NASA’s OSIRIS-REx mission is just days away from selecting the site where the spacecraft will snag a sample from asteroid Bennu. After a lengthy and challenging process, the team is finally ready to down-select from the four candidate sites to a primary and backup site.
OSIRIS-REx is NASA’s first asteroid sample return mission, so this decision of a sample collection site is key for asteroid operations and mission success.
After selecting the four candidate sample sites – Sandpiper, Osprey, Kingfisher, and Nightingale – in July, the mission completed its Reconnaissance A phase. During Recon A, the OSIRIS-REx spacecraft performed a month-long series of four flyovers – one over each potential sample collection site. This mission phase provided the team with high-resolution imagery in order to thoroughly examine the sampleability (fine-grained material), topography, albedo, and color of each site. The data collected from these high-altitude flyovers is central for determining which site is best-suited for sample collection.
These images show the four candidate sample collection sites on asteroid Bennu: Nightingale, Kingfisher, Osprey and Sandpiper. One of these four sites will ultimately be the location on which NASA’s OSIRIS-REx spacecraft will touch down to collect a sample.
Credits: NASA/Goddard/University of Arizona
While the mission is one step closer to collecting a sample, Recon A observations have revealed that even the best candidate sites on Bennu pose significant challenges to sample collection, and the choice before the site selection board is not an easy one.
“Sample site selection really is a comprehensive activity. It requires that we look at many different types of data in many different ways to ensure the selected site is the best choice in terms of spacecraft safety, presence of sampleable material, and science value,” said Heather Enos, OSIRIS-REx deputy principal investigator at the University of Arizona, Tucson, and chair of the sample site selection board. “Our team is incredibly innovative and integrated, which is what makes the selection process work.”
The most recent images show that while there is fine-grained material (smaller than 2.5 cm in diameter), much of it may not be easily accessible. The mission was originally designed for a beach-like surface, with “ponds” of sandy material, not for Bennu’s rugged terrain. In reality the potential sample sites are not large, clear areas, but rather small spaces surrounded by large boulders, so navigating the spacecraft in and out of the sites will require a bit more fine-tuning than originally planned.
Starting in Bennu’s southern hemisphere, site Sandpiper was the first flyover of the Recon A mission phase. Sandpiper is one of the “safer” sites because it is located in a relatively flat area, making it easier for the spacecraft to navigate in and out. The most recent images show that fine-grained material is present, but the sandy regolith is trapped between larger rocks, which makes it difficult for the sampling mechanism to operate.
Site Osprey was the second site observed during Recon A. This site was originally chosen based on its strong spectral signature of carbon-rich material and because of a dark patch in the center of the crater, which was thought to possibly be fine-grained material. However, the latest high-resolution imagery of Osprey suggests that the site is scattered with material that may be too large to ingest for the sampling mechanism.
Site Kingfisher was selected because it is located in a small crater – meaning that it may be a relatively young feature compared to Bennu’s larger craters (such as the one in which Sandpiper is located). Younger craters generally hold fresher, minimally-altered material. High-resolution imagery captured during the Recon A flyover revealed that while the original crater may be too rocky, a neighboring crater appears to contain fine-grained material.
Recon A concluded with a flyover of site Nightingale. Images show that the crater holds a good amount of unobstructed fine-grained material. However, while the sampleability of the site ranks high, Nightingale is located far to the north where the lighting conditions create additional challenges for spacecraft navigation. There is also a building-size boulder situated on the crater’s eastern rim, which could be a hazard to the spacecraft when backing away after contacting the site.
This flat projection mosaic of asteroid Bennu shows the relative locations of the four candidate sample collection sites on the asteroid: Nightingale, Kingfisher, Osprey and Sandpiper. NASA’s OSIRIS-REx spacecraft is scheduled to touch down on one of these four sites to collect a sample in summer 2020.
Credits: NASA/Goddard/University of Arizona
Bennu has also made it a challenge for the mission to identify a site that won’t trigger the spacecraft’s safety mechanisms. During Recon A, the team began cataloguing Bennu’s surface features to create maps for the Natural Feature Tracking (NFT) autonomous navigation system. During the sample collection event, the spacecraft will use NFT to navigate to the asteroid’s surface by comparing the onboard image catalog to the navigation images it will take during descent. In response to Bennu’s extremely rocky surface, the NFT system has been augmented with a new safety feature, which instructs it to wave-off the sampling attempt and back away if it determines the point of contact is near a potentially hazardous surface feature. With Bennu’s building-sized boulders and small target sites, the team realizes that there is a possibility that the spacecraft will wave-off the first time it descends to collect a sample.
“Bennu’s challenges are an inherent part of this mission, and the OSIRIS-REx team has responded by developing robust measures to overcome them,” said Mike Moreau, OSIRIS-REx deputy project manager at Goddard. “If the spacecraft executes a wave-off while attempting to collect a sample, that simply means that both the team and the spacecraft have done their jobs to ensure the spacecraft can fly another day. The success of the mission is our first priority.”
The team is mere months away from a sample collection attempt at the asteroid surface.
Whichever site wins the race, the OSIRIS-REx mission team is ready for whatever new challenges Bennu may bring. Next spring, the team will undertake further reconnaissance flights over the primary and backup sample sites, and will then start spacecraft rehearsals for touchdown. Sample collection is scheduled for summer 2020, and the sample will return to Earth in September 2023.
NASA’s Goddard Space Flight Center in Greenbelt, Maryland provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.
Quelle: NASA
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Update: 6.12.2019
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Now that's an active asteroid
OSIRIS-Rex catches Bennu throwing rocks around.
View of Bennu ejecting particles from its surface on 6 Jan 2019, created by combining two images taken by the navigation camera onboard OSIRIS-REx.
Scientists poring over data from NASA’s OSIRIS-RExmission are trying to figure out why the near-Earth asteroid Bennu is periodically ejecting rocks the size of ping-pong balls.
The find came “sort of by accident,” says Harold Connolly Jr, a cosmochemist and meteoriticist at Rowan University, US, when another member of the OSRIRIS-REx team noticed “stars” in the spacecraft’s navigation camera, in places where stars aren’t supposed to exist.
“It turns out they weren’t stars; they are particles being ejected from the asteroid. This was an absolutely stunning discovery,” says Connolly, who is co-author of a paper describing the find in the journal Science.
Initially, he says, the team thought they might be seeing the type of activity previously seen on comets. “But this isn’t what we are apparently seeing.”
Comet-like activity should be accompanied by plumes of gas, as well as solid particles, “but if there is gas, we can’t see it. It’s just particles ejecting off the surface.”
Another possible explanation, he says, is that stresses within the asteroid may be mounting to levels where material simply pops out, like popping popcorn.
One way this might happen, is if the asteroid contains claylike minerals that grow as they absorb water from their surroundings.
Or Bennu may be undergoing other stresses from its rapid rotation… or being hit hard enough by micrometeorites to knock rocks off its surface.
With a diameter of only 500 metres, it has a low enough surface gravity that it would be easy for any of these processes to throw rocks off the surface, Connolly says.
Whatever the process, the flying rocks might explain another of Bennu’s mysteries.
Some of the rocks are ejected at speeds fast enough to escape into interplanetary space, but others are ejected at slow enough speeds that they must eventually fall back.
So far, Connolly says, nobody has seen any of these rocks fall back. But they have seen places on the surface where small rocks lie on top of larger ones.
When these were first spotted, it was assumed that they were merely rocks that had rolled down from a higher surface. But that may not be the only reason.
The find is interesting, he says, partly because such activity wasn’t expected on a near-Earth asteroid like Bennu. But if that turns out to be common, he adds, it might explain how meteorites from such asteroids reach Earth.
It also shows that near-Earth asteroids can be quite dynamic. “There’s geological activity happening on them that is causing material to be ejected and lost over time, and that’s pretty cool,” he says.
Jessica Agarwal of Max Planck Institute for Solar System Research in Germany, who was not part of the study team but is the author of a commentary in Science, notes that the find is also important for helping to avert potential threats from Earth-impacting asteroids.
“This finding will ultimately help us to better understand the properties and composition of Bennu's material,” she says, “which is important to understanding how asteroids and the solar system formed, and to developing efficient strategies to prevent asteroids from hitting Earth, should one of them be on a collision course.”
OSIRIS-REx is currently orbiting Bennu, searching for a landing site from which it will eventually scoop up a sample for return to Earth.
The modelled trajectories of a subset of particles ejected from Bennu on 19 Jan 2019. CREDIT: LAURETTA ET AL., SCIENCE (2019)
This view of asteroid Bennu ejecting particles from its surface on January 6 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.
Credits: NASA/Goddard/University of Arizona/Lockheed Martin
Shortly after NASA’s OSIRIS-REx spacecraft arrived at asteroid Bennu, an unexpected discovery by the mission’s science team revealed that the asteroid could be active, or consistently discharging particles into space. The ongoing examination of Bennu – and its sample that will eventually be returned to Earth – could potentially shed light on why this intriguing phenomenon is occurring.
The OSIRIS-REx team first observed a particle ejection event in images captured by the spacecraft’s navigation cameras taken on Jan. 6, just a week after the spacecraft entered its first orbit around Bennu. At first glance, the particles appeared to be stars behind the asteroid, but on closer examination, the team realized that the asteroid was ejecting material from its surface. After concluding that these particles did not compromise the spacecraft’s safety, the mission began dedicated observations in order to fully document the activity.
“Among Bennu’s many surprises, the particle ejections sparked our curiosity, and we’ve spent the last several months investigating this mystery,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. “This is a great opportunity to expand our knowledge of how asteroids behave.”
After studying the results of the observations, the mission team released their findings in a Science paper published Dec. 6. The team observed the three largest particle ejection events on Jan. 6 and 19, and Feb. 11, and concluded that the events originated from different locations on Bennu’s surface. The first event originated in the southern hemisphere, and the second and third events occurred near the equator. All three events took place in the late afternoon on Bennu.
The team found that, after ejection from the asteroid’s surface, the particles either briefly orbited Bennu and fell back to its surface or escaped from Bennu into space. The observed particles traveled up to 10 feet (3 meters) per second, and measured from smaller than an inch up to 4 inches (10 cm) in size. Approximately 200 particles were observed during the largest event, which took place on Jan. 6.
The team investigated a wide variety of possible mechanisms that may have caused the ejection events, and narrowed the list to three candidates: meteoroid impacts, thermal stress fracturing, and released of water vapor.
Meteoroid impacts are common in the deep space neighborhood of Bennu, and it is possible that these small fragments of space rock could be hitting Bennu where OSIRIS-REx is not observing it, shaking loose particles with the momentum of their impact.
This animation illustrates the modeled trajectories of particles that were ejected from Bennu’s surface on January 19. After ejecting from the asteroid’s surface, the particles either briefly orbited Bennu and fell back to its surface or escaped away from Bennu and into space.
Credits: NASA/Goddard/University of Arizona/Lauretta & Hergenrother et al., Science 10.1126
The team also determined that thermal fracturing is another reasonable explanation. Bennu’s surface temperatures vary drastically over its 4.3-hour rotation period. Although it is extremely cold during the night hours, the asteroid’s surface warms significantly in the mid-afternoon, which is when the three major events occurred. As a result of this temperature change, rocks may begin to crack and break down, and eventually particles could be ejected from the surface. This cycle is known as thermal stress fracturing.
Water release may also explain the asteroid’s activity. When Bennu’s water-locked clays are heated, the water could begin to release and create pressure. It is possible that as pressure builds in cracks and pores in boulders where absorbed water is released, the surface could become agitated, causing particles to erupt.
But nature does not always allow for simple explanations. "It could be that more than one of these possible mechanisms are at play," said Steve Chesley, an author on the paper and Senior Research Scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "For example, thermal fracturing could be chopping the surface material into small pieces, making it far easier for meteoroid impacts to launch pebbles into space."
If thermal fracturing, meteoroid impacts, or both, are in fact the causes of these ejection events, then this phenomenon is likely happening on all small asteroids, as they all experience these mechanisms. However, if water release is the cause of these ejection events, then this phenomenon would be specific to asteroids that contain water-bearing minerals, like Bennu.
Bennu’s activity presents larger opportunities once a sample is collected and returned to Earth for study. Many of the ejected particles are small enough to be collected by the spacecraft’s sampling mechanism, meaning that the returned sample may possibly contain some material that was ejected and returned to Bennu’s surface. Determining that a particular particle had been ejected and returned to Bennu might be a scientific feat similar to finding a needle in a haystack. The material returned to Earth from Bennu, however, will almost certainly increase our understanding of asteroids and the ways they are both different and similar, even as the particle ejection phenomenon continues to be a mystery whose clues we’ll also return home with in the form of data and further material for study.
Sample collection is scheduled for summer 2020, and the sample will be delivered to Earth in September 2023.
NASA’s Goddard Space Flight Center in Greenbelt, Maryland provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.
Quelle: NASA
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Update: 13.12.2019
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NASA selects site where probe will attempt to collect samples of an asteroid
NASA's OSIRIS-REx science probe, orbiting a small asteroid called Bennu for the past year, will move in for an attempt to snag rock and soil samples next summer, targeting a site known as Nightingale that offers the best balance of risk and science return, mission managers announced Thursday.
It will not be easy. A towering mound of boulders half-jokingly dubbed "Mount Doom" rears up just to one side of the sample site, an obstruction that will require OSIRIS-REx to execute an extremely precise touch-and-go approach
NASA's OSIRIS-REx probe will attempt to collect surface samples from asteroid Bennu next year at a site known as Nightingale that offers the best science return. A backup site - Osprey - is available if needed.NASA
"It's a substantial, building-size obstruction, and we're trying to get into a crater that's on the order of a few parking lot spaces wide," said Dante Lauretta, the OSIRIS-REx principal investigator at the University of Arizona.
"So we are doing a really tight job parking, and we're aware that we have hazards around us. So precision navigation to that sample material is our biggest challenge."
Engineers have developed software that will enable OSIRIS-REx to abort an approach to Nightingale if it turns out the probe cannot safely reach its target. If an abort stirs up rocks and prevents a second attempt, the spacecraft will move to a backup site known as Osprey.
Either way, Lauretta is confident OSIRIS-REx will succeed in the end, bringing samples of Bennu back to Earth in 2023.
"Just thinking that we're going to get this sample back to Earth sends chills down my spine," he said during an update from the American Geophysical Union's fall meeting in San Francisco.
OSIRIS-REx — the convoluted acronym stands for Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer — was launched in September 2016 and slipped into orbit around Bennu late last year.
Since then, it has been using an advanced camera, two mineral sniffing spectrometers, a laser altimeter and a student-managed X-ray imaging system to map Bennu's surface in extraordinary detail. The asteroid is slightly wider than the Empire State Building is tall with a diameter of about 1,614 feet and a mass is estimated at about 85.5 million tons.
OSIRIS-REx is equipped with a "Touch-and-Go Sample Acquisition Mechanism," or TAGSAM, on the end of a 10-foot-long robot arm. The collect samples, the probe will creep up to Bennu, pressing the pie pan-shaped TAGSAM collector against the asteroid's surface for about five seconds before backing away.
On contact with the surface, a jet of nitrogen gas will stir up soil and small rocks that will then be captured by TAGSAM. The material will be placed in a sample return container for a two-and-a-half-year flight back to Earth. Landing in Utah is expected in September 2023.
For TAGSAM to work properly, mission planners hoped to find relatively smooth areas, free of large rocks and obstructions.
"When we first got there, the most obvious feature that we saw were these abundant, very large boulders and overall a rough and rugged surface very different than what we designed the spacecraft to sample," Lauretta said.
"We were (planning for) sampling areas that were 25 meters (80 feet) across, and quite honestly, I thought it was going to be obvious from the first images where the sample regions were and that it was going to be a straightforward site selection. And it was nothing of the sort."
An oblique view of the Nightingale sample site with "Mount Doom" visible at top right.NASA
After mapping Bennu, the team came up with four candidate sample sites. When all was said and done, Nightingale was the winner.
Data visualization of asteroid Bennu and the OSIRIS-REx sample site candidates. Scientists have selected the Nightingale and Osprey locations as the primary and backup sampling sites, respectively. Credit: NASA/Goddard/University of Arizona/CSA/York University/MDA
"We recognize that this does have some hazards around it, and so we are doing a lot of work to make sure that we're targeting the safe regions," said Lauretta. "But this one really came out on top because of the scientific value.
"The high latitudes means that it stays relatively cool, and the primary objective of OSIRIS-REx is to bring back organic material and water-bearing material from the early solar system. Being in those high latitudes gives us the best chance to preserve that kind of material."
Quelle: CBS News
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Update: 15.12.2019
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X Marks the Spot: NASA Selects Site for Asteroid Sample Collection
This image shows sample site Nightingale, OSIRIS-REx’s primary sample collection site on asteroid Bennu. The image is overlaid with a graphic of the OSIRIS-REx spacecraft to illustrate the scale of the site.
Credits: NASA/Goddard/University of Arizona
Editor's Note: The size of Nightingale crater was corrected Dec. 12, 2019 to be 460 feet (140 meters) wide.
After a year scoping out asteroid Bennu’s boulder-scattered surface, the team leading NASA’s first asteroid sample return mission has officially selected a sample collection site.
The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-Rex) mission team concluded a site designated “Nightingale” – located in a crater high in Bennu’s northern hemisphere – is the best spot for the OSIRIS-REx spacecraft to snag its sample.
The OSIRIS-REx team spent the past several months evaluating close-range data from four candidate sites in order to identify the best option for the sample collection. The candidate sites – dubbed Sandpiper, Osprey, Kingfisher, and Nightingale – were chosen for investigation because, of all the potential sampling regions on Bennu, these areas pose the fewest hazards to the spacecraft’s safety while still providing the opportunity for great samples to be gathered.
“After thoroughly evaluating all four candidate sites, we made our final decision based on which site has the greatest amount of fine-grained material and how easily the spacecraft can access that material while keeping the spacecraft safe,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona in Tucson. “Of the four candidates, site Nightingale best meets these criteria and, ultimately, best ensures mission success.”
Site Nightingale is located in a northern crater 460 feet (140 meters) wide. Nightingale’s regolith – or rocky surface material – is dark, and images show that the crater is relatively smooth. Because it is located so far north, temperatures in the region are lower than elsewhere on the asteroid and the surface material is well-preserved. The crater also is thought to be relatively young, and the regolith is freshly exposed. This means the site would likely allow for a pristine sample of the asteroid, giving the team insight into Bennu’s history.
Although Nightingale ranks the highest of any location on Bennu, the site still poses challenges for sample collection. The original mission plan envisioned a sample site with a diameter of 164 feet (50 meters). While the crater that hosts Nightingale is larger than that, the area safe enough for the spacecraft to touch is much smaller – approximately 52 feet (16 meters) in diameter, resulting in a site that is only about one-tenth the size of what was originally envisioned. This means the spacecraft has to very accurately target Bennu’s surface. Nightingale also has a building-size boulder situated on the crater’s eastern rim, which could pose a hazard to the spacecraft while backing away after contacting the site.
The mission also selected site Osprey as a backup sample collection site. The spacecraft has the capability to perform multiple sampling attempts, but any significant disturbance to Nightingale’s surface would make it difficult to collect a sample from that area on a later attempt, making a backup site necessary. The spacecraft is designed to autonomously “wave-off” from the site if its predicted position is too close to a hazardous area. During this maneuver, the exhaust plumes from the spacecraft’s thrusters could potentially disturb the surface of the site, due to the asteroid’s microgravity environment. In any situation where a follow-on attempt at Nightingale is not possible, the team will try to collect a sample from site Osprey instead.
"Bennu has challenged OSIRIS-REx with extraordinarily rugged terrain," said Rich Burns, OSIRIS-REx project manager at NASA’s Goddard Space Flight Center. "The team has adapted by employing a more accurate, though more complex, optical navigation technique to be able to get into these small areas. We'll also arm OSIRIS-REx with the capability to recognize if it is on course to touch a hazard within or adjacent to the site and wave-off before that happens."
With the selection of final primary and backup sites, the mission team will undertake further reconnaissance flights over Nightingale and Osprey, beginning in January and continuing through the spring. Once these flyovers are complete, the spacecraft will begin rehearsals for its first "touch-and-go" sample collection attempt, which is scheduled for August. The spacecraft will depart Bennu in 2021 and is scheduled to return to Earth in September 2023.
NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.
Quelle: NASA
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Update: 24.01.2020
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Status Report: OSIRIS-REx Completes Closest Flyover of Sample Site Nightingale
Preliminary results indicate that NASA’s OSIRIS-REx spacecraft successfully executed a 0.4-mile (620-m) flyover of site Nightingale yesterday as part of the mission’s Reconnaissance B phase activities. Nightingale, OSIRIS-REx’s primary sample collection site, is located within a crater high in asteroid Bennu’s northern hemisphere.
To perform the pass, the spacecraft left its 0.75-mile (1.2-km) safe home orbit and flew an almost 11-hour transit over the asteroid, aiming its science instruments toward the 52-ft (16-m) wide sample site before returning to orbit. Science observations from this flyover are the closest taken of a sample site to date.
During the OSIRIS-REx Reconnaissance B flyover of primary sample collection site Nightingale, the spacecraft left its safe-home orbit to pass over the sample site at an altitude of 0.4 miles (620 m). The pass, which took 11 hours, gave the spacecraft’s onboard instruments the opportunity to take the closest-ever science observations of the sample site.
Credits: NASA/Goddard/University of Arizona
The primary goal of the Nightingale flyover was to collect the high-resolution imagery required to complete the spacecraft’s Natural Feature Tracking image catalog, which will document the sample collection site’s surface features – such as boulders and craters. During the sampling event, which is scheduled for late August, the spacecraft will use this catalog to navigate with respect to Bennu’s surface features, allowing it to autonomously predict where on the sample site it will make contact . Several of the spacecraft’s other instruments also took observations of the Nightingale site during the flyover event, including the OSIRIS-REx Thermal Emissions Spectrometer (OTES), the OSIRIS-REx Visual and InfraRed Spectrometer (OVIRS), the OSIRIS-REx Laser Altimeter (OLA), and the MapCam color imager.
A similar flyover of the backup sample collection site, Osprey, is scheduled for Feb. 11. Even lower flybys will be performed later this spring – Mar. 3 for Nightingale and May 26 for Osprey – as part of the mission’s Reconnaissance C phase activities. The spacecraft will perform these two flyovers at an altitude of 820 feet (250 m), which will be the closest it has ever flown over asteroid Bennu’s surface.
Quelle: NASA
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Update: 16.02.2020
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Status Update: OSIRIS-REx Osprey Flyover
On Feb. 11, NASA’s OSIRIS-REx spacecraft safely executed a 0.4-mile (620-m) flyover of the backup sample collection site Osprey as part of the mission’s Reconnaissance B phase activities. Preliminary telemetry, however, indicates that the OSIRIS-REx Laser Altimeter (OLA) did not operate as expected during the 11-hour event. The OLA instrument was scheduled to provide ranging data to the spacecraft’s PolyCam imager, which would allow the camera to focus while imaging the area around the sample collection site. Consequently, the PolyCam images from the flyover are likely out of focus.
The other science instruments, including the MapCam imager, the OSIRIS-REx Thermal Emissions Spectrometer (OTES), and the OSIRIS-REx Visual and InfraRed Spectrometer (OVIRS), all performed nominally during the flyover. These instruments and the spacecraft continue in normal operations in orbit around asteroid Bennu.
The mission team is currently reviewing the available data from the flyover in order to fully assess the OLA instrument. The entire data set from the flyover, including the PolyCam images, will be completely downlinked from the spacecraft next week and will provide additional insight into any impact that the loss of the OLA data may have.
OLA has already completed all of its principal requirements for the OSIRIS-REx mission. Last year, OLA’s scans of Bennu’s surface were used to create the high-resolution 3D global maps of Bennu’s topography that were crucial for selecting the primary and backup sample collection sites last fall.
Quelle: NASA
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The OSIRIS-REx spacecraft Canadian built laser altimeter may have a failed component
NASA and the Canadian Space Agency reported yesterday that preliminary data sent back from the OSIRIS-REx spacecraft indicates that the Canadian built OSIRIS-REx Laser Altimeter (OLA) did not perform as expected on its latest usage.
The spacecraft had completed a flyover of the Osprey backup sample site on February 11 as part of the Reconnaissance B phase activities and had returned partial data which indicated a problem with OLA.
OSIRIS-REx – Asteroid Bennu sample site finalists. Credit: NASA.
The flight unit of OLA, the Canadian Space Agency’s contribution to NASA’s OSIRIS-REx mission. OLA consists of two parts: an electronics box (left) and the sensor head (right) housing two lasers that fire short laser pulses and a receiver to capture the beam that will bounce back from the surface of the asteroid Bennu. Credit: NASA / Goddard / Debora McCallum.
The colors represent the distance from the center of Bennu: dark blue areas lie approximately 197 feet (60 meters) lower than peaks indicated in red. Some parts of the asteroid have not yet been measured, which creates gaps in the image. OLA will take nearly a billion more measurements throughout 2019 to complete the first-ever high-resolution 3D lidar map of a near-Earth asteroid. Credit: NASA.
Data visualization of asteroid Bennu and the OSIRIS-REx sample site candidates. Scientists have selected the Nightingale and Osprey locations as the primary and backup sampling sites, respectively. Credit: NASA/Goddard/University of Arizona/CSA/York University/MDA
