I added my own interpretation of the TAGSAM head touch point location to my previously posted OSIRIS-REx photo compilations (based on newly released Imaging Footprint During TAG)

Considerations on the extended OSIRIS-REx mission to Apophis:

https://www.space.com/osiris-rex-asteroid-p...it-apophis-2029 :

„...scientists behind NASA's OSIRIS-REx asteroid sample-return mission are contemplating sending the spacecraft to study a second asteroid in 2029, this time the infamous Apophis. If that appointment comes to be, the spacecraft will arrive at Apophis in April 2029...
The OSIRIS-REx team plans to propose an extended mission to NASA in the summer of 2022, Lauretta said. Visiting Apophis is one option for what that extended mission could look like, but so far, it's the only target that engineers have found the spacecraft could visit long-term...”

*Orbit* Apophis. Wow.

The duration post-sample return is similar to Hayabusa2 XM's discussed starting here:
http://www.unmannedspaceflight.com/index.p...st&p=247738

... so I wonder if it's all Earth flybys, or if Venus is also in the mix.

They could even poke the surface with the sampling arm to test its strength (presumably after all other studies are complete).

I've read about some other proposals for Apophis missions, arriving before the Earth encounter and escorting it to watch for changes both on the surface and from nearby (the views at closest approach would be spectacular, too!). But a spacecraft already launched has so many advantages.
Crossing fingers for approval! It's interesting that they could find no other close encounters in the next 8 years but Apophis. Something about the orbital mechanics being special?

2021: Everyone's hoping that Osiris-Rex will have an Apophis encounter in 2029.

2004: Everyone's hoping that Earth won't have an Apophis encounter in 2029.

There would be value in closeup imaging of Apophis before its close encounter so that OSIRIS-REx can look for changes caused by the close encounter with Earth, potentially with a cubesat spacecraft.

Also, OSIRIS-REx lacks some standard remote sensing composition instruments such as a gamma-ray spectrometer. (No need for those instruments with sample being returned to Earth.)

There was a conference last year about Apophis and possible missions (including the potential OSIRIS-REx rendevous linked above). See Session 5 for the mission concepts. Conference abstracts

Yes, those are what I read, thanks for finding it! With only eight years until the encounter, the time to start solidifying any proposals is coming up.
This thread is only about O-REx though, so I won't go into those.....

I guess the author meant (long-term) orbiting an asteroid, not just a close encounter. This probably significantly narrows the possibilities.
[with reduced amount of fuel, only a relatively small difference in orbital velocity between the asteroid and the spacecraft is required...]

A final Bennu flyby is planned for April to check out the sampling site (not confirmed, but "if feasible")! 3.2 km closest approach, and also an opportunity to check the instruments are working well and not too affected by dust kicked up during the TAG.

https://www.asteroidmission.org/?latest-new...eroid-departure

It's a good news !!! I keep my fingers crossed for the OSIRIS-REx team - so that we can see this "battlefield" in April. It's now or never again !

"The International Astronomical Union (IAU) has approved more names for surface features on Bennu": https://twitter.com/OSIRISREx/status/1356300951942963200

https://www.asteroidmission.org/iau-features-3/


PS. But ... they're not officially listed yet here: https://planetarynames.wr.usgs.gov/SearchRe...ts?target=BENNU Why?

On the OSIRIS-REx website’s map I also can not see such (mentioned in the attached text) surface features, as: dorsa and fossae. Only the new names of the craters have appeared,
i.a. OSPREY is now Wuchowsen Crater; NIGHTINGALE is now Hokioi Crater etc.

A final flyby of Bennu (and Nightingale) on April 7 is approved !!!
https://www.asteroidmission.org/?latest-new...l-tour-of-bennu

„...The OSIRIS-REx mission team recently completed a detailed safety analysis of a trajectory to observe sample site Nightingale from a distance of approximately 2.4 miles (3.8 kilometers)...
...During this new mission phase, called the Post-TAG Observation (PTO) phase, the spacecraft will perform five separate navigation maneuvers in order to return to the asteroid and position itself for the flyby. OSIRIS-REx executed the first maneuver on Jan. 14 (...) the spacecraft is now slowly approaching the asteroid and will perform a second approach maneuver on Mar. 6 (...) 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...”

„This image...was taken...on March 4, from a distance of about 186 miles (300 km)...during the mission’s Post-TAG Operations phase, as the spacecraft slowly approaches Bennu in preparation for a final observational flyby on April 7.” - https://www.asteroidmission.org/galleries/s...ennuagain/#main

"...As of Mar. 12, the spacecraft was about 155 km from Bennu and approaching the asteroid at about 24.6 cm/s..." - https://www.asteroidmission.org/status-updates/

Saw this on twitter:


Click to view attachment

"The OSIRIS-REx spacecraft... is currently about 30 km from the asteroid... Bennu – traveling approximately 6 cm/s..." - https://www.asteroidmission.org/?mission_update=mar-29-2020

https://www.asteroidmission.org/?latest-new...-asteroid-bennu

„...NASA’s OSIRIS-REx completed its last flyover of Bennu in around 6 am (EDT), 4am (MDT) April 7th and is now slowly drifting away from the asteroid; however, the mission team will have to wait a few more days to find out how the spacecraft changed the surface of Bennu when it grabbed a sample of the asteroid...”
„... It will take until at least April 13th 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 Antennae with other missions like Mars Perseverance, and typically gets 4-6 hours of downlink time per day...”

Marc - Thanks for the updates. Do you know what the pressurization of the nitrogen as released ? Oh, and fwiw I retired five years ago from 292.

I was unable to find information about the exact pressure of compressed nitrogen in 3 cylinders. The descriptions only use the terms compressed nitrogen or pressurized/high-pressure nitrogen bottles. Maybe someone has such data at hand ?

However, we must remember 3 things:
1. When we talk about gas pressure, we mean the pressure under Earth conditions (including the so-called standard temperature).
2. The pressure of the gas depends on its temperature. The colder the gas, the less pressure it has.
3. There is a vacuum on the surface of Bennu. Even gas under "normal" pressure released from the cylinder will behave as compressed gas there.

Here are some quotes found in articles on this topic and pictures of the actual 3 nitrogen cylinders on TAGSAM:

"TAGSAM is the product of Lockheed Martin. The complete TAGSAM design consists of (...) three pressurized bottles containing curation-grade nitrogen gas with a small amount of helium (to check leaks prior to launch)...
There are three independent gas bottles (which are independently released), to support up to three sampling attempts...
Gas handling is passive, operating in the simple blow-down mode...
Sample collection occurs when surface contact is sensed. At this point, a pyro valve opens to a bottle of high-purity nitrogen gas... When sample gas is released from a high-pressure bottle, the gas flows through a feedline to the head and is directed into the regolith via an annular aperture...
The majority of the gas release occurs in 5 sec ...
The gas mobilizes material underneath the head as the gas expands into the regolith. The flange seal and impedance of the soil bed cause the gas naturally to flow from the high-pressure environment underneath the head to the vacuum of space via the collection volume around the perimeter of the head. A screen around the perimeter of TAGSAM retains asteroid regolith, even as the gas escapes...

The propagation of the gas through the regolith likely occurs at hypervelocity speeds for much or all of its expansion. The initial peak speed of the gas while exiting TAGSAM is around 800 m/s. Because the porosity in Bennu's regolith is occupied by a vacuum rather than an atmosphere, the expansion of the gas through the interstitial spaces of the regolith will be a choked flow. In the case of choked flow, the expansion speed of the gas is its sound speed, which depends on gas temperature...

The TAGSAM gas reaches equilibrium with the environment as it expands unto the subsurface. Thus, the temperature of the gas is controlled by the ambient temperature...

The dynamics of the sample gas, and the response of regolith, will be different in Earth-atmospheric and gravity conditions versus those on Bennu...

In the gravity regime, the speed of the nitrogen gas through the regolith spans from the peak speed of release from TAGSAM, ~800 m/s, to the “steady state” expansion of the gas through the subsurface, around 325 m/s for 255 K.

Ground-based Earth testing has an ever-present gravitational acceleration of 9.8 m/s2, which is about 100000 larger than the gravitational environment at Bennu...
On the Earth’s surface, the weight of a cm-sized particle is a larger force than the aerodynamic lifting force of flowing gas unless the wind speeds are high (fortunately, most windy days on Earth do not loft cm-sized gravel into the air). In contrast, the weight of a 1-cm particle on Bennu is roughly 100000 less than on Earth because Bennu’s surface gravity is 10000 less than Earth’s surface gravity, yet the gas-driven forces remain the same...

Although there was thermal control on the gas delivery system, the hot case corresponds to an increased bottle pressure over the cold case, and as a result the hot case had higher bottle pressures compared with the cold case..."


A lot of details are e.g. here:
https://link.springer.com/content/pdf/10.10...-018-0521-6.pdf
https://www.sciencedirect.com/science/artic...20304826#bb0085
https://arxiv.org/ftp/arxiv/papers/1702/1702.06981.pdf

Thanks so much for all of this. More than I expected! I was curious about the force imparted to the sample - visually, it was obviously very strong and was designed for a different surface. I'll take some time to read the articles. I'm annoyed that I didn't use Tagsam as a keyword in my searches . :-)

Images released:
https://www.nasa.gov/feature/goddard/2021/n...-asteroid-bennu

Video here:
https://www.youtube.com/watch?v=J8ylW0SVplM

Press conference and new images to be released Monday, together with the Earth return burn:
https://www.nasa.gov/press-release/nasa-inv...eturn-to-earth/

Jun 04, 2021: "NASA’s OSIRIS-REx spacecraft is 328,000 miles, or 528,000 kilometers, away from the asteroid Bennu (...) The May 10 departure maneuver was calculated and executed so precisely, the mission team decided not to do a clean-up maneuver last week. The next possible maneuver adjustment could occur in 2022." - https://www.asteroidmission.org/?mission_update=jun-3-2021

NASA has put out its call for proposals for extended missions (the regular senior reviews) https://www.lpi.usra.edu/NASA-academies-res...2PMSR-FINAL.pdf. For the OSIRIS-REx mission, it has specific guidance, "The OREx mission will be reviewed at this PMSR, ahead of its nominal schedule, in order to evaluate opportunities for spacecraft operations after the Sample Return Capsule has been released from the spacecraft. OREx should submit a proposal which describes an encounter with the asteroid Apophis in 2029-2031. The proposal should cover the time period FY23-FY31, including cruise, encounter, and closeout."

An abstract for the potential encounter is attached.

The other missions to be reviewed are InSight, LRO, Odyssey, MRO, MSL, MAVEN, and New Horizons.

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.

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).

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

Click to view attachment

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

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/

The proposed extension to explore Apophis has been approved.

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

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

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

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..."

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

LINK: NASA Mission blog

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.

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.

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.

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!

The sample return capsule has been released and OSIRIS-REx fired its engines for 20 minutes to divert it onto a new trajectory toward a rendezvous with Apophis in a few years.
https://blogs.nasa.gov/osiris-rex/2023/09/2...or-new-mission/

And the spacecraft bus has been officially renamed OSIRIS-REx-APEX for its new mission to asteroid Apophis.

NASA web site is very slow.

Same is on YouTube here:
NASA live re-direct

Helicopters have started taking off. There are four altogether to be involved in the project.

Entry interface.

Parachute deployed!

Capsule is on the ground.

YES!!!! EDL is always a nail-biter!


Congratulations to the team and to NASA!

Success! Touchdown slightly ahead of schedule (~3 minutes).

Great news! After all those years in deep space, everything works. Many congratulations to the team.