This week, OSIRIS-REx celebrated 3 years since launch. On September 8, 2016 the spacecraft departed from Cape Canaveral and began its 7-year roundtrip journey. The mission is nearly half-way through, but significant benchmarks — including sample collection — still await.
OSIRIS-REx also continued operations in Orbital C phase, and has now completed 13 revolutions around Bennu in this orbit.
This last week, the team executed the commands necessary to designate the Medium Gain Antenna (MGA) as the spacecraft’s Safe Mode antenna. A subsequent MGA checkout confirmed that MGA performance is nominal. This configuration will be in place through the rest of the mission.
This week, OSIRIS-REx continued nominal performance in Orbital C phase. The spacecraft has completed approximately 10 orbits around Bennu since entering this orbit on August 8.
Images from August 29 show particles that appear to be falling back toward Bennu, suggesting an ejection event.
The Touch-and-Go Camera Suite (TAGCAMS) resumed nominal operations on September 2, after initially failing to respond to a routine aliveness check that day. The instrument’s digital video recorder (DVR) temporarily stopped processing commands, but after an internal reset, the instrument resumed nominal operations.
This week, OSIRIS-REx continued operations in support of particle monitoring for Orbital C phase. The spacecraft remains in its frozen orbit around asteroid Bennu at an altitude of 1.7 km. Since entering Orbital C on August 8, the OSIRIS-REx spacecraft has completed approximately 4.5 revolutions, with an orbit period of about 61 hours.
This week, OSIRIS-REx completed its first full week of Orbital C phase. Over the week, NavCam 1 collected pairs of long-exposure images from a nadir-pointed attitude. These observations seek to characterize and monitor asteroid Bennu’s particle ejection events, which is the main science objective for Orbital C phase.
During Orbital B phase, which completed in early August, the OSIRIS-REx Laser Altimeter (OLA) collected over 2.9 billion measurements. During the close orbit of Bennu, the instrument team met their goal of attaining 4x OLA coverage of Bennu’s entire surface.
The science plan for Reconnaissance A phase was approved this week, and the OSIRIS-REx spacecraft will perform its first high reconnaissance pass over Site Sandpiper in October.
This week, OSIRIS-REx transitioned to Orbital C phase. The first navigation maneuver (MC1) executed on August 6, and initiated the transfer from Orbital B to Orbital C. On August 8, OSIRIS-REx performed a second navigation maneuver (MC2), which placed the spacecraft into its new, higher frozen orbit. During Orbital C, OSIRIS-REx will focus on monitoring the near-Bennu environment for particles ejected from the surface. While in this orbit, the spacecraft will orbit Bennu at an altitude of 1.7 km and will take approximately 57 hours to complete one full orbit around the asteroid. During Orbital B, the spacecraft maintained an altitude of 680 meters and completed one orbit every 22 hours.
The planned Natural Feature Tracking (NFT) checkout successfully executed on August 3, and the results were nominal.
This week, OSIRIS-REx successfully concluded its final week of Orbital B phase. The OLA data and PolyCam images obtained from this low altitude orbit are of unprecedented detail, and will inform the mission team as they work to select sample collection sites.
The second Light Detection And Ranging (LIDAR) and OSIRIS-REx Laser Altimeter (OLA) cross-calibration executed on August 2. The cross-calibration activity seeks to confirm that both the GNC (Guidance, Navigation and Control) LIDAR range data and OLA scans continue to be consistent with one another.
The Touch-and-Go Camera Suite (TAGCAMS) recovered from an instrument-level safing event on July 28. Due to the event, the third scheduled Natural Feature Tracking (NFT) checkout was not performed. The root cause of the issue is currently under investigation.
The OSIRIS-REx spacecraft will transition to Orbital C phase next week, when the spacecraft will orbit Bennu at a slightly higher altitude of 1.7 km. Particle monitoring will resume during Orbital C.
This week, OSIRIS-REx completed its 6th week of Orbital B phase, in which the spacecraft continued its scheduled science activities from a low altitude orbit. PolyCam images from this orbit show resolved material on Bennu’s surface, which indicates that sampleable material is present. This is the first time that images of this resolution have been captured by the spacecraft’s cameras.
The second checkout of the Natural Feature Tracking (NFT) autonomous navigation system executed successfully on July 20—demonstrating that NFT works as designed in real-life conditions. During sample collection, the spacecraft will use NFT for guidance as it descends to asteroid Bennu’s surface.
Also on July 20, the digital video recorder (DVR) for the Touch-and-Go Camera Suite (TAGCAMS) became unresponsive to spacecraft commands. As a result, no imaging was recorded by TAGCAMS. The issue was cleared on July 22 during a regularly scheduled power cycle of the system, and an investigation into the root cause of the issue is ongoing.
The team continues to prepare for the transition into Orbital C phase, which will be executed in the coming weeks.
This week, OSIRIS-REx continued its scheduled science activities from a nadir-pointed attitude. The spacecraft successfully executed its third week of global mapping in Orbital B phase, along with the first Orbital B Natural Feature Tracking (NFT) checkout. NFT is a method of autonomous navigation in which the spacecraft uses the features on Bennu’s surface for guidance. This was the first time that NFT has been used in flight.
The team is also starting to receive extremely detailed OLA data from the spacecraft’s low-altitude orbit. These data are critical for selecting the best sample collection sites as the mission moves forward.
OSIRIS-REx will transition to Orbital C in early August, where the spacecraft will orbit Bennu at a slightly higher altitude of 1.7 km. Orbital C is similar to the frozen orbit used in Orbital A. During Orbital C phase, the team and spacecraft will resume particle monitoring.
OSIRIS-REX successfully completed its second week of global mapping for Orbital B phase. This week, OLA, PolyCam, OTES, REXIS and NavCam executed their scheduled science activities from a nadir-pointed attitude (nadir is the location directly below the spacecraft). In addition to nadir tracking, the mission also successfully completed an OLA/LIDAR cross-calibration exercise on July 6. The cross-calibration activity seeks to confirm that both the GNC (Guidance, Navigation and Control) LIDAR range data and OLA scans are consistent with one another. Calibration data review is scheduled over the course of the next week.
The mission’s Sample Site Selection Board also made significant progress in down-selecting potential Regions of Interest (ROIs) this week. The team is closer to selecting the four candidate sample collection sites that will be thoroughly evaluated during the Reconnaissance phase of the mission.
This week, OSIRIS-REx successfully executed its first week of global mapping from Orbital B’s low altitude orbit. On July 1, the team observed Bennu with the spacecraft’s onboard science instruments (except for OVIRS). During the global mapping phase of Orbital B, OLA will collect data in support of 5-cm Digital Terrain Models (DTMs) for site-specific mapping. PolyCam will obtain intermediate-resolution imagery to help determine sampleability of Bennu’s topography. OTES will gather data to create local thermal inertia maps, and REXIS will analyze X-ray fluorescence. NavCam, a navigation instrument, will also contribute to the scientific investigation by continuing intensive dedicated particle imaging. July 1 also marked the first time that REXIS observed asteroid Bennu. The current global mapping effort supports the down-select process to identify the four sample sites that will be further studied as the mission moves into its Reconnaissance phase.
On July 3, OLA returned to operations after recovering from an instrument-level safe mode event. The spacecraft’s fault protection systems had safed the instrument on July 2 as a precaution when OLA did not respond to a routine aliveness check after completing 17 of 19 scans of Bennu’s surface. Investigation of telemetry subsequent to the event revealed no anomalous instrument behavior other than a few status bits that had flipped, potentially indicative of a radiation induced event. OLA was power-cycled to clear the issue, and instrument recovery and return-to-operations proved successful.
OSIRIS-REx completed its second full week of Orbital B phase. The team executed maneuvers M4B and M5B last week, which were the first Orbital B trim burn maneuvers. During the transfer from M4B to M5B, the team used the Low Thrust Reaction Engine Assembly (LTR) thrusters to place the spacecraft within 460 meters of Bennu’s surface. This is the closest OSIRIS-REx has ever been to Bennu.
Particle imaging also concluded this week, and the team will now turn on most of the spacecraft’s onboard instruments for collecting science data. Starting next week, the OSIRIS-REx Laser Altimeter (OLA) will produce a full terrain map; PolyCam will obtain context imagery of various surface geologies; the OSIRIS-REx Thermal Emission Spectrometer (OTES) and the REgolith X-ray Imaging Spectrometer (REXIS) will produce global maps in the infrared and X-ray bands.
This week, the OSIRIS-REx spacecraft successfully completed its first full week of Orbital B phase. For the first week in the new orbit, the team focused on monitoring Bennu’s horizon with the NavCam 1 imager for possible additional particle ejections. Checkouts on the two GNC (Guidance, Navigation and Control) LIDAR systems were also performed over the past week, and analysis of the data is underway.
The mission’s Science Team Meeting 15 also took place this week. Team members continued to evaluate potential sites for sample collection in preparation for the upcoming Reconnaissance phase of the mission. Data obtained during Detailed Survey phase was further analyzed to examine potential sample sites. The team categorized sites based on geologic setting (crater, ridge, basin, boulder field), color and spectral characteristics, and other properties. These categories are intended to facilitate the ongoing down-select process for potential sample collection sites.
Particle monitoring will continue next week, after which the team will begin collecting science data using onboard science instruments from the spacecraft’s low Orbital B altitude.
OSIRIS-REx has successfully completed its Detailed Survey phase and transitioned into a new record-setting orbit around Bennu!
Last week the OSIRIS-REx navigation team performed three maneuvers using the spacecraft’s attitude control thrusters to place the spacecraft into orbit around Bennu for the second time. The first two maneuvers, on June 8 and 10, were staging burns that moved the spacecraft into position for the third burn on June 12, which ultimately placed OSIRIS-REx into orbit. These maneuvers imparted a velocity change (delta-v) of 8, 6, and 7 cm/sec, respectively. Throughout the Orbital B phase, slow changes in the spacecraft’s orbit will require correction maneuvers approximately every three weeks. The spacecraft’s circular orbit period around Bennu is 22 hours, with a velocity of 7 centimeters per second, which allows for the mission’s science measurements to be observed from a uniform altitude.
June 12 marked the beginning of the mission’s Orbital B phase, and the spacecraft began its new orbit approximately 680 meters above Bennu’s surface. This orbit breaks the record that OSIRIS-REx set during its Orbital A phase for the closest a spacecraft has ever orbited a small planetary body, which was as close as 1.3 km above the asteroid’s surface. The first two weeks of Orbital B will focus on investigating the causes of Bennu’s particle ejection events by taking frequent images of the asteroid’s horizon. The remaining five weeks of Orbital B will focus on mapping the asteroid from a close range.
With the conclusion of the Detailed Survey: Equatorial Stations phase on June 7, the team completed the mission’s main global survey effort. Here are the highlights from both Detailed Survey: Baseball Diamond and Detailed Survey: Equatorial Stations phases (Feb 22 – Jun 7):
- 14 Flyovers
- 18 Observation Stations
- 2,616 NavCam Images
- 19,660 OCAMS Images
- 2,286 OTES Data Acquisitions
- 179 OVIRS Science Acquisitions
- 19 OLA Scans
- 333,591 Total Spacecraft and Payload Commands
The OSIRIS-REx spacecraft successfully completed its last week of the Detailed Survey: Equatorial Stations mission phase. This week the team flew the spacecraft at the 6:00 p.m. Local Solar Time station. Station 7 observations included MapCam, OLA, OTES, and OVIRS, which performed continuous linear scans for a full rotation of Bennu. Following these initial observations, the spacecraft performed zig-zag scans using OTES and OVIRS in order to collect data in support of the thermal emission phase function. All of the data collected this week will further inform the team’s decisions for down-selecting sample collection sites in preparation for the Reconnaissance phase of the mission. The team is now preparing for the spacecraft to enter Orbital B.
June 4, 2019, marked 1,000 days since launch, which means OSIRIS-REx has been in flight for over 1,000 days. The OSIRIS-REx spacecraft has traveled about 2.5 billion km since launch, and has been operating in close proximity to Bennu since late 2018. As of now, one-way light time is 8.34 minutes.
Several key events took place on the ground and in space this week for OSIRIS-REx.
On the ground, the mission’s Site Selection Board (SSB) met at the University of Arizona on May 30 to review candidate sample collection sites and to down-select contending sites from ~50 locations. As designed, the down-select process was based on whether each Region of Interest (ROI) met specific safety criteria. The down-select resulted in 23 candidate sites remaining viable, with several others potentially remaining viable under stricter system performance limits. The next step will be to utilize data from the Detailed Survey phase to assess the sampleability (likelihood that an ingestible sample of regolith will be collected) of each viable region, leading to the next round of site down-selection.
Team members also participated in a Technical Interchange Meeting (TIM) on May 29 to work through open items for the mission’s upcoming Reconnaissance phase, scheduled to begin in Fall 2019. Reconnaissance is the critical mission phase that will confirm that candidate sites are both safe and contain sampleable material, as well as provide the closeup imaging required to produce the features and landmarks required for autonomous navigation to the asteroid surface.
Up in space, the team successfully flew the spacecraft at the 6:00 a.m. Local Solar Time station for Detailed Survey: Equatorial Stations phase on May 30. For the Station 5 observations, MapCam, OTES and OVIRS collected data in continuous linear scans for a full rotation of Bennu. After these initial observations, the spacecraft performed two east-west zig-zag scans with OTES and OVIRS. In tandem, these observations help create a more complete global safety map, as well as a global science value map and global sampleability map. Data gathered at this station may also help determine which candidate sample sites have sufficient deliverability.
Next week marks the last week of the Detailed Survey mission phase, and OSIRIS-REx will enter its final station before beginning Orbital B.
This last week was Week 5 of Detailed Survey: Equatorial Stations phase. For each week of this phase, the spacecraft observes Bennu from a different Local Solar Time (LST) station. At each station, the spacecraft is centered on the equator at a distance of 5 km and observes the asteroid for one full Bennu rotation (4.3 hours).
On May 23, the spacecraft took observations from Station 5, located at 6:00 am LST. OVIRS, OTES and MapCam took observations and OLA scanned cross-track in ride-along mode. These observations contribute to the OVIRS and OCAMS photometric models, global spectral, temperature and thermal inertia maps, and the global shape models from SPC (35-cm) and OLA (75 cm).
As a preliminary step to the selection of the mission’s sample collection site, the team has been closely studying data obtained from 50 regions of interest on the asteroid. They are looking for sites that are safe for the spacecraft, sampleable and scientifically interesting. Starting next week, the team will begin narrowing down the number of possible sites, which will then be further characterized before a final and back-up site are chosen in July.
On May 22, the TAGCAMS navigation cameras went into brief safe-mode after missing an aliveness check. The instrument resumed operations later that day, which was confirmed during the scheduled High Gain Antenna (HGA) transmission.
This last week was Week 4 of Detailed Survey: Equatorial Stations phase. For each week of this phase, the spacecraft will observe Bennu from a different Local Solar Time (LST) station. At each station, the spacecraft will be centered on the equator at a distance of 5 km and will observe the asteroid for one full Bennu rotation (4.3 hours).
On May 16, the spacecraft took observations from Station 4, located at 10:00 am LST. The 10:00 am station is the prime station for OVIRS observations. The team is operating OVIRS in a special high-resolution mode to get the best possible information about the mineralogy and organic composition of the surface for sample site selection. MapCam and OTES also took observations with OLA scanning in ride-along mode. These observations contribute to the OVIRS and OCAMS photometric models, global spectral, temperature and thermal inertia maps, and the global shape models from SPC (35-cm) and OLA (75 cm).
Immediately following Station 4, OTES observed Bennu in a series of east-west zig-zag scans to provide data for the thermal emission phase function. OVIRS took ride along scans and MapCam took context images.
This last week was Week 3 of Detailed Survey: Equatorial Stations phase. For each week of this phase, the spacecraft will observe Bennu from a different Local Solar Time (LST) station. At each station, the spacecraft will be centered on the equator at a distance of 5 km and will observe the asteroid for one full Bennu rotation (4.3 hours).
On May 9, the spacecraft took observations from Station 3, located at 12:30 pm LST, with OVIRS, OTES, MapCam, and OLA. These observations contribute to the OVIRS and OCAMS photometric models, global spectral, temperature and thermal inertia maps, and the global shape models from SPC (35-cm) and OLA (75 cm).
On May 11, OTES observed Bennu in a series of east-west zig-zag scans to provide data for the thermal emission phase function. OVIRS took ride along scans and MapCam took context images.
This last week was Week 2 of Detailed Survey: Equatorial Stations phase. For each week of this phase the spacecraft will observe Bennu from a different Local Solar Time (LST) station. At each station, the spacecraft will be centered on the equator at a distance of 5 km and will observe the asteroid for one full Bennu rotation (4.3 hours).
On May 2, the spacecraft took observations from Station 2, located at 3:20 am LST, with MapCam, OVIRS and OTES. These observations contribute to the OVIRS and OCAMS photometric models, global temperature and thermal inertia maps, and the global 35-cm SPC shape model. This position – with Bennu backlit by the sun – also provides the team with the opportunity to perform another dust plume search of the area around the asteroid.
This last week was the first week of Detailed Survey: Equatorial Stations phase. Each week during this phase, the spacecraft will observe Bennu from a different Local Solar Time (LST) station. At each station, the spacecraft will be centered on the equator at a distance of 5 km and will observe the asteroid for one full Bennu rotation (4.3 hours). On April 25, the spacecraft took observations from Station 1, located at 3:00 pm LST, with MapCam, OVIRS, OTES and OLA.
Continued analysis of NavCam 1 images detected that another particle ejection event occurred on April 19. The study of the events and their causes is ongoing.
On April 18 and 19, the spacecraft performed Flyby 7, during which it observed Bennu with MapCam, OLA and OTES at the 12:30 pm local solar time position. The pass was divided into two phases – A and B. Flyby 7A occurred over Bennu’s northern hemisphere at 40°latitude from a distance of 3.8 km. Flyby 7B occurred over Bennu’s southern hemisphere at -40°latitude, also from a distance of 3.8 km. During both phases, the spacecraft slewed east, west and straight down to image every 24°of Bennu’s rotation.
Next week, the mission moves into Detailed Survey: Equatorial Stations phase.
On Earth, a contingent from the OSIRIS-REx team, including the PI, traveled to Japan last week for a technical interchange meeting with JAXA’s Hayabusa2 team. The topics discussed included the first Hayabusa2 sample collection event and OSIRIS-REx sample site selection.
On April 11 and 12, the spacecraft performed Flyby 6, which mirrored Flyby 5’s operations but with the hemispheres reversed. For Flyby 5, the spacecraft flew north-to-south, and then reversed directions (an unusual operation in spaceflight, given the microgravity environment around Bennu) for a south-to-north pass for Flyby 6.
During Flyby 6, the spacecraft observed Bennu with PolyCam, OLA and OTES at the 12:30 pm local solar time position. The pass was divided into two phases – A and B. Flyby 6A occurred over Bennu’s southern hemisphere at a distance of 5 km, and the spacecraft slewed east, west and straight down to image every 12° of Bennu’s rotation. Flyby 6B occurred over Bennu’s northern hemisphere at a distance of 3.06 km, and the spacecraft slewed east to image every 6° of Bennu’s rotation. These observations support the development of the 35-cm Stereo Photoclinometry (SPC) and 75-cm OLA shape models, the production of global image mosaics and the identification and cataloging of features for Natural Feature Tracking (NFT).
On April 4 and 5, the spacecraft performed Flyby 5, during which it observed Bennu with PolyCam, OLA and OTES at the 12:30 pm local solar time position. The pass was divided into two phases – A and B. Flyby 5A occurred over Bennu’s northern hemisphere at a distance of 5 km, and the spacecraft slewed east, west and straight down to image every 12° of Bennu’s rotation. Flyby 5B occurred over Bennu’s southern hemisphere at a distance of 3.06 km, and the spacecraft slewed west to image every 6° of Bennu’s rotation. These observations support the development of the 35-cm Stereo Photoclinometry (SPC) and 75-cm OLA shape models, the production of global image mosaics and the identification and cataloging of features for Natural Feature Tracking (NFT).
The spacecraft continues with operations for the mission’s Detailed Survey: Baseball Diamond phase. Each week during this phase the spacecraft executes a flyby of Bennu at a different observing angle. On March 28 and 29, the spacecraft performed Flyby 4, during which it observed Bennu with PolyCam, OLA and OTES at the 10 am local solar time position, from a distance of 3.7 km.
Due to severe winter weather conditions throughout Colorado on March 13, the facility where mission operations are conducted was closed for safety. Due to this emergency closure, a planned update to the spacecraft pointing could not be processed and uplinked. Consequently, the mission missed MapCam observations above approximately 20º north latitude on Bennu during Flyby 2. The team will evaluate whether there is a need to plan for additional observations in the future in order to meet science requirements. This decision will be made after assessing Flyby 7, which is scheduled for execution on April 18 and includes MapCam observations above Bennu’s 20ºN.
OSIRIS-REx continues operations in the mission’s Detailed Survey: Baseball Diamond phase, which comprises a total of seven pole-to-pole flybys of Bennu. On Mar. 16 the spacecraft successfully executed the M5D maneuver to position itself at the starting point of the third observation leg, and on Mar. 19, it executed the M6D maneuver to begin the third flyby. During this leg, the spacecraft observed Bennu from the 10:00 am local solar time position from a distance of 3.7 km. Both the PolyCam camera and the OTES spectrometer took observations during the pass.
The spacecraft is now operating successfully in the Detailed Survey: Baseball Diamond Phase. Each week during this phase the spacecraft will execute a flyby of Bennu at a different observing angle in order to fully map the asteroid. On March 5, the spacecraft executed the M2D maneuver to commence the first observation leg, a flyby at a local solar time of 12:30 pm and a closest approach distance of 5 km. Both the PolyCam camera and the OTES spectrometer were both on and took observations during this pass of Bennu.
On Feb. 28, shortly after completing its 23rd orbit of Bennu, the spacecraft executed a departure maneuver (M0D) to exit orbit and fly to a point 7 km from Bennu. Later this week, the spacecraft will begin the series of 3 – 5 km flybys of Bennu that comprise the Detailed Survey mission phase.
This last week the following science instruments took observations of Bennu: OCAMS, OLA, OTES, and REXIS.
OSIRIS-REx continues to orbit Bennu at an altitude ranging from 1.6 to 2.1 km, with an orbital period of ~62 hours. This last week, both the OLA altimeter and the MapCam camera made observations of Bennu from orbit.
On Feb. 21, the mission team gathered to watch JAXA’s Hayabusa-2 spacecraft execute its first sample collection activity at asteroid Ryugu. The OSIRIS-REx and Hayabusa-2 teams are working closely together on the two asteroid sample return missions, and the OSIRIS-REx team cheered the Japanese announcement that their attempt appeared to be a success.
This last week, the spacecraft continued orbiting Bennu as part of the mission’s Orbital A phase. The OLA instrument executed a linear scan over the majority of Bennu’s northern hemisphere on Feb. 13. OLA took a single 5 ½ hr scan and received 1.82 million measurements of Bennu.
The mission team is currently in the midst of the biannual checkouts and calibrations of the spacecraft’s systems. So far, TAGCAMS, GNC LIDAR-1 and-2 and REXIS have all been successfully exercised. The checkouts also provided REXIS with the first opportunity to observe Bennu. REXIS science operations are scheduled to begin this summer.
Several times since NASA’s OSIRIS-REx spacecraft entered orbit around its target asteroid Bennu on Dec. 31, 2018, the OSIRIS-REx team detected multiple, bright, point sources near Bennu in the optical navigation (OpNav) images obtained by the spacecraft’s NavCam 1 imager. The science team is currently investigating the exact cause of this phenomenon, but it is probable that these images record a number of small particles near the asteroid.
The mission team’s initial analysis determined that the particles do not pose a significant risk to the spacecraft in its current orbit, which is between 1 and 1.3 miles (1.6 and 2.1 km) from Bennu. The team will continue to study the particles and their sources. After the initial detection, the team increased the cadence of OpNav observations to better study the environment around Bennu and monitor for additional occurrences.
OSIRIS-REx is scheduled to leave its current orbit on Feb. 28, when it will begin the mission’s Sample Site Selection campaign. During this next mission phase, the OSIRIS-REx spacecraft will make a series of flybys of Bennu at a distance of around 2 miles (3 km) to start mapping the asteroid in detail.
The spacecraft continues to orbit Bennu at an altitude ranging from 1.6 to 2.1 km. As of today, the spacecraft has been orbiting the asteroid for 32 days and is in the midst of completing its 12th orbit. It is notable that the team has been able to waive all of the weekly opportunities to trim the orbit since insertion on Dec. 31. The fact that the orbit has not needed adjustment is reflective of the flight dynamics high fidelity modeling and the excellent maneuver performance of the spacecraft.
On the ground, mission leadership has given the go-ahead to proceed to the next mission phase as scheduled. Detailed Survey: Baseball Diamond phase will commence with a small spacecraft maneuver on Feb. 28. This transition marks the end of the Navigation Campaign and the beginning of the Site Selection Campaign. The primary objective of the SSC is to globally map Bennu to identify two potential sample sites for detailed characterization.
The spacecraft continues in orbit around Bennu and has completed 10 orbits so far. The spacecraft takes approximately 62 hours to complete one orbit at a speed of 5 cm/sec.
On the ground, the mission team continues to map and analyze Bennu with the primary goal of selecting a site for the Touch-and-Go (TAG) sample collection event (currently scheduled for 2020). This last week, the mission held a full-project TAG Technical Interchange Meeting (TIM) to discuss the current TAG design, possible design changes due to data gathered from Bennu since Arrival, and future refinements to the TAG plan.
This past week, the spacecraft continued orbiting Bennu as part of the Orbital A navigation campaign, traveling around 5 cm/sec (relative to the asteroid). This phase was designed to provide the mission team with experience navigating in close proximity to a small body, and as such, there are no science requirements. The only Bennu observations being taken during Orbital A phase are optical navigation (OpNav) images using the NavCam1 camera. Orbital A continues through mid-February.
This week, the navigation team was able to officially cancel trim burn maneuvers through Feb. 9 due to the sustained performance of the spacecraft’s trajectory implemented during the Dec. 31 orbital insertion.
The OSIRIS-REx spacecraft continues to orbit Bennu at an altitude ranging from 1.6 to 2.1 km, with an orbital period of 61 hours. The spacecraft has completed 5.5 orbits of Bennu to date. The one-way communication time from the spacecraft back to Earth is around 5.5 minutes.
On the ground, the mission held its 14th Science Team Meeting at the University of Arizona last week. This was the first science team meeting since the spacecraft’s arrival at the asteroid, which means it was also the first gathering where the entire science team was able to work with detailed Bennu data from the spacecraft.
On Dec. 29 and 31, the OSIRIS-REx spacecraft successfully completed the two maneuvers required to enter orbit about Bennu. The accurate performance of these orbit insertion maneuvers, as well as the continued accurate navigation performance since orbit insertion, allowed for the wave-off of several planned updates to the spacecraft’s orbit determination (OD). The mission’s navigation team will continue to study OD performance over the first few weeks of spacecraft orbits to further refine and predict orbital operations – which will eventually allow the team to reduce the trim burn schedule.
The first orbit of Bennu, which started on Dec. 31, ended 61.4 hours later on Jan. 3. The spacecraft will continue orbiting the asteroid through mid-February.
Today at 2:43 p.m. EST, the spacecraft carried out a single, eight-second burn of its thrusters and entered into orbit around Bennu, making Bennu the smallest object ever to be orbited by a spacecraft.
This month, the spacecraft has been progressing through the maneuvers of the mission’s Preliminary Survey phase. Starting on Dec 3, the spacecraft executed seven maneuvers (M1P – M7P) to make three passes over Bennu’s north pole and one each over its equator and south pole. Each flyby brought OSIRIS-REx within seven km from Bennu’s surface.
The M2P and M3P burns, executed on Dec. 5 and 7 respectively, for the first time completely reversed the direction of the spacecraft’s motion in order to initiate further flybys of Bennu’s north pole. These maneuvers highlight the unique character of the complex trajectories required for this mission’s asteroid proximity operations, which can be described as the spacecraft “formation flying” with Bennu.
During these Bennu passes, the spacecraft’s MapCam camera, OTES and OVIRS spectrometers, and OLA laser altimeter have been taking close observations of Bennu’s surface. This is the first time that the spacecraft has been close enough to employ OLA, which takes ranging measurements of the asteroid. These observations will be used to make 3D topographic maps of the asteroid.
On Dec. 3, the spacecraft completed its 2 billion km outbound journey and arrived at the asteroid Bennu. At a distance of 19 km from Bennu, the spacecraft executed a maneuver (M1P) to turn and fly over the asteroid’s north pole, beginning the mission’s Preliminary Survey phase and asteroid proximity operations.
This week, the team put the spacecraft’s sample acquisition arm through its paces for the first time in flight. More here.
On Nov. 5, the spacecraft successfully executed a trim maneuver (AAM-3a) to re-target conditions for the AAM-4 maneuver scheduled for Nov. 12. It also realigned the spacecraft’s trajectory with the precise approach corridor needed for the PolyCam shape model imaging planned over the next several weeks. The 6 cm/s maneuver was only the second burn utilizing the spacecraft’s Attitude Control System (ACS) thrusters, which are capable of velocity changes as small as 1 cm/s.
On Nov. 7, the Mission Planning Board evaluated the mission’s readiness to proceed from Approach Phase into Preliminary Survey Phase and determined that OSIRIS-REx is a GO. Barring any anomalies on the flight system or any unforeseen Bennu surprises, the spacecraft will “arrive” at Bennu on Dec. 3 and begin Preliminary Survey’s hyperbolic flyovers of the poles and equator.
The science payload also executed the following observations in the past week: OCAMS MapCam Daily Phase Function, OTES Full Disk Integrated Spectroscopy, OVIRS Full Disk Integrated Spectroscopy, OVIRS Solar Calibration, OCAMS PolyCam Natural Satellite Search, OCAMS MapCam Natural Satellite Search, and TAGCAMS Natural Satellite Search ride-along with OpNavs.
OSIRIS-REx has had another busy period of science and spacecraft operations. From Oct. 25 to Nov. 5, the OCAMS cameras made observations for the Daily Phase Function science campaign. The images from this campaign provide data to measure changes in light reflected from Bennu’s surface as the Sun illuminates the asteroid from different angles. These observations will provide information on Bennu’s albedo and the way light is reflected from the asteroid’s surface.
On Oct. 25, the five Frangibolts keeping the Touch-and-Go Sample Acquisition Mechanism (TAGSAM) arm against the spacecraft structure were successfully released. On Oct. 26, the Motor Articulation Control Module (MACM-2) card was powered on for the first time in flight. The three motors were effectively commanded to move the TAGSAM arm out of the launch container and into the parked position.
The Natural Satellite Search campaign also continued during this time using both the PolyCam and MapCam cameras of the OCAMS instrument, as well as the TAGCAMS navigation cameras as ride-alongs.
On Oct. 29, the spacecraft executed its third Asteroid Approach Maneuver (AAM-3), slowing the spacecraft by approximately 5.13 m/sec. This was also the mission’s first two-part burn maneuver, which accommodated constraints for the science instruments to not be pointed too closely to the Sun.
On Oct. 29, PolyCam also obtained images of Bennu to provide a “super-resolution” view of the asteroid that exceeded the best ground-based data collected.
This week, the OSIRIS-REx spacecraft executed its third Asteroid Approach Maneuver, slowing the spacecraft’s speed down to .24 mph (.11 m/sec).
This last week was very busy for the mission. On Oct. 15, the spacecraft successfully executed its second Asteroid Approach Maneuver (AAM-2), which slowed its rate of approach toward Bennu by approximately 305 mph (137 m/s) and burned around 186 lbs. (84.4 kg) of fuel. There are two more AAMs scheduled over the next month to further slow and more precisely target the spacecraft’s trajectory toward Bennu. The final two maneuvers are much smaller than AAMs 1 and 2, and will use the spacecraft’s Trajectory Correction Maneuver (TCM) engines instead of its Main Engines.
On Oct. 17, the OSIRIS-REx team jettisoned the cover that protected the TAGSAM head during launch and early flight. The team used several methods to confirm that the cover ejection was successful. Directly before the deployment, the spacecraft executed its third sample mass measurement (SMM-3) spin to measure the spacecraft’s mass properties while the cover was still attached. The day after the deployment, the spacecraft executed SMM-4, which confirmed that the spacecraft’s mass had decreased by around 2.67 lbs. (1.21 kg) from the previous day. The team was also able to confirm the cover ejection through telemetry indicating changes in thermal signatures and forces on the spacecraft.
On the mission’s science side, the spacecraft also continued with its Bennu Phase Function Observation campaign this week. Bennu now appears larger than a pixel in the PolyCam imager’s field of view, and the team is looking forward to the next few weeks as the asteroid’s shape is finally revealed.
This week, the OSIRIS-REx spacecraft executed its second Asteroid Approach Maneuver, as it continues slowing down while approaching Bennu.
New tracking data confirm that the spacecraft completed its first Asteroid Approach Maneuver (AAM-1) on Oct. 1, starting the final approach to Bennu. The main engine burn slowed the spacecraft speed by 785.831 miles per hour (351.298 meters per second) and consumed 532.4 pounds (241.5 kilograms) of fuel.
From the beginning of the mission’s science operations on Aug. 17 through AAM-1, PolyCam obtained optical navigation images (OpNavs) of Bennu on a Monday, Wednesday and Friday cadence. After AAM-1, PolyCam is taking daily OpNavs as the spacecraft continues to close in on the asteroid.
This last week the spacecraft’s MapCam camera also began taking daily Phase Function images. These images support the mission’s science requirement to measure changes in light reflected from Bennu’s surface as the Sun illuminates the asteroid across a range of angles. These observations provide information on Bennu’s albedo and the way light reflects under various observing conditions.
This week, the OSIRIS-REx spacecraft executed its first Asteroid Approach Maneuver to put it on course for its scheduled Bennu arrival in December.
As of today, OSIRIS-REx is approximately 480,000 km from Bennu and is 6 days from executing Asteroid Approach Maneuver 1 (AAM-1) on Oct. 1. AAM-1 is the first of four major maneuvers that will slow the spacecraft’s velocity on its final approach to Bennu. The spacecraft is currently flying at approximately 490 m/s (~1,100 mph), and AAM-1 will slow the spacecraft’s rate of approach to Bennu by 350 m/s (~780 mph) to 140 m/s (~310 mph).
This last week, the mission’s navigation team delivered the preliminary designs for AAM-1, and the final design will be completed and radiated to the spacecraft in the upcoming week.
On Sept. 14, the spacecraft’s REXIS instrument opened its Radiation Cover and REXIS now has a clear view of space for the first time. The Radiation Cover protected the detectors from radiation damage during the cruise to Bennu, but it also blocked the aperture of the instrument. With OSIRIS-REx nearing Bennu, the mission team opened the cover to enable REXIS to observe external calibration targets like the Crab Nebula, as well as ultimately the asteroid.
The Radiation Cover had been held shut by a Frangibolt since before launch. On Friday, the Frangibolt was actuated by heating it up, which expanded a shape-memory alloy cylinder, breaking the titanium bolt holding the cover shut. By inspecting heater and temperature telemetry and comparing the difference between spectra taken before and after the Frangibolt firing, the REXIS team was able to determine that the cover opened successfully and the instrument is now seeing the cosmic X-ray background. Going forward, REXIS will take measurements on several astrophysical X-ray sources in preparation for observations of Bennu starting next summer.
This last week the OSIRIS-REx spacecraft continued its approach toward Bennu. Now that we have visually acquired the asteroid, the PolyCam camera images Bennu three times a week to provide data to the navigation team. At a distance of 1.1 million km, Bennu appears as just a dot. However, the navigation team can still use these images to calculate the spacecraft trajectory and refine Bennu’s orbit.
This last week the mission’s Science Operations Planning Group held the tactical kickoff for the upcoming Natural Satellite Search. The mission operates on an 8-week science planning schedule, so between now and the search’s commencement on Oct. 23, the finalized commands for the activity will be built, tested, and radiated to the spacecraft. Beyond the inherent science value of the possible discovery of natural satellites at Bennu, the search is key to assess the spacecraft’s safety while it operates in the area around the asteroid.
This last week the team processed and released its first set of images of the mission’s target asteroid Bennu. The spacecraft’s PolyCam camera took the images from a distance of approximately 2.2 million km. Now that OSIRIS-REx has come into instrument range of Bennu, the spacecraft’s science payload will make regular observations of Bennu and its surroundings as it continues to approach the asteroid.
Last week marked the beginning of OSIRIS-REx’s Approach Phase, which is the first phase of mission asteroid operations. Visit the Asteroid Operations page to discover how the spacecraft and the mission team will be exploring Bennu over the next few years.
This last week, the mission team ran a checkout of the spacecraft’s two GNC (Guidance, Navigation and Control) LIDAR systems. These sensors are designed to provide navigational information while the spacecraft is operating in close proximity to the asteroid, in particular during the TAG sampling maneuver. The LIDAR system calculates the distance to Bennu by bouncing laser pulses off Bennu’s surface and measuring the time it takes for the light to return to the detector. Because there were no targets in the vicinity to bounce the laser off during the test, this LIDAR checkout solely focused on system outputs. Preliminary results indicate that the checkouts executed as expected.
The mission team also spent this last week preparing for the kick-off of asteroid operations, which is scheduled to occur on Aug. 17 when the spacecraft’s OCAMS camera takes its first image of Bennu.
On July 30-31, the spacecraft conducted another Sample Mass Measurement (SMM) calibration activity. After sample collection, the mission team will use the SMM pirouette to measure the mass of the collected regolith in the TAGSAM head. The team is awaiting the downlink of the complete data set from the spacecraft to be able to analyze the performance of the spin maneuvers, but preliminary data indicates that they executed as expected.
This last week, the mission team assessed that the second week of the Launch+22 months instrument checkouts and calibrations proceeded as expected. This was the last set of checkouts and calibrations the spacecraft will execute before the beginning of Approach Phase on August 17 and the resulting Bennu imaging campaign.
Since launch on September 8, 2016, the OSIRIS-Rex spacecraft has travelled 1.73 billion km, and it has around 302 million km to travel before its scheduled arrival at Bennu on December 3.
Last week, the Launch+22 months instrument checkouts and calibrations progressed through their second week of observations. The mission team also assessed that the instruments exercised during the campaign’s first week, OCAMS, OVIRS and REXIS, operated as expected.
Also last week, the spacecraft passed the 4 million km range-to-Bennu mark, and is now 3.8 million km from the asteroid.
This week the team began a two-week campaign of instrument checkouts and calibrations. The mission exercises the spacecraft’s payloads approximately every six months during flight to ensure that all instruments are working as expected. This also provides an opportunity to collect additional calibration data on each instrument, which is used to further refine the science data ground processing. These checkouts are the final checkouts before the Approach phase begins mid-August.
Further reconstruction analysis this week by the mission teamconfirmed that the spacecraft’s deep space maneuver on June 28 was successful and closely followed the team’s design and predicts. Also on Earth, the Science Operations Planning Group (SOPG) is in the midst of planning operations for the first three weeks of Approach Phase, which will start on August 17.
On June 28, the spacecraft executed the second deep space maneuver of its outbound cruise. Preliminary analysis indicates that the spacecraft performed the maneuver as planned, and the team is conducting more detailed analysis to determine the maneuver’s exact results.
On June 19, the Science Operations and Planning Group (SOPG) held the tactical kickoff for the first week of Approach Phase, which commences August 17. This means that the day-to-day operational planning of the mission’s Bennu science operations has begun.
This week the OSIRIS-REx mission team has also been enthusiastically watching our JAXA partner mission, Hayabusa2, return its first images of the asteroid Ryugu. In these images, Ryugu has shown itself to be shaped remarkably similarly to what Bennu is expected to look like. OSIRIS-REx and Hayabusa2 are working collaboratively on their respective asteroid sample return missions to reduce risk and increase the science knowledge obtained.
The mission team this week continued preparations for the spacecraft’s arrival at Bennu by holding series of technical interchange meetings (TIMs) focusing on asteroid proximity operations. The team also held an initial walkthrough of the Touch-and-Go (TAG) sampling sequence.
The spacecraft is now less than 7 million kilometers from Bennu and has 388 million km left to travel as it chases down the asteroid for its scheduled arrival this December.
This past week, OSIRIS-REx continued nominal operations en route to asteroid Bennu. The spacecraft has been in space for 640 days and is currently 56.4 million km from Earth.
On the ground, several members of the OSIRIS-REx team were recognized with 2018 NASA Agency Honor Awards:
- Peter Antreasian – Exceptional Public Service Medal
- Coralie Jackman and Devin Poland – Early Career Public Achievement Medal
- Dennis Reuter – Distinguished Service Medal
- OSIRIS-REx Earth Gravity Assist (EGA) Team – Group Achievement Award
- OCAMS Instrument Team/Bashar Rizk – Silver Achievement Medal
OSIRIS-REx continued nominal operations in support of Outbound Cruise Phase this week, and the spacecraft team is planning Deep Space Maneuver-2 — the last significant maneuver before Approach Phase — scheduled for June 28. The instrument teams are planning the Launch+22 month instrument checkouts, which will execute in mid-July.
The range between OSIRIS-REx and Bennu is currently 8.5 million km. Because both the spacecraft and the asteroid are orbiting the Sun, OSIRIS-REx has 417 million km left to travel before arriving at Bennu in December.
This last week the mission marked a major milestone. On May 22, the Science Operations Planning Group (SOPG) held the kickoff of the mission’s Approach Phase. The SOPG Approach Kickoff marked the official start of detailed planning for the spacecraft’s instrument operations to study Bennu, which will begin on Aug. 17. The first instrument operation being planned is the spacecraft’s first observation of Bennu, which will be taken by the PolyCam imager from a distance of approximately 2 million km.
Last week the mission team conducted a successful checkout of the spacecraft’s Medium Gain Antenna (MGA). With this test, all of the spacecraft’s antennas have now been used in flight.
OSIRIS-REx has four antennas for communicating between the spacecraft and Earth. The largest, the High Gain Antenna (HGA), has the highest data rate but has a narrow gain pattern, meaning that it must be directly pointed at Earth for successful transmission. The MGA has a larger pattern, but a lower data rate. In favorable geometries, it will be used to communicate status telemetry back to Earth during the sampling maneuver. The two Low Gain Antennas (LGAs) provide near complete coverage and very low data rate communications. The LGAs are especially useful for transmitting progress telemetry during events, such as maneuvers, when the spacecraft’s other antennas aren’t facing Earth.
On May 7 and 9, the spacecraft conducted its second Sample Mass Measurement (SMM) pirouette activity. The SMM pirouette allows the mission team to measure the mass of the collected sample once it is in the TAGSAM head. Before sample collection, the spacecraft will do a number of spin maneuvers while the sample head is still empty. After sample collection, OSIRIS-REx will back away from the asteroid surface and pirouette again. The ground team will then compare the spacecraft’s mass properties for the “empty” and “full” spins to yield a basic estimate of the collected sample’s mass. The SMM maneuver this week provided the team with calibration information for the activity.
OSIRIS-REx continued nominal operations last week. The spacecraft is currently traveling at a speed of 5.86 km/sec (21,090 km/hr) relative to Earth, and 2.19 km/sec (7,883 km/hr) relative to Bennu. It has approximately 482 million km left in its journey before it arrives at the asteroid later this December.
Last week was the final execution week of the Operational Readiness Test (ORT), with the mission team simultaneously supporting nine weeks of parallel planning to simulate late Approach Phase, Preliminary Survey Phase, and part of Orbital A Phase. The week concluded with the simulated uplink of execution commands to the spacecraft. This ORT proved to be an extremely valuable exercise involving the entire operations team and has provided significant experience in the various stages of mission planning, implementation, and execution that will begin in earnest with the start of asteroid operations later this year.
This week the mission received good news regarding the Sample Return Capsule (SRC) outgassing mitigation campaign that was implemented last fall to remove excess water from the SRC. Over the last few months, the spacecraft has been placed into various positions to expose different sides of the capsule to the Sun in order to bake the moisture out. After completing the analysis of the various maneuvers, the navigation team this week confirmed that there is no longer detection of outgassing at a level that could interfere with the spacecraft’s navigation requirements during Bennu proximity operations.
OSIRIS-REx continued outbound cruise operations this last week. On the ground, members of the navigation team worked through the results of a Navigation Training Exercise (NTE) test on asteroid shape modeling. The test was designed to demonstrate the team’s readiness to perform landmark optical navigation techniques during asteroid proximity operations. This means the team would be able to navigate the spacecraft using Bennu’s landmarks as a guide instead of using star fields. Landmark navigation provides more precise and timely information on the spacecraft’s location around Bennu, which improves mission safety and efficiency.
The spacecraft remained in nominal operations this week. On the ground, the team continued planning asteroid proximity operations for execution starting late summer, while also participating in the ongoing Operational Readiness Test simulation.
On April 4, the team uplinked a patch for the Relative Asteroid Target List up to the spacecraft. This upgrade will allow the team to point the spacecraft using its sense of nadir (the location directly below the spacecraft) when taking science observations. Currently, the spacecraft uses absolute (instead of relative) pointing, so each time the ground team sends a new ephemeris, planned observations must be updated. This new capability will greatly reduce the number of late information updates required for observations and will make observation products reusable.
As of this week, OSIRIS-REx has travelled over 1.5 billion km since its launch in Sept. 2016. It is currently 47.7 million km from Earth and has a little over .5 billion km left to travel until it reaches the asteroid Bennu.
This last week the mission team continued the analysis of data obtained during the Launch + 18 months payload checkout and extended OCAMS and TAGCAMS calibrations. The team also concurrently worked through week 5 of the Operational Readiness Test simulation, which replicates the mission’s operations schedule for late Fall.
The spacecraft passed the 20 million km range-to-Bennu mark this week and is currently 19.5 million km from Bennu.
The OSIRIS-REx spacecraft continued to operate nominally this last week. The extended calibration opportunity for the OCAMS and TAGCAMS instruments began on March 15 and ran through March 24. This exercise allowed both instruments to run through a full slate of imaging activities in advance of asteroid proximity operations, which start later this summer.
The OSIRIS-REx spacecraft is currently travelling 5.57 km/sec (20,052 km/hr) relative to Earth.
The Launch + 18 Months payload checkout and calibration campaign finished this last week with the REXIS checkout on March 13. The mission is now in the midst of extended calibrations for the OCAMS and TAGCAMS cameras, which will run until the end of this week. The OVIRS spectrometer will also get an opportunity to collect extra calibration data as a ride-along activity during a portion of the extended exercise.
As of today, the spacecraft is a little under 23 million km from Bennu and still has almost 541 million km left to travel before catching up to the asteroid this fall.
This last week was a busy one for the mission. Throughout the week, the spacecraft executed the Launch + 18 Months payload checkout and calibration campaign. Twice a year during Cruise Phase, the mission exercises its payload – the science and navigation instruments – to ensure they are working as expected and to continue instrument calibrations in preparation for asteroid operations. The campaign extends over the next two weeks to provide continued calibration opportunities for OCAMS (the science cameras) and TAGCAMS (the navigation cameras).
This week the spacecraft also performed a checkout of newly approved downlink rates for communications back to Earth, and it completed the last of the scheduled SRC outgassing activities. The team on the ground is also progressing through the nine-week Super ORT (Operational Readiness Test) simulation exercise in parallel with real world activities.
This last week the OSIRIS-REx team commenced an extensive Operational Readiness Test (ORT), known as the Super ORT, in preparation for asteroid proximity operations. Over the next nine weeks, the mission’s planning teams, instrument teams, and ops teams will be simulating the full range of activities required to support the mission during the last week of Approach Phase (currently scheduled for late November). By rehearsing the actual operations the mission team will perform once OSIRIS-REx arrives at Bennu, the Super ORT will thoroughly exercise the mission’s team, tools, and processes.
Flight operations continued normally this last week. The mission team on the ground is in the midst of preparing the Launch + 18 Months calibration campaign scheduled for execution in early March.
OSIRIS-REx is currently 61.6 million km from Earth.
This week the spacecraft conducted activities that validated its ability to perform some of the maneuvers required for sample collection. On Feb. 12, the spacecraft conducted a TAG (Touch-and-Go) Backaway Maneuver, demonstrating the propulsive maneuver the spacecraft will use to leave the asteroid’s surface after sampling. On Feb. 15 and 16, the spacecraft ran a checkout of its two precision LTR (Low Thrust Rocket-Engine-Assembly) Thrusters. These tiny rocket engines will be used to make fine velocity adjustments when OSIRIS-REx is in orbit about Bennu, such as the spacecraft’s critical orbit phasing burn to set up the proper orbit departure point leading to sample acquisition.
OSIRIS-REx is currently 30 million km from Bennu and has 648 million km to left to travel before it reaches the asteroid.
This last week, spacecraft operations continued normally. On the ground, further analysis of the 80 TAGCAMS images from the January stray light characterization activity discovered that some of NavCam1’s testing images had captured the Earth and Moon system. The images were taken from over 63 million km away while the spacecraft was moving away from Earth at approximately 8.6 km/second.
Flight operations continued normally this last week. The team finished up the OSIRIS-REx Laser Altimeter (OLA) regression test checkout with the new flight software in place and are now running an analysis of the results. The second in-flight checkouts of LIDARs 1 and 2 were also run on January 29 and February 2.
As of today, the spacecraft has traveled a total of 1.35 billion kilometers since launch in September 2016.
This last week the team uploaded new flight software for the OSIRIS-REx Laser Altimeter (OLA) to the spacecraft and conducted an instrument checkout, which confirmed that it is operating as expected. On the ground, the spacecraft’s instrument scientists and engineers met at the OREx Science Processing and Operations Center (SPOC) at the University of Arizona to help finalize the mission’s science operations schedule of activities, which will begin in August 2018.
The spacecraft is currently travelling approximately 29,072 km/hr (18,064 mph) relative to Earth.
On January 16-17, the mission team conducted a stray light characterization activity involving the OCAMS (OSIRIS-REx Camera Suite) instrument and the TAGCAMS navigation cameras.
Stray light occurs whenever sunlight shines on the OSIRIS-REx science deck and the sun’s rays bounce off its taller structures, such as PolyCam, OTES, and the Sample Return Capsule. Through a series of second, third and higher-level reflections, this redirected light finds its way into the cameras’ fields of view and produces glare in the images, especially for long exposures.
The goal of the stray light test is to study and determine the direction and amount of unwanted light that is scattered into the cameras. The Image Processing Working Group uses these stray-light background patterns to correct images that are acquired when the science deck points toward the Sun, such as during the search for possible dust and gas plumes around Bennu.
The amount of stray light that the spacecraft’s cameras have detected is within normal system performance requirements. This stray light characterization study is simply an effort to understand the behavior of the system in flight in the real space environment, which couldn’t be fully realized on the ground or in computer simulations before launch.
Last week, OSIRIS-REx continued normal Outbound Cruise operations. On Jan. 10, the spacecraft performed another tilting maneuver in support of the ongoing outgassing campaign. On Jan. 15, the spacecraft resumed communicating back to Earth over its High Gain Antenna, following a four-month period limited to the Low Gain Antennas with attendant low downlink rates.
The spacecraft’s one-way light time for communications back to Earth is currently 3 minutes and 27 seconds.
On Jan. 4 and 5 the mission continued outgassing campaign activities by again rotating the spacecraft to expose the SRC to the sun. The mission team will study the results of this activity over the next few weeks to determine whether the campaign has removed sufficient water from the capsule or if further outgassing operations are required.
As of today, the spacecraft has traveled 1.3 billion km and has 721 million km left to travel before it is scheduled to arrive at Bennu on Dec. 3, 2018.
On Dec. 20, the mission transitioned into Outbound Cruise sub-phase 5, which is the final sub-phase of Outbound Cruise operations. To mark the transition, the spacecraft returned to using the +X Low Gain Antenna (LGA) for its communications back to Earth. The spacecraft had previously been communicating over the –X LGA.
The next mission operations transition will be into Approach Phase, which begins Aug. 17, 2018, when the spacecraft is approximately 2 million km from Bennu.
The spacecraft maintained its trajectory this last week as it continues on its outbound journey to Bennu. On Dec. 8, the spacecraft conducted a Sample Mass Measurement (SMM) pirouette activity as part of the ongoing outgassing campaign.
The SMM pirouette was originally designed to help the mission team measure the mass of the sample after it is collected from Bennu’s surface in 2020. Once the sample is in the TAGSAM head, OSIRIS-REx will back away from the asteroid surface and perform a spin maneuver. The ground team will then compare the spacecraft’s mass properties with those of a previous, sample-less spin in order to yield a basic estimate of the collected sample’s mass. For the outgassing campaign, however, the mission team employed this SMM spin maneuver to expose different parts of the spacecraft to the Sun in order to further remove water from the spacecraft. This exercise will prevent water from interfering with the spacecraft’s balance when it performs the maneuver after sampling. Preliminary reports indicate that the activity proceeded as expected.
The spacecraft has travelled 1.2 billion km since launch and will travel another 781.7 million km before it reaches Bennu.
Last week, OSIRIS-REx continued Outbound Cruise operations. The spacecraft is currently 47.6 million km from Earth and is executing a program designed to study and reduce the presence of water on the spacecraft.
During routine in-flight testing of the spacecraft’s thermal properties earlier this year, the mission’s navigation team noticed an unexpected minor acceleration of the spacecraft when the Sample Return Capsule (SRC) was exposed to sunlight. The mission team determined that this small thrust was caused by the outgassing of water that had been adsorbed by the SRC’s heat shield and backshell before launch. Retention of water in blanketing and other materials – and the subsequent outgassing of this water – occurs with all spacecraft. For OSIRIS-REx, it was determined that when the SRC is exposed to the Sun at a distance of <1.0 AU, this trapped water escapes and imparts a small thrust. While this small thrust would not be a problem for other missions, the gravity at the target asteroid Bennu is low enough that even this small amount of thrust could make orbital operations more difficult for OSIRIS-REx.
To better understand the outgassing effects on the spacecraft’s trajectory – and to bake out much of the remaining water before the spacecraft arrives at Bennu – the OSIRIS-REx mission team designed an outgassing program for execution starting earlier this fall. The choice of timing took into account both the spacecraft’s proximity to the Sun (<1.0 AU) and the fact that there were no science activities planned during this period. The outgassing program is being run concurrently with Outbound Cruise operations and does not affect the timing of the spacecraft’s arrival at Bennu.
Starting in mid-October, the spacecraft has been placed into various attitudes to expose different parts of the SRC to direct sunlight and initiate outgassing. Priority is given to the portions of the SRC that will face the Sun during asteroid proximity operations. The mission team has been able to detect and measure the rate of outgassing at each attitude and has determined that water is being removed as expected. The goal is to reduce the outgassing to the point where the spacecraft can fly the planned baseline trajectories around Bennu without modifications, and preliminary indications show that the program is progressing toward this goal. The program is scheduled to run through early January 2018.
The spacecraft continues to operate nominally. This last week the team updated some of the spacecraft’s onboard navigation files and, on Nov. 20, OSIRIS-REx’s downlink rate increased to 2 kbps from 200 bps.
OSIRIS-REx has travelled 1.17 billion km since launch and still has 824 million km to go until it arrives at Bennu.
Last week OSIRIS-REx continued Outbound Cruise operations. The spacecraft is currently 39 million km from Earth and 55 million km from Bennu.
Last week the spacecraft maintained normal operations for its Outbound Cruise Phase. On Nov. 13, the spacecraft’s communications downlink rate decreased to 200 bps from 10 kbps. The spacecraft continues to communicate back to Earth through its low gain antenna (LGA).
On the ground this last week, the OSIRIS-REx Science Team gathered in Tucson, Ariz. for its bi-annual meeting. This meeting focused on further refining the science planning processes that will be implemented when the spacecraft arrives at Bennu.
OSIRIS-REx continued normal Outbound Cruise operations last week. As of today, the spacecraft is 57 million km from Bennu, traveling at 8 km/sec relative to Earth. The one-way light time for transmissions from the spacecraft back to the ground is 100 seconds, which is an increase of 15 seconds in the last week. The spacecraft’s communications downlink rate remains at 10 kbps.
Last week the spacecraft maintained normal operations for its Outbound Cruise Phase. OSIRIS-REx is currently 25.6 million km from Earth and is traveling at approximately 28,000 km/h relative to Earth. One-way light time for transmissions from the spacecraft back to the ground is 85 seconds.
This past week, the mission took advantage of the spacecraft’s long outbound cruise to study the spacecraft’s thermal profile. As part of the exercise, the spacecraft was placed into certain orientations that it will employ during asteroid proximity operations in order to more precisely determine the thermal properties of each part of the spacecraft. As different spacecraft components were exposed to the Sun, the team measured how quickly they warmed and cooled. This in-flight characterization of OSIRIS-REx’s thermal properties will help the team more accurately predict the spacecraft’s thermal state while the spacecraft is operating close to Bennu.
Back on Earth, the ground team continues to be busy planning spacecraft operations and science observations for Bennu proximity operations, which will begin in August 2018 and continue through sample collection, scheduled for July 2020.
As of Oct. 23, the OSIRIS-REx spacecraft is traveling at approximately 25,000 kph relative to Earth. The spacecraft is approximately 17 million km from Earth and 57.7 million km from Bennu. But because Bennu is orbiting around the Sun and isn’t stationary, the spacecraft must still travel 948 million km before it can catch up to the asteroid.
On Oct. 16, the spacecraft’s communications downlink rate decreased to 10 kbps. Because of the low data rates and other mission planning activities, no science observations are planned through Jan. 7, 2018.
Last week, the OSIRIS-REx spacecraft continued on its new post-EGA trajectory toward Bennu. A REXIS Solar X-Ray Monitor testing and calibration activity began Oct. 9 and ran through Oct. 12. On Oct. 7, the spacecraft’s communications downlink rate decreased to 40 kbps from 200 kbps. The spacecraft continues to communicate back to Earth through its low gain antenna (LGA).
As of Oct. 16, the OSIRIS-REx spacecraft is approximately 12.9 million km from Earth and has traveled around 1.03 billion km since launch. It has another 970 million km to travel before it reaches Bennu.
The mission’s instrument teams and science working groups continue to actively process EGA science observations for the OCAMS, OVIRS, OTES and TAGCAMS instruments. Early indications show outstanding performance of the instruments, giving confidence that they will operate as designed at Bennu. Although the EGA maneuver and subsequent observations went smoothly overall, the science operations team is looking at lessons learned from EGA on both planning and ground tools to assess whether there are further improvements that could be made for Bennu operations.
As of Oct. 9, the OSIRIS-REx spacecraft is approximately 8.8 million km from Earth and its one-way light time is around 30 seconds.
Following a successful Earth Gravity Assist on Sept. 22, the spacecraft engaged its OCAMS and TAGCAMS cameras and OTES and OVIRS spectrometers on Sept. 22, Sept. 25 and Sept. 28 to observe the Earth and Moon. The instruments operated nominally and the mission team was able to use the opportunity to exercise its science operations procedures and calibrate the spacecraft’s instruments. Images and spectra of Earth and images of the Earth and Moon were also released. A final day of observations is scheduled for Oct. 2.
The mission’s navigation team determined that the spacecraft’s post-EGA trajectory was on course as planned. As a result, the trajectory correction maneuver (TCM-6) scheduled for Oct. 4 was cancelled.
On Friday, the OSIRIS-REx spacecraft completed its planned Earth Gravity Assist.
Last week, the OSIRIS-REx spacecraft maintained nominal operations as it continued on a trajectory toward Earth for its scheduled Sept. 22 Earth Gravity Assist (EGA). On Sept. 14, the spacecraft’s communications downlink rate increased to 300 kbps from 200 kbps as the spacecraft’s distance to Earth continues to shrink. The spacecraft is currently communicating through its low gain antenna (LGA).
As of Sept. 18, the spacecraft is 2.6 million km from Earth and its one-way light time is around 9 seconds.
This week, OSIRIS-REx’s navigation team determined that the spacecraft’s 23 Aug. trajectory correction maneuver (TCM-3) accurately set the spacecraft on the correct trajectory for its Sept. 22 Earth Gravity Assist (EGA). This means that there will be no need to execute TCM-4 or TCM-5, which were originally scheduled to further target the spacecraft at the optimal EGA aim-point.
Preparations for EGA continue for the team on the ground. In particular, the instrument teams are getting ready for science observations of Earth and the Moon as the spacecraft swings by Earth and continues on a new orbital plane out toward Bennu.
As of Sept. 11, the spacecraft is 6.5 million km from Earth, having traveled 933.9 million km since launch on Sept. 8, 2016.