Tag: Bennu

Samples from the asteroid Bennu reshape entirely our understanding of the solar system’s early make-up

11:11 am

Nightingale landing site on Bennu
The sample site on Bennu, with OSIRIS-REx
superimposed for scale. Click for full image.

First, I hope my readers will notice that — unlike NASA and the entire press — I make no mention in my headline above of the discovery of a “mix of life’s ingredients” or “the key building blocks of life” from the samples brought back by the probe OSIRIS-REx from the asteroid Bennu.

This is the game NASA does all the time, to hint at the discovery of life when this is not the real discovery. NASA does it because it knows that if you hint at such a discovery, the press will go crazy and give you lots of press.

The real news from the two papers published this week, available here and here, however, is more fundamental. Before the samples from Bennu and Ryugu (brought back by the Japanese probe Hayabusa-2) had arrived, our understanding of the make-up and chemistry of the early solar system was very incomplete and badly biased. The only asteroid samples we had of carbonaceous chondrite asteroids, the most primitive and fragile carbon-rich asteroids in the solar system, had came from meteorites that had survived the journey through the Earth’s atmosphere. Thus, the only material that survived was robust enough to do so. The more fragile molecules however were always destroyed and thus missing from meteorites, even though it was very clear from spectroscopy of these asteroids in the solar system that such molecules did exist, and likely formed the majority of these asteroids’ make-up.

Thus, though carbonaceous chondrite asteroids represent the early solar system, our understanding of them was warped and very incomplete. The whole point of both missions to Bennu and Ryugu was to fill in this data, to get a more complete census of the real make-up of the early solar system.

The two papers published this week have given us that. That’s their real discovery.
» Read more

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Scientists: most asteroids come from a limited number of earlier break-ups

10:04 am

According to three different recently published papers (available here, here, and here), the majority of all meteorites hitting the Earth likely came from a limited number of specific past break-ups of larger asteroids.

New studies show that 70% of the 70,000 meteorites that have been found on Earth have come from 3 recent collisions in the main asteroid belt which sits between the orbits of Mars and Jupiter. The collisions occurred 5.8, 7.5 and 40 million years ago, according to the studies. They correspond to 3 young asteroid “families” known as Karin, Koronis and Massalia. These families formed from the destruction of asteroids at least 30km across.

The 70% number comes from data in the last two papers above, while the first paper claims it is more like 80% of all asteroids. The Massalia family is the most dominate, with it estimated to be the source 37% of all meteorites as well as a major impact half a billion years ago.

The first study also found that both Ryugu and Bennu came from the same event and are part of another family of asteroids called Polana.

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OSIRIS-REx brought home twice as much material from Bennu than planned

10:17 am

The inside of OSIRIS-REx's sample return capsule
The material found inside the sample return
capsule. Click for original image.

Curators cataloging the material returned by OSIRIS-REx’s sample capsule from the asteroid Bennu have now completed weighing the material,l and have discovered that the spacecraft grabbed more than twice as much material from Bennu as planned.

NASA’s OSIRIS-REx spacecraft delivered 4.29 ounces (121.6 grams) of material from asteroid Bennu when it returned to Earth on Sep. 24, 2023; the largest asteroid sample ever collected in space and over twice the mission’s requirement. The mission team needed at least 60 grams of material to meet the mission’s science goals, an amount that had already been exceeded before the Touch-and-Go Sample Acquisition Mechanism (TAGSAM) head was completely opened.

More than 60 grams were recovered outside the capsule that had stuck to it during touch-and-go operations. Once they were able to open the capsule and weigh the material inside, they found it had captured as much stuff, so that in total the mission brought back a double complement of material.

This material will now be distributed to scientists worldwide for study. It is likely that it will overturn almost all assumptions presently held about the make-up of the solar system’s asteroid population, since previous to the recent asteroid sample return missions of OSIRIS-REx and Japan’s Hayabusa-2 our only samples came from material that survived after burning through the Earth’s atmosphere. That journey resulted in an incomplete and biased census, with the most delicate material destroyed.

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Scientists finally look at prime samples captured by OSIRIS-REx of the asteroid Bennu

9:21 pm

The inside of OSIRIS-REx's sample return capsule
Click for original image.

Scientists have finally opened the sample capsule from OSIRIS-REx to see the prime asteroid material obtained from the asteroid Bennu during the spacecraft’s touch-and-go sample grab.

The captured material inside the capsule can be seen in the picture to the right. It is the debris inside the ring.

Erika Blumenfeld, creative lead for the Advanced Imaging and Visualization of Astromaterials (AIVA) and Joe Aebersold, AIVA project lead, captured this photograph of the open TAGSAM head including the asteroid material inside using manual high-resolution precision photography and a semi-automated focus stacking procedure. The result is an image that shows extreme detail of the sample.

Next, the curation team will remove the round metal collar and prepare the glovebox to transfer the remaining sample from the TAGSAM head into pie-wedge sample trays.

The final mass of material will be determined once it is removed and weighed, though the team has already recovered more than 70 grams that had clung to the outside the capsule, which in itself exceeded the mission’s targeted goal.

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Engineers succeed in releasing two fasteners that blocked access to OSIRIS-REx Bennu samples

9:22 am

Using new specially designed tools, engineers have finally succeeded in removing the two fasteners that had prevented them from opening the sample return capsule that holds the bulk of material from the asteroid Bennu that was grabbed by OSIRIS-REx and brought back to Earth.

Curation processors paused disassembly of the TAGSAM head hardware in mid-October after they discovered that two of the 35 fasteners could not be removed with the tools approved for use inside the OSIRIS-REx glovebox.

In response, two new multi-part tools were designed and fabricated to support further disassembly of the TAGSAM head. These tools include newly custom-fabricated bits made from a specific grade of surgical, non-magnetic stainless steel; the hardest metal approved for use in the pristine curation gloveboxes.

The fasterners have been removed, but the sample capsule still needs to be dissassembled before the samples can be accessed and analyzed. It is now expected that by the spring the material will be fully catelogued and available for scientists to study.

In an ironic twist, OSIRIS-REx brought back so much extra material clinging to the outside of that sample return capsule that such research has already begun. In fact, that extra material actually exceeded in weight the minimum amount the mission wanted to capture inside the capsule. What will be found inside the capsule will only add to the mission’s success.

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Stripped screws preventing access to Bennu samples

9:07 am

According to the scientists working to extract the samples from the asteroid Bennu brought back by the OSIRIS-REx sample return capsule, the work has been stymied because of two stripped screws.

Last month, researchers at the Johnson Space Center in Houston, Texas, discovered that two of the 35 screws that fasten the lid of the sample-return canister couldn’t be opened — blocking access to the remainder of the space rock. Curators used tweezers to pull out what they could, but NASA is now making new screwdrivers so it can get into the equipment it flew billions of kilometres across the Solar System to the asteroid Bennu and back.

Because the capsule is kept within a sealed glovebox to prevent the samples from being contaminated by the Earth environment, removing the screws requires NASA to manufacture special screwdrivers that will also not contaminate that environment. This work is what is causing the delay.

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British scientists get their own Bennu sample to study

9:16 am

The British History Museum has now received a small sample of material from the asteroid Bennu, brought back to Earth by the planetary probe OSIRIS-REx.

The first two years of research at the Natural History Museum will focus on non-destructive tests, such as X-ray diffraction and electron microscopy to learn about Bennu’s mineral composition and structure. The largest grains in the sample are on the order of millimetres wide, while the smallest are mere dust particles. “It doesn’t sound like a lot of material, but it’s plenty to work with,” King said.

The museum is home to one of the world’s leading meteorite collections, and the staff are well-used to handling small amounts of extremely precious materials from outer space. Unlike meteorites that have been baked and battered on their fiery passage through Earth’s atmosphere, the dust and rocky fragments from Bennu were brought to Earth in pristine condition, allowing scientists a rare glimpse of the unaltered asteroid.

The last sentence says it all. Up until recently, researchers have had a distorted view of the overall make-up of asteroids because the oldest kinds, carbonaceous chondrite, are the most delicate and get significantly changed by their passage through the Earth’s atmosphere. The samples from Bennu and Ryugu are changing this, and will eventually revolutionize the understanding scientists have of our present solar system.

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First Bennu asteroid samples recovered from OSIRIS-REx return capsule

10:26 am

Scientists have successfully removed the asteroid samples from the OSIRIS-REx return capsule that the spacecraft obtained from the asteroid Bennu in 2020.

What is more exciting is that though they now have slightly more material than the mission hoped to bring back, they haven’t even opened the capsule’s sample compartment.

The curation team processing NASA’s asteroid Bennu sample has removed and collected 2.48 ounces (70.3 grams) of rocks and dust from the sampler hardware – surpassing the agency’s goal of bringing at least 60 grams to Earth.

And the good news is, there’s still more of NASA’s OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) sample to collect.

The sample processed so far includes the rocks and dust found on the outside of the sampler head, as well as a portion of the bulk sample from inside the head, which was accessed through the head’s mylar flap. Additional material remaining inside the sampler head, called the Touch-and-Go Sample Acquisition Mechanism, or TAGSAM, is set for removal later, adding to the mass total.

The large amount of material means there will be plenty to distribute to many scientists for study.

The reason the recovery process is going so slowly is to ensure the samples do not get contaminated by the Earth’s atmosphere. The capsule is inside a glovebox filled with nitrogen. The only way any work can be done is by inserting hands inside gloves that extend into the box. This keeps the samples protected but prevents any direct contact, which makes work slow and difficult.

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OSIRIS-REx Sample from Bennu successfully recovered

10:18 am

Engineers today successfully recovered the asteroid sample capsule from the probe OSIRIS-REx, carrying several grams of material from the potentially dangerous asteroid Bennu.

The samples will be shipped to special facilities to protect the material from being exposed to Earth’s environment when the capsule is opened. It will take several months at least before the first research results are announced.

OSIRIS-REx, now renamed OSIRIS-APEX, now heads for the potentially dangeous asteroid Apophis, where it will orbit that asteroid beginning in 2029, shortly after Apophis makes its next close fly-by of Earth.

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OSIRIS-REx completes last major mid-course correction before sending its sample capsule back to Earth

9:38 am

OSIRIS-REx yesterday completed a 63 second engine burn, successfully aiming the spacecraft so that its September 24th drop off of its sample capsule will hit the Earth as planned.

Preliminary tracking data indicates OSIRIS-REx changed its velocity, which includes speed and direction, by 1.3 miles, or 2 kilometers, per hour. It’s a tiny but critical shift; without course adjustments like this one the spacecraft would not get close enough to Earth on Sept. 24 to drop off its sample of asteroid Bennu. The spacecraft is currently 24 million miles, or 38.6 million kilometers, from Earth, traveling at about 22,000 miles, or about 35,000 kilometers, per hour.

In the two weeks prior to that drop-off the spacecraft will do two more short burns to refine its aim so that the sample capsule will land precisely as planned on the Defense Department’s Utah Test and Training Range near Salt Lake City.

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OSIRIS-REx does mid-course correction

8:36 am

To better refine its path back to Earth in order to properly aim its sample return capsule, engineers had OSIRIS-REx do a short successful 30 second engine burn on September 21, 2022.

Nor will this be the only course correction prior to sample return on September 24, 2023 in Utah.

To ensure a safe delivery, “Over the next year, we will gradually adjust the OSIRIS-REx trajectory to target the spacecraft closer to Earth,” said Daniel Wibben, trajectory-and-maneuver design lead with KinetX Inc. “We have to cross Earth’s orbit at the time that Earth will be at that same location.” Wibben works closely with the Lockheed Martin team in Littleton, Colorado, that flies the spacecraft.

Last month’s maneuver was the first time the OSIRIS-REx team changed the spacecraft’s trajectory since it left Bennu on May 10, 2021. Following this course adjustment, OSIRIS-REx would pass about 1,367 miles (2,200 kilometers) from Earth. A series of maneuvers beginning in July 2023 will bring OSIRIS-REx even closer, to 155 miles (250 kilometers) off the surface, close enough to release its sample capsule for a precision landing – via parachute at the Air Force’s Utah Test and Training Range in the Great Salt Lake Desert.

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OSIRIS-REx’s sample grab at Bennu in 2020 proved the rubble-pile asteroid has far less cohesion than predicted

10:10 am

The post touchdown crater on Bennu

The OSIRIS-REx science team, using data gathered during the spacecraft’s sample grab at Bennu in 2020, has determined that the rubble-pile asteroid has far less cohesion than predicted, with its rubble behaving less like a solid object and more like the playground ball-pits found in amusement parks.

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

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

The image above shows what the touch down crater looked like after the sample grab, taken from the video that was part of the press release. The false colors indicate the depth changes produced by the touch down. The final crater was 26 feet across and more than two feet in depth, far larger than expected. Moreover, the energy from the spacecraft’s thrusters as it lifted off had increased the size of that crater further, by about 40%.

These results about the asteroid’s lack of cohesion match the earlier results studying a different impact crater on Bennu.

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Scientists: Impacts on rubble-pile asteroid are different than on planets

10:27 am

Landslide on Bennu from impact
Click for full image.

Using data collected by OSIRIS-REx at the asteriod Bennu, scientists have determined that the ejecta from impacts on a rubble-pile asteroid behaves in a very different manner than on planets with higher gravity.

Instead of flying away at about the same speed as the impactor and escaping into space, as expected in the weak gravity, the material is lifted up at a very slow speed, falls back down, and then rolls downhill like a landslide. The graphic to the right from the press release, reduced and enhanced to post here, illustrates what the scientists think happened when one of Bennu’s larger craters was created.

[M]ost of that material, called ejecta, returned to the surface and slid down the face of the asteroid, starting a wide avalanche that slowly rolled toward Bennu’s equator. Perry said the only way this could happen on a small object like Bennu, which is less than 500 meters (1,640 feet) in diameter and has low gravity, is if the dust had low or next to no cohesion.

“Because Bennu is so small, its escape velocity is less than a few tenths of a mile per hour, so any particle ejected faster than that would leave the surface,” he said. “These slow speeds are possible only if Bennu’s surface is weaker than we thought, even weaker than very loose, dry sand. This extremely low surface strength also means material on a slope is easily disturbed, and that’s what led to the landslide.”

In other words, the low cohesion prevents the impact’s energy from being transferred efficiently to the asteroid’s particles. They move, but only slowly, and thus end up sliding away more or less along the asteroid’s surface.

This discovery helps explain how these rubble-pile asteroids accumulate material, despite their low gravity.

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OSIRIS-REx scientists refine Bennu’s future Earth impact possibilities

1:28 pm

Using the orbital and gravity data compiled during OSIRIS-REx’s visit to the asteroid Bennu, scientists have refined its future orbits as well as the most likely moments it might impact the Earth.

In 2135, asteroid Bennu will make a close approach with Earth. Although the near-Earth object will not pose a danger to our planet at that time, scientists must understand Bennu’s exact trajectory during that encounter in order to predict how Earth’s gravity will alter the asteroid’s path around the Sun – and affect the hazard of Earth impact.

Using NASA’s Deep Space Network and state-of-the-art computer models, scientists were able to significantly shrink uncertainties in Bennu’s orbit, determining its total impact probability through the year 2300 is about 1 in 1,750 (or 0.057%). The researchers were also able to identify Sept. 24, 2182, as the most significant single date in terms of a potential impact, with an impact probability of 1 in 2,700 (or about 0.037%).

Although the chances of it hitting Earth are very low, Bennu remains one of the two most hazardous known asteroids in our solar system, along with another asteroid called 1950 DA.

This paper’s conclusions are confirming what had been found earlier in the mission, while OSIRIS-REx was still flying in formation with the asteroid. Nonetheless, it is essential to refine these numbers as precisely as possible, so this confirmation is excellent news.

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OSIRIS-REx on its way back to Earth

10:54 pm

OSIRIS-REx today fired its engines and successfully put itself on course for returning its samples from the asteroid Bennu to Earth on September 24, 2023.

The May 10 departure date was precisely timed based on the alignment of Bennu with Earth. The goal of the return maneuver is to get the spacecraft within about 6,000 miles (approximately 10,000 kilometers) of Earth in September 2023. Although OSIRIS-REx still has plenty of fuel remaining, the team is trying to preserve as much as possible for a potential extended mission to another asteroid after returning the sample capsule to Earth. The team will investigate the feasibility of such a mission this summer.

The spacecraft’s course will be determined mainly by the Sun’s gravity, but engineers will need to occasionally make small course adjustments via engine burns.

The science team has already proposed one option, sending the spacecraft on a rendezvous with the potentially dangerous asteroid Apophis shortly after its 2029 close-fly of Earth. It could be that there are other targets as interesting that they need to choose from.

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New OSIRIS-REx photos of Bennu sample site after sample grab

1:40 pm

Nightingale before and after sample grab
Click here and here for original images.

The OSIRIS-REx science team today released the photos the spacecraft obtained in its last fly-by of the asteroid Bennu on April 7th of the Nightngale sample site, showing how it changed after the sample grab in October 2020.

The two photos to the right compare that site, with the top image taken before the sample grab and the bottom image taken on April 7th.

Comparing the two images reveals obvious signs of surface disturbance. At the sample collection point, there appears to be a depression, with several large boulders evident at the bottom, suggesting that they were exposed by sampling. There is a noticeable increase in the amount of highly reflective material near the TAG [touch-and-go] point against the generally dark background of the surface, and many rocks were moved around.

Where thrusters fired against the surface, substantial mass movement is apparent. Multiple sub-meter boulders were mobilized by the plumes into a campfire ring–like shape — similar to rings of boulders seen around small craters pocking the surface.

Jason Dworkin, the mission’s project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, noticed that one boulder measuring 4 feet (1.25 meters) across on the edge of the sampling site seemed to appear only in the post-TAG image. “The rock probably weighs around a ton, with a mass somewhere between a cow and a car.”

Dante Lauretta, of the University of Arizona and the mission’s principal investigator, later pointed out that this boulder is likely one of those present in the pre-TAG image, but much nearer the sampling location, and estimates it was thrown a distance of 40 feet (about 12 meters) by the sample collection event.

The sample grab arm penetrated the surface by more than a foot, and that event is marked by that dark depression at the center of the site.

OSIRIS-REX will now prepare for its May 10th engine firing that will send it on its route back to Earth to return that sample in September 24, 2023. After that the spacecraft could be sent on another mission, this time to the potentially dangerous asteroid Apophis.

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OSIRIS-REx completes last close-fly of Bennu

12:39 pm

OSIRIS-REx today successfully completed its last close-fly of Bennu before it will fire its engines on May 10th and begin its journey back to Earth to return its samples.

During the flyby, OSIRIS-REx imaged Bennu for 5.9 hours, covering more than a full rotation of the asteroid. It flew within 2.1 miles’ (3.5 kilometers) distance to the surface of Bennu – the closest it’s been since the TAG sample collection event.

It will take until at least April 13 for OSIRIS-REx to downlink all of the data and new pictures of Bennu’s surface recorded during the flyby. It shares the Deep Space Network antennas with other missions like Mars Perseverance, and typically gets 4–6 hours of downlink time per day. “We collected about 4,000 megabytes of data during the flyby,” said Mike Moreau, deputy project manager of OSIRIS-REx at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Bennu is approximately 185 million miles from Earth right now, which means we can only achieve a downlink data-rate of 412 kilobits per second, so it will take several days to download all of the flyby data.”

While they will get images of the asteroid’s entire surface, the region scientists are most interested in is the Nightingale sample return site where the spacecraft grabbed its samples. To best understand the asteroid they need to have before and after shots, and this last fly-by gave them the latter.

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OSIRIS-REx begins last approach of Bennu

9:12 am

Approaching Bennu for the last time
Click for full image.

The science team for OSIRIS-REx released today the first picture taken as the spacecraft begins its last approach of the asteroid Bennu. To the right is that picture, cropped and expanded to post here. From the caption:

This image shows a top-down view of asteroid Bennu, with a portion of the asteroid’s equatorial ridge and northern hemisphere illuminated. It was taken by the PolyCam camera on NASA’s OSIRIS-REx spacecraft on March 4, from a distance of about 186 miles (300 km). The spacecraft’s cameras are pointed directly at Bennu’s north pole. Two large equatorial craters are visible on the asteroid’s edge (center and center left).

If all goes well, the probe will fly past the asteroid on April 7th, obtaining high resolution images of its entire surface as it rotates below, including very close-up images of the Nightingale sample grab location during its closest approach.

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OSIRIS-REx has begun its return to Bennu

2:17 pm

On January 14th the OSIRIS-REx team fired the spacecraft’s engines to halt its drift away from the asteroid Bennu and begin its return for one last reconnaissance before heading to Earth with its samples.

OSIRIS-REx executed the first maneuver on Jan. 14, which acted as a braking burn and put the spacecraft on a trajectory to rendezvous with the asteroid one last time. Since October’s sample collection event, the spacecraft has been slowly drifting away from the asteroid, and ended up approximately 1,635 miles (2,200 km) from Bennu. After the braking burn, the spacecraft is now slowly approaching the asteroid and will perform a second approach maneuver on Mar. 6, when it is approximately 155 miles (250 km) from Bennu. OSIRIS-REx will then execute three subsequent maneuvers, which are required to place the spacecraft on a precise trajectory for the final flyby on Apr. 7.

OSIRIS-REx is scheduled to depart Bennu on May 10 and begin its two-year journey back to Earth. The spacecraft will deliver the samples of Bennu to the Utah Test and Training Range on Sep. 24, 2023.

While they will gather images of the whole asteroid, their number one goal will be to get high resolution photos of the sample-grab site Nightingale to see how it was changed by that sample grab. The spacecraft pushed into the asteroid’s rubble pile about 1.6 feet, and that act certainly disturbed both the interior and surface. By comparing the before and after pictures scientists can garner a lot of information about the asteroid’s make-up, density, and structure. It will also teach future engineers what to expect when next they try to touch another rubble-pile asteroid.

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OSIRIS-REx to make one last observation of Bennu before heading back to Earth

10:56 am

The OSIRIS-REx science team has figured out a way to make one last observation of Bennu and the Nightingale sample return site before heading back to Earth on May 10th.

This activity was not part of the original mission schedule, but the team is studying the feasibility of a final observation run of the asteroid to potentially learn how the spacecraft’s contact with Bennu’s surface altered the sample site. If feasible, the flyby will take place in early April and will observe the sample site, named Nightingale, from a distance of approximately 2 miles (3.2 kilometers). Bennu’s surface was considerably disturbed after the Touch-and-Go (TAG) sample collection event, with the collector head sinking 1.6 feet (48.8 centimeters) into the asteroid’s surface. The spacecraft’s thrusters also disturbed a substantial amount of surface material during the back-away burn.

The mission is planning a single flyby, mimicking one of the observation sequences conducted during the mission’s Detailed Survey phase in 2019. OSIRIS-REx would image Bennu for a full rotation to obtain high-resolution images of the asteroid’s northern and southern hemispheres and equatorial region. The team would then compare these new images with the previous high-resolution imagery of Bennu obtained during 2019.

Getting at look at Nightingale post-sample-grab is critical to better understanding the nature of the asteroid. Knowing how much changed from that contact will tell scientists a lot about the density, interior, and surface of this rubble-pile asteroid.

This last flyby will also give them the chance to assess the spacecraft’s equipment following the touch-and-go sample grab. They want to know if everything still works as designed in order to plan any post-Bennu missions, including the possibility that OSIRIS-REx will rendezvous with the asteroid Apophis in ’29, shortly after the asteroid makes its next close flyby of Earth.

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Another movie of OSIRIS-REx’s sample-grab-and-go at Bennu

10:08 am

The OSIRIS-REx science team has released another movie showing the sample-grab-and-go at Bennu, this time from a different camera.

The movie, made up of 189 images taken over three hours by the spacecraft’s navigation camera NavCam-2, can be seen at the link.

In the middle of the sequence, the spacecraft slews, or rotates, so that NavCam 2 looks away from Bennu, toward space. OSIRIS-REx then performs a final slew to point the camera (and the sampling arm) toward the surface again.

As the spacecraft nears site Nightingale, the sampling arm’s shadow comes into view in the lower part of the frame. Shortly after, the sampling head impacts site Nightingale (just outside the camera’s field of view to the upper right) and fires a nitrogen gas bottle, which mobilizes a substantial amount of the sample site’s material. Several seconds later, the spacecraft performs a back-away burn and the sampling arm’s shadow is visible against the disturbed surface material.

The team continues to investigate what caused the extremely dark areas visible in the upper and middle parts of the frame. The upper area could be the edge of the depression created by the sampling arm, a strong shadow cast by material lofted from the surface, or some combination of the two. Similarly, the middle dark region that first appears in the lower left of the image could be a depression caused by one of the spacecraft thrusters as it fired, a shadow caused by lofted material, or a combination of both.

It strikes me that getting post impact images of Nightingale is essential, if at all possible.

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OSIRIS-REx completes storage of Bennu sample

2:33 pm

OSIRIS-REx has now completed placing its sample from the asteroid Bennu in the Sample Return Capsule that will bring it back to Earth.

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

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

Because they decided it was better to store the sample immediately and not risk losing it, they were unable to do the spin test that would told them how much sample they obtained. For this reason we will not know the amount until the sample capsule is opened here on Earth, after its return on September 24, ’23.

UPDATE: You can watch if short movie of the Sample Return Capsule closing here.

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OSIRIS-REx engineers successfully place sample collector in return capsule

7:55 am

Stowing OSIRIS-REx's sample from Bennu
Click for full image.

OSIRIS-REx engineers have successfully placed the sample collector head holding the material captured from the asteroid Bennu in the return capsule that will bring it back to Earth.

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

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

The next step will be to seal the capsule for return to Earth. However, based on the two images above, the sample is now relatively secure, as the opening where material could escape is now held face down in the capsule.

The spacecraft will head back to Earth in March ’21, with the sample capsule landing on Earth on September 24, 2023. I do not know whether it will be possible in the next six months to get new images of the Nightingale touch-and-go site, but have emailed Erin Morton, head of the communications for the science team, and asked. I will update this post when I hear back from her.

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OSIRIS-REx sample grab so successful they are losing material

2:47 pm

The samples from Bennu
Click for full two frame gif movie.

In a briefing today and press release, the OSIRIS-REx science team announced that they estimate that they have gathered a lot of material from the asteroid Bennu, at least 100s of grams, about twice the minimum of what they hoped to get.

In fact, images of the TAGSAM sample grab equipment suggest that there are some larger rocks lodged in its opening (preventing the flap from closing), and that the small movements they have done to photograph it has caused some of the captured material to escape. The image to the right shows this. You can see floating specks and their shadows (the horizontal streaks) that have escaped. At about 9 o’clock you can see a curve in the contact between a lighter material and blackness to its outside, bending towards the center of the TAGSAM. At other exposures they can clearly see a rock there, distorting the shape and thus preventing the flap from closing properly.

Because of this, they are foregoing the spin maneuver that would have weighed the sample, as well as one engine burst that would have slowed the spacecraft’s movement away from Bennu.

This means they will not know the exact amount captured until the sample gets back to Earth. This is a gamble, but they are confident that they have gotten a lot of material. According to Dante Lauretta, the principal investigator, the sample grab-and-go “got very down” into Bennu, as much as 19 inches. He is also confident that they grabbed more than a 100 grams.

They are therefore going to as quickly as possible store the samples in the Sample Return Capsule for return to Earth, beginning on October 27. They need to do a complex series of steps to make this happen, which is why it cannot happen until then.

One more detail: In their simulations prior to the touch-and-go, they had a range of estimates of how deep the spacecraft would penetrate. According to Lauretta, OSIRIS-REx plunged into Bennu at the softest part of that range, telling them that the asteroid is probably much more loosely packed than expected.

Because they are not doing that last engine burst means that they are moving away from Bennu for good. They will not return to the asteroid. Whether they will be able to get post sample grab images of Nightingale is unknown.

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Images taken during OSIRIS-REx sample grab on Bennu

3:40 pm

Below is an embed of a short eight second video of OSIRIS-REx’s sample grab yesterday from the surface of Bennu, created from 82 images, and covering at high speed the five minutes of approach, contact, and retreat. If you set the speed rate at 0.25, you can get a better view of the whole sequence of events.

From the science team’s press release,

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

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

At the moment it appears they don’t yet know how much sample they have gotten, but they are very optimistic that they have gotten enough, based on the performance above. On October 24th, when they have gotten far enough away from the asteroid, they give the spacecraft a spin to measure its present mass and compare that to a spin done prior to the sample grab. The difference will tell them how much sample they have captured.

They will also be looking at images of TAGSAM over the next few days, which will also indicate what’s been captured.

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Sample grab appears to be a success at Bennu

3:17 pm

OSIRIS-REx has apparently successfully touched the surface of Bennu, grabbed a sample, and backed away without damage.

The link takes you to my embed of NASA’s live stream, which is mostly pr garbage. However, it is providing live updates from the mission control team, as it happens. Most of time, the NASA people running their pr effort even have the sense to shut up when such updates come it.

Right now we do not know how much of a sample was obtained. It will take some analysis of data and images to find out. They will know by the time of tomorrow’s press conference at 5 pm (Eastern).

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Today’s OSIRIS-REx sample grab from Bennu

10:28 am

Nightingale landing site on Bennu
The Nightingale landing site on Bennu, with
OSIRIS-REx superimposed. Click for full image.

Spaceflight Now today published a nicely detailed article summarizing the entire OSIRIS-REx mission to the asteroid Bennu, in anticipation of today’s attempt to grab a sample from that asteroid’s surface.

If you want to understand what is happening today, this article does a nice job of outlining everything.

I have embedded the live stream of the sample grab below the fold. It begins at 5 pm (Eastern) today. Be warned that it will show very little of the actual event, as the spacecraft will not be sending much data back to Earth today, during these operations. All we will really find out is if the grab happened, or was aborted to avoid risks, or occurred but the spacecraft was impacted by flying material during the grab. (Let us hope that this last option does not occur.)

The first images and data will not arrive until tomorrow, to be released during a press conference scheduled for 5 pm (Eastern).
» Read more

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NASA announces broadcast schedule for OSIRIS-REx’s sample grab at Bennu

6:32 pm

NASA today announced the broadcast schedule that will be available to the public of OSIRIS-REx’s sample grab at the asterod Bennu on October 20, 2020.

Much of the schedule is NASA’s public relations blather, filled with some good information intermixed with a lot of lobbying for the government agency. Much of it will also be the equivalent of watching paint dry, as nothing will be happening quickly.

However, if you wish to watch the important part, tune into NASA TV from 5 to 6:30 p.m on October 20th.

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

This will be on the public feed. If you find yourself choking on the NASA hype, you can then switch over to the media feed, which will be “A clean feed of the Mission Support Area during TAG [touch-and-go].”

Regardless, the actual attempt will be heart-stopping, because there is a real chance flying rocks from the asteroid’s surface will hit and damage the spacecraft.

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More results about Bennu from OSIRIS-REx

10:21 am

Scientists using the OSIRIS-REx spacecraft have now published a special collection of papers outlining some of their discoveries made during that spacecraft’s observations of the asteroid Bennu from February to October 2019.

These papers just make official much of what was revealed during a conference I attended in November 2019. To sum up the papers:

  • Bennu has a lot of carbonates across its surface.
  • Some of that material came from another object that had to have had water.
  • The asteroid’s boulders come in two types, dark-porous and bright-solid, with the latter likely from that water-bearing other asteroid
  • Bennu’s surface is fresh, only recently exposed to space, including the sample site Nightingale.
  • Bennu’s interior has large voids, and its equatorial region is less dense.

The discovery of carbonates, produced from the interaction of water and carbon dioxide, is a big deal. As Dante Lauretta, OSIRIS-REx principal investigator, explained at that November conference, “To me this is one of the most exciting results from the conference.”

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

The material could not have been created on Bennu itself, which means it formed on a different object that was large enough and existed long enough to create the veins in these boulders. That material was then flung back into space to settle onto Bennu’s surface.

The freshness of Bennu’s surface is also a big deal, as it means that etither the asteroid is not that old, or that its surface somehow gets plowed over periodically. It also means that when OSIRIS-REx grabs samples at the Nightingale site on October 20th, they will be grabbing material that has not been altered much by the harsh environment of space.

Finally, the data about Bennu’s interior and density is maybe the neatest discovery. As the press release notes,

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

Bennu’s very weak gravity makes it a very alien and hard-to-comprehend place. It appears that the gravel in this floating gravel pile is barely held together, some interlocking in a way that leaves many open gaps, with other pieces pulled outward by the spin of the asteroid.

In reading these results, my first impression was an overwhelming sense of time and its inconceivable vastness. Much of Bennu’s most primitive material comes from the early solar system, about six billion years ago. Other material is newer, but required many many millions of years to get created elsewhere, and then somehow end up in space to be captured by this asteroid.

A million years is a very long time. A billion years is a thousand times longer. To conceive such time frames and all that can happen during that time is practically impossible. Bennu has shown us just a hint of how much can happen, some of which we would never have imagined otherwise.

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OSIRIS-REx team confirms date for sample grab from Bennu

12:16 pm

Nightingale landing site on Bennu
Click for full image.

The OSIRIS-REx science team has confirmed October 20, 2020 as the date the spacecraft will attempt a sample grab from the asteroid Bennu.

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

The press release at the link provides a lot of technical and interesting details about the sample-grab-and-go attempt, expected to put the spacecraft in contact with the asteroid’s surface for no more than sixteen seconds.

The maneuver itself is quite risky, as the available smooth landing area, as shown in the image above, is only half the size the equipment was designed for, and surrounded by large boulders.

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