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Unmanned Spaceflight.com _ Telescopic Observations _ 'Exciting' news from SOFIA, about the Moon
Posted by: marsbug Oct 22 2020, 02:26 AM
http://www.independent.co.uk/life-style/gadgets-and-tech/nasa-moon-announcement-when-watch-mission-b1209506.htmlNASA will be making an 'exciting' announcement regarding SOFIA observations of the Moon on the 26th... And that's more or less all we've got. Given what we know about the wavelengths SOFIA uses, and observation campaigns it's been used for that might be relevant to the Moon, I wondered if anyone might have any insight?
Posted by: djellison Oct 22 2020, 03:03 AM
This is the only selected SOFIA observation out of 7 rounds to mention the moon.
https://www.sofia.usra.edu/science/proposing-and-observing/proposal-calls/cycle-7/selected-proposals/abstracts#61
Proposal ID: 07_0061
Principal Investigator: Paul Lucey
Title: Water abundance on the Moon from 6 µm observations
Abstract: This Thesis Enabling Program aims to detect or place upper limits on the abundance of molecular water on the lunar surface. A hydrogen-bearing species is causing an unexpected 3 µm absorption on the lunar surface. However existing data, including the proposers’ observations of the Moon at 3 µm using the InfraRed Telescope Facility (IRTF), cannot resolve the chemical form of this hydrogen, whether molecular water or the hydroxyl radical. The chemical form of the 3 µm absorber provides information on solar wind interaction with the lunar surface, and whether the hydrogen bearing compound is mobile. Low resolution spectroscopy at 6 µm is uniquely sensitive to the presence of molecular water in a spectral region both inaccessible from the ground and lacking in existing and planned spacecraft observations. SOFIA observations will enable definitive establishment of abundance limits of water and its degree of mobility. The project will produce 6 µm spectra of the Moon as a function of time, location and temperature for use by the wider planetary astronomy and lunar science community.
Posted by: marsbug Oct 22 2020, 08:16 AM
Thanks Doug!
Posted by: marsbug Oct 22 2020, 04:12 PM
Space.com is running an article which gives the names and positions of the presenters:
Apologies for the speculation, but from that and the information found by djellison I would not be surprised if this was a detection of molecular water, as opposed to hydroxyl, and might be pegged as significant for hopes of ISRU in the next decade or so. If they've actually found a big black rectangle, well more fool me.
Posted by: ollopa Oct 22 2020, 11:42 PM
This may also be relevant.
https://www.hou.usra.edu/meetings/lpsc2019/pdf/2199.pdf
My spies tell me this discussion is not off-track 
Posted by: marsbug Oct 26 2020, 04:23 PM
The SOFIA related paper from the announcement:
Widespread hydration was detected on the lunar surface through observations of a characteristic absorption feature at 3 µm by three independent spacecraft1,2,3. Whether the hydration is molecular water (H2O) or other hydroxyl (OH) compounds is unknown and there are no established methods to distinguish the two using the 3 µm band4. However, a fundamental vibration of molecular water produces a spectral signature at 6 µm that is not shared by other hydroxyl compounds5. Here, we present observations of the Moon at 6 µm using the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA). Observations reveal a 6 µm emission feature at high lunar latitudes due to the presence of molecular water on the lunar surface. On the basis of the strength of the 6 µm band, we estimate abundances of about 100 to 400 µg g−1 H2O. We find that the distribution of water over the small latitude range is a result of local geology and is probably not a global phenomenon. Lastly, we suggest that a majority of the water we detect must be stored within glasses or in voids between grains sheltered from the harsh lunar environment, allowing the water to remain on the lunar surface.
Posted by: abalone Oct 27 2020, 05:21 AM
100-400g per ton of regolith, possibly only 1L for every 10T, not a lot. The news media is overblowning the significance. Unlikely to be able to collect enough economically to produce rocket fuel.
Posted by: Xerxes Oct 27 2020, 02:00 PM
Of course, you don't have to sample random patches of lunar regolith when you're trying to mine water. The paper indicates that most of the water is expected to be found in glassy ejecta, where it occurs in concentrations up to 1300 µg/g. You would simply set down your solar-powered mining apparatus in the region of highest concentration. Compared to finding or transporting power into a permanently shadowed crater, it may be much more convenient.
Posted by: marsbug Oct 27 2020, 03:59 PM
I think it's fair to say that is possible, but we don't know it's true at this (what is in fact still quite early) stage in the investigation. I'd be surprised if there weren't regions of hogher concentration, as distributions of things in nature tend to be patchy, at least on some scale. But at this point all we can say is that this is probably enough data to justify in-situ follow up investigations - which are already planned. Judgement either way on practical fuel production is still premature at this point (my opinion only).
As a Moon hugger it is fascinating though. The more we explore the more interesting our nearest neighbour becomes (as is always the case with exploration).
Edit: I litre per 10 tons means processing a cube of regolith 2 meters-ish (regolith bulk density is around 1500kg /m^3 IIRC) on a side for 1 liter of water. If the water bearing regolith is easy to scoop up and process, then I might imagine a highly/fully automated 'slow accumulator' type process producing small amounts for niche applications (such as refuelling GEO satellites at intervals of years or more) But that's not just speculative, right now it's damn near sci-fi, which is the point I'm making.
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