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IonStorm

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    NASA's OSIRIS-REx

    in Science & Spaceflight

    Posted

    On 8/10/2020 at 4:16 PM, IonStorm said:

    Tomorrow is a very important milestone for the OSIRIS-REx mission - the final rehearsal before sample collection! We invite you all to join us for a live play-by-play on Twitter August 11 at 2:30 EDT on Twitter@osirisrex    

    The OSIRIS-REx team (following social distancing and wearing masks) will conduct its Matchpoint Maneuver Rehearsal over the Nightingale Site on asteroid Bennu. There will be a 16 minute one-way communication delay between the spacecraft and Earth. So the event commands will be uploaded to the spacecraft and the maneuver will be conducted autonomously. The low gain antenna will transmit data to Earth with images and science data downlinked when the rehearsal is completed.

    For more details on the Matchpoint Maneuver and a summary poster.

     

    No F9 required.  A perfect rehearsal.

    https://www.asteroidmission.org/?latest-news=a-successful-second-rehearsal-puts-nasas-osiris-rex-on-a-path-to-sample-collection

    NASA's OSIRIS-REx

    in Science & Spaceflight

    Posted

    42 minutes ago, Arugela said:

    I wonder if this is Raxxla related. How long has that name and this mission been planned?

    The name OSIRIS-REx?  We picked OSIRIS in 2004 to describe the mission goals: 

    • Origins
    • Spectral Interpretation
    • Resource Investigation
    • Security

    We proposed OSIRIS twice as a Discovery class mission.  After OSIRIS was not selected after a Phase A study (the Grail mission was selected instead), heart-broken, we needed to re-propose in the New Frontiers program.  New Frontiers requires a bigger scientific impact than Discovery, so initially as a joke in 2008 we added Rex after OSIRIS since it would be bigger, kingly, T. rex like.  Mixing Egyptian with Latin was odd, but oh well.  We then bacronymed Rex into REx for Regolith Explorer.

    It is fortunate that OSIRIS wasn't selected.  Bennu has been much more challenging than predicted with the best science at the time and we have needed every bit of the extra capabilities provided by a New Frontiers class spacecraft.

    See also, https://dslauretta.com/2015/01/22/osiris-rex-whats-in-a-name/

     

    NASA's OSIRIS-REx

    in Science & Spaceflight

    Posted · Edited by IonStorm
    Un merge posts

    Tomorrow is a very important milestone for the OSIRIS-REx mission - the final rehearsal before sample collection! We invite you all to join us for a live play-by-play on Twitter August 11 at 2:30 EDT on Twitter@osirisrex    

    The OSIRIS-REx team (following social distancing and wearing masks) will conduct its Matchpoint Maneuver Rehearsal over the Nightingale Site on asteroid Bennu. There will be a 16 minute one-way communication delay between the spacecraft and Earth. So the event commands will be uploaded to the spacecraft and the maneuver will be conducted autonomously. The low gain antenna will transmit data to Earth with images and science data downlinked when the rehearsal is completed.

    For more details on the Matchpoint Maneuver and a summary poster.

     

    NASA's OSIRIS-REx

    in Science & Spaceflight

    Posted

    3 minutes ago, tater said:

    The exposure is great—are the (very few) blown areas (exposure wise) just because the rest of the surface is so very dark, or are they very highly reflective, or merely slightly reflective and at just the right angles?

    The surface is super dark with a few comparatively bright spots.  The dark spots are like coal and the bright spots are like the Moon.

    You can compare that to the 380MB global mosaic.  It has about 1/10 the resolution but the whole asteroid https://www.asteroidmission.org/bennu_global_mosaic/

    NASA's OSIRIS-REx

    in Science & Spaceflight

    Posted

    6 minutes ago, Mr. Peabody said:

    The cratering concentrated along a linear path (center of image) is interesting to note. What might have caused this phenomenon?

    We have speculated, "The retention of large craters on Bennu’s equatorial ridge requires that the surface age predates the expected approximately 10-million-year duration as a NEA. There is no clear geologic indication of the process that formed the ridge, and given its relation to the large craters it could be a feature preserved from the formation of Bennu, which would make it the oldest feature on its surface. Bennu’s surface therefore also recorded processes from its time in the main belt; the formation timescales of the largest craters suggest that Bennu recorded hundreds of millions of years of history during this period."  (Walsh et al., 2019)

    https://science.gsfc.nasa.gov/sed/content/uploadFiles/publication_files/Walsh2019.pdf

     

    NASA's OSIRIS-REx

    in Science & Spaceflight

    Posted

    On 2/14/2020 at 8:43 AM, IonStorm said:

    This can happen either due to random single event errors (i.e. cosmic ray hits) or something deeper.  OLA has been asked to do additional work beyond its requirements due to the extra imaging required for the rocky surface.  It is expected that some fraction of the images will be out of focus by an unknown amount, we will see when it gets downlinked.  There is a Guidance and Navigation LIDAR which was to have been used for sampling--if the asteroid wasn't so rocky.  This could be reprogrammed to help PolyCam focus--this will take time.  Just reflying the pass to retake the bad images would take less time.

    So it was something deeper after all, but restricted to the low power laser not the whole instrument.  The high power laser will be used instead.  It is sufficient resolution for focusing and does not require a big software change:

    Quote

    The mission has made the decision to use OLA’s High Energy Laser Transmitter (HELT) to provide the ranging data to focus PolyCam during the Mar. 3 flyover of site Nightingale. OLA consists of two laser subsystems, the HELT and the Low-Energy Laser Transmitter (LELT). OLA’s LELT was originally scheduled to provide these data, however, as a result of the anomaly  that occurred during the Recon B site Osprey flyover, the team has determined that the LELT system is no longer operable. Despite the LELT’s condition, the HELT system has continued to operate as expected, and will be used to focus PolyCam for the remaining reconnaissance passes.

    OLA has already completed all of its principal requirements for the OSIRIS-REx mission. OLA’s scans of Bennu’s surface were used to create the high-resolution 3D global maps of Bennu’s topography that were crucial for selecting the primary and backup sample collection sites last fall.

    https://www.asteroidmission.org/?mission_update=mar-2-2020

     

    NASA's OSIRIS-REx

    in Science & Spaceflight

    Posted

    9 hours ago, insert_name said:

    The lidar altimeter bugged out and the images from the flyover of the backup landing site are likely out of focus :(

    http://nasa.gov/feature/goddard/2020/osiris-rex-completes-closest-flyover-of-backup-sample-site-osprey

    This can happen either due to random single event errors (i.e. cosmic ray hits) or something deeper.  OLA has been asked to do additional work beyond its requirements due to the extra imaging required for the rocky surface.  It is expected that some fraction of the images will be out of focus by an unknown amount, we will see when it gets downlinked.  There is a Guidance and Navigation LIDAR which was to have been used for sampling--if the asteroid wasn't so rocky.  This could be reprogrammed to help PolyCam focus--this will take time.  Just reflying the pass to retake the bad images would take less time.

    NASA's OSIRIS-REx

    in Science & Spaceflight

    Posted

    1 hour ago, tater said:

    @IonStorm, Obviously the sample return container is sealed. After return, is it opened in a larger sealed container to analyze any volatiles that come off, or is there a connector to remove those gases first for analysis?

    The sample return canister (SRC) is sealed, but not airtight.  There is a filter (Figure 1 and 2) allows the pressure inside to equalize with the outside during reentry without introducing water or heatshield ablation products.  Upon collection the SRC is kept under N2 purge to prevent ingest of moisture and contaminants.  Otherwise, the canister would need to be heavy enough to hold vacuum, which is more expensive than OSIRIS-REx can afford.  Also, based on the nitrogen agitation to collect the sample, the warm surface temperature of Bennu, and reentry heating we don't expect a lot of loosely bound gases so it would not have been a good use of resources to build an airtight and thus and heavier return capsule.  Instead we will be observing the gases that are evolved upon heating in the laboratory.

     

    11214_2017_439_Fig19_HTML.gif

    Fig 1. Note the location of the filter inside the SRC in panel b

    11214_2017_439_Fig20_HTML.gif

    Fig 2. Diagram of the filter

    Filter performance and other fussy details can be found at https://rdcu.be/bYXUe

     

    NASA's OSIRIS-REx

    in Science & Spaceflight

    Posted

    6 hours ago, AngrybobH said:

    Those videos are amazing. Why was nightingale chosen over Osprey? From the looks of the video osprey looks easier to land in/on.

    It was a complex series of analyses and models with more than just the topographic models.  We also used rock counting to the cm-scale, color variation, local tilts, and spectra.  Osprey has slightly better backaway vectors but a lower density of fine material.  So the probability of a successful contact times the probability of a successful collection for the two sites was about the same. After vigorous debate we selected Nightingale as prime and Osprey as backup and rejected the other two.  We received concurrence from headquarters that our rationale is sound.

    8 hours ago, Racescort666 said:

    I know they describe asteroids as "rubble piles" but these high res pictures with OSIRIS-REx overlaid really puts it into perspective. It's literally a pile of rocks bound by gravity.

    Yes, we had modeled our pre-launch data based on Itokawa and expected vast smooth regions like the Muses-C regio and assumed worst case would be like the rough areas of Itokawa. 

    Surprise!

    1-s2.0-S0019103513004739-gr1.jpg

    NASA's OSIRIS-REx

    in Science & Spaceflight

    Posted

    On 8/28/2019 at 4:57 PM, cubinator said:

    It's interesting because we've all seen rocks with cracks and all kinds of textures, but the things that made these rocks look the way they do are completely different than how it happens on Earth. For instance, lots of these rocks have long, straight cracks! What's up with that? Did little meteor impacts chisel out big shards of rock? Or is it something else? 

    Earth rocks also can show linear cracks, but often with very different types or rocks than Bennu http://maps.unomaha.edu/maher/STEP07/supportinfo/cracks.html  There are phyllosilicates (clays) on the surface, they could exhibit a preferred fracture orientation.  It may be due to thermal fracturing, and perhaps related to the particle ejection events.  So much science to do.

    NASA's OSIRIS-REx

    in Science & Spaceflight

    Posted

    1 hour ago, cubinator said:

    @IonStorm What's the scale on each image? Might help distinguishing what to call a 'rock' vs. a 'boulder'.

    Here is the real answer:

    Quote

     

    The images are all ~5cm/pixel and the CQ frame is 450x450 pixels so a single CosmoQuest image is about 22.5m across 

    Best, 
    Carina

     

     

    NASA's OSIRIS-REx

    in Science & Spaceflight

    Posted · Edited by IonStorm

    1 hour ago, cubinator said:

    @IonStorm What's the scale on each image? Might help distinguishing what to call a 'rock' vs. a 'boulder'.

    I'm not sure which image set these are drawn from.  A funny thing about fractal rocks is you can't tell the scale by looking at them.  I'll need to check with the image team.  Anyway, if you can use the boulder tool it is a boulder.  If it is too small to draw the line it is a rock.  

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