The sample arm will then retract to the side of the spacecraft for the final time, the SRC will close, and the spacecraft will prepare for its departure from Bennu in March 2021 — this is the next time Bennu will be properly aligned with Earth for the most fuel-efficient return flight.

If, however, it turns out that the spacecraft did not collect enough sample at Nightingale, it will attempt another TAG maneuver on Jan. 12, 2021. If that occurs, it will touch down at the backup site called “Osprey,” which is another relatively boulder-free area inside a crater near Bennu’s equator.

OSIRIS-REx launched from Cape Canaveral Air Force Station in Florida Sept. 8, 2016. It arrived at Bennu Dec. 3, 2018, and began orbiting the asteroid for the first time on Dec. 31, 2018. The spacecraft is scheduled to return to Earth Sept. 24, 2023, when it will parachute the SRC into Utah’s west desert where scientists will be waiting to collect it.

Goddard provides overall mission management, systems engineering and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

NASA will broadcast coverage of a first for the agency as its Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) mission attempts to collect a sample of asteroid Bennu on Tuesday, Oct. 20, at 6:12 p.m. EDT.

Live coverage of the spacecraft’s descent to the asteroid’s surface for its “Touch-And-Go,” or TAG, maneuver, which will be managed by Lockheed Martin Space near Denver, will begin at 5 p.m. on NASA Television and the agency’s website.

Beginning with an orbit departure maneuver around 1:50 p.m., the full sequence of the complicated engineering feat will be covered on @OSIRISREx, and media and the public can ask questions using the hashtag #ToBennuandBack.

In addition to the broadcast Tuesday, Oct. 20, briefings and social media activities will cover the mission and asteroid science on Monday, Oct. 19.

OSIRIS-REx, which is about the size of a 15-passenger van, is currently orbiting the asteroid Bennu 200 million miles from Earth. Bennu contains material from the early solar system and may contain the molecular precursors to life and Earth’s oceans. The asteroid is about as tall as the Empire State Building and could potentially threaten Earth late in the next century, with a 1‐in‐2,700 chance of impacting our planet during one of its close approaches. OSIRIS-REx is now ready to take a sample of this ancient relic of our solar system and bring its stories and secrets home to Earth.

Due to the coronavirus (COVID-19) pandemic, media participation in the news conferences will be remote. Only a limited number of media will be accommodated at Lockheed Martin. Denver-area media may contact Gary Napier at gary.p.napier@lmco.com for more information. For the protection of Lockheed Martin flight operations employees, the OSIRIS-REx mission operations facilities will remain closed to all media throughout these events.

Full mission coverage and participants (all times Eastern):

Monday, October 19

1 p.m. – Asteroid Science and Planetary Defense media teleconference with the following participants:

• Lori Glaze, Planetary Science Division director, NASA Headquarters, Washington
• Hal Levison, Lucy mission principal investigator, Southwest Research Institute, Boulder, Colorado
• Lindy Elkins-Tanton, Psyche mission principal investigator, Arizona State University, Tempe
• Andrea Riley, DART mission program executive, NASA Headquarters
• Jamie Elsila Cook, co-investigator for the NASA Astrobiology Institute at the Goddard Center for Astrobiology and OSIRIS-REx asteroid sample return science team collaborator

For dial-in information, media should contact Alana Johnson at alana.r.johnson@nasa.gov no later than 11 a.m. Oct. 19.

3 p.m. – OSIRIS-REx Science and Engineering televised briefing with the following participants:

• Thomas Zurbuchen, associate administrator, Science Mission Directorate, NASA Headquarters, Washington
• Lori Glaze, Planetary Science Division director, NASA Headquarters
• Heather Enos, OSIRIS-REx deputy principal investigator, University of Arizona, Tucson
• Kenneth Getzandanner, OSIRIS-REx flight dynamics manager, NASA’s Goddard Space Flight Center, Greenbelt, Maryland
• Beth Buck, OSIRIS-REx mission operations program manager, Lockheed Martin Space, Littleton, Colorado

For phone bridge information, media should contact Lonnie Shekhtman at lonnie.shekhtman@nasa.gov no later than 1 p.m. Monday, Oct. 19.

Tuesday, October 20

1:20 to 6:30 p.m. – Live stream animation displaying OSIRIS-REx’s sample collection activities in real time. The animation commences with the spacecraft’s slew into position for the Orbit Departure Maneuver and runs through the entire sequence of TAG events, concluding after the spacecraft’s back-away burn. Event will be broadcast on the mission’s website.

5 to 6:30 p.m. – Live broadcast from Lockheed Martin of OSIRIS-REx’s descent to the surface of Bennu and attempt at sample collection.

Hosted by Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, and Michelle Thaller, science communicator at Goddard, the broadcast will cover milestones in the last 90 minutes leading up to TAG and spacecraft back-away. It will include perspectives from team members and science leaders about the mission’s challenges and accomplishments.

A clean feed of the Mission Support Area during TAG is planned to run on NASA’s media channel.

Wednesday, October 21

5 p.m. – Post-sampling news conference – and release of new images – with the following participants:

• Dante Lauretta, OSIRIS-REx principal investigator, University of Arizona, Tucson
• Rich Burns, OSIRIS-REx project manager, NASA’s Goddard Space Flight Center in Greenbelt, Maryland
• Sandra Freund, OSIRIS-REx mission operations manager, Lockheed Martin Space, Littleton, Colorado

For phone bridge information, media should contact Lonnie Shekhtman at lonnie.shekhtman@nasa.gov no later than 1 p.m. Oct. 21.

6:15 to 6:45 p.m. – A NASA Science Live episode will air with team members answering live questions from the public about TAG, OSIRIS-REx, and asteroid science. Use #ToBennuAndBack to participate.

NASA Social

NASA also will host a #ToBennuAndBack Virtual NASA Social. RSVP to the Facebook event for social media updates.

NASA Social participants will get a chance to:

• Connect virtually with like-minded space enthusiasts as we prepare for TAG
• Receive a NASA Social badge to share online or print at home
• Virtually tour the asteroid Bennu
• Access the broadcast and other activities around TAG

By applying to the group, participants are explicitly agreeing to the group’s rules as set forth by NASA. All membership questions must be answered to be accepted to the group.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space near Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

For more information on the OSIRIS-REx mission, visit:

https://www.nasa.gov/osiris-rex

The OSIRIS-REx press kit is available at:

https://www.asteroidmission.org/press-kit/

 

NASA’s first asteroid sample return mission now knows much more about the material it’ll be collecting in just a few weeks. In a special collection of six papers published today in the journals Science and Science Advances, scientists on the OSIRIS-REx mission present new findings on asteroid Bennu’s surface material, geological characteristics, and dynamic history. They also suspect that the delivered sample of Bennu may be unlike anything we have in the meteorite collection on Earth.

These discoveries complete the OSIRIS-REx mission’s pre–sample collection science requirements and offer insight into the sample of Bennu that scientists will study for generations to come.

One of the papers, led by Amy Simon from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, shows that carbon-bearing, organic material is widespread on the asteroid’s surface, including at the mission’s primary sample site, Nightingale, where OSIRIS-REx will make its first sample collection attempt on October 20. These findings indicate that hydrated minerals and organic material will likely be present in the collected sample.

This organic matter may contain carbon in a form often found in biology or in compounds associated with biology. Scientists are planning detailed experiments on these organic molecules and expect that the returned sample will help answer complex questions about the origins of water and life on Earth.

“The abundance of carbon-bearing material is a major scientific triumph for the mission. We are now optimistic that we will collect and return a sample with organic material – a central goal of the OSIRIS-REx mission,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona in Tucson.

Authors of the special collection have also determined that carbonate minerals make up some of the asteroid’s geological features. Carbonate minerals often precipitate from hydrothermal systems that contain both water and carbon dioxide. A number of Bennu’s boulders have bright veins that appear to be made of carbonate – some of which are located near the Nightingale crater, meaning that carbonates might be present in the returned sample.

The study of the carbonates found on Bennu was led by Hannah Kaplan, from Goddard. These findings have allowed scientists to theorize that Bennu’s parent asteroid likely had an extensive hydrothermal system, where water interacted with and altered the rock on Bennu’s parent body. Although the parent body was destroyed long ago, we’re seeing evidence of what that watery asteroid once looked like here – in its remaining fragments that make up Bennu. Some of these carbonate veins in Bennu’s boulders measure up to a few feet long and several inches thick, validating that an asteroid-scale hydrothermal system of water was present on Bennu’s parent body.

Scientists made another striking discovery at site Nightingale: its regolith has only recently been exposed to the harsh space environment, meaning that the mission will collect and return some of the most pristine material on the asteroid. Nightingale is part of a population of young, spectrally red craters identified in a study led by Dani DellaGiustina at the University of Arizona. Bennu’s “colors” (variations in the slope of the visible-wavelength spectrum) are much more diverse than originally anticipated. This diversity results from a combination of different materials inherited from Bennu’s parent body and different durations of exposure to the space environment.

This paper’s findings are a major milestone in an ongoing debate in the planetary science community – how primitive asteroids like Bennu change spectrally as they are exposed to “space weathering” processes, such as bombardment by cosmic rays and solar wind. While Bennu appears quite black to the naked eye, the authors illustrate the diversity of Bennu’s surface by using false-color renderings of multispectral data collected by the MapCam camera. The freshest material on Bennu, such as that found at the Nightingale site, is spectrally redder than average and thus appears red in these images. Surface material turns vivid blue when it has been exposed to space weathering for an intermediate period of time. As the surface material continues to weather over long periods of time, it ultimately brightens across all wavelengths, becoming a less intense blue – the average spectral color of Bennu.

The paper by DellaGiustina et al. also distinguishes two main types of boulders on Bennu’s surface: dark and rough, and (less commonly) bright and smooth. The different types may have formed at different depths in the parent asteroid of Bennu.

Not only do the boulder types differ visually, they also have their own unique physical properties. The paper led by Ben Rozitis from The Open University in the UK shows that the dark boulders are weaker and more porous, whereas the bright boulders are stronger and less porous. The bright boulders also host the carbonates identified by Kaplan and crew, suggesting that the precipitation of carbonate minerals in cracks and pore spaces may be responsible for their increased strength.

However, both boulder types are weaker than scientists expected. Rozitis and colleagues suspect that Bennu’s dark boulders (the weaker, more porous, and more common type) would not survive the journey through Earth’s atmosphere. It’s therefore likely that the returned samples of asteroid Bennu will provide a missing link for scientists, as this type of material is not currently represented in meteorite collections.

Bennu is a diamond-shaped pile of rubble floating in space, but there’s more to it than meets the eye. Data obtained by the OSIRIS-REx Laser Altimeter (OLA) – a science instrument contributed by the Canadian Space Agency – have allowed the mission team to develop a 3D digital terrain model of the asteroid that, at 20 cm resolution, is unprecedented in detail and accuracy. In this paper, led by Michael Daly of York University, scientists explain how detailed analysis of the asteroid’s shape revealed ridge-like mounds on Bennu that extend from pole-to-pole, but are subtle enough that they could be easily missed by the human eye. Their presence has been hinted at before, but their full pole-to-pole extents only became clear when the northern and southern hemispheres were split apart in the OLA data for comparison.

The digital terrain model also shows that Bennu’s northern and southern hemispheres have different shapes. The southern hemisphere appears to be smoother and rounder, which the scientists believe is a result of loose material getting trapped by the region’s numerous large boulders.

Another paper in the special collection, led by Daniel Scheeres of University of Colorado Boulder, examines the gravity field of Bennu, which has been determined by tracking the trajectories of the OSIRIS-REx spacecraft and the particles that are naturally ejected from Bennu’s surface. The use of particles as gravity probes is fortuitous. Prior to the discovery of particle ejection on Bennu in 2019, the team was concerned about mapping the gravity field to the required precision using only spacecraft tracking data. The natural supply of dozens of mini gravity probes allowed the team to vastly exceed their requirements and gain unprecedented insight into the asteroid interior.

The reconstructed gravity field shows that the interior of Bennu is not uniform. Instead, there are pockets of higher and lower density material inside the asteroid. It’s as if there is a void at its center, within which you could fit a couple of football fields. In addition, the bulge at Bennu’s equator is under-dense, suggesting that Bennu’s rotation is lofting this material.

All six publications in the special collection use global and local datasets collected by the OSIRIS-REx spacecraft from Feb. through Oct. 2019. The special collection underscores that sample return missions like OSIRIS-REx are essential to fully understanding the history and evolution of our Solar System.

The mission is less than two weeks away from fulfilling its biggest goal – collecting a piece of a pristine, hydrated, carbon-rich asteroid. OSIRIS-REx will depart Bennu in 2021 and deliver the sample to Earth on Sep. 24, 2023.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

A historic moment is on the horizon for NASA’s OSIRIS-REx mission. In just a few weeks, the robotic OSIRIS-REx spacecraft will descend to asteroid Bennu’s boulder-strewn surface, touch down for a few seconds and collect a sample of the asteroid’s rocks and dust – marking the first time NASA has grabbed pieces of an asteroid, which will be returned to Earth for study.

On Oct. 20, the mission will perform the first attempt of its Touch-And-Go (TAG) sample collection event. This series of maneuvers will bring the spacecraft down to site Nightingale, a rocky area 52 ft (16 m) in diameter in Bennu’s northern hemisphere, where the spacecraft’s robotic sampling arm will attempt to collect a sample. Site Nightingale was selected as the mission’s primary sample site because it holds the greatest amount of unobstructed fine-grained material, but the region is surrounded by building-sized boulders. During the sampling event, the spacecraft, which is the size of a large van, will attempt to touch down in an area that is only the size of a few parking spaces, and just a few steps away from some of these large boulders.

During the 4.5-hour sample collection event, the spacecraft will perform three separate maneuvers to reach the asteroid’s surface. The descent sequence begins with OSIRIS-REx firing its thrusters for an orbit departure maneuver to leave its safe-home orbit approximately 2,500 feet (770 meters) from Bennu’s surface. After traveling four hours on this downward trajectory, the spacecraft performs the “Checkpoint” maneuver at an approximate altitude of 410 ft (125 m). This thruster burn adjusts OSIRIS-REx’s position and speed to descend steeply toward the surface. About 11 minutes later, the spacecraft performs the “Matchpoint” burn at an approximate altitude of 177 ft (54 m), slowing its descent and targeting a path to match the asteroid’s rotation at the time of contact. The spacecraft then descends to the surface, touches down for less than sixteen seconds and fires one of its three pressurized nitrogen bottles. The gas agitates and lifts Bennu’s surface material, which is then caught in the spacecraft’s collector head. After this brief touch, OSIRIS-REx fires its thrusters to back away from Bennu’s surface and navigates to a safe distance from the asteroid.

After the orbit departure maneuver, the spacecraft undertakes a sequence of reconfigurations to prepare for sampling. First, OSIRIS-REx extends its robotic sampling arm – the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) – from its folded storage position out to the sample collection position. The spacecraft’s two solar panels then move into a “Y-wing” configuration over the spacecraft’s body, which positions them safely up and away from the asteroid’s surface during touch down. This configuration also places the spacecraft’s center of gravity directly over the TAGSAM collector head, which is the only part of the spacecraft that will contact Bennu’s surface during the sample collection event.

Because the spacecraft and Bennu are approximately 207 million miles (334 million km) from Earth during TAG, it will take about 18.5 minutes for signals to travel between them. This time lag prevents the live commanding of flight activities from the ground during the TAG event, so the spacecraft is designed to perform the entire sample collection sequence autonomously. Prior to the event’s start, the OSIRIS-REx team will uplink all of the commands to the spacecraft and then send a “GO” command to begin.

To autonomously navigate to site Nightingale, OSIRIS-REx uses the Natural Feature Tracking (NFT) navigation system. The spacecraft begins collecting navigation images about 90 minutes after orbit departure. It then compares these real-time images to an onboard image catalog, using identified surface features to make sure that it’s on the right course toward the site. As the spacecraft approaches the surface, OSIRIS-REx updates the Checkpoint and Matchpoint maneuvers based on the NFT’s estimate of the spacecraft’s position and velocity. OSIRIS-REx continues to use the NFT estimates as it descends to the surface after the Matchpoint maneuver to monitor its position and descent rate. The spacecraft will autonomously abort should its trajectory vary outside of predefined limits.

To ensure that the spacecraft touches down on a safe area that avoids the region’s many boulders, the navigation system is equipped with a hazard map of site Nightingale, which delineates areas within the sample site that could potentially harm the spacecraft. If the spacecraft’s NFT system detects that it is on course to touch one of these hazardous zones, the spacecraft will autonomously wave off its approach once it reaches an altitude of 16 ft (5 m). This keeps the spacecraft safe and allows for a subsequent sample collection attempt at a future date.

As the spacecraft performs each event in the sample collection sequence, it will send telemetry updates back to the OSIRIS-REx team, albeit at an extremely slow data rate. The team will monitor the telemetry during the excursion and will be able to confirm that the spacecraft has successfully touched down on Bennu’s surface soon after TAG occurs. The images and other science data collected during the event will be downlinked after the spacecraft has backed away from the asteroid and can point its larger antenna back to Earth to transmit at higher communication rates.

OSIRIS-REx is charged with collecting at least 2 oz. (60 grams) of Bennu’s rocky material to deliver back to Earth – the largest sample return from space since the Apollo program – and the mission developed two methods to verify that this sample collection occurred. On Oct. 22, OSIRIS-REx’s SamCam camera will capture images of the TAGSAM head to see whether it contains Bennu’s surface material. The spacecraft will also perform a spin maneuver on Oct. 24 to determine the mass of collected material. If these measures show successful collection, the decision will be made to place the sample in the Sample Return Capsule (SRC) for return to Earth. If sufficient sample has not been collected from Nightingale, the spacecraft has onboard nitrogen charges for two more attempts. A TAG attempt at the back-up Osprey site would be made no earlier than January 2021.

The mission team has spent the last several months preparing for the sample collection event while maximizing remote work as part of its COVID-19 response. On the day of TAG, a limited number of team members will monitor the spacecraft from Lockheed Martin Space’s Mission Support Area, taking appropriate safety precautions. Other members of the team will also be at other locations on-site to cover the event, while also observing safety protocols.

The spacecraft is scheduled to depart Bennu in 2021 and it will deliver the collected sample to Earth on Sep. 24, 2023.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

For graphics from the Sept. 24 media telecon, go to: https://svs.gsfc.nasa.gov/13724

In an interplanetary faux pas, it appears some pieces of asteroid Vesta ended up on asteroid Bennu, according to observations from NASA’s OSIRIS-REx spacecraft. The new result sheds light on the intricate orbital dance of asteroids and on the violent origin of Bennu, which is a “rubble pile” asteroid that coalesced from the fragments of a massive collision.

“We found six boulders ranging in size from 5 to 14 feet (about 1.5 to 4.3 meters) scattered across Bennu’s southern hemisphere and near the equator,” said Daniella DellaGiustina of the Lunar & Planetary Laboratory, University of Arizona, Tucson. “These boulders are much brighter than the rest of Bennu and match material from Vesta.”

“Our leading hypothesis is that Bennu inherited this material from its parent asteroid after a vestoid (a fragment from Vesta) struck the parent,” said Hannah Kaplan of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Then, when the parent asteroid was catastrophically disrupted, a portion of its debris accumulated under its own gravity into Bennu, including some of the pyroxene from Vesta.”

DellaGiustina and Kaplan are primary authors of a paper on this research appearing in Nature Astronomy September 21.

The unusual boulders on Bennu first caught the team’s eye in images from the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) Camera Suite (OCAMS). They appeared extremely bright, with some almost ten times brighter than their surroundings. They analyzed the light from the boulders using the OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) instrument to get clues to their composition. A spectrometer separates light into its component colors. Since elements and compounds have distinct, signature patterns of bright and dark across a range of colors, they can be identified using a spectrometer. The signature from the boulders was characteristic of the mineral pyroxene, similar to what is seen on Vesta and the vestoids, smaller asteroids that are fragments blasted from Vesta when it sustained significant asteroid impacts. 

Of course it’s possible that the boulders actually formed on Bennu’s parent asteroid, but the team thinks this is unlikely based on how pyroxene typically forms. The mineral typically forms when rocky material melts at high-temperature. However, most of Bennu is composed of rocks containing water-bearing minerals, so it (and its parent) couldn’t have experienced very high temperatures. Next, the team considered localized heating, perhaps from an impact. An impact needed to melt enough material to create large pyroxene boulders would be so significant that it would have destroyed Bennu’s parent-body. So, the team ruled out these scenarios, and instead considered other pyroxene-rich asteroids that might have implanted this material to Bennu or its parent.

Observations reveal it’s not unusual for an asteroid to have material from another asteroid splashed across its surface. Examples include dark material on crater walls seen by the Dawn spacecraft at Vesta, a black boulder seen by the Hayabusa spacecraft on Itokawa, and very recently, material from S-type asteroids observed by Hayabusa2 at Ryugu. This indicates many asteroids are participating in a complex orbital dance that sometimes results in cosmic mashups.

As asteroids move through the solar system, their orbits can be altered in many ways, including the pull of gravity from planets and other objects, meteoroid impacts, and even the slight pressure from sunlight. The new result helps pin down the complex journey Bennu and other asteroids have traced through the solar system.

Based on its orbit, several studies indicate Bennu was delivered from the inner region of the Main Asteroid Belt via a well-known gravitational pathway that can take objects from the inner Main Belt to near-Earth orbits. There are two inner Main Belt asteroid families (Polana and Eulalia) that look like Bennu: dark and rich in carbon, making them likely candidates for Bennu’s parent. Likewise, the formation of the vestoids is tied to the formation of the Veneneia and Rheasilvia impact basins on Vesta, at roughly about two billion years ago and approximately one billion years ago, respectively.

“Future studies of asteroid families, as well as the origin of Bennu, must reconcile the presence of Vesta-like material as well as the apparent lack of other asteroid types. We look forward to the returned sample, which hopefully contains pieces of these intriguing rock types,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona in Tucson. “This constraint is even more compelling given the finding of S-type material on asteroid Ryugu. This difference shows the value in studying multiple asteroids across the solar system.”

The spacecraft is going to make its first attempt to sample Bennu in October and return it to Earth in 2023 for detailed analysis. The mission team closely examined four potential sample sites on Bennu to determine their safety and science value before making a final selection in December 2019. DellaGiustina and Kaplan’s team thinks they might find smaller pieces of Vesta in images from these close-up studies.

The research was funded by the NASA New Frontiers Program. The primary authors acknowledge significant collaboration with the French space agency CNES on this paper. NASA’s Goddard Space Flight Center in Greenbelt, Maryland provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. The late Michael Drake of the University of Arizona pioneered the study of vestoid meteorites and was the first principal investigator for OSIRIS-REx. Lockheed Martin Space in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington. NASA is exploring our Solar System and beyond, uncovering worlds, stars, and cosmic mysteries near and far with our powerful fleet of space and ground-based missions.

It’s 5 o’clock somewhere – and while here on Earth, “happy hour” is commonly associated with winding down and the optional cold beverage, that’s when things get going on Bennu, the destination asteroid of the University of Arizona-led OSIRIS-REx mission.

In a special collection of research papers published Sep. 9 in the Journal of Geophysical Research: Planets, the OSIRIS-REx science team reports detailed observations that reveal Bennu is shedding material on a regular basis. The OSIRIS-REx spacecraft has provided planetary scientists with the opportunity to observe such activity at close range for the first time ever, and Bennu’s active surface underscores an emerging picture in which asteroids are quite dynamic worlds.

The publications provide the first in-depth look at the nature of Bennu’s particle ejection events, detail the methods used to study these phenomena, and discuss the likely mechanisms at work that cause the asteroid to release pieces of itself into space.

The first observation of particles popping off the asteroid’s surface was made in January 2019, mere days after the spacecraft arrived at Bennu. This event may have gone completely unnoticed were it not for the keen eye of the mission’s lead astronomer and UArizona’s Lunar and Planetary Laboratory scientist, Carl Hergenrother, one of the lead authors of the collection and its introduction.

Much like ocean-going explorers in centuries past, the space probe relies on stars to fix its position in space and remain on course during its years-long voyage across space. A specialized navigation camera onboard the spacecraft takes repeat images of background stars. By cross-referencing the constellations the spacecraft “sees” with programmed star charts, course corrections can be made as necessary.

Hergenrother was poring over these images that the spacecraft had beamed back to Earth when something caught his attention. The images showed the asteroid silhouetted against a black sky dotted with many stars – except there seemed to be too many.

“I was looking at the star patterns in these images and thought, ‘huh, I don’t remember that star cluster,'” Hergenrother said. “I only noticed it because there were 200 dots of light where there should be about 10 stars. Other than that, it looked to be just a dense part of the sky.”

A closer inspection and an application of image-processing techniques unearthed the mystery: the “star cluster” was in fact a cloud of tiny particles that had been ejected from the asteroid’s surface. Follow-up observations made by the spacecraft revealed the telltale streaks typical of objects moving across the frame, setting them apart from the background stars that appear stationary due to their enormous distances.

“We thought that Bennu’s boulder-covered surface was the wild card discovery at the asteroid, but these particle events definitely surprised us,” said Dante Lauretta, OSIRIS-REx principal investigator and professor at LPL. “We’ve spent the last year investigating Bennu’s active surface, and it’s provided us with a remarkable opportunity to expand our knowledge of how active asteroids behave.”

Since arriving at the asteroid, the team has observed and tracked more than 300 particle ejection events on Bennu. According to the authors, some particles escape into space, others briefly orbit the asteroid, and most fall back onto its surface after being launched. Ejections most often occur during Bennu’s local two-hour afternoon and evening timeframe.

The spacecraft is equipped with a sophisticated set of electronic eyes – the Touch-and-Go Camera Suite, or TAGCAMS. Although its primary purpose is to assist in spacecraft navigation, TAGCAMS has now been placed into active duty spotting any particles in the vicinity of the asteroid.

Using software algorithms developed at UArizona’s Catalina Sky Survey, which specializes in discovering and tracking near-Earth asteroids by detecting their motion against background stars, the OSIRIS-REx team found the largest particles erupting from Bennu to be about 6 centimeters (2 inches) in diameter. Due to their small size and low velocities – this is like a shower of tiny pebbles in super-slo-mo – the mission team does not deem the particles a threat to the spacecraft.

“Space is so empty that even when the asteroid is throwing off hundreds of particles, as we have seen in some events, the chances of one of those hitting the spacecraft is extremely small,” Hergenrother said, “and even if that were to happen, the vast majority of them are not fast or large enough to cause damage.”

During a number of observation campaigns between January and September 2019 dedicated to detecting and tracking mass ejected from the asteroid, a total of 668 particles were studied, with the vast majority measuring between 0.5 and 1 centimeters (0.2-0.4 inches), and moving at about 20 centimeters (8 inches) per second, about as fast – or slow – as a beetle scurrying across the ground. In one instance, a speedy outlier was clocked at about 3 meters (9.8 feet) per second.

On average, the authors observed one to two particles kicked up per day, with much of the material falling back onto the asteroid. Add to that the small particle sizes, and the mass loss becomes minimal, Hergenrother explained.

“To give you an idea, all of those 200 particles we observed during the first event after arrival would fit on a 4-inch x 4-inch tile,” he said. “The fact that we can even see them is a testament to the capabilities of our cameras.”

The authors investigated various mechanisms that could cause these phenomena, including released water vapor, impacts by small space rocks known as meteoroids and rocks cracking from thermal stress. The two latter mechanisms were found to be the most likely driving forces, confirming predictions about Bennu’s environment based on ground observations preceding the space mission.

As Bennu completes one rotation every 4.3 hours, boulders on its surface are exposed to a constant thermo-cycling as they heat during the day and cool during the night. Over time, the rocks crack and break down, and eventually particles may be thrown from the surface. The fact that particle ejections were observed with greater frequency during late afternoon, when the rocks heat up, suggests thermal cracking is a major driver. The timing of the events is also consistent with the timing of meteoroid impacts, indicating that these small impacts could be throwing material from the surface. Either, or both, of these processes could be driving the particle ejections, and because of the asteroid’s microgravity environment, it doesn’t take much energy to launch an object from Bennu’s surface.

Of the particles the team observed, some had suborbital trajectories, keeping them aloft for a few hours before they settled back down, while others fly off the asteroid to go into their own orbits around the sun.

In one instance, the team tracked one particle as it circled the asteroid for almost a week. The spacecraft’s cameras even witnessed a ricochet, according to Hergenrother.

“One particle came down, hit a boulder and went back into orbit,” he said. “If Bennu has this kind of activity, then there is a good chance all asteroids do, and that is really exciting.”

As Bennu continues to unveil itself, the OSIRIS-REx team continues to discover that this small world is glowingly complex. These findings could serve as a cornerstone for future planetary missions that seek to better characterize and understand how these small bodies behave and evolve.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

NASA’s first asteroid-sampling spacecraft just completed its second successful sample collection rehearsal and is now ready for the main event – touching down on asteroid Bennu’s surface in October. Yesterday, the OSIRIS-REx spacecraft performed its final practice run of the sampling sequence, reaching an approximate altitude of 131 feet (40 meters) over sample site Nightingale before executing a back-away burn. Nightingale, OSIRIS-REx’s primary sample collection site, is located within a crater in Bennu’s northern hemisphere.

The approximately four-hour “Matchpoint” rehearsal took the spacecraft through the first three of the sampling sequence’s four maneuvers: the orbit departure burn, the “Checkpoint” burn and the Matchpoint burn. Checkpoint is the point where the spacecraft autonomously checks its position and velocity before adjusting its trajectory down toward the event’s third maneuver. Matchpoint is the moment when the spacecraft matches Bennu’s rotation in order to fly in tandem with the asteroid surface, directly above the sample site, before touching down on the targeted spot.

Four hours after departing its 0.6-mile (1-km) safe-home orbit, OSIRIS-REx performed the Checkpoint maneuver at an approximate altitude of 410 feet (125 meters) above Bennu’s surface. From there, the spacecraft continued to descend for another eight minutes to perform the Matchpoint burn. After descending on this new trajectory for another three minutes, the spacecraft reached an altitude of approximately 131 ft (40 m) – the closest the spacecraft has ever been to Bennu – and then performed a back-away burn to complete the rehearsal.

During the rehearsal, the spacecraft successfully deployed its sampling arm, the Touch-And-Go Sample Acquisition Mechanism (TAGSAM), from its folded, parked position out to the sample collection configuration. Additionally, some of the spacecraft’s instruments collected science and navigation images and made spectrometry observations of the sample site, as will occur during the sample collection event. These images and science data were downlinked to Earth after the event’s conclusion.

Because the spacecraft and Bennu are currently about 179 million miles (288 million km) from Earth, it takes approximately 16 minutes for the spacecraft to receive the radio signals used to command it. This time lag prevented live commanding of flight activities from the ground during the rehearsal. As a result, the spacecraft performed the entire rehearsal sequence autonomously. Prior to the rehearsal’s start, the OSIRIS-REx team uplinked all of the event’s commands to the spacecraft and then provided the “Go” command to begin the event. The actual sample collection event in October will be conducted the same way.

This second rehearsal provided the mission team with practice navigating the spacecraft through the first three maneuvers of the sampling event and with an opportunity to verify that the spacecraft’s imaging, navigation and ranging systems operated as expected during the first part of the descent sequence.

Matchpoint rehearsal also confirmed that OSIRIS-REx’s Natural Feature Tracking (NFT) guidance system accurately estimated the spacecraft’s trajectory after the Matchpoint burn, which is the final maneuver before the sample collection head contacts Bennu’s surface. This rehearsal was also the first time that the spacecraft’s on-board hazard map was employed. The hazard map delineates areas that could potentially harm the spacecraft. If the spacecraft detects that it is on course to touch a hazardous area, it will autonomously back-away once it reaches an altitude of 16 ft (5 m). While OSIRIS-REx did not fly that low during the rehearsal, it did employ the hazard map to assess whether its predicted touchdown trajectory would have avoided surface hazards, and found that the spacecraft’s path during the rehearsal would have allowed for a safe touchdown on sample site Nightingale.

During the last minutes of the spacecraft’s descent, OSIRIS-REx also collected new, high-resolution navigation images for the NFT guidance system. These detailed images of Bennu’s landmarks will be used for the sampling event, and will allow the spacecraft to accurately target a very small area.

“Many important systems were exercised during this rehearsal – from communications, spacecraft thrusters, and most importantly, the onboard Natural Feature Tracking guidance system and hazard map,” said OSIRIS-REx principal investigator Dante Lauretta of the University of Arizona, Tucson. “Now that we’ve completed this milestone, we are confident in finalizing the procedures for the TAG event. This rehearsal confirmed that the team and all of the spacecraft’s systems are ready to collect a sample in October.”

The mission team has spent the last several months preparing for Matchpoint rehearsal while maximizing remote work as part of the COVID-19 response. On the day of rehearsal, a limited number of personnel monitored the spacecraft’s telemetry from Lockheed Martin Space’s facility, NASA’s Goddard Space Flight Center and the University of Arizona, taking appropriate safety precautions, while the rest of the team performed their roles remotely.

The spacecraft will travel all the way to the asteroid’s surface during its first sample collection attempt, scheduled for Oct. 20. During this event, OSIRIS-REx’s sampling mechanism will touch Bennu’s surface for several seconds, fire a charge of pressurized nitrogen to disturb the surface and collect a sample before the spacecraft backs away. The spacecraft is scheduled to return the sample to Earth on Sept. 24, 2023.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

NASA’s first asteroid sampling spacecraft is making final preparations to grab a sample from asteroid Bennu’s surface. Next week, the OSIRIS-REx mission will conduct a second rehearsal of its touchdown sequence, practicing the sample collection activities one last time before touching down on Bennu this fall.

On Aug. 11, the mission will perform its “Matchpoint” rehearsal – the second practice run of the Touch-and-Go (TAG) sample collection event. The rehearsal will be similar to the Apr. 14 “Checkpoint” rehearsal, which practiced the first two maneuvers of the descent, but this time the spacecraft will add a third maneuver, called the Matchpoint burn, and fly even closer to sample site Nightingale – reaching an altitude of approximately 131 ft (40 m) – before backing away from the asteroid.

This second rehearsal will be the first time the spacecraft executes the Matchpoint maneuver to then fly in tandem with Bennu’s rotation. The rehearsal also gives the team a chance to become more familiar navigating the spacecraft through all of the descent maneuvers, while verifying that the spacecraft’s imaging, navigation and ranging systems operate as expected during the event.

During the descent, the spacecraft fires its thrusters three separate times to make its way down to the asteroid’s surface. The spacecraft will travel at an average speed of around 0.2 mph (0.3 kph) during the approximately four-hour excursion. Matchpoint rehearsal begins with OSIRIS-REx firing its thrusters to leave its 0.5-mile (870-m) safe-home orbit. The spacecraft then extends its robotic sampling arm – the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) – from its folded, parked position out to the sample collection configuration. Immediately following, the spacecraft rotates to begin collecting navigation images for the Natural Feature Tracking (NFT) guidance system. NFT allows OSIRIS-REx to autonomously navigate to Bennu’s surface by comparing an onboard image catalog with the real-time navigation images taken during descent. As the spacecraft approaches the surface, the NFT system updates the spacecraft’s predicted point of contact depending on OSIRIS-REx’s position in relation to Bennu’s landmarks.

The spacecraft’s two solar panels then move into a “Y-wing” configuration that safely positions them up and away from the asteroid’s surface. This configuration also places the spacecraft’s center of gravity directly over the TAGSAM collector head, which is the only part of the spacecraft that will contact Bennu’s surface during the sample collection event.

When OSIRIS-REx reaches an altitude of approximately 410 ft (125 m), it performs the Checkpoint burn and descends more steeply toward Bennu’s surface for another eight minutes. At approximately 164 ft (50 m) above the asteroid, the spacecraft fires its thrusters a third time for the Matchpoint burn. This maneuver slows the spacecraft’s rate of descent and adjusts its trajectory to match Bennu’s rotation as the spacecraft makes final corrections to target the touchdown spot. OSIRIS-REx will continue capturing images of Bennu’s landmarks for the NFT system to update the spacecraft’s trajectory for another three minutes of descent. This brings OSIRIS-REx to its targeted destination around 131 ft (40 m) from Bennu – the closest it has ever been to the asteroid. With the rehearsal complete, the spacecraft executes a back-away burn, returns its solar panels to their original position and reconfigures the TAGSAM arm back to the parked position.

During the rehearsal, the one-way light time for signals to travel between Earth and the spacecraft will be approximately 16 minutes, which prevents the live commanding of flight activities from the ground. So prior to the rehearsal’s start, the OSIRIS-REx team will uplink all of the event’s commands to the spacecraft, allowing OSIRIS-REx to perform the rehearsal sequence autonomously after the GO command is given. Also during the event, the spacecraft’s low gain antenna will be its only antenna pointing toward Earth, transmitting data at the very slow rate of 40 bits per second. So while the OSIRIS-REx team will be able to monitor the spacecraft’s vital signs, the images and science data collected during the event won’t be downlinked until the rehearsal is complete. The team will experience these same circumstances during the actual TAG event in October.

Following Matchpoint rehearsal, the OSIRIS-REx team will verify the flight system’s performance during the descent, including that the Matchpoint burn accurately adjusted the spacecraft’s descent trajectory for its touchdown on Bennu. Once the mission team determines that OSIRIS-REx operated as expected, they will command the spacecraft to return to its safe-home orbit around Bennu.

The mission team has spent the last several months preparing for the Matchpoint rehearsal while maximizing remote work as part of its COVID-19 response. On the day of rehearsal, a limited number of personnel will monitor the spacecraft from Lockheed Martin Space’s facility, taking appropriate safety precautions, while the rest of the team performs their roles remotely. The mission implemented a similar protocol during the Checkpoint rehearsal in April.

On Oct. 20, the spacecraft will travel all the way to the asteroid’s surface during its first sample collection attempt. During this event, OSIRIS-REx’s sampling mechanism will touch Bennu’s surface for approximately five seconds, fire a charge of pressurized nitrogen to disturb the surface and collect a sample before the spacecraft backs away. The spacecraft is scheduled to return the sample to Earth on Sept. 24, 2023.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

Asteroids don’t just sit there doing nothing as they orbit the Sun. They get bombarded by meteoroids, blasted by space radiation, and now, for the first time, scientists are seeing evidence that even a little sunshine can wear them down.

Rocks on asteroid Bennu appear to be cracking as sunlight heats them up during the day and they cool down at night, according to images from NASA’s OSIRIS-REx (Origins Spectral Interpretation Resource Identification Security – Regolith Explorer) spacecraft.

“This is the first time evidence for this process, called thermal fracturing, has been definitively observed on an object without an atmosphere,” said Jamie Molaro of the Planetary Science Institute, Tucson, Arizona, lead author of a paper appearing in Nature Communications June 9. “It is one piece of a puzzle that tells us what the surface used to be like, and what it will be like millions of years from now.”

“Like any weathering process, thermal fracturing causes the evolution of boulders and planetary surfaces over time – from changing the shape and size of individual boulders, to producing pebbles or fine-grained regolith, to breaking down crater walls,” said OSIRIS-REx principal investigator Dante Lauretta of the University of Arizona, Tucson. “How quickly this occurs relative to other weathering processes tells us how and how quickly the surface has changed.”

Rocks expand when sunlight heats them during the day and contract as they cool down at night, causing stress that forms cracks that grow slowly over time. Scientists have thought for a while that thermal fracturing could be an important weathering process on airless objects like asteroids because many experience extreme temperature differences between day and night, compounding the stress. For example, daytime highs on Bennu can reach almost 127 degrees Celsius or about 260 degrees Fahrenheit, and nighttime lows plummet to about minus 73 degrees Celsius or nearly minus 100 degrees Fahrenheit. However, many of the telltale features of thermal fracturing are small, and before OSIRIS-REx got close to Bennu, the high-resolution imagery required to confirm thermal fracturing on asteroids didn’t exist.

The mission team found features consistent with thermal fracturing using the spacecraft’s OSIRIS-REx Camera Suite (OCAMS), which can see features on Bennu smaller than one centimeter (almost 0.4 inches). It found evidence of exfoliation, where thermal fracturing likely caused small, thin layers (1 – 10 centimeters) to flake off of boulder surfaces. The spacecraft also produced images of cracks running through boulders in a north-south direction, along the line of stress that would be produced by thermal fracturing on Bennu.

Other weathering processes can produce similar features, but the team’s analysis ruled them out. For example, rain and chemical activity can produce exfoliation, but Bennu has no atmosphere to produce rain. Rocks squeezed by tectonic activity can also exfoliate, but Bennu is too small for such activity. Meteoroid impacts do occur on Bennu and can certainly crack rocks, but they would not cause the even erosion of layers from boulder surfaces that were seen. Also, there’s no sign of impact craters where the exfoliation is occurring.

Additional studies of Bennu could help determine how rapidly thermal fracturing is wearing down the asteroid, and how it compares to other weathering processes. “We don’t have good constraints yet on breakdown rates from thermal fracturing, but we can get them now that we can actually observe it for the first time in situ,” said OSIRIS-REx project scientist Jason Dworkin of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Laboratory measurements on the properties of the samples returned by the spacecraft in 2023 will help us learn more about how this process works.”

Another area of research is how thermal fracturing affects our ability to estimate the age of surfaces. In general, the more weathered a surface is, the older it is. For example, a region with a lot of craters is likely to be older than an area with few craters, assuming impacts happen at a relatively constant rate across an object. However, additional weathering from thermal fracturing could complicate an age estimate, because thermal fracturing is going to happen at a different rate on different bodies, depending on things like their distance from the Sun, the length of their day, and the composition, structure and strength of their rocks. On bodies where thermal fracturing is efficient, then it may cause crater walls to break down and erode faster. This would make the surface look older according the cratering record, when in fact it is actually younger. Or the opposite could occur. More research on thermal fracturing on different bodies is needed to start to get a handle on this, according to Molaro.

The research was funded by NASA’s OSIRIS-REx Participating Scientist program as well as the OSIRIS-REx mission. NASA’s Goddard Space Flight Center in Greenbelt, Maryland provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington. NASA is exploring our Solar System and beyond, uncovering worlds, stars, and cosmic mysteries near and far with our powerful fleet of space and ground-based missions.

Scientists with NASA’s first asteroid sample return mission, OSIRIS-REx, are gaining a new understanding of asteroid Bennu’s carbon-rich material and signature “spinning-top” shape. The team, led by the University of Arizona, has discovered that the asteroid’s shape and hydration levels provide clues to the origins and histories of this and other small bodies.

Bennu, the target asteroid for the OSIRIS-REx mission, and Ryugu, the target of the Japan Aerospace Exploration Agency’s Hayabusa2 asteroid sample return mission, are composed of fragments of larger bodies that shattered upon colliding with other objects. The small fragments reaccumulated to form an aggregate body. Bennu and Ryugu may actually have formed in this way from the same original shattered parent body. Now, scientists are looking to discover what processes led to specific characteristics of these asteroids, such as their shape and mineralogy.

Bennu and Ryugu are both classified as “spinning-top” asteroids, which means they have a pronounced equatorial ridge. Until now, scientists thought that this shape formed as the result of thermal forces, called the YORP effect. The YORP effect increases the speed of the asteroid’s spin, and over millions of years, material near the poles could have migrated to accumulate on the equator, eventually forming a spinning-top shape – meaning that the shape would have formed relatively recently.

However, in a new paper published in Nature Communications, scientists from the OSIRIS-REx and Hayabusa2 teams argue that the YORP effect may not explain the shape of either Bennu or Ryugu. Both asteroids have large impact craters on their equators, and their size suggests that these craters are some of Bennu’s oldest surface features. Since the craters cover the equatorial ridges, their spinning-top shapes must also have been formed much earlier.

“Using computer simulations that model the impact that broke up Bennu’s parent body, we show that these asteroids either formed directly as top-shapes, or achieved the shape early after their formation in the main asteroid belt,” said Ronald Ballouz, co-lead author and OSIRIS-REx postdoctoral research associate at the UArizona. “The presence of the large equatorial craters on these asteroids, as seen in images returned by the spacecraft, rules out that the asteroids experienced a recent re-shaping due to the YORP effect. We would expect these craters to have disappeared with a recent YORP-induced re-shaping of the asteroid.”

In addition to their shapes, Bennu and Ryugu also both contain water-bearing surface material in the form of clay minerals. Ryugu’s surface material is less water-rich than Bennu’s, which implies that Ryugu’s material experienced more heating at some point.

Assuming Bennu and Ryugu formed simultaneously, the paper explores two possible explanations for the different hydration levels of the two bodies based on the team’s computer simulations. One hypothesis suggests that when the parent asteroid was disrupted, Bennu formed from material closer to the original surface, while Ryugu contained more material from near the parent body’s original center. Another possible explanation for the difference in hydration levels is that the fragments experienced different levels of heating during the parent asteroid’s disruption. If this is the case, Ryugu’s source material is likely from an area near the impact point, where temperatures were higher. Bennu’s material would have come from a region that didn’t undergo as much heating, and was likely farther from the point of impact. Analysis of the returned samples and further observational analysis of the asteroids’ surfaces will provide a clearer idea of the possible shared history of the two asteroids.

“These simulations provide valuable new insights into how Bennu and Ryugu formed,” said Dante Lauretta, OSIRIS-REx principal investigator and UArizona professor of planetary sciences. “Once we have the returned samples of these two asteroids in the lab, we may be able to further confirm these models, possibly revealing the true relationship between the two asteroids.”

Scientists anticipate that the samples will also provide new insights into the origins, formation and evolution of other carbonaceous asteroids and meteorites. The Japan Aerospace Exploration Agency’s Hayabusa2 mission is currently making its way back to Earth, and is scheduled to deliver its samples of Ryugu late this year. The OSIRIS-REx mission will perform its first sample collection attempt at Bennu on Oct. 20 and will deliver its samples to Earth on Sep. 24, 2023.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

NASA’s first asteroid-sampling spacecraft has had another close encounter with asteroid Bennu. Yesterday, NASA’s OSIRIS-REx spacecraft executed its lowest pass yet over sample site Osprey, taking observations from an altitude of 820 feet (250 m). Osprey, OSIRIS-REx’s backup sample collection site, is located within a crater just north of Bennu’s equator.

To perform the five-hour flyover, the spacecraft left its 0.6-mile (1-km) counterclockwise orbit (as viewed from the Sun) and aimed its science instruments toward the 52-ft (16-m) wide site. The science observations from this pass are the closest taken of Osprey to date. In March, the spacecraft executed a similar pass over primary sample site Nightingale.

A primary goal of the low flyover was to collect high-resolution imagery of the site’s surface material. The spacecraft’s sample collection mechanism is designed to pick up rocks smaller than 0.8 inches (2 cm), and the detailed PolyCam images from yesterday’s low pass will allow the team to identify rocks of this size.

The flyover also provided the opportunity to capture images for the Natural Feature Tracking (NFT) image catalog for site Osprey – documenting the site’s surface features. If the mission decides to collect a sample from backup site Osprey, the spacecraft will use this NFT image catalog to autonomously navigate down to Bennu’s surface. The mission originally planned to collect this imagery during a 0.4-mile (620-m) flyover in February, but the images from that pass are out of focus due to an anomaly in the low energy laser transmitter (LELT) subsystem with the OSIRIS-REx Laser Altimeter (OLA), which was providing range measurements to focus PolyCam. OLA’s high energy laser transmitter (HELT) was used in this most recent Osprey flyover, as was done in a similar flyover of the Nightingale site.

Several of the spacecraft’s other instruments also took observations of the Osprey site during the flyover event, including the OSIRIS-REx Thermal Emissions Spectrometer (OTES), the OSIRIS-REx Visual and InfraRed Spectrometer (OVIRS), and the OSIRIS-REx Laser Altimeter (OLA).

After completing the pass, OSIRIS-REx returned to its safe-home orbit and is now circling Bennu clockwise. The spacecraft normally orbits Bennu counterclockwise, but this shift in orbital direction was necessary to position the spacecraft for its next close encounter with the asteroid – the second rehearsal for the sample collection event.

The mission successfully executed the first sample-collection rehearsal on Apr. 14, completing a practice run of some of the activities leading up to the sampling event and bringing the spacecraft 213 ft (65 m) from the asteroid’s surface. The second rehearsal, scheduled for Aug. 11, will bring the spacecraft through the first three maneuvers of the sample collection sequence to an approximate altitude of 131 ft (40 m) over the surface of Bennu.

The spacecraft will attempt to venture all the way to the asteroid’s surface on Oct. 20, for its first attempt to collect a sample from site Nightingale. During this event, OSIRIS-REx’s sampling mechanism will touch Bennu and fire a charge of pressurized nitrogen to disturb the surface and collect its sample before the spacecraft backs away.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

NASA’s first asteroid sample return mission is officially prepared for its long-awaited touchdown on asteroid Bennu’s surface. The Origins, Spectral Interpretation, Resource Identification and Security – Regolith Explorer (OSIRIS-REx) mission has targeted Oct. 20 for its first sample collection attempt.

“The OSIRIS-REx mission has been demonstrating the very essence of exploration by persevering through unexpected challenges,” said Thomas Zurbuchen, NASA’s associate administrator for science. “That spirit has led them to the cusp of the prize we all are waiting for – securing a sample of an asteroid to bring home to Earth, and I’m very excited to follow them through the home stretch.”

From discovering Bennu’s surprisingly rugged and active surface, to entering the closest-ever orbit around a planetary body, OSIRIS-REx has overcome several challenges since arriving at the asteroid in December 2018. Last month, the mission brought the spacecraft 213 ft (65 m) from the asteroid’s surface during its first sample collection rehearsal — successfully completing a practice run of the activities leading up to the sampling event.

Now that the mission is ready to collect a sample, the team is facing a different kind of challenge here on Earth. In response to COVID-19 constraints and after the intense preparation for the first rehearsal, the OSIRIS-REx mission has decided to provide its team with additional preparation time for both the final rehearsal and the sample collection event. Spacecraft activities require significant lead time for the development and testing of operations, and given the current requirements that limit in-person participation at the mission support area, the mission would benefit from giving the team additional time to complete these preparations in the new environment. As a result, both the second rehearsal and first sample collection attempt will have two extra months for planning.

“In planning the mission, we included robust schedule margin while at Bennu to provide the flexibility to address unexpected challenges,” said Rich Burns, OSIRIS-REx project manager at NASA’s Goddard Space Flight Center. “This flexibility has allowed us to adapt to the surprises that Bennu has thrown at us. It’s now time to prioritize the health and safety of both team members and the spacecraft.”

The mission had originally planned to perform the first Touch-and-Go (TAG) sample collection event on Aug. 25 after completing a second rehearsal in June. This rehearsal, now scheduled for Aug. 11, will bring the spacecraft through the first three maneuvers of the sample collection sequence to an approximate altitude of 131 ft (40 m) over the surface of Bennu. The first sample collection attempt is now scheduled for Oct. 20, during which the spacecraft will descend to Bennu’s surface and collect material from sample site Nightingale.

“This mission’s incredible performance so far is a testament to the extraordinary skill and dedication of the OSIRIS-REx team,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. “I am confident that even in the face of the current challenge, this team will be successful in collecting our sample from Bennu.”

During the TAG event, OSIRIS-REx’s sampling mechanism will touch Bennu’s surface for approximately five seconds, fire a charge of pressurized nitrogen to disturb the surface, and collect a sample before the spacecraft backs away. The mission has resources onboard for three sample collection opportunities. If the spacecraft successfully collects a sufficient sample on Oct. 20, no additional sampling attempts will be made. The spacecraft is scheduled to depart Bennu in mid-2021, and will return the sample to Earth on Sept. 24, 2023.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

After the successful completion of its “Checkpoint” rehearsal, NASA’s first asteroid-sampling spacecraft is one step closer to touching down on asteroid Bennu. Yesterday, NASA’s OSIRIS-REx spacecraft performed the first practice run of its sample collection sequence, reaching an approximate altitude of 246 feet (75 meters) over site Nightingale before executing a back-away burn from the asteroid. Nightingale, OSIRIS-REx’s primary sample collection site, is located within a crater in Bennu’s northern hemisphere.

The four-hour Checkpoint rehearsal took the spacecraft through the first two of the sampling sequence’s four maneuvers: the orbit departure burn and the Checkpoint burn. Checkpoint is so named because it is the location where the spacecraft autonomously checks its position and velocity before adjusting its trajectory down toward the location of the event’s third maneuver.

Four hours after departing its 0.6-mile (1-km) safe-home orbit, the spacecraft performed the Checkpoint maneuver at an approximate altitude of 410 feet (125 meters) above Bennu’s surface. From there, the spacecraft continued to descend for another nine minutes on a trajectory toward – but not reaching – the location of the sampling event’s third maneuver, the “Matchpoint” burn. Upon reaching an altitude of approximately 246 ft (75 m) – the closest the spacecraft has ever been to Bennu – OSIRIS-REx performed a back-away burn to complete the rehearsal.

During the rehearsal, the spacecraft successfully deployed its sampling arm, the Touch-And-Go Sample Acquisition Mechanism (TAGSAM), from its folded, parked position out to the sample collection configuration. Additionally, some of the spacecraft’s instruments collected science and navigation images and made spectrometry observations of the sample site, as will occur during the sample collection event.

This first rehearsal provided the mission team with practice navigating the spacecraft through both the orbit departure and Checkpoint maneuvers and with an opportunity to verify that the spacecraft’s imaging, navigation and ranging systems operated as expected during the first part of the descent sequence. Checkpoint rehearsal also gave the team confirmation that OSIRIS-REx’s Natural Feature Tracking (NFT) guidance system accurately estimated the spacecraft’s position and speed relative to Bennu as it descended toward the surface.

The mission team has maximized remote work over the last month of preparations for the Checkpoint rehearsal, as part of the COVID-19 response. On the day of rehearsal, a limited number of personnel monitored the spacecraft’s telemetry from Lockheed Martin Space’s facility, NASA’s Goddard Space Flight Center and the University of Arizona, taking appropriate safety precautions, while the rest of the team performed their roles remotely.

“This rehearsal let us verify flight system performance during the descent, particularly the autonomous update and execution of the Checkpoint burn,” said Rich Burns, OSIRIS-REx project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Executing this monumental milestone during this time of national crisis is a testament to the professionalism and focus of our team. It speaks volumes about their ‘can-do’ attitude and hopefully will serve as a bit of good news in these challenging times.”

The spacecraft will travel all the way to the asteroid’s surface during its first sample collection attempt, scheduled for Aug. 25. During this event, OSIRIS-REx’s sampling mechanism will touch Bennu’s surface for approximately five seconds, fire a charge of pressurized nitrogen to disturb the surface and collect a sample before the spacecraft backs away. The spacecraft is scheduled to return the sample to Earth on Sept. 24, 2023.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

In August, a robotic spacecraft will make NASA’s first-ever attempt to descend to the surface of an asteroid, collect a sample, and ultimately bring it safely back to Earth. In order to achieve this challenging feat, the OSIRIS-REx mission team devised new techniques to operate in asteroid Bennu’s microgravity environment – but they still need experience flying the spacecraft in close proximity to the asteroid in order to test them. So, before touching down at sample site Nightingale this summer, OSIRIS-REx will first rehearse the activities leading up to the event.

On Apr. 14, the mission will pursue its first practice run – officially known as “Checkpoint” rehearsal – which will also place the spacecraft the closest it’s ever been to Bennu. This rehearsal is a chance for the OSIRIS-REx team and spacecraft to test the first steps of the robotic sample collection event.

During the full touchdown sequence, the spacecraft uses three separate thruster firings to make its way to the asteroid’s surface. After an orbit departure burn, the spacecraft executes the Checkpoint maneuver at 410 ft (125 m) above Bennu, which adjusts the spacecraft’s position and speed down toward the point of the third burn. This third maneuver, called “Matchpoint,” occurs at approximately 164 ft (50 m) from the asteroid’s surface and places the spacecraft on a trajectory that matches the rotation of Bennu as it further descends toward the targeted touchdown spot.

The Checkpoint rehearsal allows the team to practice navigating the spacecraft through both the orbit departure and Checkpoint maneuvers, and ensures that the spacecraft’s imaging, navigation and ranging systems operate as expected during the first part of the descent sequence. Checkpoint rehearsal also gives the team a chance to confirm that OSIRIS-REx’s Natural Feature Tracking (NFT) guidance system accurately updates the spacecraft’s position and velocity relative to Bennu as it descends towards the surface.

Checkpoint rehearsal, a four-hour event, begins with the spacecraft leaving its safe-home orbit, 0.6 miles (1 km) above the asteroid. The spacecraft then extends its robotic sampling arm – the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) – from its folded, parked position out to the sample collection configuration. Immediately following, the spacecraft slews, or rotates, into position to begin collecting navigation images for NFT guidance. NFT allows the spacecraft to autonomously guide itself to Bennu’s surface by comparing an onboard image catalog with the real-time navigation images taken during descent. As the spacecraft descends to the surface, the NFT system updates the spacecraft’s predicted point of contact depending on OSIRIS-REx’s position in relation to Bennu’s landmarks.

Before reaching the 410-ft (125-m) Checkpoint altitude, the spacecraft’s solar arrays move into a “Y-wing” configuration that safely positions them away from the asteroid’s surface. This configuration also places the spacecraft’s center of gravity directly over the TAGSAM collector head, which is the only part of the spacecraft that will contact Bennu’s surface during the sample collection event.

In the midst of these activities, the spacecraft continues capturing images of Bennu’s surface for the NFT navigation system. The spacecraft will then perform the Checkpoint burn and descend toward Bennu’s surface for another nine minutes, placing the spacecraft around 243 ft (75 m) from the asteroid – the closest it has ever been.

Upon reaching this targeted point, the spacecraft will execute a back-away burn, then return its solar arrays to their original position and reconfigure the TAGSAM arm back to the parked position. Once the mission team determines that the spacecraft successfully completed the entire rehearsal sequence, they will command the spacecraft to return to its safe-home orbit around Bennu.

Following the Checkpoint rehearsal, the team will verify the flight system’s performance during the descent, and that the Checkpoint burn accurately adjusted the descent trajectory for the subsequent Matchpoint burn.

The mission team has maximized remote work over the last month of preparations for the checkpoint rehearsal, as part of the COVID-19 response. On the day of rehearsal, a limited number of personnel will command the spacecraft from Lockheed Martin Space’s facility, taking appropriate safety precautions, while the rest of the team performs their roles remotely.

The mission is scheduled to perform a second rehearsal on Jun. 23, taking the spacecraft through the Matchpoint burn and down to an approximate altitude of 82 ft (25 m). OSIRIS-REx’s first sample collection attempt is scheduled for Aug. 25.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

Asteroid Bennu’s most prominent boulder, a rock chunk jutting out 71 ft (21.7 m) from the asteroid’s southern hemisphere, finally has a name. The boulder – which is so large that it was initially detected from Earth – is officially designated Benben Saxum after the primordial hill that first arose from the dark waters in an ancient Egyptian creation myth.

Benben Saxum and 11 other features on the asteroid are the first to receive official Bennu feature names approved by the International Astronomical Union (IAU), the internationally recognized authority for naming celestial bodies and their surface features. The accepted names were proposed by NASA’s OSIRIS-REx team members, who have been mapping the asteroid in detail over the last year. The OSIRIS-REx spacecraft, NASA’s first asteroid sample return mission, is currently visiting the asteroid and is scheduled to collect a sample from Bennu’s surface this summer.

“Since arriving at the asteroid, the OSIRIS-REx team has become incredibly familiar with all of the geological features on Bennu,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. “These features are providing us with insight into Bennu’s history, and their new names symbolize the essence of the mission – studying the past to both discover our origins and understand our future,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson.

The approved Bennu surface feature names are listed below. Bennu’s diverse terrain types – including regiones (broad geographic regions), craters, dorsa (ridges), fossae (grooves or trenches) and saxa (rocks and boulders) – will be named after birds and bird-like creatures in mythology, and the places associated with them.

 

Tlanuwa Regio is named for the giant birds who scattered the Earth with pieces of a serpent that turned into standing pillars of rocks in Cherokee mythology. Tlanuwa Regio is an area covered by large boulders in Bennu’s southern hemisphere.

 

 

 

 

 

 

Benben Saxum is named for an ancient Egyptian mound that arose from the primordial waters Nu. In Egyptian mythology, the god Atum settled upon Benben to create the world after his flight over the waters in the form of the Bennu bird. Benben Saxum is the tallest boulder on Bennu.

 

 

 

 

 

 

Roc Saxum is named for the Roc, an enormous bird of prey in Arabian mythology of the Middle East. Roc Saxum is the largest boulder feature on Bennu.

 

 

 

 

 

 

 

Simurgh Saxum is named for the benevolent, mythological bird in Persian mythology. The Simurgh was said to possess all knowledge, and Simurgh Saxum defines the prime meridian on Bennu and is the basis for the asteroid’s coordinate system.

 

 

 

 

 

 

 

 

Huginn Saxum and Muninn Saxum are adjacent boulders named for the two ravens, Huginn and Muninn, who accompany the god Odin in Norse mythology.

 

 

 

 

 

 

 

 

 

Ocypete Saxum is named for one of the Greek harpies, the half-maiden and half-bird personification of storm winds that would snatch and carry things away from Earth. Ocypete Saxum is located near the origin of the Jan. 19, 2019, particle ejection event on Bennu.

 

 

 

 

 

 

Strix Saxum is named for the Strix bird of ill-omen from Roman mythology. Strix Saxum is a large boulder flanking the OSIRIS-REx mission’s backup sample collection site.

 

 

 

 

 

 

 

 

 

Amihan Saxum is named for the Tagalog (Philippines) mythological deity, who is depicted as a bird and was the first creature to inhabit the universe. This large, flat boulder appears to be partly buried and is located in Tlanuwa Regio, which has an unusually high concentration of large boulders.

 

 

 

 

 

 

Pouakai Saxum is named for the monstrous bird who kills and eat humans in Māori (Polynesia) mythology. Pouakai Saxum is a 55 ft (10.6 m)-wide boulder located in Bennu’s southern hemisphere, slightly north of Benben Saxum.

 

 

 

 

 

 

 

 

Aetos Saxum is named for the childhood playmate of the supreme god Zeus, who was turned into an eagle by Hera in Greek mythology. Aetos Saxum is a conspicuously flat boulder, with a general wing-like shape located near Bennu’s equator.

 

 

 

 

 

 

 

 

Gargoyle Saxum is named for the French dragon-like monster with wings, bird-like neck, and the ability to breathe fire. Gargoyle Saxum is a large prominent boulder near the mission’s backup sample site that is one of the darkest objects on the surface.

 

 

 

 

 

 

 

 

 

NASA’s Goddard Space Flight Center in Greenbelt, Maryland provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

NASA’s first asteroid-sampling spacecraft just got its best look yet at asteroid Bennu. Yesterday, the OSIRIS-REx spacecraft executed a very low pass over sample site Nightingale, taking observations from an altitude of 820 feet (250 m), which is the closest that OSIRIS-REx has flown over the asteroid so far. Nightingale, OSIRIS-REx’s primary sample collection site, is located within a crater in Bennu’s northern hemisphere.

To perform the 5-hour flyover, the spacecraft left its 0.6-mile (1-km) safe-home orbit and aimed its science instruments toward the 52-ft (16-m) wide sample site. The science observations from this pass are the closest taken of Bennu to date.

The main goal of yesterday’s low flyover was to collect high-resolution imagery of the site’s surface material. The spacecraft’s sample collection mechanism is designed to pick up small rocks less than 0.8 inches (2 cm) in size, and the PolyCam images from this low pass are very detailed, allowing the team to identify and locate rocks of this size. Several of the spacecraft’s other instruments also took observations of the Nightingale site during the flyover event, including the OSIRIS-REx Thermal Emissions Spectrometer (OTES), the OSIRIS-REx Visual and InfraRed Spectrometer (OVIRS), the OSIRIS-REx Laser Altimeter (OLA), and the MapCam color imager.

After completing the flyover, the spacecraft returned to orbit – but for the first time, OSIRIS-REx reversed the direction of its safe-home orbit and is now circling Bennu clockwise (as viewed from the Sun). This shift in orbital direction positioned the spacecraft for its next close encounter with the asteroid – its first rehearsal for the sample collection event.

This spring, the mission will perform two rehearsals in preparation for the sample collection event. The first rehearsal, scheduled for Apr. 14, navigates the spacecraft down to 410 feet (125 m) over Bennu’s surface. At this altitude, the spacecraft will execute the Checkpoint maneuver, designed to put the spacecraft on a descent trajectory toward the sample collection site on the surface. The spacecraft will stop its descent ten minutes later at an altitude of approximately 164 ft (50 m) by executing a maneuver to back away from the asteroid. The second rehearsal, scheduled for June, follows the same trajectory but takes the spacecraft to a lower altitude of 164 feet (50 m), where it will perform the Matchpoint maneuver, designed to slow the spacecraft’s descent rate. Subsequent to this burn the spacecraft will execute a back away maneuver between 131 ft (40 m) and 82 ft (25 m) from Bennu’s surface. The spacecraft will venture all the way to the asteroid’s surface in late August, for its first attempt to collect a sample. During this event, OSIRIS-REx’s sampling mechanism will touch Bennu’s surface and fire a charge of pressurized nitrogen to disturb the surface and collect its sample before the spacecraft backs away.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.

On Feb. 11, NASA’s OSIRIS-REx spacecraft safely executed a 0.4-mile (620-m) flyover of the backup sample collection site Osprey as part of the mission’s Reconnaissance B phase activities. Preliminary telemetry, however, indicates that the OSIRIS-REx Laser Altimeter (OLA) did not operate as expected during the 11-hour event. The OLA instrument was scheduled to provide ranging data to the spacecraft’s PolyCam imager, which would allow the camera to focus while imaging the area around the sample collection site. Consequently, the PolyCam images from the flyover are likely out of focus.

The other science instruments, including the MapCam imager, the OSIRIS-REx Thermal Emissions Spectrometer (OTES), and the OSIRIS-REx Visual and InfraRed Spectrometer (OVIRS), all performed nominally during the flyover. These instruments and the spacecraft continue in normal operations in orbit around asteroid Bennu.

The mission team is currently reviewing the available data from the flyover in order to fully assess the OLA instrument. The entire data set from the flyover, including the PolyCam images, will be completely downlinked from the spacecraft next week and will provide additional insight into any impact that the loss of the OLA data may have.

OLA has already completed all of its principal requirements for the OSIRIS-REx mission. OLA’s scans of Bennu’s surface were used to create the high-resolution 3D global maps of Bennu’s topography that were crucial for selecting the primary and backup sample collection sites last fall.

Preliminary results indicate that NASA’s OSIRIS-REx spacecraft successfully executed a 0.4-mile (620-m) flyover of site Nightingale yesterday as part of the mission’s Reconnaissance B phase activities. Nightingale, OSIRIS-REx’s primary sample collection site, is located within a crater high in asteroid Bennu’s northern hemisphere.

To perform the pass, the spacecraft left its 0.75-mile (1.2-km) safe home orbit and flew an almost 11-hour transit over the asteroid, aiming its science instruments toward the 52-ft (16-m) wide sample site before returning to orbit. Science observations from this flyover are the closest taken of a sample site to date.

The primary goal of the Nightingale flyover was to collect the high-resolution imagery required to complete the spacecraft’s Natural Feature Tracking image catalog, which will document the sample collection site’s surface features – such as boulders and craters. During the sampling event, which is scheduled for late August, the spacecraft will use this catalog to navigate with respect to Bennu’s surface features, allowing it to autonomously predict where on the sample site it will make contact . Several of the spacecraft’s other instruments also took observations of the Nightingale site during the flyover event, including the OSIRIS-REx Thermal Emissions Spectrometer (OTES), the OSIRIS-REx Visual and InfraRed Spectrometer (OVIRS), the OSIRIS-REx Laser Altimeter (OLA), and the MapCam color imager.

A similar flyover of the backup sample collection site, Osprey, is scheduled for Feb. 11. Even lower flybys will be performed later this spring – Mar. 3 for Nightingale and May 26 for Osprey – as part of the mission’s Reconnaissance C phase activities. The spacecraft will perform these two flyovers at an altitude of 820 feet (250 m), which will be the closest it has ever flown over asteroid Bennu’s surface.