Earth Return & Sample Science Options

[Hungry4info]

The OSIRIS-REx team used an alternative method to determine the sample mass.

Alternative Sample Mass Measurement Technique for OSIRIS-REX Sample Collection Phase
https://arxiv.org/abs/2109.05561

...The alternative SMM technique utilized reaction wheel momentum data from identical TAGSAM movements prior to and following the TAG event to estimate changes in spacecraft moment of inertia. Conservation of momentum was used to isolate the sample mass from this inertia change. Using this new method, the spacecraft team was able to successfully estimate collected sample mass to be 250.37 +/- 101 g.

[vjkane]

The OSIRIS-REx team used an alternative method to determine the sample mass.

Alternative Sample Mass Measurement Technique for OSIRIS-REX Sample Collection Phase
https://arxiv.org/abs/2109.05561

That's a clever approach. They collected ~4-6 times more material than their mission success criteria! I was thinking that with the sampling head literally overflowing, it might be even more. Perhaps a lot of porosity?

Looking forward to the return of the samples.

[fredk]

They collected ~4-6 times more material than their mission success criteria!

They collected 150-350g, so 2.5 to almost 6 times the 60g requirement.

They reported (250.37 +/- 101)g - to be pedantic, that's a pretty severe example of overstated precision! (0.25 +/- 0.10)kg is more realistic.

But it is indeed a cool application of momentum conservation (as was the original plan).

[Phil Stooke]

I have updated my Bennu map to include the date of the final flyover of Nightingale, and to add the crater names approved by the IAU last year.

Phil

[JRehling]

Beautiful work, Phil. And it's fun to see a global map where objects this small and their shadows and texture show up.

[Explorer1]

A very interesting NYT article about the Apophis flyby proposal:
https://www.nytimes.com/2021/12/15/science/...osiris-rex.html

Also a link to a Korean mission proposal to rendezvous and land prior to the flyby:
https://www.cnet.com/news/scientists-plan-t...re-earth-flyby/

[StargazeInWonder]

The proposed extension to explore Apophis has been approved.

https://news.arizona.edu/story/nasa-gives-g...nother-asteroid

[Explorer1]

Summary of new results on the TAG event:
https://www.nasa.gov/feature/goddard/2022/s...astic-ball-pit/

The paper goes into granular (sorry!) detail on the interactions, as well as results from the final flyby.
https://www.science.org/doi/10.1126/sciadv.abm6229

[Marcin600]

Another two (fairly) new articles on processes on the surface of Bennu:

1. "... Bennu’s profusion of boulders acts as a shield, preventing many small meteoroids from forming craters. Instead, these impacts are more likely to break apart the boulders or chip and fracture them. Also, some impactors that do make it through the boulders make smaller craters than they would if Bennu’s surface was covered in smaller, more uniform particles, like beach sand. This activity causes the surface of Bennu to change differently than objects with fine-grained or solid surfaces. “The displacement or disruption of an individual or small group of boulders by a small impact is probably one of the most fast-acting processes on a rubble-pile asteroid’s surface. On Bennu, this contributes to making the surface appear to be many times younger than the interior..."
https://www.asteroidmission.org/?latest-new...lder-body-armor
https://www.nature.com/articles/s41561-022-00914-5 - paid

2. "... surface regeneration happens a lot quicker on asteroids than on Earth. (...) the Sun’s heat fractures rocks on Bennu in just 10,000 to 100,000 years. This information will help scientists estimate how long it takes boulders on asteroids like Bennu to break down into smaller particles, which may either eject into space or stay on the asteroid’s surface (...) we thought surface regeneration on asteroids took a few millions of years (...) We were surprised to learn that the aging and weathering process on asteroids happens so quickly, geologically speaking..."
https://www.asteroidmission.org/?latest-new...-sun-nasa-finds
https://www.nature.com/articles/s41561-022-...1XN-5xRyck0kRm-
paper - open

[Marcin600]

Only 6 months left until the arrival of the Bennu samples on September 24 this year - https://www.nasa.gov/feature/goddard/2023/n...ry-sept-24-2023 , https://www.asteroidmission.org/?latest-new...very-on-sept-24

"...over the next six months, the OSIRIS-REx team will practice and refine the procedures required to recover the sample in Utah and transport it to a new lab built for the material at NASA’s Johnson Space Center in Houston..."

Attached thumbnail(s)

 

[Holder of the Tw...]

OSIRIS-REx has sucessfully completed is final course correction before releasing the sample capsule.

LINK: NASA Mission blog

On Sept. 17, NASA’s OSIRIS-REx engineers slightly shifted the spacecraft’s trajectory to refine the landing location of its sample capsule, which the spacecraft will deliver to Earth on Sept. 24. The spacecraft briefly fired its thrusters Sunday to change its velocity by 7 inches per minute (3 millimeters per second) relative to Earth.

This final correction maneuver moved the sample capsule’s predicted landing location east by nearly 8 miles, or 12.5 kilometers, to the center of its predetermined landing zone inside a 36-mile by 8.5-mile (58-kilometer by 14-kilometer) area on the Defense Department’s Utah Test and Training Range.

[Xerxes]

3 millimeters per second

That's surprising. What is the separation mechanism for the SRC that has precision at the order of mm/s? I dug around in the specs, but I could only find some references to a "sep/spin mechanism" and "sep nuts". In my imagination, separation occurs with precision of cm/s, but I guess that's wrong.

[stevesliva]

Release is September 24. I'd imagine that 3mm/s is about being in the right place in the gravity well when separation happens, after which the spacecraft 'diverts':
https://blogs.nasa.gov/osiris-rex/2023/09/1...s-landing-zone/

... an important diversion, because it's supposed to rendezvous and orbit Apophis in 2029-2030.

[djellison]

...In my imagination, separation occurs with precision of cm/s, but I guess that's wrong.

3 mm/sec a week out from landing is a ~1.8km change.

3 cm/sec 4 hrs from landing is less than a 500 meter change.

[Marcin600]

Sunday, Sept. 24
10 a.m. — Live coverage of NASA's OSIRIS-REx asteroid sample return
5 p.m. — Media briefing on NASA's OSIRIS-REx asteroid sample return
https://www.nasa.gov/nasalive
https://www.nasa.gov/content/live-coverage-...x-sample-return

The weather at the landing site is expected to be dry and windless, which is perfect!