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Herve Sainct

I am very happy to see MainlyMartian also is SometimesTitanic!
Hervé Sainct, former tech. responsible for the Huygens probe (in prime contractor)

Leo Enright

Heartfelt commiserations, bro! I lost two last year by sitting on them. Have you been checking out https://anthony.liekens.net/huygens_static.html
The cybernauts seem to be leaving ESA in their rocket exhaust when it comes to churning out imaging product. Hopefully the science teams will wow us again come Friday!

Joe Mansfield

Any ideas bouncing around on any implications arising from Opportunity's discovery of an Iron Nickel meteorite. Its apparently gentle lie on the land appears to be very similar to meteorites found in Antartica ( https://www.astrobiology.com/news/viewpr.html?pid=13654 ) so I wonder what implications this has for how it actually landed - after all it must have hit with significant velocity but now it's neatly perched atop a fairly soft (if not downright delicate) sandy plane. Could this point to it actually landing in the water that is theorised to have covered (some of) Meridiani, or landing in an ice sheet that has sublimated away in the past, or is it realistic to think it has weathered out of Meridiani rock\regolith that has weathered and blown away? Or is there any possibility that something like freeze\thaw boulder heave pushed it up out of the crater it must have formed when it initially hit?

Oliver Morton

Joe

If it's a small meteorite it won't have left a crater, having been slowed to terminal velocity by the martian atmosphere. People have long expected to find small meteorites just lying around on Mars. So there might be a story there, but it might just be a rock that fell from the sky...

Oliver Morton

Joe

If it's a small meteorite it won't have left a crater, having been slowed to terminal velocity by the martian atmosphere. People have long expected to find small meteorites just lying around on Mars. So there might be a story there, but it might just be a rock that fell from the sky...

Joe Mansfield

Of course - should have thought about it a bit more. Out of curiosity I threw some numbers together:

vt=sqrt((2*W)/Cd*Rho*Area))

W=weight, mass*g. For a basketball sized lump of Nickel Iron mass will be ~ 60kg.
g on mars ~ 3.8m/s^2 I think
Cd - Coeff of drag, 0.7 seems acceptable for a lump like this.
Rho - Atmospheric density, around 12g/m3 at Meridiani give or take a few grams.
Area - 0.046 m^2 ssuming it is basketball sized
So vt ~ 1000m/s or 2500mph for those who haven't gone metric.

I wouldn't want to get hit by this but punching the numbers into this https://www.lpl.arizona.edu/tekton/crater_c.html gives a maximum resulting crater diameter of 1m if it came in vertically. It almost certainly came in at a shallower angle though so it would have probably made a barely noticable dent then bounced and rolled a bit before coming to rest gently in the sand. The "just another rock that fell from the sky" description seems to be perfectly apt.

Charles Schmidt

I wonder how well the dark precipitated material on Titan matches Carl Sagan's conjecture about "tholin."

https://www.esa.int/SPECIALS/Cassini-Huygens/SEMHB881Y3E_0.html

Bruce Moomaw

To Charles: last night's ESA press conference said flatly that the dark material on Titan is just what they thought it would be: dark organic smog of the sort Sagasn predicetd. (That orange color has got to be from compounds that contain nitrogen -- not just hydrocarbons.)

The two big (and they ARE big) surprises that Huygens turned up:

(1) Methane rain, instead of re-evaporating before reaching the ground as many theorists thought, actually does reach all the way to Titan's surface -- and in significant quantities, although it seems to come only from those small clumps of methane cloud that go wandering about the satellite. What Huygens saw was an eerie cryogenic analog of a terrestrial desert, complete with arroyos and a still-muddy playa created by occasional flash floods. Those clumps of methane cloud are probably packed with major rainstorms (althoyugh given Voyager 1's already announced inability to pick up any radio bursts from lightning, such storms may be lightning-free).

(2) Titan has VERY active cryovolcanism -- one of Huygens' photos clearly showed a long tongue of fresh, light-colored water ice running along the surface, which seems to be have a hard domelike surface off which the methane rain runs, taking the dark smog with it, to create a bunch of dark runoff arroyos in the older and more ground-up ice regolith at its foot. But this ice strip therefore must have been extruded out of the subsurface fairly recently in order not to be similarly ground up by whtever process (probably meteoroid impacts) creates the regolith. And Huygens' stereo pairs revealed ridges up to 100 meters high but only several hundred meters wide. (You'll notice that several of the dark arroyos, unlike the others, are strangely straight -- like irrigation ditches rather than rivers -- and are parallel. I presume these run down the troughes between parallel tectonic compression ridges.)

Moreover, its GCMS found trace of argon-40 (produced in its rocky core and then gradually transported all the way up through the thick icy mantle), but not even the faintest detectable trace of the other argon isotopes, krypton or xenon -- unlike every other world whose air has been analyzed so far by a mass spectometer -- despite the fact that they must have existed in the icy planetesimals out of which Titan formed. These must have been driven out of Titan's ice after its formation, presumably by tidal heating driven by its eccentric orbit. (One recent paper suggests that the baffling continued eccentricity of that orbit is driven by Saturn's orbital resonance with Jupiter -- which, according other theory, may also have caused Saturn's axial tilt and the Terminal Bombardment Period.) And that tidal heating must also drive Titan's active cryovolcanism -- making it, internally, into a strange icy analog of Io, complete with volcanic vents that belch methane (probably from its clathrate supply) out of its interior, and occasionally pour water-ammonia "lava" onto its surface. However, this same internal activity also drives tectonic processes producing parallel grooves and ridges similar to Ganymede's -- and all this has totally obliterated its impact craters.

In short, a more dramatic world than virtually any theorists had predicted, even if its surface liquid is limited to a few small desert lakes rather than oceans. And any long-lasting centers of lava-producing volcanic activity could provide a good if local environment for the much more complex prebiotic chemistry made possible by liquid water -- one of the major goals for the future study of Titan.

Joe Mansfield

Slight correction to my impact estimate - 7-10m is probably closer so it could conceivably have caused something like Fram. It doesn't change the conclusion though - no surprise to find it just lying around.

Leo Enright

Bruce rightly focuses on Huygens as an atmospheric sounder, but here are just a few notes on my conversations with the DISR people. Marty Tomasco is very laid back indeed about the amateur image processing (https://anthony.liekens.net/huygens_static.html). Some of it is good, he says, some of it not. He was especially amused by some efforts to clean up what seemed to be camera artifacts: "They airbrushed out a very interesting crack in one of the rocks!".
The principal criticism of the perspective views is that they are using off-the-shelf mapping software which converts "shadows" into terrain relief - a mistake, apparently.
I asked if they had seen any changes in the imagery from the surface over time and they report a single frame where a white object appears fleetingly and disappears again. I assume they are talking about frames 802 and 804 in
https://www.lpl.arizona.edu/%7Ekholso/t2.mov
It's interesting that they are not currently dismissing this as an artifact. Large methane snowflakes?
Finally, there are more pictures. But not a lot. Apparently the bandwith management close to landing means that the final images (three or four, I'm told) were uploaded piecemeal to Cassini and are being processed separately. Some of the comments seemed to suggest that these have a stereo element and that they may be informing some of the 100-meter relief comments we heard last Friday. They will do terrain mapping and flyovers and all that cool stuff........but not right away!

Leo Enright

Sorry, but there was a typo, and he's Dr. Martin Tomasko to you!

Daniel Crotty

Leo: I'm glad to hear that Dr. Tomasko has enjoyed at least some of the amateur works.
I made a few of the overhead projection mosaics that are featured there.
I tried to minimize the distortion created by smoothing out the images, to remove the compression blocking and flatfield, but it was necessary in order to do feature matching to lineup the images (without altitude or pointing data, there's really no other way). I have no doubt the DISR teams methods are much more refined than mine, and look forward to seeing those as well as the maps, stereo work and flyovers!

Bruce Moomaw

Thanks for the tip on the final DISR photos, Leo! I've been trying frantically to screw information on those out of the DISR people ever since the landing.

While the last "triplet" image sets from all three DISR cameras were supposed to be taken between 3 km and 500 meters, there were then supposed to be individual downward-looking frames from the HRI taken at 8-second intervals between 500 and 200 meters -- which, given Huygens' 5 meter/sec drop rate, means there would have been time for 7 or 8 photos. Assuming that about half of those were returned on Channel B, that does mean 3 or 4 photos from those final low altitudes -- but I couldn't identify them in the raw frames, and I couldn't get a response from the DISR people on the subject. The fact that all the released raw frames were presented as triplets didn't mean anything -- there were lots of duplicate frames in those triplets, implying that the order of frames from the three different cameras was all wildly scrambled up -- but the movie of the final frames on the ESA site said that the last released HRI frames before landing were taken at either 700 or 500 meters. I couldn't even be sure that they had gotten back ANY HRI frames from lower than that. Your comment indicates that they did.

stevet-l

It was 40 years ago almost to the day that the GM tube on Mariner 4 failed. And, more importantly....

Happy Birthday mate

Charles Schmidt

Thank you Bruce for your comments on the dark material on Titan.

I was just perusing the images from MER Spirit. What in blazes is this?

https://marsrovers.jpl.nasa.gov/gallery/all/2/m/376/2M159745359EFFA2HPP2936M2M1.HTML

Rupert Goodwins

Where is Morton? There are rum doings afoot.

"WASHINGTON -- A pair of NASA scientists told a group of space officials at a private meeting here Sunday that they have found strong evidence that life may exist today on Mars, hidden away in caves and sustained by pockets of water.

The scientists, Carol Stoker and Larry Lemke of NASA’s Ames Research Center in Silicon Valley, told the group that they have submitted their findings to the journal Nature for publication in May, and their paper currently is being peer reviewed

What Stoker and Lemke have found, according to several attendees of the private meeting, is not direct proof of life on Mars, but methane signatures and other signs of possible biological activity remarkably similar to those recently discovered in caves here on Earth."

https://www.space.com/scienceastronomy/mars_life_050216.html

Lots of meaty stuff there - leaking before the peer review? - even before you get close to the issue of windy biota.

R

marrije

Oooh, rum doings indeed, Rupert Goodwins: NASA have issued a press release talking about a False Claim.

https://www.nasa.gov/home/hqnews/2005/feb/HQ_05052_mars_claim.html

I hope Oliver returns to these parts soon to shed light!

Bruce Moomaw

Brian Berger has now issued a semi-retraction: ( https://www.space.com/scienceastronomy/mars_methane_050218.html ). I think he wildly misinterpreted what the "half-dozen space officials" at that Sunday meeting told him (although he's clearly trying to pin the blame on them) -- I think Stoker just said that she had reached the conclusion that the methane MIGHT possibly be biological in origin, which is what most scientists are saying right now. I cannot conceive of any actual evidence she could have that it probably WAS biological -- especially since there's no possible way she could have any data on its isotopic makeup at this point.

She also has an abstract at the upcoming LPSC ( https://www.lpi.usra.edu/meetings/lpsc2005/pdf/1534.pdf ) in which she does seem to express a belief that the Martian methane MAY be biogenic but isn't definitely such. And Berger has now backed down on his statement that she's delivered a paper on the subject to "Nature" (which "Nature" has already denied, breaking their long-time habit of silence on such subjects).

Bruce Moomaw

While Stoker isn't talking to me, she HAS sent what looks like a definitive account of the incident to Penelope Boston, who in turn sent it to the invaluable "Bad Astronomy" site: https://www.badastronomy.com/phpBB/viewtopic.php?p=418683#418683 . Yep, she was just talking about her Rio Tinto research (see her LPSC abstract above), which falls entirely into the category of saying that methanogens are POSSIBLE -- not probable -- on Mars.

Jeremy Cherfas

Oliver!

Commiserations

My iBook must be of the same Voodoo vintage. I was without it for almost 8 weeks from December 2003 to February 2004 and needed fixing twice in that spell. Then it died again last Saturday. I'd be bereft it it weren't for the loan of a friend's Powerbook. And a jolly big one at that.

Cheers

Jeremy

Jagdeep

A properly runinng methane digester is producing around 1psi, that so happens to be able to run a gas burner. It is common practice to store the methane in a inner tube from a tire. when the rubber expands its keeping a pressure on the methane. The problem is, where do you put an inner tube on a camper that allows it to expand and contract. On one hand you could just hook up your collector to the digester when you are in place as part of setting up camp, and that is probably what I will do until I come up with something more romantic

Dody

Wow. These are breathtaking.Isn't Titan the moon that, aionrdccg to astronomer's theories, may have other life forms or may be able to sustain life (as we know it)?This is so amazing that this is happening in my lifetime. First, we're getting solid information about Mars, including some evidence that's suggesting that Mars may have supported life forms. Now, we're getting closer looks at other celestial bodies that seemed so far away.I wish that faster distant space travel would happen in my lifetime, but I don't think that will be the case.

Caroline

Chandra Posted on Love it! Glad I had a chance to run with you the other day! Helped me to get back on track while I was up there! Know that you keep me isinpred!

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