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Short Takes on Events in ‘Local’ Space

You wouldn’t think that a place 100 times drier than the Sahara desert would have a lot to offer, but when that place is the sunlit surface of the Moon, the import of the new discovery from the SOFIA airborne observatory is clear. H2O in Clavius Crater, in concentrations of 100 to 412 parts per million, is said by NASA to be equivalent to a 12-ounce bottle of water trapped in a cubic meter of soil spread across the lunar surface. The results in Nature Astronomy point to interesting possibilities for future missions if the water is accessible.

Exactly what would be involved in extracting such a resource? While we try to figure that out, where the water comes from is an interesting question. Thus Casey Honniball (NASA GSFC), lead author on the SOFIA paper:

“Without a thick atmosphere, water on the sunlit lunar surface should just be lost to space. Yet somehow we’re seeing it. Something is generating the water, and something must be trapping it there.”

We also have Paul Hayne and team’s work using the Lunar Reconnaissance Orbiter to map shadowed regions, the ‘cold traps’ once thought restricted to deep craters. But micro-traps also seem to be in play, meters across and even less. The Hayne estimate is that cold traps may occupy 40,000 square kilometers, about 0.1 per cent of the moon’s surface. Between the two studies, we have reason to be energized about future human operations on the Moon.

Image: These three images of the lunar surface show shadows at all scales, from several kilometers to less than a centimeter. (A) Lunar Reconnaissance Orbiter oblique view over the rim of the Cabeus crater near the Moon’s south pole (NASA/GSFC/ASU). (B) Chang’e-3 close-up surface image taken by the Yutu rover some distance from the landing site (CNSA/CLEP). (C) Apollo 14 close-up camera image of undisturbed regolith. Some of these shadows are permanent and could remain cold enough to harbor ice. Credit: NASA.

Oded Aharonson (PSI) is a co-author on the Hayne paper:

“I think the way this changes our perspective of water on the Moon is that until now, our efforts were focused on the largest reservoirs situated within the broadest and deepest craters at high latitudes. But we now understand that we expect a large number of much smaller reservoirs of water. The smaller deposits should be more accessible for at least two reasons: the distance to the nearest one from a hypothetical landing site might be shorter; and the deposit would not be surrounded by imposing tall crater rims, but rather much gentler slopes.”

The papers in play here are Honnibal et al., “Molecular Water Detected on the Sunlit Moon by SOFIA,” Nature Astronomy 26 October 2020 (abstract); and Hayne et al., “Micro Cold Traps on the Moon,” Nature Astronomy 26 October 2020 (abstract).

The more lunar water we can use in future missions, the less we have to take with us. And speaking of taking things with us, let’s look again at OSIRIS-REx and the disposition of its sample from asteroid Bennu. In a day of quick follow-ups, I also want to take a look at Jupiter’s upper atmosphere and a recent find uncovered in a study of four years of Juno data.

What OSIRIS-REx Does Next

An ‘early stow’ is what NASA calls the operation that will protect the precious sample of surface material from asteroid Bennu that was collected just recently by the OSIRIS-REx spacecraft. The goal was to collect about 60 grams and the spacecraft managed more than that, enough so that the collector head was found to be overflowing with Bennu’s regolith. The problem: Some of the particles, as seen in images from the spacecraft, have been escaping from the collector (properly speaking, the Touch-And-Go Sample Acquisition Mechanism, or TAGSAM).

As you would imagine, TAGSAM is supposed to seal back up once the surface material is inside, with a mylar flap safely containing the material, but it became clear that some rocks had wedged the flap open, which explains the leakage. Given the size of the sample despite minor losses, the stowage was re-scheduled, moving it up from November 2, with the materials to be moved to the OSIRIS-REx Sample Return Capsule (SRC). Multiple days are involved in all this, including new imaging and a careful check of the collector head’s placement in the SRC.

The OSIRIS-REx team is working with a light delay of 18.5 minutes each way, all the while trying to monitor the wrist alignment on TAGSAM to manage proper placement of the collector head. Says Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson:

“The abundance of material we collected from Bennu made it possible to expedite our decision to stow. The team is now working around the clock to accelerate the stowage timeline, so that we can protect as much of this material as possible for return to Earth.”

Image; This illustration shows NASA’s OSIRIS-REx spacecraft stowing the sample it collected from asteroid Bennu on Oct. 20, 2020. The spacecraft will use its Touch-And-Go Sample Acquisition Mechanism (TAGSAM) arm to place the TAGSAM collector head into the Sample Return Capsule (SRC).
Credits: NASA/University of Arizona, Tucson

’Sprites’ in Jupiter’s Upper Atmosphere

A lot is going on in ‘local’ space (meaning in this site’s parlance, within the Solar System), and I haven’t even mentioned the competing papers on Venusian phosphine today. I can also throw in the Mars 2020 Perseverance rover, which has just reached the halfway point on its journey to Mars, at this writing about 235 million kilometers out, with arrival on February 18, 2021. Now we get word from Juno, NASA’s ongoing Jupiter mission, involving the detection of transient events in the huge world’s upper atmosphere, which the space agency is referring to as ‘sprites.’

We can also call them ‘transient luminous events,’ or TLE’s in the acronym-rich milieu of aerospace, and they come in several forms, including ‘elves’ (Emission of Light and Very Low Frequency perturbations due to Electromagnetic Pulse Sources) and ‘sprite halos.’ The data come from Juno’s ultraviolet spectrograph instrument (UVS), which detected in 2019 the narrow streak of ultraviolet in question. UVS is primarily used to image Jupiter’s northern and southern auroras. Rohini S. Giles (SwRI) is lead author of the paper describing the flashes, which is in process at the Journal of Geophysical Research: Planets:

“UVS was designed to characterize Jupiter’s beautiful northern and southern lights. But we discovered UVS images that not only showed Jovian aurora, but also a bright flash of UV light over in the corner where it wasn’t supposed to be. The more our team looked into it, the more we realized Juno may have detected a TLE on Jupiter.”

Image: This illustration shows what a sprite could look like in Jupiter’s atmosphere. Named after a mischievous, quick-witted character in English folklore, sprites last for only a few milliseconds. They feature a central blob of light with long tendrils of light extending down toward the ground and upward. In Earth’s upper atmosphere, their interaction with nitrogen give sprites a reddish hue. At Jupiter, where the predominance of hydrogen in the upper atmosphere would likely give them a blue hue. Credit: NASA/JPL-Caltech/SwRI.

Eleven bright events of this nature have now been found in the Juno data, occurring in a region where lightning from storms is common, but located some 300 kilometers above the water-cloud area where most of Jupiter’s lightning forms. The spectra recorded by the UVS is dominated by hydrogen emissions. As the paper notes, the three types of TLE occur on Earth:

…in response to tropospheric lightning strikes. This is supported by visible light imaging, which shows cloud features typical of lightning source regions at the locations of several of the bright flashes. TLEs have previously only been observed on Earth, although theoretical and experimental work has predicted that they should also be present on Jupiter.

With a second source of TLEs off our planet, we’ll have a new tool for investigating electrical activity in planetary atmospheres.

Image: The south pole of Jupiter is seen in this annotated image of data from the ultraviolet spectrograph (UVS) instrument aboard NASA’s Juno spacecraft. Bands of bright white and blue near the south pole are Jupiter’s southern aurora. But researchers also noticed an unusual bright flash of light well away from the auroral region, highlighted here by the yellow circle at about the 10 o’clock position (between longitudinal lines 270 and 240). Juno scientists believe it could be an indication of a bright, unpredictable, and extremely brief flash of light — known as a transient luminous event — that was triggered by lightning discharges from thunderstorms far below. The data for this UVS image was acquired on April 10, 2020. Credit: NASA/JPL-Caltech/SwRI.

The paper is Giles et al., “Possible Transient Luminous Events observed in Jupiter’s upper atmosphere,” accepted at the Journal of Geophysical Research: Planets 27 October 2020 (abstract).


Comments on this entry are closed.

  • charlie October 28, 2020, 15:12

    “Image; This illustration shows NASA’s OSIRIS-REx spacecraft stowing the sample it collected from asteroid Bennu on Oct. 20, 2020. The spacecraft will use its Touch-And-Go Sample Acquisition Mechanism (TAGSAM) arm to place the TAGSAM collector head into the Sample Return Capsule (SRC).
    Credits: NASA/University of Arizona, Tucson”

    This is confusing; when you get on here and you read ‘Image; This illustration … ‘; I’ve always found certain words confusing when used in certain settings. On what appears to be a picture you put the word ‘Image’ and then you say the word ‘illustration’ and to me the word ‘illustration’ has the implication that it is some kind of composed drawing or other. If this is some kind of composed drawing or sophisticated photograph it’s very good. Is that an actual picture from the spacecraft or not ?
    Since this collection head is chock-full of material, they said they were going to move up the date to stow the head at an earlier date than November 2. What date are they planning to actually do the stowing of the collection head? Also what date are they planning to actually leave from the asteroid?

    On a totally different topic regarding the presence of ice in the craters that are in perpetual darkness – even if said crater has been exposed to sunlight, I have asked myself the question what ice even deposited originally from some asteroid or comet that crashed into the surface will that ice actually persist ? I personally checked a water-ice-gas phase diagram, and it appears that even down to ultra low temperatures there does appear to be at least some vapor pressure and over course of billions of years (possibly) I wonder whether or not a good portion of this ice will still evaporate into the vacuum of space. Any comments on this?

    • Paul Gilster October 28, 2020, 15:55

      I almost always use the word ‘image’ before I run the caption, unless I’m dealing with an animation. The caption is NASA’s, and they call it an illustration. I’ll drop a note here if I get any clarification. The departure from Bennu is listed as April 2021. All that NASA is saying about the stowing operation is that it will take ‘multiple days.’

      • Robin Datta October 29, 2020, 4:25

        The nuances of meaning are mostly absent in the US of A:

        OneLook Dictionary:




        Online etymology dictionary:


    • Alex Tolley October 28, 2020, 16:30

      Ice could be primordial or deposited by a water-containing body. If primordial, it could be slowly leaking up from the lunar interior in response to impacts or other processes. [Have we definitely ruled out any residual volcanism?] If the ice is from a comet or asteroid, it could be quite recent, rather than billions of years old.

      If the water escapes by evaporation, it will still be trapped by the lunar gravity. This suggests that it will migrate to cold traps. This is why it is most likely at the poles. The water from comet impacts has migrated until it collects in places it no longer evaporates from. Water found outside of these cold traps may be in the process of evaporating or being released from the interior or bound in some form to the rocks making it difficult to be lost. I can imagine lava tubes as being excellent cold traps anywhere they occur on the surface.

      Another argument for sending a rover with the appropriate equipment to investigate.

  • djlactin October 28, 2020, 15:30

    re: water on the Moon. Ask any soil scientist about ‘bound water’. The regolith bears water because binding to the particles exceeds the pressure gradient. If the vacuum of space cannot extract the water, how can humans? (By burning a huge amount of fuel.)

    • Alex Tolley October 28, 2020, 16:21

      Heating of any sort should be sufficient. mirror or lens concentrators can be used to heat the regolith to drive off the water.

      But let’s consider the worst case. The Moon is dry, without even hydrated minerals. However, they will have oxygen as part of their composition – e.g. SiO2. Heating those silicate rocks to liberate O2 just as we extract silicon ingots from sand and combining it with H2 to make the water. As H2 is 1/16th of the mass of O2, this makes it far cheaper to ship up a hydrogen source for the water from Earth. This could be LH2 or CH4 as 2 examples. If solar energy is free after the mass of the infrastructure is accounted for, this would be another potential way to create the needed water.

      While it is obviously better to have free water on teh Moon, even as just a tiny percentage in the regolith, the absence of water is not a show stopper if water is required.

      • Michael November 2, 2020, 16:20

        We can generate very large magnetic fields on the moon to trap solar hydrogen, the poles are very cold and allow the operation of superconductors and even a few meters underground anywhere on the surface would do it. We could potentially make hundreds of kilograms of water with a large enough magnetic field to trap the hydrogen particles.

    • Brett P Bellmore October 28, 2020, 18:53

      No fuel. One consequence of no atmosphere, is that it is quite easy to concentrate sunlight on the Moon to very high intensities. Easily high enough to drive off adsorbed water.

  • John walker October 28, 2020, 16:34

    Venus. Groan. The rebuttals. Read the papers. Villanuevo with particularly strong language that may reflect some degree of annoyance with Greaves et al. Not unexpected. Still disappointing. I assume you will be offering a full breakdown of the new analyses so I won’t spoil tomorrows post. I feel reminded of the grand anouncement in 1996 of evidence of fossilized Martian microbes.

  • Geoffrey Hillend October 28, 2020, 17:23

    The sprites on Jupiter probably form the same way as the sprites on Earth. Electrons are accelerated in a strong electric field during a bolt of lightning and collide with atoms in the upper atmosphere where electrons are excited in the atoms and emit light in the visible spectrum to make the sprites.

  • Geoffrey Hillend October 28, 2020, 17:28

    No vapor pressure only means that water can’t stay as a liquid, but it will only freeze or evaporate. If it is too cold, the water quickly freezes, it is is too hot then it turns into a vapor. It can also turn into floating ice crystals. The Sunlight might evaporate ice and turn it into a vapor. We see this on Mars which has a very thin atmosphere.

  • Geoffrey Hillend October 28, 2020, 17:30

    The Moon also has no vapor pressure.

  • Brett P Bellmore October 28, 2020, 18:50

    “and the deposit would not be surrounded by imposing tall crater rims, but rather much gentler slopes.””

    I should think, based on geometry, that the closer you are to the Moon’s equator, the MORE imposingly tall a crater rim would have to be to generate a cold trap. At the pole it hardly takes any rim at all.

    That’s why cold traps shrink and become less common as you depart from the pole: It requires more extreme geometry to produce them.

  • laintal October 28, 2020, 19:45

    Hi Paul

    There always seem to be so much interesting stuff happening, and here is an interesting update on the search for “Planet 9”


  • Ron S. October 28, 2020, 23:18

    I was curious whether the inclination of the Moon’s rotational axis to the ecliptic changes over long periods of time. It turns out it’s pretty stable but may have been somewhat larger early in Earth-Moon history. Were the inclination to be more variable the shadowed areas would be more geologically recent and so the surface ice would be of more recent origin. Since the inclination is stable the ice could be very very old.

  • Michael Fidler October 29, 2020, 8:37

    I am surprised no one has mentioned the lava tubes or giant caves and rills. This would seem to be a sump for moisture from the surface and the interior. William R. Corliss has a very good review of TLP (Transient Lunar Phenomenon) in his book The Moon and Planets. The history of which goes back to 1783 and the great astronomer William Herschel and up to the 1980’s. The interesting point is many of the observations were made at luner sunrise and seem to be associated rills and areas with Luna lava tubes. It may be worthwhile to observe the entrances to these caves for outgassing of H2O since they may contain a large glaciers worth of ice.

  • Henry Cordova October 29, 2020, 10:33

    In the film “Interview with the Vampire”, there is a scene where the “good” vampires are captured in Paris by the “evil” vampires and cast into a deep well from which there is no escape. The next day, at noon, the midday sun shines down the well and the captives evaporate from exposure to the light.

    It is a testament to the average American’s ignorance of the most elementary astronomy and geography that, at Paris’ latitude, the sun is never directly overhead.

    In a related observation, the photographs of the lunar surface published to demonstrate the large number of shadowed locations forget that lunar photography is always acquired along the terminator, where the sun angle is low, so that the long shadows will better display the relief of the terrain.

    There may well be sheltered water ice in perpetually shadowed places on the moon, but there are few deep wells there. And even at the highest latitudes the midnight sun effect will see to it that most of the surface will see the sun sometime during the lunar month. I think it unlikely that whatever ice is there will be distributed in sufficient quantities for our industrial exploitation.

    When I visited Barringer Crater in Arizona, it was springtime, and there were still traces of snow clinging to the shadowed, north-facing slopes of the south wall of the crater. In those days, the caretakers (not as fearful of litigation as they would be today) had blazed a trail with spray paint through the rubble from the rim to the bottom. My companion and I were young and fit, but it still took us hours to complete the mile-long round trip to the bottom. It was rough, almost impassable terrain. I doubt we would have been able to do it, even in lower gravity, wearing pressure suits. For a vehicle of any sort, it would have been out of the question.

    • charlie November 2, 2020, 13:49

      That’s an extremely and enormously important observation on your part as well as practical experience in an environment which is extremely friendly to begin with.

      I always gripe about these things because people go off on flights of fancy about how easy things are going to be if they go into these hostile and foreign environments being totally unaware of all the complications that seem to accompany any endeavor that explorers make. No one here is trying to belittle or ridicule ideas simply because of the fact they wish to do so. There’s an old expression in life – the good things will take care of themselves, it’s the bad things that you need to worry about.

      All this talk about extracting water in craters which have unknown topography and which have temperatures that border around liquid nitrogen would seem to suggest that individuals going into these darkened environments even with using some type of light from the sun to focus into them would encounter extreme difficulties wearing these pressure suits that these astronauts need to have to survive. Our robotic machines are primitive and it doesn’t appear that they have a great deal of flexibility needed to do even simple tasks. I just think we should be realistic in our assessment on how things are going to unfold in the future.

  • Geoffrey Hillend October 29, 2020, 15:33

    Moons and smaller planets are thought to be not volcanically active because the core cools off over deep time and there is no plate tectonics due to their smaller size and mass.


  • ljk November 11, 2020, 12:25

    Is this how they are going to get rid of Arecibo, one cable at a time?