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.
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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.

OSIRIS-REx has successfully completed its last maneuver engine burn to place it in proximity orbit around the asteroid Bennu.

The link takes you to the live NASA stream, which has been a bit hokey. This event is actually not that visually exciting, a bunch of engineers staring at computer screens awaiting data back from the spacecraft indicating that all has occurred as planned. In fact, some felt a bit staged, though the actual event was really happening.

The OSIRIS-REx team has released relatively little data so far, compared to most NASA missions. There will be a press conference in a week when they say they will release more information. I guess we will have to wait until then.

Update: the live stream has shifted to the docking of the manned Soyuz capsule at ISS, which is in itself a more riveting event than OSIRIS-REx’s last engine burn.

In preparation for its December 3 rendezvous with the asteroid Bennu OSIRIS-REx successfully unfolded its robot arm for the first time since launch this week.

The website has a nice short video showing how the arm will grab its samples. Very innovative, and not what you would expect. The technique had to be clever because Bennu is so small and has such a tiny gravity.

OSIRIS-REx yesterday successfully completed the fourth planned engine firing to refine its course towards the asteroid Bennu, planned for December 3.

They will do one more course correction on November 30th.

The image above of the two hemispheres of the asteroid Bennu, cropped and reduced very slightly to post here, was created from several images taken by OSIRIS-REx on two different days last week.

These two super-resolution views of asteroid Bennu were created using eight 2.5-millisecond exposure images captured by OSIRIS-REx on two separate days. The view on the left is composed of eight PolyCam images taken over the span of two minutes on Nov. 1, 2018, when the spacecraft was about 126 miles (203 km) from the asteroid. The one on the right – showing the opposite side of the asteroid – was generated using eight images taken during the same two-minute time slot on Nov. 2, from a distance of about 122 miles (196 km).

The rock on the southern limb is the same in both images, merely seen from opposite sides. Bennu appears very similar to Ryugu, except that there do appear to be dark areas on its surface, possibly crater sites, that might be smooth enough for landing.

The rendezvous at Bennu will occur on December 3.

UPDATE: The OSIRIS-REx science team has now released a short movie showing Bennu’s rotation as imaged during this same time period.

OSIRIS-REx has snapped its sharpest image yet of its target asteroid Bennu, set for a rendezvous on December 3. The image on the right is that image, at full resolution but cropped.

This “super-resolution” view of asteroid Bennu was created using eight images obtained by NASA’s OSIRIS-REx spacecraft on Oct. 29, 2018 from a distance of about 205 miles (330 km). The spacecraft was moving as it captured the images with the PolyCam camera, and Bennu rotated 1.2 degrees during the nearly one minute that elapsed between the first and the last snapshot. The team used a super-resolution algorithm to combine the eight images and produce a higher resolution view of the asteroid. Bennu occupies about 100 pixels and is oriented with its north pole at the top of the image.

It is beginning to appear that the OSIRIS-REx engineering team is going to have the same kind of problems now faced by the Hayabusa-2 engineering team. In this first glance Bennu appears very similar to Ryugu, a rubble pile shaped approximately like a box, rotating on one point. If so, they are also going to find it difficult to locate a smooth landing site.

Bennu by the way is in an orbit that makes a collision with the Earth possible in the late 22nd century. Knowing its composition, density, and solidity is critical for determining what to do, should that collision become likely.

OSIRIS-REx has taken its first images of Bennu from a distance of 1.4 million miles.

The images are not much to look at, showing a mere dot moving across a star field. Nonetheless, they show that the spacecraft’s camera is working, and that it is on course for its December 3rd arrival.

OSIRIS-REx, on its way to a December rendezvous with the potentially dangerous asteroid Bennu, successfully made its second course correction last week.

Rendezvous is scheduled for December 3rd. The probed will orbit the asteroid for about six months, then dive in to get a sample in July 2020, returning it to Earth in 2023.

NASA has released the images that OSIRIS-REx took as it flew past Earth last week on its way to its 2018 rendezvous with the asteroid Bennu.

The image shows the Pacific Ocean from Australia to California. Its main significance it demonstrates that the spacecraft’s camera and pointing system is working perfectly.

The OSIRIS-REx asteroid probe flew past Earth today as part of its flight plan to slingshot to the asteroid Bennu.

I expect images of the fly-by to be released shortly.

OSIRIS-Rex’s instruments have been successfully turned on and are all operating perfectly.

In what might be a first for the planetary science/engineering community, an unmanned probe, being built to bring samples back from the asteroid Bennu, is turning out to be lighter than expected, thus allowing engineers to stuff its tanks with extra fuel to extend its mission.

The OSIRIS-REx spacecraft, being built at a Lockheed Martin facility in Denver, is coming in lighter than the lift capability of the Atlas 5 rocket, which will lift off in its “411” configuration with a four-meter payload fairing, a single-engine Centaur upper stage, and one strap-on solid rocket booster.

The proposal — described as a “heavy launch option” — would add an extra 341 pounds of fuel to the spacecraft’s fuel tank.

Planetary probes never end up lighter than planned, at least until now. During construction scientists have always found it impossible to resist adding more instruments or capabilities, and thus engineers always struggle to get the spacecraft built within its weight budget. For OSIRIS-REx to have this wonderful problem is surely astonishing.