The spacecraft OSIRIS-REx yesterday made its closest reconnaissance yet of the asteroid Bennu, sweeping past its primary touch-and-go landing site Nightingale by a distance of only 820 feet.

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

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

The touch-and-go sample grab is targeted to take place in August.

Click for full image.

The OSIRIS-REx science team today released one of the images taken during the spacecraft’s recent close reconnaissance of its secondary touch-and-go landing site on the asteroid Bennu.

I have cropped their oblique image to focus, in full resolution, on that landing site, dubbed Osprey, which is the crater on the left side of the photo. The boulder in that crater “is 17 ft (5.2 m) long, which is about the length of a box truck.”

After the fly-by, the science team had announced that the spacecraft’s laser altimeter had failed to operate, and the images taken by its highest resolution camera (not the camera that took today’s image) “are likely out of focus.”

Based on this image, what look like tiny pebbles inside the crater are actually boulders ranging in size from mere inches to as much as five feet across. If their high resolution images are soft, it will thus be hard to map out the terrain sufficiently to safely make a touch-and-go landing here.

More important, there is still no word on whether they have fixed the laser altimeter. Without it I suspect a landing will be very difficult, if not impossible.

During its close fly-over of its secondary candidate touch-and-go landing site on the asteroid Bennu, OSIRIS-REx’s laser altimeter failed to work as planned.

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.

They are analyzing their data to figure out what went wrong and whether it can be fixed. The press release implies that this loss will not impact the touch-and-go at the primary landing site, but does not say so directly. Without the laser altimeter I wonder, how they will know their exact distance as they approach?

Then again, they have not yet downloaded the full dataset from the fly-over, so they might be able to get the instrument working again.

OSIRIS-REx has successfully completed the first of a series of increasingly closer fly-overs of its primary sample grab sites on the asteroid Bennu.

The spacecraft got as close as about 2,000 feet in order to take more high resolution images of the Nightingale landing site where they hope in August to do a touch-and-go sample grab.

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.

Click for full image.

OSIRIS-REx has completed its high resolution reconnaissance of the four candidate sites on the asteroid Bennu, chosen for possible sample capture during touch-and-go operations planned for the summer of 2020.

In the next few days the science team will decide which of these four sites, shown above, will be the primary and back-up landing locations. The decision however appears challenging, based on the information gathered.

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.

Based on the information at the link, plus the presentation by Dante Lauretta, OSIRIS-REx’s principal investigator, given at the asteroid conference I attended in November, I suspect that Nightingale will be primary landing site.

Regardless, it appears the science team has recognized that the landing will difficult, and will likely require multiple attempts before the spacecraft’s navigation system lets it happen.

The OSIRIS-REx engineering team has released a short video that flies over in close-up, showing the spacecraft’s four candidate sites on the asteroid Bennu, one of which will be where they will do a touch-and-go sample grab.

They continue to accumulate data on the four sites, all of which pose issues and risks because of nearby boulders and the looseness of Bennu’s rubble pile make-up.

Though all the sites are being considered, my sources in the industry suggest that the two dubbed Sandpiper and Nightingale are being favored. I like Osprey, because it is inside a crater and looks clear, but then, what do I know?

After months of photographing and analyzing the very rocky-shrewn surface of the rubble-pile asteroid Bennu, the OSIRIS-REx team has chosen four finalist sites, one of which they will do a touch-and-go sample grab.

This fall, OSIRIS-REx will begin detailed analyses of the four candidate sites during the mission’s reconnaissance phase. During the first stage of this phase, the spacecraft will execute high passes over each of the four sites from a distance of 0.8 miles (1.29 km) to confirm they are safe and contain sampleable material. Closeup imaging also will map the features and landmarks required for the spacecraft’s autonomous navigation to the asteroid’s surface. The team will use the data from these passes to select the final primary and backup sample collection sites in December.

The second and third stages of reconnaissance will begin in early 2020 when the spacecraft will perform passes over the final two sites at lower altitudes and take even higher resolution observations of the surface to identify features, such as groupings of rocks that will be used to navigate to the surface for sample collection. OSIRIS-REx sample collection is scheduled for the latter half of 2020, and the spacecraft will return the asteroid samples to Earth on Sept. 24, 2023.

They given the four sites the names Nightingale, Kingfisher, Osprey and Sandpiper.

Click for full image.

The OSIRIS-REx science team today released one of the first images taken of Bennu after the spacecraft lowered itself into its closest orbit in early June. I have reduced and cropped slightly that image slightly to post here on the right. As they note,

From the spacecraft’s vantage point in orbit, half of Bennu is sunlit and half is in shadow. Bennu’s largest boulder can also be seen protruding from the southern hemisphere. The image was taken from a distance of 0.4 miles (690 m) above the asteroid’s surface by NavCam 1, one of three navigation cameras that comprise the spacecraft’s TAGCAMS (the Touch-and-Go Camera System) suite. At this distance, details as small as 1.6 ft (0.5 m) across can be resolved in the center of the image.

In other words, if a person was moving across the asteroid’s surface you could see them.

OSIRIS-REx has moved into its next phase of research by lowering its orbit around the asteroid Bennu to only 2,231 feet above the surface.

Upon arrival at Bennu, the team observed particles ejecting into space from the asteroid’s surface. To better understand why this is occurring, the first two weeks of Orbital B will be devoted to observing these events by taking frequent images of the asteroid’s horizon. For the remaining five weeks, the spacecraft will map the entire asteroid using most of its onboard science instruments: the OSIRIS-REx Laser Altimeter (OLA) will produce a full terrain map; PolyCam will form a high-resolution, global image mosaic; and 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. All of these measurements are essential for selecting the best sample collection site on Bennu’s surface.

The goal is to narrow to four the possible touch-and-go landing sites for grabbing a surface sample. They will pick the final choice in a reconnaissance phase now scheduled for the fall.

The present research phase will last until the middle of August, when they will raise the orbit slightly to give them a different perspective of its surface and the particles being released from it.

Click for full image.

Cool image from OSIRIS-REx. The picture on the right, cropped to post here, was taken by OSIRIS-REx and shows a square boulder about the size of a 15-passenger van, precariously perched on the rim of a large crater on the asteroid Bennu. The picture was taken April 11 from about 2.9 miles distance.

This scale is human-sized. If that rock is a 15 passenger van, then the small rocks around it are about the size of a person and that cliff is about 20-30 feet high. I can imagine strolling down the slope to check out the cliff face, though I would make sure I gave a wide berth to the part of the cliff directly below that boulder.

The OSIRIS-REx science team has shifted the spacecraft’s operation into a new phase aimed at carefully mapping the surface of the asteroid Bennu in preparation for an eventual touch-and-go sample grab.

During Detailed Survey: Equatorial Stations phase, the spacecraft’s instruments will make the scientific observations needed to help the team home in on the best location on Bennu to collect a sample of regolith (loose surface material). To obtain these data, the spacecraft will execute a series of slews between Bennu’s north and south poles while taking observations from seven different stations above the equator. These data will be studied to understand the geology of Bennu. The spacecraft will also conduct searches for dust and gas plumes.

During this phase, planned to last through mid-June, they are asking for the public’s help in mapping the surface and its innumerable rocks.

For this effort, NASA is partnering with CosmoQuest, a project run out of the Planetary Science Institute that supports citizen science initiatives. Volunteers will perform the same tasks that planetary scientists do – measuring Bennu’s boulders and mapping its rocks and craters – through the use of a simple web interface. They will also mark other scientifically interesting features on the asteroid for further investigation.

The boulder mapping work involves a high degree of precision, but it is not difficult. The CosmoQuest mapping app requires a computer with a larger screen and a mouse or trackpad capable of making precise marks. To help volunteers get started, the CosmoQuest team provides an interactive tutorial, as well as additional user assistance through a Discord community and livestreaming sessions on Twitch.

Seems like fun!

The OSIRIS-REx science team have released a short movie, compiled from data obtained in November 2018 as the spacecraft was first approaching the asteroid Bennu, that shows the dayside surface temperature and how it changes as the asteroid rotates.

I have embedded the movie below the fold.

Within a distance of only about 850 feet the temperature rises more than 270 degrees, from -99.67 °F to 170.33 °F. This change also occurs at every spot as the asteroid rotates. At dawn it will be that cold, and by noon it will be that hot.
» Read more

Click for full image.

In late March OSIRIS-REx completed its fourth fly-by of the asteroid Bennu. The image on the right, cropped and reduced to post here, was taken when the spacecraft was only 2.1 miles above the surface. If you were standing among these large boulders, we could easily see you.

The image itself shows the asteroid’s southern limb, and thus the shadows are accentuated. This makes it easier to see surface details. Though it is clear once again that Bennu is a pile of boulders and rocks cemented together and floating in space, the photograph also shows that it also has areas where the material is either much larger or fused together more solidly, as shown by the more massive sections in the left center of this picture. We might be looking a very large boulders peeking up from below the surface, or possibly this is the hint of some real bedrock.

The OSIRIS-REx team is continuing the spacecraft’s survey phase, gathering high resolution images in order to compile a detailed map of the surface, prior to planning the touch-and-go sample grab.

The OSIRIS-REx science team today released a global map of Bennu, compiled from images taken in December.

The map is above. It was released with no commentary. In comparing it with this global map of Ryugu, created by the Japanese probe Hayabusa-2, I am struck by how much both asteroids resemble each other.

This fact is in many ways a first. Since the first planetary probes left Earth in the 1960s the one reliable expectation that has consistently proven true is that no planetary object, be it planet, dwarf planet, moon, asteroid, or comet, was going to resemble any other planetary object. Each has been entirely unique, and unique in very startling and obvious ways.

Ryugu and Bennu represent the first planetary objects that actually look pretty much the same. Scientist will of course be able to note differences, but overall these objects clearly belong to a specific class of asteroids, which in this case is the rubble pile.

In a sense, this similarity marks a significant advancement in our knowledge. Up until now, we had observed so few objects that our knowledge base wasn’t large enough to start seeing patterns within our general classifications of planet, asteroid, or comets. That is now finally changing.

Click for full resolution.

The OSIRIS-REx science team has released new high resolution images of one particular area on Bennu’s northern hemisphere. The image on the right, cropped and reduced to post here, shows what they label a “pond of regolith,” seen as the relatively smooth area in the upper left.

This is not literally a pond, but instead is a low-lying spot where smaller particles have settled over time, producing a flattish area that looks, and in some ways, resembles a pond or puddle, only in this case the material isn’t water but fine-grained dust or pebbles.

On March 19 the science team will be presenting their initial results at a special session at the 50th Lunar and Planetary Science Conference in Texas. That same day they will hold a press conference summarizing the most interesting aspects of those results. Stay tuned.

The OSIRIS-REx science team has released two new images of Bennu’s southern hemisphere, taken from orbit. The image on the right is a cropped section of the highest resolution version of a montage of two images. Click on the image to see the entire two-image montage.

These two OpNav images of Bennu’s southern hemisphere, which each have an exposure time of about 1.4 milliseconds, were captured Jan. 17 from a distance of about one mile (1.6 km). They have been cropped and the contrast has been adjusted to better reveal surface features. The large boulder – fully visible in the middle of the left frame and in partial shadow in lower portion of right frame – is about 165 feet (50 meters) across.

The cropped section to the right shows that large boulder in the middle of the frame.

I’m sorry, but when I look at this rubble-pile asteroid I cannot help but think of the cat-litter clumps I remove from our cats’ litter box. The only fundamental difference is that the grains in cat litter are made to be a uniform size, while at Bennu the grains are much coarser and not uniform. Nonetheless, this asteroid is a clump of many grains, just like those cat litter clumps, and will likely crumple easily into a cloud of grains if smacked just hard enough.

This knowledge is actually very critical, as Bennu is a potentially dangerous asteroid with an orbit that might have it impact the Earth in about two hundred years.

OSIRIS-REx has successfully completed an eight second engine burn to place it into a close orbit with the asteroid Bennu.

Now, the spacecraft will circle Bennu about a mile (1.75 kilometers) from its center, closer than any other spacecraft has come to its celestial object of study. (Previously the closest orbit of a planetary body was in May 2016, when the Rosetta spacecraft orbited about four miles (seven kilometers) from the center of the comet 67P/Churyumov-Gerasimenko.) The comfortable distance is necessary to keep the spacecraft locked to Bennu, which has a gravity force only 5-millionths as strong as Earth’s. The spacecraft is scheduled to orbit Bennu through mid-February at a leisurely 62 hours per orbit.

There is a bit of hype here. Other spacecraft have gotten far closer (NEAR, Hayabusa-1, Hayabusa-2) but then retreated for a variety of reasons. What makes this different is the plan to stay this close while they compile detailed data about Bennu’s surface in preparation for touchdown to grab a sample.

Cool movie time! OSIRIS-REx has completed its first planned fly-over of Bennu, this time above its north pole, and the science team has released a short movie showing part of that fly-over. I have embedded the movie below the fold.

This series of MapCam images was taken over the course of about four hours and 19 minutes on Dec. 4, 2018, as OSIRIS-REx made its first pass over Bennu’s north pole. The images were captured as the spacecraft was inbound toward Bennu, shortly before its closest approach of the asteroid’s pole. As the asteroid rotates and grows larger in the field of view, the range to the center of Bennu shrinks from about 7.1 to 5.8 miles (11.4 to 9.3 km).

They have four more fly-overs of the asteroid’s poles and equator as they assemble a detailed map of its surface.
» Read more

One of OSIRIS-REx’s instruments has now found evidence of water on the rubble-pile asteroid Bennu.

Recently analyzed data from NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) mission has revealed water locked inside the clays that make up its scientific target, the asteroid Bennu.

During the mission’s approach phase, between mid-August and early December, the spacecraft traveled 1.4 million miles (2.2 million km) on its journey from Earth to arrive at a location 12 miles (19 km) from Bennu on Dec. 3. During this time, the science team on Earth aimed three of the spacecraft’s instruments towards Bennu and began making the mission’s first scientific observations of the asteroid. OSIRIS-REx is NASA’s first asteroid sample return mission.

Data obtained from the spacecraft’s two spectrometers, the OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) and the OSIRIS-REx Thermal Emission Spectrometer (OTES), reveal the presence of molecules that contain oxygen and hydrogen atoms bonded together, known as “hydroxyls.” The team suspects that these hydroxyl groups exist globally across the asteroid in water-bearing clay minerals, meaning that at some point, Bennu’s rocky material interacted with water. While Bennu itself is too small to have ever hosted liquid water, the finding does indicate that liquid water was present at some time on Bennu’s parent body, a much larger asteroid.

The image on the right, reduced to show here, was created from 12 images taken on December 2, 2018 from about 15 miles. If you click on the image you can see the full resolution photograph, which is quite incredible. While the asteroid’s shape is approximately what was expected from ground-based observations and computer modeling, the giant boulder on the limb on the bottom right is about four times bigger than expected.