1. Some Asteroids ‘Aged Early’ by Sun, NASA Finds

    July 25, 2022 -

    Scientists from NASA’s OSIRIS-REx mission recently learned that surface regeneration happens a lot quicker on asteroids than on Earth. By analyzing rock fractures on asteroid Bennu from high-resolution images taken by the OSIRIS-REx spacecraft, the team discovered that the Sun’s heat fractures rocks on Bennu in just 10,000 to 100,000 years. This information will help scientists estimate how long it takes boulders on asteroids like Bennu to break down into smaller particles, which may either eject into space or stay on the asteroid’s surface.

    Tens of thousands of years might sound pretty slow, but “we thought surface regeneration on asteroids took a few millions of years,” said Marco Delbo, senior scientist at Université Côte d’Azur, CNRS, Observatoire de la Côte d’Azur, Laboratoire Lagrange, Nice, France, and lead author of a paper published June 2022 in Nature Geoscience. “We were surprised to learn that the aging and weathering process on asteroids happens so quickly, geologically speaking.”

    The PolyCam aboard NASA’s OSIRIS-REx spacecraft provided high-resolution, microscope-like images of asteroid Bennu’s surface. This made it possible for researchers to map more than 1,500 rock fractures. Fractures highlighted in red.Credits: NASA/Goddard/University of Arizona

    The PolyCam aboard NASA’s OSIRIS-REx spacecraft provided high-resolution, microscope-like images of asteroid Bennu’s surface. This made it possible for researchers to map more than 1,500 rock fractures. Fractures highlighted in red.
    Credits: NASA/Goddard/University of Arizona

    Although landslides, volcanoes, and earthquakes can change the surface suddenly on Earth, usually changes are gradual. Water, wind, and temperature changes slowly break down rock layers, creating new surfaces over millions of years. For example, if you were to hike into the Grand Canyon, you would see distinct rock layers; the top layers tend to be the youngest rocks, dating around 270 million years old, and the layers at the bottom of the canyon are the oldest, about 1.8 billion years old. According to the U.S. National Park Service, the Colorado River has been carving down rocks in the Grand Canyon for 5 million to 6 million years.

    Rapid temperature changes on Bennu create internal stress that fractures and breaks down rocks, similar to how a cold glass breaks under hot water. The Sun rises every 4.3 hours on Bennu. At the equator, daytime highs can reach almost 260F (about 127 C), and nighttime lows plummet to nearly minus 10 F (about minus 23 C).

    OSIRIS-REx scientists spotted cracks in the rocks in spacecraft images from the first surveys of the asteroid. The fractures seemed to point in the same direction, “a distinct signature that temperature shocks between the day and the night could be the cause,” said Delbo.

    Delbo and his colleagues measured the length and angles of more than 1,500 fractures in OSIRIS-REx images by hand: some shorter than a tennis racket, others longer than a tennis court. They found the fractures predominantly align in the northwest-southeast direction, indicating they were caused by the Sun, which is shown here to be the primary force changing Bennu’s landscape.

    “If landslides or impacts were moving boulders faster than the boulders were cracking, the fractures would point in random directions,” said Delbo.

    The scientists used a computer model and their fracture measurements to calculate the 10,000 to 100,000-year timeframe for thermal fractures to propagate and split rocks.

    “The thermal fractures on Bennu are quite similar to what we find on Earth and on Mars in terms of how they form,” said Christophe Matonti, a co-author of the paper at Université Côte d’Azur, CNRS, Observatoire de la Côte d’Azur, Géoazur, Sophia-Antipolis, Valbonne, France. “It is fascinating to see that they can exist and are similar in very ‘exotic’ physical conditions [low gravity, no atmosphere], even compared to Mars.”

    “Keep in mind, the topography of Bennu is young, but the rocks on the asteroids are still billions of years old and hold valuable information about the beginning of the solar system,” said Jason Dworkin, OSIRIS-REx project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

    OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) will return a sample from Bennu to Earth on Sept. 24, 2023. “We will be able to learn more details about the age of the surface when we are able to directly study the sample,” said Dworkin.


    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. The university leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Littleton, Colorado, 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, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate Washington.

    By Rani C. Gran
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    Related link: Some Asteroids ‘Aged Early’ by Sun, NASA Finds

  2. NASA Reveals Surface of Asteroid Bennu is Like Plastic Ball Pit

    July 8, 2022 -

    After analyzing data gathered when NASA’s OSIRIS-REx spacecraft collected a sample from asteroid Bennu in October 2020, scientists have learned something astonishing: The spacecraft would have sunk into Bennu had it not fired its thrusters to back away immediately after it grabbed dust and rock from the asteroid’s surface.

    Side-by-side images from NASA’s OSIRIS-REx spacecraft of the robotic arm as it descended towards the surface of asteroid Bennu (left) and as it tapped it to stir up dust and rock for sample collection (right). OSIRIS-REx touched down on Bennu at 6:08pm EDT on October 20, 2020. Credits: NASA’s Goddard Space Flight Center.

    It turns out that the particles making up Bennu’s exterior are so loosely packed and lightly bound to each other that if a person were to step onto Bennu they would feel very little resistance, as if stepping into a pit of plastic balls that are popular play areas for kids.

    “If Bennu was completely packed, that would imply nearly solid rock, but we found a lot of void space in the surface,” said Kevin Walsh, a member of the OSIRIS-REx science team from Southwest Research Institute, which is based in San Antonio.

    The latest findings about Bennu’s surface were published on July 7 in a pair of papers in the journals Science and Science Advances, led respectively by Dante Lauretta, principal investigator of OSIRIS-REx, based at University of Arizona, Tucson, and Walsh. These results add to the intrigue that has kept scientists on the edge of their seats throughout the OSIRIS-REx mission, as Bennu has proved consistently unpredictable.

    The asteroid presented its first surprise in December 2018 when NASA’s spacecraft arrived at Bennu. The OSIRIS-REx team found a surface littered with boulders instead of the smooth, sandy beach they had expected based on observations from Earth- and space-based telescopes. Scientists also discovered that Bennu was spitting particles of rock into space.

    This view of asteroid Bennu ejecting particles from its surface on January 19 was created by combining two images taken by the NavCam 1 imager onboard NASA’s OSIRIS-REx spacecraft: a short exposure image (1.4 ms), which shows the asteroid clearly, and a long exposure image (5 sec), which shows the particles clearly. Other image processing techniques were also applied, such as cropping and adjusting the brightness and contrast of each layer. Credit: NASA/Goddard/University of Arizona/Lockheed Martin. For more information, go here.

    “Our expectations about the asteroid’s surface were completely wrong” said Lauretta.

    The latest hint that Bennu was not what it seemed came after the OSIRIS-REx spacecraft picked up a sample and beamed stunning, close-up images of the asteroid’s surface to Earth. “What we saw was a huge wall of debris radiating out from the sample site,” Lauretta said. “We were like, ‘Holy cow!’”

    Scientists were bewildered by the abundance of pebbles strewn about, given how gently the spacecraft tapped the surface. Even more bizarre was that the spacecraft left a large crater that was 26 feet (8 meters) wide. “Every time we tested the sample pickup procedure in the lab, we barely made a divot,” Lauretta said. The mission team decided to send the spacecraft back to take more photographs of Bennu’s surface “to see how big of a mess we made,” Lauretta said.

    Mission scientists analyzed the volume of debris visible in before and after images of the sample site, dubbed “Nightingale.” They also looked at acceleration data collected during the spacecraft’s touch down. This data revealed that as OSIRIS-REx touched the asteroid it experienced the same amount of resistance – very little – a person would feel while squeezing the plunger on a French press coffee carafe. “By the time we fired our thrusters to leave the surface we were still plunging into the asteroid,” said Ron Ballouz, an OSIRIS-REx scientist based at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland.

    Ballouz and the research team ran hundreds of computer simulations to deduce Bennu’s density and cohesion based on spacecraft images and acceleration information. Engineers varied the surface cohesion properties in each simulation until they found the one that most closely matched their real-life data.

    Now, this precise information about Bennu’s surface can help scientists better interpret remote observations of other asteroids, which could be useful in designing future asteroid missions and for developing methods to protect Earth from asteroid collisions.

    Near-Earth asteroid Bennu is a rubble pile of rocks and boulders left over from the formation of the solar system. On October 20, 2020, NASA’s OSIRIS-REx spacecraft briefly touched down on Bennu and collected a sample for return to Earth. During this event the spacecraft’s arm sank far deeper into the asteroid than expected, confirming that Bennu’s surface is loosely bound. Now, scientists have used data from OSIRIS-REx to revisit the sample-collection event and better understand how Bennu’s loose upper layers are held together. Credits: NASA’s Goddard Space Flight Center/CI Lab/SVS

    It’s possible that asteroids like Bennu — barely held together by gravity or electrostatic force — could break apart in Earth’s atmosphere and thus pose a different type of hazard than solid asteroids. “I think we’re still at the beginning of understanding what these bodies are, because they behave in very counterintuitive ways,” said Patrick Michel, an OSIRIS-REx scientist and director of research at the Centre National de la Recherche Scientifique at Côte d’Azur Observatory in Nice, France.

    ###

    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. The university leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Littleton, Colorado, 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, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate Washington.

    By Lonnie Shekhtman
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

  3. NASA Spacecraft Observes Asteroid Bennu’s Boulder “Body Armor”

    June 16, 2022 -

    Asteroid Bennu’s boulder-covered surface gives it protection against small meteoroid impacts, according to observations of craters by NASA’s OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) spacecraft.

    “These observations give new insight into how asteroids like Bennu respond to energetic impacts,” said Edward (Beau) Bierhaus of Lockheed Martin Space, Littleton, Colorado, lead author of a paper published in this month’s issue of Nature Geoscience.

    This image shows boulder formations on asteroid Bennu’s surface. It was taken by the PolyCam camera on NASA’s OSIRIS-REx spacecraft on April 11, 2019 from a distance of 2.8 miles (4.5 km). Credit: NASA/Goddard/University of Arizona

    Bennu is a “rubble-pile” asteroid, meaning that it formed from the debris of a much larger asteroid that was destroyed by an ancient impact. Fragments from the collision coalesced under their own weak gravity to form Bennu.

    The team used unprecedented, high-resolution global data sets to examine craters on Bennu: images from the OSIRIS-REx Camera Suite and surface-height data (topography) derived from the OSIRIS-REx Laser Altimeter, a laser-ranging (lidar) instrument on the spacecraft.

    “Measuring craters and their population on Bennu was exceptionally exciting,” said David Trang of the University of Hawaii at Mānoa, Honolulu, a co-author of the paper. “At Bennu, we discovered something unique to small and rocky bodies, which expanded our knowledge of impacts.”

    Planetary scientists can estimate the age of surfaces by measuring the abundance and sizes of craters. Impact craters accumulate over time, so a surface with many craters is older than a surface with few craters. Also, the size of the crater depends on the size of the impactor, with larger impactors generally making larger craters. Because small meteoroids are far more abundant than large meteoroids, celestial objects like asteroids usually have many more small craters than large ones.

    Bennu’s larger craters follow this pattern, with the numbers of craters decreasing as their size increases. However, for craters smaller than about 6.6 to 9.8 feet (around 2 – 3 meters) in diameter, the trend is backwards, with the number of craters decreasing as their size decreases. This indicates something unusual is happening on Bennu’s surface.

    The researchers think that Bennu’s profusion of boulders acts as a shield, preventing many small meteoroids from forming craters. Instead, these impacts are more likely to break apart the boulders or chip and fracture them. Also, some impactors that do make it through the boulders make smaller craters than they would if Bennu’s surface was covered in smaller, more uniform particles, like beach sand.

    This activity causes the surface of Bennu to change differently than objects with fine-grained or solid surfaces. “The displacement or disruption of an individual or small group of boulders by a small impact is probably one of the most fast-acting processes on a rubble-pile asteroid’s surface. On Bennu, this contributes to making the surface appear to be many times younger than the interior,” said Bierhaus.

    The research was supported by NASA under the New Frontiers Program and the OSIRIS-REx Participating Scientist Program, the Canadian space agency, the French space agency, the Italian space agency, the European Union’s Horizon 2020 research and innovation program, and the Academies of Excellence of the Initiative D’ Excellence Joint, Excellent and Dynamic Initiative of Université Côte d’Azur.

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

    By: Bill Steigerwald

    Related link: NASA Feature

    Media Contact:

    Rani Gran

    NASA Goddard Space Flight Center, Greenbelt, Maryland

    rani.c.gran@nasa.gov

    301.286.2483

     

  4. NASA gives green light for OSIRIS-REx spacecraft to visit another asteroid

    April 25, 2022 -

    NASA’s OSIRIS-REx spacecraft will swing by Earth to deliver a sample from asteroid Bennu on Sept. 24, 2023. But it won’t clock out after that.

    APEX Graphic

    This is an artists illustration of the OSIRIS-REx spacecraft firing thrusters near the surface of the asteroid Apophis. Credit: Heather Roper

    NASA has extended the University of Arizona-led mission, which will be renamed OSIRIS-APEX, to study near-Earth asteroid Apophis for 18 months. Apophis will make a close approach to Earth in 2029.

    Imaging scientist Dathon Golish created this simulated image of the view of near-Earth asteroid Apophis in the APEX camera, based on a shape model produced by JPL’s Marina Brozović and her colleagues. Credit: UArizona/JPL/Arecibo

    The University of Arizona will lead the mission, which will make its first maneuver toward Apophis 30 days after the OSIRIS-REx spacecraft delivers the sample it collected from Bennu back in October 2020. At that point, the original mission team will split – the sample analysis team will analyze the Bennu sample, while the spacecraft and instrument team transitions to OSIRIS-APEX, which is short for OSIRIS-Apophis Explorer.

    Regents Professor of Planetary Sciences Dante Lauretta will remain principal investigator of OSIRIS-REx through the remaining two-year sample return phase of the mission. Planetary sciences assistant professor and OSIRIS-REx deputy principal investigator Dani DellaGiustina will then become principal investigator of OSIRIS-APEX. The extension adds another $200 million to the mission cost cap.

    The mission team did an exhaustive search for potential asteroid targets. The OSIRIS-REx spacecraft was built for what’s called a rendezvous mission, meaning instead of making a single flyby of an object and quickly snapping images and collecting data, it was designed to “get up close and personal with the object.” DellaGiustina said. “Our spacecraft is really phenomenal at that.”

    “Apophis is one of the most infamous asteroids,” DellaGiustina said. “When it was first discovered in 2004, there was concern that it would impact the Earth in 2029 during its close approach. That risk was retired after subsequent observations, but it will be the closest an asteroid of this size has gotten in the 50 or so years asteroids have been closely tracked, or for the next 100 years of asteroids we have discovered so far. It gets within one-tenth the distance between the Earth and moon during the 2029 encounter. People in Europe and Africa will be able to see it with the naked eye, that’s how close it will get. We were stoked to find out the mission was extended.”

    OSIRIS-REx was launched in 2016 to collect a sample from Bennu that will help scientists learn about the formation of the solar system and Earth as a habitable planet. OSIRIS-REx is the first NASA mission to collect and return a sample from a near-Earth asteroid.

    OSIRIS-APEX will not collect a sample, but when it reaches Apophis, it will study the asteroid for 18 months and collect data along the way. It also will make a maneuver similar to the one it made during sample collection at Bennu, by approaching the surface and firing its thrusters. This event will expose the asteroid’s subsurface, to allow mission scientists to learn more about the asteroid’s material properties.

    The scientists also want to study how the asteroid will be physically affected by the gravitational pull of Earth as it makes its close approach in 2029.

    They also want to learn more about the composition of the asteroid. Apophis is about the same size as Bennu – nearly 1000 feet at its longest point – but it differs in what’s called its spectral type. Bennu is a B-type asteroid linked to carbonaceous chondrite meteorites, whereas Apophis is an S-type asteroid linked to ordinary chondrite meteorites.

    “The OSIRIS-REx mission has already achieved so many firsts and I am proud it will continue to teach us about the origins of our solar system,” said University of Arizona President Robert C. Robbins. “The OSIRIS-APEX mission extension keeps the University of Arizona in the lead as one of the premier institutions in the world to study small bodies with spacecraft and demonstrates again our incredible capacity in space sciences.”

    DellaGiustina is also excited that the mission provides an excellent opportunity for early career scientists to gain professional development. OSIRIS-REx veterans will work closely with these early career scientists as mentors in the early mission phases. By the time the spacecraft arrives at Apophis, the next generation will step into leadership roles on OSIRIS-APEX.

    “OSIRIS-APEX is a manifestation of a core objective of our mission to enable the next generation of leadership in space exploration. I couldn’t be prouder of Dani and the APEX team,” Lauretta said. “Dani first started working with us in 2005 as an undergraduate student. To see her take on the leadership of the mission to asteroid Apophis demonstrates the outstanding educational opportunities at the University of Arizona.”

    Writer: Mikayla Mace Kelley
    The University of Arizona

    Related Link:

    NASA Press Release: NASA Extends Exploration for 8 Planetary Science Missions

  5. NASA’s OSIRIS-REx Asteroid Sample Return Team Receives 2022 John L. ‘Jack’ Swigert, Jr., Award for Space Exploration

    April 5, 2022 -

    NASA’s OSIRIS-REx asteroid sample return mission team received the 2022 John L. “Jack” Swigert, Jr., Award for Space Exploration by the Space Foundation, a nonprofit organization that advocates for space exploration and space-inspired industries.

    The award recognizes the OSIRIS-REx team’s extraordinary accomplishments in space exploration and discoveries made at asteroid Bennu. The award honors the memory of astronaut John L. “Jack” Swigert, Jr., the command module pilot for the Apollo 13 mission. During Apollo 13’s April 1970 voyage to the Moon, an oxygen tank ruptured, placing the crew in peril. People around the globe watched NASA work against the clock and against the odds to return the crew safely to Earth.

    Left to Right: Tom Zelibor, CEO of the Space Foundation; Mike Moreau, deputy project manager, NASA Goddard; Thomas Zurbuchen, NASA’s associate administrator for the Science Mission Directorate; Sandy Freund, Lockheed Martin mission operations manager; Peter Antreasian, navigation team chief, KinetX; Dante Lauretta, principal investigator at University of Arizona, Tucson; Rich Burns, project manager at NASA Goddard. The Space Foundation honored representatives from NASA, the University of Arizona and Lockheed Martin on April 4, 2022, during the opening ceremonies of the 37th Space Symposium in Colorado Springs, Colorado. Credit: Space Foundation

    The Space Foundation honored representatives from NASA, University of Arizona and Lockheed Martin on April 4, 2022, during the opening ceremonies of the 37th Space Symposium in Colorado Springs, Colorado. “The OSIRIS-REx team has raised the bar when it comes to extraordinary accomplishments in the realm of space exploration and discovery,” said Space Foundation CEO, Tom Zelibor. The OSIRIS-REx team’s work in literally grabbing a piece of our universe and bringing it back to Earth for further study and understanding lays the groundwork for forging the next generation of scientists, astronomers, geologists and more.”]

    “It’s humbling to be a part of such an effective mission team who made the difficult seem easy by knocking down every unexpected challenge, from the extraordinarily rugged surface of Bennu to operating in the depths of the pandemic, with the poise and perseverance that Jack Swigert personified,” said Rich Burns, OSIRIS-REx project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

    The OSIRIS-REx spacecraft reached Bennu in December 2018. The mission’s first close-up images of Bennu revealed a rough and rocky surface instead of the sandy, pebbly “beach” the team had expected. Earth-based observations of the asteroid suggested it had a much smoother surface. This discovery forced the team to rethink how the spacecraft would collect a sample from Bennu. They decided to switch to a backup navigation system that increased mission accuracy and allowed OSIRIS-REx to accommodate Bennu’s rugged obstacles.

    OSIRIS-REx spent more than two years near the asteroid, gathering information about its size, shape, mass, and composition, while monitoring its spin and orbital trajectory.

    On Oct. 20, 2020, OSIRIS-REx gently touched a relatively smooth spot in a crater on the northern hemisphere of asteroid Bennu and collected an overwhelming amount of material. So much so, small rocks wedged the sample collector’s lid open a little bit, causing regolith to leak from the capsule. As a result, the team canceled an activity to measure the amount of material collected, called the sample mass measurement spin, as the test would cause OSIRIS-REx to lose more of the collected sample. Instead, carefully and quickly, the mission stowed the precious material in its sample return capsule.

    “The team is deeply grateful to be honored by the Space Foundation and to have our achievements recognized with the Swigert Award,” said Dante Lauretta, OSIRIS-REx principal investigator at University of Arizona, Tucson. “We accomplished something truly amazing with our exploration of near-Earth asteroid Bennu. The best times are ahead of us, and the team is focused on ‘the ground game,’ recovering the sample return capsule and delivering the sample to NASA’s Johnson Space Center. The analysis team is busy preparing our arsenal of laboratory instruments, Bennu still has much to teach us.”

    OSIRIS-REx left Bennu on May 10, 2021 and will deliver significantly more sample than the minimum target of two ounces, or 60 grams, (about the mass of a C battery) to Earth on Sept. 24, 2023, with the capsule touching down in the Utah Test and Training Range.

    The University of Arizona leads the OSIRIS-REx science team and the mission’s science observation planning and data processing. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Lockheed Martin Space in Littleton, Colorado, 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, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate at NASA Headquarters in Washington, D.C.