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Posted by: Sunspot Dec 4 2006, 09:25 PM

Dec. 4, 2006

Dwayne Brown/Erica Hupp
Headquarters, Washington
202-358-1726/1237

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278

MEDIA ADVISORY: M06-186

NASA SCHEDULES BRIEFING TO ANNOUNCE SIGNIFICANT FIND ON MARS

WASHINGTON - NASA hosts a news briefing at 1 p.m. EST, Wednesday, Dec.
6, to present new science results from the Mars Global Surveyor. The
briefing will take place in the NASA Headquarters auditorium located
at 300 E Street, S.W. in Washington and carried live on NASA
Television and www.nasa.gov.

The agency last week announced the spacecraft's mission may be at its
end. Mars Global Surveyor has served the longest and been the most
productive of any spacecraft ever sent to the red planet. Data
gathered from the mission will continue to be analyzed by scientists.


Panelists include:
- Michael Meyer -- Lead Scientist, Mars Exploration Program, NASA
Headquarters, Washington
- Michael Malin -- President and Chief Scientist, Malin Space Science
Systems, San Diego, Calif.
- Kenneth Edgett -- Scientist, Malin Space Science Systems
- Philip Christensen -- Professor, Arizona State University, Tempe,
Ariz.

Posted by: monitorlizard Dec 4 2006, 10:08 PM

The presence of Philip Christensen (PI for TES) on the panel may indicate the discovery of a new spectral feature on Mars. That could be very interesting, and downright thrilling if CRISM and HiRISE follow up on it!

Posted by: Tesheiner Dec 5 2006, 09:22 AM

I just found this while reading NASA Watch; perhaps it is related to Wednesday's briefing. Take it with A LOT of care; it might be just smoke.

Editor's note: According to an item first posted by Aviation Week and Space Technology magazine: "NASA is ready to announce major new findings about the presence of water currently emerging onto the surface of Mars.

http://www.nasawatch.com/archives/2006/12/aviation_week_e_1.html

Posted by: djellison Dec 5 2006, 09:51 AM

It's impossible to know where smoke ends and facts start with NW nowadays - it's turned into KC's personal ranting-blog instead of a reliable news source, a pity really. However the AW speculation is likely to be fairly sound.

Doug

Posted by: AlexBlackwell Dec 5 2006, 04:10 PM

As for Cowing's "ranting," what's really funny is this little bit:

QUOTE

Apparently some reporters were given access to embargoed information from the participants and NASA JPL while others were not. So much for providing equal access to all media. NASA is playing favorites once again.

I guess he hasn't been getting any http://www.spaceref.com/news/viewnews.html?id=939 lately.

EDIT: Apparently, my original post has created some flak for Doug. Although this is a discussion forum, I should have stated what I thought was obvious, that that was my opinion, not Doug's. I apologize for any inconvenience to Doug or UMSF, both of whom/which I hold in high regard. For that reason, I've edited the statement by deleting a sentence. Hopefully, this will end the harangue Doug has been enduring from a certain person. Though I do stand by the "ranting" part

Posted by: AlexBlackwell Dec 5 2006, 04:14 PM

Listen very carefully, and I mean carefully, to the very last bit of Christensen's recent interview on Planetary Radio (which was http://planetary.org/radio/show/00000213/ yesterday).

Posted by: Sunspot Dec 5 2006, 04:52 PM

Gullies

Posted by: tglotch Dec 5 2006, 05:53 PM

A few points:

1) Remember that a TES "pixel" or footprint is 3 x 8 km, so any interesting region with a new spectral feature would have to be at least this big. Typically we like to see the same feature in a few pixels to believe that its really there. In addition, TES hasn't been mapping mineralogy for quite some time due to a "glitch" that has degraded the spectral data. Recently TES has been used for thermal inertia and atmospheric studies.

2) I don't know, because I haven't talked to him about it, but listening to the interview, I would guess that the gullies to which Phil was referring were those he discussed in a Nature (I think) paper a few years ago which also show a "pasted-on" terrain near the gullies which he hypothesized to be dust-covered snow. If there's a new major announcement regarding these gullies and MGS, its probably some new interesting MOC imagery.

but then again, I've been wrong before, so who knows?

Posted by: AlexBlackwell Dec 5 2006, 06:08 PM

Hmmm...

I'm wondering if we should bone up http://www.sciencemag.org/cgi/content/full/288/5475/2330, as well as http://www.nature.com/nature/journal/v422/n6927/abs/nature01436.html.

Also, a http://www.psrd.hawaii.edu/Aug03/MartianGullies.html might be good reading.

Posted by: ugordan Dec 5 2006, 06:29 PM

This definitely sounds like it belongs to a separate thread. It's urelated to the MGS mishap. And Alex, why do I get the distinct feeling you know something we don't?

Posted by: AlexBlackwell Dec 5 2006, 08:00 PM

Per Gordan's suggestion, I'll start a new thread on this topic and merge the other posts into it.

EDIT:

Like most people here, I'm just guessing. That said, I wonder if Christensen will mention his "http://themis.asu.edu/projects/thor" http://www.asu.edu/news/stories/200602/20060201_THOR.htm tomorrow?

Posted by: AlexBlackwell Dec 5 2006, 08:24 PM

Leonard David has a http://www.livescience.com/blogs/2006/12/05/mars-doesnt-read-our-textbooks/ in his blog.

Posted by: volcanopele Dec 5 2006, 08:31 PM

Maybe a gully seen recently but not seen in older MOC images? Phil Christensen could be there to present spectroscopy results of said "new" gully from TES or THEMIS.

Posted by: AlexBlackwell Dec 6 2006, 01:03 AM

You could be right. However, since we're just speculating, I'm wondering if, as tglotch alluded to above, Christensen might be there to discuss and expand on his gully formation model, as published in the Nature paper. And note that Christensen's results in 2003 were based not on THEMIS IR (let alone lower res TES) but rather on THEMIS VIS imagery, which gave a more synpotic view of the gully sites than MOC NA.

Again, just speculating, but maybe Malin and Edgett have detected noticeable changes in already-mapped gully sites and/or have added more gully sites to the existing database increasing the coverage over the mid-latitudes?

Whatever the results turn out to be, tomorrow should be interesting.

EDIT: One should note the fundamental difference between the Malin/Edgett model and Christensen's. In the former, a subsurface origin for the seeps, which implies near-surface reservoirs and/or aquifers, is posited; in the latter, basal melting from overlying snowpacks (due to Mars' obliquity excursions) is invoked. So if tomorrow's press conference is about gullies, and if Malin/Edgett and Christensen have come to some common view on the formation mechanism(s), that, in and of itself, is interesting.

Posted by: JonClarke Dec 6 2006, 06:47 AM

Why should they not both be right in different places?

Posted by: AlexBlackwell Dec 6 2006, 04:21 PM

That's certainly plausible, Jon, and I wouldn't be surprised if that is indeed the case.

Posted by: MizarKey Dec 6 2006, 04:30 PM

I know that this group is usually great about posting highlights during the briefing, I was hoping this trend would continue as I'm blocked from watching anything by the network at my job. So please, keep a running thread about what's being said. Thanks in advance.

Posted by: AlexBlackwell Dec 6 2006, 04:54 PM

It looks like the story is http://www.dailymail.co.uk/pages/live/articles/news/news.html?in_article_id=420833&in_page_id=1770, no pun intended, courtesy of The Daily Mail.

Posted by: ugordan Dec 6 2006, 05:08 PM

The Daily Mail:

Hmmm....

Posted by: Stu Dec 6 2006, 05:10 PM

Good old Daily Mail... can't be Michael Hanlon's piece, he knows his stuff. Some sausage-fingered staff writer has provided us with these nuggets...

NASA researchers have documented the formation of new craters on the plant's surface and found bright, light-coloured deposits in gullies that were not present in previous photos.

The "plant's " surface?!?!?!? They've spotted plants on Mars big enough to have craters on them! How the **** did the Vikings miss those?!?

Earlier this week the MOC took pictures of the NASA exploration vehicle rover Spirit on the planet's surface.

MOC imaged Spirit? Wow, they kept that quiet.... Oops! Someone didn't do their research...

Posted by: tuvas Dec 6 2006, 05:16 PM

Are you sure you can trust this source?



Is Stephen Hawking British? And MOC isn't working, let along taking a picture of Spirit... Unless....

ADDED: I guess I was wrong about Stephen Hawking. For some reason I never had thought of him as British... But he is...

Posted by: Stu Dec 6 2006, 05:16 PM

More details...

Martian find raises chances of life
ALICIA CHANG
ASSOCIATED PRESS
December 6, 2006

LOS ANGELES - A provocative new study of photographs taken from orbit
suggests that liquid water flowed on the surface of Mars as recently as
several years ago, raising the possibility that the Red Planet could
harbour an environment favourable to life.

The crisp images taken by the Mars Global Surveyor do not directly show
water. Rather, they show apparently recent changes in surface features
that provide the strongest evidence yet that water even now sometimes
flows on the dusty, frigid world. Water and a stable heat source are
considered keys for life to emerge.

Until now, the question of liquid water has focused on ancient Mars, and
on the Martian north pole, where water ice has been detected. Scientists
have long noted Martian features that appear to have been scoured by
water or look like shorelines, and have tried to prove that the Red
Planet had liquid water eons ago.

"This underscores the importance of searching for life on Mars, either
present or past," said Bruce Jakosky, an astrobiologist at the
University of Colorado at Boulder, who had no role in the study. "It's
one more reason to think that life could be there.''

The new findings were published Wednesday in the journal Science and
NASA scheduled a news conference for Wednesday afternoon to announce the
results.

Oded Aharonson, an assistant professor of planetary science at the
California Institute of Technology, said that while the interpretation
of recent water activity on Mars was "compelling," it's just one
possible explanation. Aharonson said further study is needed to
determine whether the deposit could have been left there by the flow of
dust rather than water.

The latest research emerged when the Global Surveyor spotted gullies and
trenches that scientists believed were geologically young and carved by
fast-moving water coursing down cliffs and steep crater walls.

Scientists at the San Diego-based Malin Space Science Systems, who
operate a camera aboard the spacecraft, decided to retake photos of
thousands of gullies in search of evidence of recent water activity.

Two gullies that were originally photographed in 1999 and 2001 and
re-imaged in 2004 and 2005 showed changes consistent with water flowing
down the crater walls, according to the study.

In both cases, scientists found bright, light-colored deposits in the
gullies that weren't present in the original photos. They concluded the
deposits - possibly mud, salt or frost - were left there when water
recently cascaded through the channels.

The Global Surveyor, managed by NASA's Jet Propulsion Laboratory,
abruptly lost radio contact with Earth last month. Attempts to locate
the spacecraft, which has mapped Mars since 1996, have failed and
scientists fear it is unusable.

NASA's durable Mars rovers have sent scientists strong evidence that the
planet once had liquid water at or near the surface, based on
observations of alterations in ancient rocks.

"We're now realizing Mars is more active than we previously thought and
that the mid-latitude section seems to be where all the action is," said
Arizona State University scientist Phil Christensen, who was not part of
the current research.

Mars formed more than 4.5 billion years ago and scientists generally
believe it went through an early wet and warm era that ended after 1.5
billion to 2.5 billion years, leaving the planet extremely dry and cold.

Water can't remain a liquid for long because of subzero surface
temperatures and low atmospheric pressure that would turn water into ice
or gas.

But some studies have pointed to the possibility of liquid water flowing
briefly on the surface through a possible underground water source that
periodically shoots up like an aquifer.

Posted by: imipak Dec 6 2006, 05:17 PM

Oh, I'm not so sure of that... (though the Daily Mail, the original "fascist rag", is hardly a journal of record.) Steve Squyres did say that Spirit and environs was pretty high up the priority target lists. Unlike the VC image, I imagine there'd be no need to rush-release the image. I'm rather hoping it's both... perhaps a gully has appeared on the side of Husband Hill

BTW - yes please, if anyone has access to NASA TV and feels like posting notes... please do!

Posted by: Stu Dec 6 2006, 05:17 PM

Does a bear [rest of post deleted]

Posted by: Stu Dec 6 2006, 05:20 PM

Sorry, I didn't insert a "sarcastic g*t" icon when I said about them keeping quiet MOC imaging Spirit...

Posted by: tuvas Dec 6 2006, 05:22 PM

I appologize, I guess he really is... Guess I should have looked that up myself before posting... Duh!

Posted by: imipak Dec 6 2006, 05:40 PM

Oh, right, I see ... serves me right for posting without catching up with a weeks' backlog of unread posts! If only I didn't have to work, or sleep, or spend 2h a day driving...

Posted by: elakdawalla Dec 6 2006, 05:42 PM

You probably thought he was American because his voice-generating computer was built by an American company -- so he has an American accent! He's also one of the few Brits who appears regularly on The Simpsons...

I don't see the Mars gullies story appearing on http://www.sciencemag.org/sciencexpress/recent.dtl yet...

--Emily

Posted by: AlexBlackwell Dec 6 2006, 05:45 PM

Science (and Science Express) has an automated web management system that posts items when the embargo times out. Just keep hitting "Reload" or "Refresh."

Posted by: elakdawalla Dec 6 2006, 05:55 PM

It's typically more efficient for me to wait until you post a link here, Alex

--Emily

Posted by: ustrax Dec 6 2006, 05:57 PM

"MARS
Recent Activity Revealed"

That's the header...

Posted by: AlexBlackwell Dec 6 2006, 05:57 PM

Your wish is my command. http://www.msss.com/mars_images/moc/2006/12/06/index.html.

EDIT: And I believe the paper will be published in the http://www.sciencemag.org/content/vol314/issue5805/index.dtl.

Posted by: ElkGroveDan Dec 6 2006, 06:12 PM

We now have a new unit of measure; Swimming Pools.

Posted by: remcook Dec 6 2006, 06:15 PM

very nice summaries on the msss page. Something else to look at with more detail with HiRISE perhaps?

edit-downloads on: http://www.nasa.gov/mission_pages/mars/main/index.html

Posted by: tuvas Dec 6 2006, 06:23 PM

I'd be willing to bet that it's far more likely to have CRISM follow up then HiRISE, although HiRISE will almost certainly photograph these areas quite soon (I have no idea when, so...)

Posted by: Analyst Dec 6 2006, 07:09 PM

A very good press confernce, good questions.

I have been a child during the Voyager encounters, but the discovery of frequent liquid water on mars is something I compare to volcanism on Io or gryovulcanism on Triton. Just great. The legacy of MGS continues. May she rest (or circle) in peace.

Analyst

Posted by: volcanopele Dec 6 2006, 07:15 PM

I wouldn't go THAT far. It is interesting, but the news that Mars gets hit by impact craters, and that gullies are present-day phenomena (given the crater counts on previously observed gullies) isn't that shocking. Interesting, but not shocking. I would put it on the level of the discovery of lakes on Titan, a discovery which just confirmed that we were at least on the right track with Titan.

Posted by: centsworth_II Dec 6 2006, 07:16 PM

You mean recent, not frequent, right?

Posted by: um3k Dec 6 2006, 07:18 PM

I recorded the NASA TV internet stream of the entire conference. I'll upload it somewhere once I convert it to an appropriate format.

Posted by: Steve Dec 6 2006, 07:21 PM

I'd be willing to bet that when CRISM focuses on these gullies they'll find salts of some kind. I'd even put a smaller wager on sulphate salts. As Steve Squyres mentioned in response to a question at Open University, the "water" on mars is acidic and inhospitable to life. That suggests that this AP article may be premature.


Steve

Posted by: volcanopele Dec 6 2006, 07:29 PM

I agree. I would not be surprised if the bright deposits are some kind of sulphate salt.

Posted by: AlexBlackwell Dec 6 2006, 07:39 PM

http://www.jpl.nasa.gov/news/news.cfm?release=2006-145
NASA/JPL
December 6, 2006

Note: I'm going to change the name of this thread to the title above (or something close to it, depending on the space in the topic line).

Posted by: AlexBlackwell Dec 6 2006, 07:42 PM

Aside from HiRISE and CRISM, Malin mentioned SHARAD. I'm interested to see if the putative aquifers are detectable by GPR.

Posted by: vmcgregor Dec 6 2006, 07:53 PM

Additional multimedia products (video, podcast, slideshow) have been added to the JPL homepage at www.jpl.nasa.gov

-Veronica McGregor
JPL Media Relations

Posted by: tglotch Dec 6 2006, 07:56 PM

Well, we have evidence from two landing sites for acidic water in the form of sulfates. But don't forget that OMEGA has found plenty of evidence for gypsum and kieserite all over Mars, which are neutral salts and don't necessarily imply an acidic envrionment.

Posted by: AlexBlackwell Dec 6 2006, 08:03 PM

Oh Jason, your outer planets biases are showing

I think any scientist would agree that liquid water flowing at the surface or near-surface of present-day Mars is more than merely "interesting."

Posted by: ElkGroveDan Dec 6 2006, 08:03 PM

Welcome to UMSF Veronica
(from one silently suffering media relations person to another)

Posted by: John M. Dollan Dec 6 2006, 08:27 PM

Considering the rate that the Earth intercepts meteors, and adding to that Mars' thinner atmopshere, would it not stand to reason that impacts would reach the surface much, much more often?

And if that is true, what does it say about those regions that are relatively crater-free? Could there be some active geology involved, or are Martian aeolian forces enough to erase some of these smaller craters?

...John, curious as always...

Posted by: Paolo Dec 6 2006, 08:29 PM

Are artillery projectile-probes like these http://web.mit.edu/iang/www/pubs/artillery_05.pdf the only method suggested so far to explore the gullies?

Posted by: climber Dec 6 2006, 08:30 PM

I was sure YOU'll pick this one up
BTW, they had another one but can't remeber what it was; Swimming Pools is good enough anyway

Posted by: climber Dec 6 2006, 08:38 PM

While listening to the show, a question crossed my mind : OK we can see gullies 5-10 Swimming Pools big but DO smaller ones exist? I mean smaller than MGS resolution i.e. the one MRO could see...
If Mickael Malin dam theory is right this could provide smaller one to occur but I'm looking forward to MRO pictures of the 2 gullies presented tonight as well as all bright one that are probably quite recent if I understood correctly.

PS : a to Doug. When you interview Jim Bell, your line is still much better than Ames'

Posted by: Stu Dec 6 2006, 08:40 PM

"Interesting"?



"INTERESTING?"



Are you a VULCAN volcanopele [corrected] ?!!!! Does cold, coppery green blood flow through those veins? Did your left eyebrow merely lift quizically when you saw those images when you peered into your science monitor??

Do you know how long many of us "Out here" have been waiting for these images and this news? What we have there is the strongest evidence yet for Mars being a potential habitat for life, nothing more, nothing less. And I know some sticks in the fresh martian mud will say that that's too optimistic, too simplistic and going over the top - I don't care!!!!! I want to go out and laugh at the sky now! Look at the pictures!! Something poured out down those crater walls for a while. Something... wonderful... Something that is calling to us, siren-like, "Come and look more closely... come... come..."

Imagine standing there, on the rim of that crater, and seeing a gully in flow...

... imagine feeling the rumble beneath your boots as the water breaks through and starts to gush... imagine seeing the water steaming and boiling in the low atmospheric pressure, sliding and slavering down the crater wall's slopes, dying even as you watched it... imagine watching the gushing stop, and the last of the free water evaporate away, leaving behind a glistening snakeskin of freshly-exposed salts, covered with glinting frost, like someone has spilled molten glass from above... Doesn't that make you feel amazed?!

We thought we knew Mars but we don't. We were fooling ourselves all along. It has secrets still, locked away in its rocks, maybe even just a gloved hand's depth beneath its dusty surface. Imagine that, an evolved monkey's hand trailing through the dust of Mars, its fingers digging down, down... what would it find...?

I know this post might seem over the top but I'm sorry, I'm on a high right now and in no mood to be cold and scientific. There wasn't just water on Mars a billion, a million or a thousand years ago, there was water there a couple of years ago, flowing... and there probably is now, as I type this. The implications of that are enormous, simply enormous. We should be celebrating, not downplaying it.

Go on volcanopele, put a party hat on, I dare ya...

Posted by: John M. Dollan Dec 6 2006, 08:46 PM

Stu...

Where did you find that image? It is absolutely, stunningly beautiful! Please, is it some kind of public image, or is it covered by copyright? I'd love to use it on one of my websites....

...John...

Posted by: volcanopele Dec 6 2006, 08:48 PM

I'm not tuvas. I'm not a vulcan, either, I'm an Ionian, and red-hot, ultramafic lava flows through my veins... My reaction was that this news was interesting and that I wanted to see those features in HiRISE images. But, no, I didn't get all that excited. Maybe it is my outer planets bias, but flowing, boiling acidic water just isn't as exciting as huge lava flows on Io, the Earth-like geology of Titan, the geysers of Triton, or I dare say, the ocean on Europa.

EDIT: I forgot Enceladus' geysers, how silly of me

Posted by: AlexBlackwell Dec 6 2006, 08:57 PM

And through your basilar and carotid arteries, too

Posted by: ngunn Dec 6 2006, 09:01 PM

I can't get either the msss or nasa links to work (Are they awash with hits?) so I've still only seen one pair of pictures on a BBC TV news screen. Could somebody post just the pictures?

Posted by: climber Dec 6 2006, 09:07 PM

I'm not Stu (you'd better change to Stugully now ). I get the point volcanopele and I also love "your" places, but we'll go physicaly to Mars ONE full century before the places you're talking about...and THAT is exciting...

Posted by: Stu Dec 6 2006, 09:10 PM

Apologies for the mistake, written in haste, I've corrected it.

I agree that all your other things are exciting (except maybe the geysers of Triton... not too fussed about them), but they're a looooong way away, and we have no chance of seeing them up close and personal, with wide, startled human eyes, in our lifetimes or even two lifetimes after that. It's not the water itself that's exciting to me it's what it represents - a dynamic, warm-and-wet-in-places Mars - and what it teases, that there could be life there, right now. That "flowing, boiling acidic" water might be thick with microbes all shouting "Wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee!!!!!!!!!!!!!!" as they fly through the air... admittedly mere seconds before dying a horrible death, but hey...

The future just shifted beneath our feet, settling into a new structure and pattern. Surely someone else felt it too?

(that pic, by the way, is one I've had on my computer for ages, can't even remember where I got it now, but I think it was from a space calendar a friend gave me... sorry I can't be of much more help...)

Posted by: climber Dec 6 2006, 09:10 PM

here's a link : http://www.jpl.nasa.gov/news/news.cfm?release=2006-145
And images

Posted by: Stu Dec 6 2006, 09:16 PM

Pics...

Posted by: Nix Dec 6 2006, 09:21 PM

I'm very excited with these new foundings, also on the new impact features.

A quick search for other light-toned areas associated with gullies turned up this image; there is such an area in the big crater near the middle of the image.

http://www.msss.com/moc_gallery/s05_s10/full_gif_non_map/S10/S1001717.gif

The hunt is open..

Nico

Posted by: Analyst Dec 6 2006, 09:36 PM

English is not my native language. I mean the water is not flowing for long periods of time (like a river), but only for short periods (maybe hours), but again and again. AND it's been recent.

Analyst

Posted by: imipak Dec 6 2006, 09:38 PM

I concur. It is interesting; it demonstrated the usefulness of extended missions (and launching long-lived hardware), demonstrated again the power of serendipity and a sharp pair of eyes (Edgett/Malin appear to be saying the first new crater was spotted visually in a wide-angle context image, ie without comparison to the previous image of the same area!) and adds a nice detail to the current state of knowledge about sub-surface fluids. It probably helps eliminate up a couple of alternative explanations for the gullies (and if not, HiRISE et al will do so.) (Tho' AFAIK CO2 ice is still a possibility?) But exciting? More so than, say, the MER EDL, or Opportunity's arriving at Victoria Crater? I confess I was mildly excited when I heard the first rumours of a major NASA announcement, but having seen the names listed (and read this thread), the actual news was pretty much as expected. Spotting new craters is MORE exciting, to me, and I think will be seen to be a more significant single discovery in 10 years' time.

Moreover, I heard someone from the Beagle team interviewed on Radio 4 ("PM"), and he made a point of saying "yes, I know we've had these same stories about "water on Mars!!" every couple of years for the last decade." He was just getting his retaliation in first - I predict comedians (funny and otherwise) will be pointing that out before Saturday morning.

However, liquid flowing down the gullies shouldn't be news to anyone who's been paying attention. The original paper revealing the gullies already made it clear that they were clearly relatively recent features, and it is not that surprising that one or two would trickle for a minute or two once or twice a decade.

I think the image, attractive though it is, looks more like the Three Gorges than Mars From what I remember of the original paper, if you were there on the surface when one of these things was active you'd see a small, narrow strip of dirty water running straight down the slope, subliming as it went; not bursting out under enormous pressure and spraying tens of feet out into the air... the gully would cut much more deeply into the crater wall if it were that violent. I also wonder about the concentration of any putative salts... if it were very high, would that affect the flow characteristics of the water?

Right, I'm off to find another roaring fire to drape my wet blanket over

Posted by: Stu Dec 6 2006, 09:47 PM

sigh... okay... so this isn't brand new "news", we all suspected what was going on, and little voices in our heads have been saying "water carved" ever since the first gullies were spotted... and yes, that image is over-dramatised, a real gully"burst" wouldn't be anything like as violent... and no, this wasn't as heart-pumpingly exciting as Spirit's EDL or Oppy's triumphant, knackered roll up to the rim of Victoria.... but come ON people!!! WATER ON MARS!!!! I refuse to let anyone spoil this night for me, not after I've longed for this news for so long. Get your dirty wet blanket away from my fire! I'm going to spend the night sitting by it under the stars, watching the golden sparks rise into the air, imagining each one is Mars, complete with gullies of steaming, silver-scaled water...

Posted by: RichardLeis Dec 6 2006, 09:57 PM

Weird. To me, they are all equally as exciting (including the geysers on Enceladus). Whatever floats our boats, I guess

The solar system is wonderfully active, H20 plays a huge role everywhere, and we have a new foundation for this incredible revolution in planetary science.

Hats off to Mars Global Surveyor and team! What a history!

Posted by: RichardLeis Dec 6 2006, 09:58 PM

Is the HiRISE camera going to take images of these areas? Do people really need to ask that!? The whole array of MRO's tools will be used, no doubt.

Posted by: climber Dec 6 2006, 09:58 PM

I'm on your side Stugully! Come on Far Rimers, Far Dreamers, wake up, we need your help. Where are you Dan?
Sorry Near Blanketers I feel Water less letal than projectiles forming craters. I was there when they said "water is flowing on Mars today", I was listening, there's NO doubt : T-O-D-A-Y, they said. I'm gona have a (salty) bath right away and T-O-D-A-Y

Posted by: mhoward Dec 6 2006, 10:07 PM

There was never much question in *my* mind on that, nor probably in anyone's at this point

Fantastic images... hats off to MGS indeed.

Posted by: ngunn Dec 6 2006, 10:13 PM

Thanks, Stu and climber for the pictures direct, much appreciated as the links are still "server not found" for me. I was able to scan some of the news releases though. I believe someone in the know said that on the evidence the probability of recent aqueous flow is 'high but not very high'. From most of the news reports you would think the certainty had been demonstrated. The trick now will be to catch one of these things moving on the scale of seconds or minutes - the maximum time one can imagine aqueous liquid surviving on the surface.

Posted by: JonClarke Dec 6 2006, 10:15 PM

Bah! Seen one komatiite, you seen them all. I've seen thousands.

Jon

Posted by: AlexBlackwell Dec 6 2006, 10:17 PM

That's weird. I'm not having any problems loading and re-loading the http://www.msss.com/mars_images/moc/2006/12/06/index.html.

Posted by: deglr6328 Dec 6 2006, 10:29 PM

It should be noted that IF this is water (I want to see NIR spectra with a niiiiiice OH stretch absorption peak right at 1.5 microns before I totally discount liquid CO2) then the conditions are perfect for lyophilization of bacteria etc. in the water as it escapes the ice dam and vaporizes/freezes. This would be THEE ideal spot to collect samples for a return analysis.

Posted by: AlexBlackwell Dec 6 2006, 10:33 PM

I believe the links below won't go active until tomorrow, unless one has special access during the embargo. In any event, here are the references to the paper and a related news article in the same issue:

Present-Day Impact Cratering Rate and Contemporary Gully Activity on Mars
Michael C. Malin, Kenneth S. Edgett, Liliya V. Posiolova, Shawn M. McColley, and Eldar Z. Noe Dobrea
Science 314, 1573-1577 (2006)
http://www.sciencemag.org/cgi/content/abstract/314/5805/1573
http://www.sciencemag.org/cgi/content/full/314/5805/1573
http://www.sciencemag.org/cgi/content/full/314/5805/1573/DC1

Richard Kerr's accompanying "News of the Week" article: "http://www.sciencemag.org/cgi/content/summary/314/5805/1528"

Posted by: Nirgal Dec 6 2006, 10:44 PM

*LOL*
Stu, I just loooooooove that refreshing, vivid pictorial writing style of yours

Posted by: tuvas Dec 6 2006, 10:46 PM

Jason, come on now, this has to rank there with liquid water being identified at Europa as one of the most exciting discoveries in the Solar System!

Posted by: tuvas Dec 6 2006, 10:48 PM

Liquid CO2? Is that even possible at Mars? Somehow I don't think so... But I could be wrong...

Posted by: mhoward Dec 6 2006, 10:50 PM

You pays your money, you takes your chances...

Posted by: AlexBlackwell Dec 6 2006, 10:52 PM

Most of us don't think so.

But I see you haven't visited the Wild, Wild World of Hoffmanland. In that case, you'll need http://www.earthsci.unimelb.edu.au/mars/.

Make sure you're seated during the tour, though

Posted by: Anoolios Dec 6 2006, 11:11 PM

This amateur is still skeptical, is the only evidence of water in these gullies the relative albedo (light instead of dark like most other dust/sand deposits)? The most likely explaination seems to me to be dry avalanches.

Posted by: AlexBlackwell Dec 6 2006, 11:17 PM

It's always good to be skeptical, Anoolios. That is a hallmark of good science.

As for your question, have you seen http://www.msss.com/mars_images/moc/2006/12/06/gullies/groundwater_evidence/index.html? Note that Malin et al. don't rely just on albedo, though that is a key piece of evidence.

Posted by: helvick Dec 6 2006, 11:23 PM

The rate is higher but it's not as high as you might think given the difference in densities at the surface. The martian atmosphere is extremely thin and at the surface is comparable to the Earth's at around 35KM but because of the lower martian gravity it's scale height is higher (~11km vs ~6km for earth) it is remarkably similar in density to the Earth's atmosphere once you get above 75km or so if I remember correctly. For the most part it filters out a similar amount of "stuff". By similar I'd guess we're talking about a similar order of magnitude here but I'd have to do some digging to get a number I'd be willing to defend.

The percentage that reaches the ground is higher for another reason that could well be as important - the average atmospheric impact speed at mars orbit is slightly slower (5-10km/sec slower) and so there is less energy to dissipate. For asteroidal debris this is quite significant as the impact speed can be as low as 7km/sec at mars (vs ~17km/sec typically for Earth) so only about 17% of the energy needs to be disipated. Cometary and retrograde impacts are a different animal and the difference at Mars for these (compared to earth) is 80% and 50% respectively.

The main reason there are more apparent craters on Mars is that the surface is (for the most part) really and truly ancient and erosion rates are many orders of magnitude slower than on earth.

Posted by: AlexBlackwell Dec 6 2006, 11:29 PM

Also, proximity to the asteroid belt and Jupiter.

Posted by: John M. Dollan Dec 6 2006, 11:31 PM

Thanks for that clarification. It definitely helped me with an off-list discussion.

...John...

Posted by: centsworth_II Dec 6 2006, 11:40 PM

The reason this news IS really exciting is that for the first time we can think of sending instruments to examine material which recently interacted with liquid water on Mars. Previously it was looking like we would have to wait for a machine which could drill hundreds of meters beneath the surface. The big question now is was the water ancient ice, melted and released in one brief event or are there liquid aquifers which occasionally find their way to the surface?

Posted by: ElkGroveDan Dec 6 2006, 11:47 PM

You decide:

Posted by: Myran Dec 6 2006, 11:58 PM

Liquid CO2 will not be possible in 'open air' with the Martian air as thin as it is, same as on Earth.
But nothing prevents liquid CO2 from being kept underground if it have a good nice aquifier or perhaps a lid of frozen water. Yes the pressure would be great, but this could also explain features like the ones we see here.

I personally think CO2 are a more likely explanation. This simply from looking at the martian temperature range. The surface are simply cold, and when we look underground it should be even colder in most places!
(This except any and still-not-found-despite-looking geotermal hotspots).
Colder conditions underground places the thermometer in the right range for frozen CO2, which happens at -78 °C.

Narrow cracks in the ground might become CO2 traps when the area chills down in the night. We also seen signs of karst topography in Meridiani, if that idea turns out to be correct there might even be larger caves where CO2 ice accumulate on the walls. When it melts at −57 °C there might not be space for it to expand and reach the gasous phase and so it rush towards the nearest opening - and so we have a gully.

So I am fairly in the same camp as deglr6328 on this one.

Posted by: AlexBlackwell Dec 7 2006, 12:06 AM

There are plausibility arguments against sequestration of liquid CO2 in the martian near-surface. For example, see Stewart and Nimmo [2002] (http://es.ucsc.edu/~fnimmo/website/paper16.pdf).

Posted by: Myran Dec 7 2006, 12:28 AM

Thank you, and I took the time to speed read a part of that text you linked.

But you are absolutely right, I wrote about liquid CO2 in the first paragraph since that was what tuvas asked about.

But the following sentence lacks the word 'frozen' and should have read.
"I personally think frozen CO2 are a more likely explanation .......... at -78 °C."

(And for once I dont edit, since I got back to the subject so fast)

Finally I take the opportunity to link a text where the author points out that the gullies seems to appear on the http://www.earthsci.unimelb.edu.au/mars/Polar.html Something that again are one sign that we might not be seeing the activity of water here.

And then again another link to one text that also discuss the CO2 as one alternative explanation for the gullies. http://unisci.com/stories/20012/0402013.htm

Posted by: AlexBlackwell Dec 7 2006, 12:33 AM

Thanks, Myran. And yes, I'm http://www.unmannedspaceflight.com/index.php?s=&showtopic=3559&view=findpost&p=77064 with Nick Hoffman's views.

Posted by: exoplanet Dec 7 2006, 12:33 AM

Ahem . . . but we have at least one if not many more examples . . . which proves that life in extemely acidic niches on earth is actually TEEMING with microbes.

Please see this article. If you need more, Steve . . . please let me know.

http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2005/04/21/MNGBCCCDD21.DTL

I hope that Steve Squires has at least noted recently that extremely acidic environments on earth are not barren of life but do support strong colonies of microorganisms. What this means on Mars should not preclude that life does not exist. To the contrary with regards to the recent images and future images to come:)

Posted by: AlexBlackwell Dec 7 2006, 12:57 AM

Emily now has a story http://www.planetary.org/news/2006/1206_Mars_Global_Surveyor_Discovers_Current.html at TPS.

EDIT: As well as a http://www.planetary.org/blog/article/00000789/.

Posted by: jamescanvin Dec 7 2006, 01:00 AM

Have you watched/listened to SS talk at the OU? In the Q'n'A, when asked about the prospects of life he mentions that although life can survive well on earth in extremely acidic environments it is not clear that it can come into being in one. On earth, the microorganisms formed in a more benign environment and *then* evolved into being able to tolerate the harsh conditions.

Posted by: exoplanet Dec 7 2006, 02:24 AM

The warm little pond theory may well be proven false in the near future. It has only been a theory that has to my knowledge "not" been proven. This basic article shows some of the current dissent among "the experts" about the origin of life:

http://www.economist.com/science/displaystory.cfm?story_id=5518892

The last two paragraphs are noteworthy. Regardless, whether life started on Earth in an acidic/basic hydrothermal spring, at the bottom of an early ocean in a hydrothermal vent, from a meterorite - the panspermia theory, or in a "warm little pond". The fact is we don't know. And we still don't know that much about Mars to make generalizations about whether or not if there was water on Mars - it was too acidic to inhibit the start of life there.

Posted by: tfisher Dec 7 2006, 02:30 AM

This is really exciting. Oh, to have a rover there! Maybe MSL will manage to be in a gully-prone area to get an up close look at these things. Until we get a ground truth look at these flows, there will always be doubts on water vs. CO2 vs. dust. But it is really looking more and more like water, which is so much more than just plain interesting. Wow.

Posted by: jamescanvin Dec 7 2006, 02:50 AM

Quite right I'm sure, I'm no expert on this.

All I was really trying to point out is that Steve Squyres has commented recently on this issue as you "hoped" and that that was (I think, I haven't had the chance to watch it again) his take on the matter.

Posted by: Steve Dec 7 2006, 02:51 AM

As I read the Economist article, the point at issue there is hot or cold, not acidic or basic.

SS's comment, as I remember it, centered on the acidic environment. He suggested that while primitive life could develop in a neutral environment and then evolve a way to maintain an internal neutral state in acidic surroundings, this was not likely to happen from scratch in an acidic environment.

BTW Jim, do you happen to have a transcription of SS's OU talk? All I have is the audio file and I'd like to be able to search for the passages in question. (Even this Q & A would help).

Steve

Posted by: CosmicRocker Dec 7 2006, 05:23 AM

Is there anyone here who will help me drag this poor, misguided individual behind the barn, where he can be taught a little bit of inner planet respect?
There is so much we probably don't know about life's origins. I figure, if there is hope for water, there is hope for life...

It wasn't so long ago that we all would have been jumping up and down about the discovery of any observed, recent change on Mars. I agree that these locations need to be be monitored with our newest orbiting instruments for verification, but hey, this is exciting news being released to commemorate the memory of a ten year veteran who has been lost in battle.

Let us all bow our heads in respect for a fallen comrade in arms.

Posted by: climber Dec 7 2006, 08:23 AM

You know, what give me real hope is that, let say, 20 years ago, life on Earth and water on Mars were understood a way that as been totaly changed nowaday. There IS life in extreme on Earth, there IS water on Mars today. I'll not related these two facts, I understand there could even be some politics behind this, BUT I feel that we are moving in the direction of "possible" life on Mars NOW. This has the BIG advantage to shake the people that decide the direction of future Exploration programs and, yes, as tsfisher say, they'll may be direct MSL in a place where gullies will be reachable. In my opinion, this is good new because this is one of the goal of exploring Mars and who imagined 3 years ago, before Oppy proved that Meridianii once see water, before MGS found active gullies that we could be talking now of landing a rover in a "waterworld"?

Posted by: AndyG Dec 7 2006, 11:43 AM

A question!

What's a likely figure for the viscosity of this water? I don't think I've ever seen viscosity estimates produced for (transient) liquid water in a Mars environment. Is it high (because the water's cold) or low (because it's near-boiling)?



Andy

Posted by: ustrax Dec 7 2006, 12:24 PM

What triggers my imagination in this great discovery is not the gullies...
Is the place where they we're originated...
Beneath...What can hide beneath?

I'll just join the choir...What great days we are living!

Posted by: ustrax Dec 7 2006, 01:58 PM

If the water excavates the gullies deplacing the darker material underneath where are the vestiges of that material?
Mixed with the lighter one?

Posted by: Stu Dec 7 2006, 02:30 PM

If you look at the ends of some of the gullies there are http://i.a.cnn.net/cnn/2006/TECH/space/03/22/mars.water/vert.mars.gully.jpg that has come down the gully and then been spread out across the lower ground...

Posted by: ngunn Dec 7 2006, 02:37 PM

I assume it's being proposed that as the wet avalanches dry out the deposited materials become encrusted with light coloured salts.

Posted by: babakm Dec 7 2006, 02:39 PM

I think this one is very interesting since it seems like the terrain where the gully formed is relatively flat. This tells me:

a. The flow was likely relatively persistent (i.e., probably not a short explosive burst)

b. Both the source and the gully look eminently roveable!

Posted by: ustrax Dec 7 2006, 03:00 PM

Looking through http://i16.photobucket.com/albums/b14/ustrax3/gully01.jpg there are some lighter layers being disrupted by the mouvement (in blue).
Can they influence in the colour of the material deposited at the end of the flow?...
If you look there's a first stage where the rush excavates but then, finding one of this layers (a), maybe because it's force has lost strenght, is no longer capable of "breaking" it and it jumps over, running now only over the surface...Then this second stage white flow looks like is loosening power again untill finds another bright layer ( B ) and it ceases a short after this and there's no other under...

http://www.msss.com/mars_images/moc/2006/12/06/gullies/other_examples/R0100902sub_noannot.gif

Posted by: Gray Dec 7 2006, 03:00 PM

I just read Emily's article (the one that Alex cited above) and I have to say that it's raised some questions in my mind. The evidence cited for the white streaks as being from flowing water were: the light color, the fact that they moved around obstacles and the digitate nature of their terminus. Yet if you look at the image of the dark flows, which are considered to be dry dust flows, you can see two of the same features: a digitate terminus and flow around an obstacle. That leaves only the white color as distiguishing them from the dark, dust streaks. Perhaps the light streaks are just a different type of dry flow (we have seen white dust churned up by Spirit) or perhaps the dark streaks are a different type of aqueous flow.

Posted by: ugordan Dec 7 2006, 03:12 PM

Mike Malin addressed that as well. The slopes where these deposits are made are fairly gentle, a dry process would have trouble making it that far - was it 1 mile or so? They did computer simulations showing it's most plausible to be a liquid-driven process, liquids flow much more easily than dry stuff.

Posted by: Gray Dec 7 2006, 03:19 PM

Ahh, thanks. I missed that part of the evidence.

Posted by: odave Dec 7 2006, 03:32 PM

Wow - my UMSF habit gets interrupted by work and life for a few days and look what I miss

What a great exit for MGS, good to see she "died with her boots on" (if indeed she's dead, of course)

Posted by: nprev Dec 7 2006, 04:05 PM

Absolutely. Go to any old mining town in the western US like Butte, MT or Lead, SD & you'll find all kinds of hardy little critters enjoying themselves in extraordinarily toxic, acidic environments...

Posted by: ElkGroveDan Dec 7 2006, 04:14 PM

And if you go in the winter, the conditions will be remarkably similar to Mars (with -50F not being uncommon in Butte). There's also a very large crater there.

Posted by: AlexBlackwell Dec 7 2006, 04:30 PM

I was waiting to see how long it would take Nick Hoffmann to http://www.habitablezone.com/space/messages/450242.html. Not surprisingly, I could have predicted this response.

Posted by: gpurcell Dec 7 2006, 04:42 PM

Actually, and I may be wrong about this, my understanding of the current planetary protection plan is that we want to avoid sending missions to these gullies to ensure that they stay in pristine state. I would be very, very uncomfortable having MSL trundle up to one.

Posted by: tuvas Dec 7 2006, 05:21 PM

My understanding is much the same, what a pity... The really interesting targets, and we can't even send anything there... Oh well, I guess that's life...

Posted by: AlexBlackwell Dec 7 2006, 05:34 PM

Both of you may be right; I'll have to go back and re-read the latest PP guidelines for Mars. However, I thought that, for example, MSL-related restrictions were due mainly to possible crash scenarios with an RTG power source. I thought that a "go-to" traverse capability (i.e., landing at a safe distance and then roving to the area of interest) would permit visitation of biologically interesting sites, assuming the lander/rover was subjected to Viking-level sterilization.

Posted by: AlexBlackwell Dec 7 2006, 05:41 PM

http://www.esa.int/SPECIALS/Mars_Express/SEMN4E9L6VE_0.html
ESA News Release
7 December 2006

Posted by: aldo12xu Dec 7 2006, 05:55 PM

I looked at the Planetary Protection Guidelines posted on the MSL Marsoweb site and it states:

"1. Prepare the landing system to meet Viking post-sterilization cleanliness requirements (controlled cleaning and assembly as noted below, followed by a system-level dry heat microbial reduction step in accordance with NPR 8020.12C), with control of recontamination through launch and delivery to Mars:

Under this option no restrictions on landing sites or on horizontal or vertical mobility into martian special regions would be imposed on the MSL mission by my office.

John D. Rummel, Planetary Protection Officer"


From Planetary Protection Constraints, dated Aug. 23, 2005: http://marsoweb.nas.nasa.gov/landingsites/msl/memoranda/MSL_PPCategorizationLetter.pdf

http://marsoweb.nas.nasa.gov/landingsites/


So it looks like GoTo sites, like the gullies, would be acceptale

Posted by: AlexBlackwell Dec 7 2006, 06:06 PM

Thanks, aldo12xu. You saved me from having to wade through Rummel's paperwork.

Posted by: odave Dec 7 2006, 06:09 PM

That's quite a job title - I mean, think of the conversation at a BBQ: "so John, what do you do?"

Posted by: AlexBlackwell Dec 7 2006, 06:17 PM

It is, and now, I believe, it belongs to Dr. Catharine Conley, at least on an interim basis.

As I understand it, Rummel was recently named to replace Dr. Carl Pilcher as Senior Scientist for Astrobiology in SMD's Planetary Sciences Division. Pilcher is moving on to become Director of the NASA Astrobiology Institute (NAI).

You should listen to the http://planetary.org/radio/show/00000191/ of Rummel (last July) on Planetary Radio. Bob Zubrin still gets under his skin

Posted by: JRehling Dec 7 2006, 06:47 PM

A question this raises is how a top-notch exploration could be performed of one of these sites when it is active. What is the shortest possible reaction time?

Obviously, committing extravagant resources buys you something in ability to respond.

Detecting these events when they happen would be one part of the capacity. First, the frequency of the events at different candidate sites should be determined. Then, we could have some number of them on a "watchlist" that are monitored frequently. Imagine an orbiter that circled Mars every two hours, checking 12 suspect locations under its apomars at about 45 south.

Then you'd have a lander stashed in an orbit that would "follow" the orbiter, apomars for apomars, in making similar close approaches to the same locations at a "lag time" that allowed operations on Earth to proceed. Let's say the lag time was one sol.

When a positive observation of a gully flow was made, the lander could arrive one day later and settle right onto the gully path. Perhaps show up in time to see successive flows in successive sols.

In situ analysis alone would be the stuff of scientific gluttony, but a tremendous (and very pricey) combo would also settle a sample-return craft downslope (which would seem to ease engineering constraints if that means reducing the slope), allowing a minirover at the flow site to deliver the goodies to the sample return. More exploration of the areas *upslope* would also be interesting.

Clearly, this would be the ultimate "red meat" of solar system exploration: To deliver a sample of liquid water, or stuff that was immediately prior wet with liquid water, back to earthly labs offers an excellent opportunity to get a Big Answer on astrobiology and/or one heck of a giant leap into understanding where ELSE you might have to look in case the sample were (as I bet it would be, FWIW) sterile.

It would also be a hell of an expensive program, with many points of failure, and perhaps too subject to chance if these flows are too rare for the above architecture to produce a likely flow detection before the life of the orbiting elements gives out. Obviously, two-way planetary protection concerns would require superlative measures. And just doing this at all would cost a lot more than any generic sample return mission.

Still, if we don't do this, sooner or later, we've left a stone unturned. We have to do this, eventually.

I think when the MERs were launched we knew far too little about Mars to commit serious resources to lander missions. This event, IMO, changes that. Now we know something very big. We're not going to get a clearer "go ahead" signal than this.

Posted by: climber Dec 7 2006, 06:57 PM

Does somebody know the altitude of geo...oups Marsostationary orbit ? Could be a good place to look for changes with adequate cameras and software. Phobos could be a good place too.

Posted by: AlexBlackwell Dec 7 2006, 07:00 PM

I'll have to double check but I think it's ~17,000 km.

Posted by: PhilCo126 Dec 7 2006, 07:26 PM

This was all over the news and immediately the suggestion was given that it might be a ‘dust-flow’ instead of ‘water-flow’ …

Stu, You’re so right… we have been waiting over 30 years for this …
By The Way where the artist impression from (is it by Pat Rawlings)?

My favorite photo for now is:
http://www.msss.com/mars_images/moc/2006/12/06/gullies/sirenum_crater/sirenum_crater_mosaic.gif

Will it now be easier to decide where to land the first human crew ?

Posted by: nprev Dec 7 2006, 07:33 PM

In fact, the "crater" is full of nasty acidic heavy-metal enriched water that supports an ecosystem:

http://www.mtech.edu/math_science/biology/pit_biodiversity.htm

...and, I'll personally vouch for the -50F winter temps...walking to school in that wasn't fun. Fortunately, it was only uphill one way...

Posted by: JRehling Dec 7 2006, 08:14 PM

That is correct. Pretty high up to get high-resolution images. Also, these events have been on slopes facing away from the Sun, which means that a equatorial vantage point would be less than ideal.

Posted by: AlexBlackwell Dec 7 2006, 08:15 PM

I forgot to post these yesterday but below are a few related stories:

http://www.nature.com/news/2006/061204/full/061204-7.html
http://www.sciam.com/article.cfm?articleid=596EADAB-E7F2-99DF-3F373E177D108C1D
http://www.astronomy.com/asy/default.aspx?c=a&id=4747
http://skytonight.com/news/home/4852501.html

Posted by: AlexBlackwell Dec 7 2006, 08:40 PM

I http://www.planetary.org/blog/article/00000790/ that Jim Bell had a nit to pick.

Posted by: climber Dec 7 2006, 08:49 PM

It depends the hour you take the pictures! You're Marsostationary not Sunstationary
But you're right it's very far

Posted by: gpurcell Dec 7 2006, 09:56 PM

Thanks, aldo. I had a dim memory that there was a restriction for the special regions, but I wasn't sure what it was.

Posted by: AlexBlackwell Dec 7 2006, 10:12 PM

For those with regular online access to Science, the articles are now available for download.

Posted by: ustrax Dec 7 2006, 10:33 PM

After Mr. Bell correction some correction is needed...:

What I'm trying to say is that, on this particular image seems to me like this brighter layers have an important role on the tone of the flow...
What can that material be (other hypothesis than salt...)?

Posted by: Steve Dec 7 2006, 10:44 PM

Here's Steve Squyre's comment on Life on Mars from his Open University Talk. I transcribed it from the audio file.

Steve (the other Steve, that is. )

-----

Steve Squyres Lecture at CEPSAR (Centre for Earth, Planetary, Space, & Astronomical Research), The Open University, 7 November 2006

Time: 65:12

Questions:

Stewart Hirst(?): After your 100– 1012 Sols on Mars are you more or less optimistic in finding evidence of life– or not you, but that evidence of life will be found on Mars?

SS: Oh, it’s hard to say. I think that what this has shown us is that early interpretations, going back as far as Mariner 9, that liquid water has been present below the surface and at the surface of Mars were correct. There has been water on Mars; that’s been believed since we first saw valleys in the Mariner 9 images and I think our data show that but you can go much more beyond just saying yeah, there was water on Mars.
Umm.
At these locations – particularly at the Opportunity site, which is, I guess, the more favorable of the two – Uh, as I said there are a number of things here that would be really I think very daunting for life. The acidity, the highly oxidizing character, the highly saline environment. Now you can go to very acidic, very oxidizing, very saline environments on Earth and they’re teaming with life, they’re teaming with microbes. You can find bugs that are perfectly happy at a PH of one: acidophiles. But those are organisms that developed first under more neutral, more normal if you will, conditions and then managed to find a way to evolve into that very challenging ecological niche. If you go to one of these acidophiles, and you measure the PH of their environment, the PH outside of their cell membrane is one and the PH inside is seven. OK and they have wonderful ion pumps across their cell membrane keeps them at a neutral PH inside. Umm. So while life can exist in that kind of environment, whether or not it can get started in that environment is another question.

Now one thing you’ve got to keep in mind is that these two places are just two little pin pricks on the surface of an incredibly diverse and complicated planet. For example, the Omega instrument on the Mars Express, the European Mars Express mission, French instrument, and also now the CRISM instrument on MRO have both detected philosyllicates, clay minerals, at some locations on Mars that may be indicative of more neutral PH at some point. Umm so there are no– It’s a complicated story that’s still evolving. There are a number of places where we see both morphological and mineralogical evidence for water on the surface of Mars. In terms of the habitability, yeah it was habitable but it was a challenge. I think we’ve still got a lot of work to do. I think what we need to do is send instruments like Colin [Pillinger]’s instrument package to the surface of Mars and look for organics and I think we need to bring some rocks back.

68:12

Posted by: AlexBlackwell Dec 8 2006, 12:16 AM

Instead of waiting for a site to become active and then dropping a probe/lander, I was thinking of the opposite. "Seed" gully sites with penetrators or Netlander-type packages, and then cue orbital assets when something (e.g., seismic activity, water vapor, etc.) is detected.

Posted by: AlexBlackwell Dec 8 2006, 12:20 AM

I've read the paper, which was interesting and, of course, provided the hard numbers and references in "Science-ese." I have to say, though, that most, if not all, of the information was provided via the http://www.msss.com/mars_images/moc/2006/12/06/index.html.

Posted by: tglotch Dec 8 2006, 12:55 AM

A little off-topic, but its worth noting that light-toned units on Mars often, but not always, exhibit different color properties than the surrounding terrains. Typically, they're redder. This has been a research interest of mine for a while, and presents an excuse to show a few pretty pictures.

http://www.gps.caltech.edu/~tglotch/glotch_rogers_jgr_figure8_v3.tif are some THEMIS VIS examples from Aram, Aureum, and Iani Chaos, where the lighter-toned units are also "redder"--a quantity that is shown in the lower set of images as THEMIS VIS 540 nm band depth images. Anyway, these deposits are quite different from the gully light-toned material, but if that material has similar color properties to the above images, it would be indicative of an increased Fe3+ content.

Posted by: nprev Dec 8 2006, 01:00 AM

Hate to say it, but I think it's gonna be a long time till we can conclusively answer the "L.O.M." question unless we get extremely lucky & identify a completely alien organism in a returned sample. (If hypothetical Martians are biochemically similar to Earth life, it will be much harder to distinguish them from contamination).

If there really isn't any life, it'll take centuries of in situ exploration to reach that conclusion definitively...

Posted by: JRehling Dec 8 2006, 01:01 AM

If the slopes are facing away from the equator and the probe is over the equator, then the hour won't matter.

Technically, the term "stationary" does stipulate that the orbiter be directly over the equator. It is possible to have an inclined orbit that is synchronized for longitude that will bob between latitudes X north and X south. But that wouldn't give you continuous viewing of any particular perspective, so I don't see the advantage this would have over a much lower orbit with higher resolution. It would give you periodic viewings of the same point.

My notion was to have a 2-hour orbit that would also give you periodic viewings of the same point(s), but MUCH closer up.

Posted by: JRehling Dec 8 2006, 01:05 AM

The pessimistic outlook for LOM re: this discovery would be that the same areas on Mars may not be getting anywhere near enough repeat soakings to entail a habitat. There are areas on Earth where various lifeforms lie dormant until flash rains come, but that surely requires some favorable ratio, however slight of wet-to-dry. For example, 10 minutes wet every ten thousand years probably would not do the trick. Mars could be awfully cruel in this way.

My hypothesis on why the sun-facing slopes don't have gullies is that there is a finite subsurface reservoir and the sun-facing slopes already had their gullies and exhausted their supply a long time ago. In essence, I'm positing that the sun-facing slopes are like short-period comets and the sun-hidden slopes are like long-period comets.

Posted by: um3k Dec 8 2006, 02:40 AM

Here is a link to the conference on Google Video:

http://video.google.com/videoplay?docid=3425366306986961245&hl=en

Posted by: AlexBlackwell Dec 8 2006, 04:17 PM

http://www.salon.com/news/feature/2006/12/08/mars/index.html
By Adrienne So
Salon.com
December 8, 2006

Posted by: AlexBlackwell Dec 8 2006, 08:05 PM

http://egghead.ucdavis.edu/?p=158
Andy Fell
Egghead Blog at UC Davis
December 7, 2006

Posted by: AlexBlackwell Dec 8 2006, 08:35 PM

Thanks, Tim. Is this figure from the paper "Evidence for aqueous deposition of hematite and sulfate-rich light-toned layered deposits in Aureum and Iani Chaos," which you and A. Deanne Rogers have submitted to JGR-Planets?

Posted by: tglotch Dec 8 2006, 09:07 PM

yep.

Posted by: AlexBlackwell Dec 9 2006, 01:06 AM

I had a couple of inquiries about Christensen's paper from people who don't have access to Nature. You can download it from http://www.mars.asu.edu/christensen/bibliography.html - specifically, the http://www.mars.asu.edu/christensen/docs/christensen_snow_nature.pdf.

As for Malin and Edgett's paper, I believe that the full text to all papers in Science are freely available online after a year, so that particular paper should be accessible.

Posted by: CosmicRocker Dec 10 2006, 06:56 AM

Oh shucks...I have access to some online journals, but Science is out of my reach. I have tried mostly every trick in my book to locate a copy of that file, but still came up short. Living 90+ miles from the nearest library that is likely to have a subscription is one of the problems I face while living on the edge of civilization. I so hoped I would be able to read it without a 12 month wait.

Oh well. I guess a drive to a large city is in my future.

The water stuff has grabbed everyone's attention, but the new calibration point for the recent cratering rate is also noteworthy.

Posted by: tty Dec 10 2006, 06:14 PM

It isn't. You can access most content older than 12 months (including Malin & Edgetts paper) for free, but you have to register as a user first. Details at:

http://www.sciencemag.org/about/access.dtl


tty

Posted by: Steve Dec 10 2006, 07:59 PM

Sorry to add another bit to the water discussion, but I saw a version of this in a Christmas catalogue and couldn't quite resist the temptation.

Little Willie was a chemist.
Little Willie is no more.
For what he thought was H2O,
Was H2SO4.

Steve

Posted by: Julius Dec 10 2006, 08:05 PM

Well,if you followed the press briefing towards the end of it,Mike Malin himself sort of hinted that mars scientists could be still getting it wrong as regards the geochemistry of the gully flows.So there you may have a point Steve!

Posted by: djellison Dec 10 2006, 08:32 PM

I knew it as

"Johnny Brown whent to school
but now he is no more
For what he thought was H2O
Was really H2SO4"

Doug

Posted by: AlexBlackwell Dec 11 2006, 04:18 PM

Yes, I believe that's true, tty.

Interestingly, though, the PDF version of this particular paper wasn't available for several days last week on the Science website, though the full text HTML version was. I haven't checked since then to see if the problem was fixed.

http://destinationspace.net/frontier/scimag.asp is another site (scroll down to the bottom of the page) that has the PDF version of the Malin and Edgett paper, as well as a rare PDF version of the accompanying Perspectives piece by Ken Tanaka.

Posted by: nprev Dec 11 2006, 05:20 PM

Re dormancy: If hypothetical Martian bugs can survive extended freeze-drying, then they should have been distributed globally by the wind long ago. Maybe we just need to land an ultra-sterile nutrient solution with an automated microscope pretty much anywhere, toss in some soil, and see what grows...

Even negative results would be most informative. If sporulated bacteria aren't all over the place waiting for water (or dilute H2SO4?) to wake up, then that would set some significant constraints on Mars' biological history--if there ever has been any.

Posted by: ElkGroveDan Dec 11 2006, 05:46 PM

Would those nutrients consist of nitrates or sulfates? or perhaps http://www.daviddarling.info/encyclopedia/S/siliconlife.html? That was one of the things that made me scratch my head over the Viking experiment. How do we know our "nutrients" weren't a sterilizing agent? (I know, I know, you have to start somewhere.)

Posted by: nprev Dec 11 2006, 05:54 PM

If the $$$s were there, why not have several different mixes & maybe just a distilled water-only vial as a control? Come to that, if the postulated critters were REALLY efficient, maybe the water is all they'd need; they'd eat whatever they usually do in the soil itself.

Now, light exposure is a whole other problem. Might want to do full dark, low-UV visible, and high-UV conditions (saving the high-UV for last).

Posted by: AlexBlackwell Dec 11 2006, 09:43 PM

I'm not sure this has been mentioned elsewhere in UMSF, and if it has, I apologize for the repeat; however, the June 2006 issue of http://www.elementsmagazine.org/ is a special issue entitled "Water on Mars."

(http://www.elementsmagazine.org/Elements_online/ELEM_V2n3.pdf)

Posted by: AlexBlackwell Dec 11 2006, 11:42 PM

For those who are interested, David Catling of the University of Washington has an article, "Atmospheric Evolution of Mars" (http://www.atmos.washington.edu/~davidc/papers_mine/Catling-MarsAtmos-inpress2006.pdf), which is in press with http://www.springer.com/west/home/geosciences?SGWID=4-10006-22-173660035-0.

Posted by: JRehling Dec 11 2006, 11:42 PM

I would have to think it would depend on the numbers. If habitability comes down to a few hectares per minute per year, I think even Good Ol' Durable Life would have a problem spreading enough bugs from one outburst site, spread planetwide, to have a prayer of any of them dropping into another eventual outburst site.

Another problem is that bacteria tend to take time to divide, whereas we haven't seen yet that anyplace would actually be wet for more than minutes. (Or at all, to be a stickler.)

This reminds me of a problem for possible bugs in the clouds of giant planets. There may always be a zone that is wet with comfortable temperatures, but any given bug would get swept down to sterilizing heat in typical situations. In the martian case, the bacteria thriving at one outburst site would have to be so numerous that a tiny fraction of them would land in friendly environments. It's sort of like the math of a nuclear chain-reaction... in reverse.

And of course, airborne dust isn't a great place to hide from UV radiation.

It seems more likely that something would sustain itself locally than to live and travel in the global dustbowl.

Posted by: JRehling Dec 11 2006, 11:48 PM

It's amusing that both possibilities make some sense.

It will depend, of course, on the frequency and predictability of the outbursts. If there are a million possible gully locations but only 1000 of them will gush per century and we can't predict which ones will go next, then the 1/1000 stab in the dark with landers-in-waiting would not be remotely cost-effective. It's easier to imagine that cheap surveying could be done from orbit.

On the other hand, if the events turn out to be somewhat or highly predictable as to location and time then anything goes.

It has to be a priority to start to characterize the events' patterns of occurrence.

A problem would be if every gully site only gushed *n* times, exhausting a finite reservoir of ice. If so, then the places where gullies have already shown themselves could be the places where there are least likely to be new ones.

Posted by: AlexBlackwell Dec 11 2006, 11:55 PM

Actually, a combination of the two ideas might make the most sense. Assuming multiple probes/landers/penetrators could be carried, land a few at carefully selected, predetermined sites, and then hold one or two in orbit to exploit any "fresh" sites.

Posted by: AlexBlackwell Dec 12 2006, 12:05 AM

http://planetary.org/radio/show/00000214/
Planetary Radio
December 11, 2006

Posted by: CosmicRocker Dec 12 2006, 06:40 AM

Thanks. I forgot to check that out. There were several papers being discussed, and I didn't make it clear which one I was talking about. I was trying to get the latest paper titled "Present-Day Impact Cratering Rate and Contemporary Gully Activity on Mars." Thanks to a philanthropic donor, I now have that.

The search for life on Mars is a tricky problem. We are only very recently learning what Mars is really like. It seems quite possible that any microbes launched onto the surface environment might be toasted, but life is a resilient and robust thing. Life has managed to evolve quite a number of mechanisms to deal with challenging environments on Earth. Who yet knows what it is capable of elsewhere.

Assuming it can not survive on the surface of Mars, we might need to capture it as it is expelled from a more benign, subsurface environment. Drilling down to a wet reservoir seems to be a hit-or-miss proposition unless we can accurately identify and rove to the correct locations. Yes, there are more frigid places near the outer planets where liquid water may exist, but Mars is where we need to do more exploration.

Posted by: AlexBlackwell Dec 12 2006, 06:10 PM

FYI, I made a change to a http://www.unmannedspaceflight.com/index.php?s=&showtopic=3559&view=findpost&p=76850 earlier in this thread.

Posted by: climber Dec 12 2006, 08:09 PM

I was "shoked" by M.Malin's assesment of the high probability of having a crater formed in your viscinity if you stay 20 years at the same spot. So, now, I wonder of the probabilty that a meteroid hit a "gully" zone and/or hit close enough that the effect will be to activate some gullies. Has this been already addressed or the probabilities are too remote to be considered?

Posted by: AlexBlackwell Dec 13 2006, 01:08 AM

It's rare that I reference another board but I recommend reading Jon Clarke's posts on this topic on the Space.com Message Boards (Space Science & Astronomy Forum), starting with http://uplink.space.com/showthreaded.php?Cat=&Board=sciastro&Number=630205&page=1&view=collapsed&sb=5&o=0&vc=1. Some might note Jon occasionally posts here, too. "borman" also has some interesting posts in that thread.

Of course, I'd also recommend that you completely disregard some of the others

Posted by: AlexBlackwell Dec 13 2006, 01:12 AM

I haven't read or heard anyone make a connection, direct or indirect, with impact events and gully activity, though some sort of seismic activity triggering the outbursts is very plausible.

Posted by: AlexBlackwell Dec 13 2006, 01:50 AM

For some discussion on "alternate" theories of the gullies' formation, take this http://www.unmannedspaceflight.com/index.php?showtopic=2428&hl= down nostalgia memory lane.

Posted by: AndyG Dec 13 2006, 09:54 AM

But that wouldn't address the apparent issues of disparity between sunward/shadeward facing slopes.

Andy

Posted by: climber Dec 13 2006, 12:14 PM

You're rigth Andy. Unless there's a very (improbable) narrow equilbrium. Would be important to know if brusts-gullies occure anytime during the year or more like the "geysers" at particular time of the year. Only a dedicated orbiter could address this. I wonder if there are other interests of having a regular picture (every 2 weeks) of Mars other than addressing the gullies formation. Up to last week, before the announcement, I didn't read about such a project, except for meteorological purposes. I forsee polar caps behaviour to add, landers relay, what else?

Posted by: AlexBlackwell Dec 13 2006, 04:11 PM

That's true, AndyG. And I should have been more precise in my reply. What I was driving at was that with only two apparent examples of recent (ca. 7 years) activity among the "thousands" of gullies, a non-insolation trigger might be plausible. I'm assuming, of course, that the putative near-surface reservoirs of liquid water do not vary temporally and spatially.

Posted by: AlexBlackwell Dec 15 2006, 05:17 PM

Hecht and Vasavada have a new paper, "http://marsjournal.org/contents/2006/0006," which was just published online in the open-access MARS Journal.

Posted by: JRehling Dec 15 2006, 06:47 PM

My long-standing suggestion here is that the sun-facing slopes don't form gullies because they would have already exhausted their reservoirs long ago, like short-period comets.

In a nutshell, a gully can form when a slope experiences something close to a meteorological record high temperature plus other factors (a little more dustpack on top of the crater) add enough stress to break the camel's back.

Seismic activity would have to be particularly well timed to have an effect.

Note that certain fault systems on Earth are more likely to experience a seismic event depending upon the tides. But obviously the overwhelming majority of tidal events (every 13 hours) do not cause quakes. It just becomes the straw that (rarely) breaks the camel's back.

Frozen rivers (such as the Nenena) break every spring when the ice melts. Presumably, a stick of dynamite well-placed on the day the ice was going to break anyway could speed the event by minutes or hours. But a stick of dynamite would not possibly cause it to break (riverwide) in January.

Posted by: AlexBlackwell Dec 15 2006, 06:56 PM

An exogenic trigger for seismic activity (e.g., impact-induced) would, I agree, suffer from the dreaded "Tooth Fairy" hurdle, which I http://www.unmannedspaceflight.com/index.php?s=&showtopic=2482&view=findpost&p=47757 in another context.

However, it's not too much of a stretch to posit that endogenic seismic activity, assuming it occurs on Mars, could trigger outbursts. And, again, the paucity of detectable activity among the tens of thousands of sites is not an insignificant issue.

Posted by: climber Dec 15 2006, 08:04 PM

There's something that make me scratch my head.
They're talking of ten of thousands gullies with only two changes in 6 years.
I can't imagine the "light tone" deposits stay for a very short period (< 6 years), so, why MGS didn't see light tone deposits at first, back in 1999?

Posted by: ustrax Dec 16 2006, 06:35 PM

Don't scratch...Think!
Maybe MGS catch a transition period?...
Don't you see the main bright flow getting darker and darker in a short years's period?
Mars is EX-TRE-ME-LY dynamic...

Posted by: AlexBlackwell Dec 19 2006, 12:03 AM

The Planetary Radio interview with Ken Edgett is now http://planetary.org/radio/show/00000215/.

Posted by: Bob Shaw Dec 25 2006, 09:33 PM

Is it his accent, perhaps?

Bob Shaw

Posted by: AlexBlackwell Dec 27 2006, 09:15 PM

Here are a couple of new martian gullies-related papers in press with Icarus:

Martian gullies in the southern mid-latitudes of Mars: Evidence for climate-controlled formation of young fluvial features based upon local and global topography
Icarus, In Press, Accepted Manuscript, Available online 23 December 2006
James L. Dickson, James W. Head and Mikhail Kreslavsky
http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6WGF-4MMWHM1-1-1&_cdi=6821&_user=1349829&_orig=browse&_coverDate=12%2F23%2F2006&_sk=999999999&view=c&wchp=dGLbVlb-zSkWz&md5=dbdd69c453287079264aa722eabceb5e&ie=/sdarticle.pdf

Comparison of small lunar landslides and martian gullies
Icarus, In Press, Corrected Proof, Available online 21 December 2006
Gwendolyn D. Bart
http://dx.doi.org/10.1016/j.icarus.2006.11.004

For non-subscribers, click http://gwen.barnesos.net/LPLmainpage for more information on Gwen Bart's work (scroll down for links to her martian gullies work, which was presented at LPSC earlier this year).

As for Dickson et al., you may also wish to keep an eye on the http://www.planetary.brown.edu/html_pages/publications.htm. I suspect the paper will be available there fairly soon.

Posted by: AlexBlackwell Jan 3 2007, 09:43 PM

I just noticed a new paper in press with Icarus:

Observations of Martian Gullies and Constraints on Potential Formation Mechanisms, Part II: The Northern Hemisphere
Icarus, In Press, Accepted Manuscript, Available online 3 January 2007
Jennifer L. Heldmann, Ella Carlsson, Henrik Johansson, Michael T. Mellon and Owen B. Toon
http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6WGF-4MR86N3-2-1&_cdi=6821&_user=1349829&_orig=browse&_coverDate=01%2F03%2F2007&_sk=999999999&view=c&wchp=dGLzVlz-zSkzk&md5=7805d54be23f9b40a1b560153520fbd5&ie=/sdarticle.pdf

I believe this is a companion piece to an earlier paper in Icarus by http://dx.doi.org/10.1016/j.icarus.2003.11.024. For those without access to Icarus, here is a (http://marsairplane.arc.nasa.gov/TECHNICAL%20presentation/Heldmann%20Gullies.pdf).

By the way, in case anyone wants to wade through a master's thesis on this particular aspect of martian gullies research, see http://nlanza.web.wesleyan.edu/cv.html's submission earlier this year in May 2006 to Wesleyan University: "Geometries of martian hillside gullies in the northern hemisphere: evidence for an insolation-driven mechanism of formation" (http://web.mit.edu/aysin/www/thesis_ma/Lanza_thesis_ALL.pdf).

Posted by: climber Jan 6 2007, 02:51 AM

At first this topic included the discovery of recent craters and as I don't know other place to post this message, I post it here.
I didn't realise that, from MGS observations, the rate of formation is one crater per MONTH. Whoua, that's a lot. They also said that is you stay in the same place for 20 years, you'll be close to one impact. Vicking landers have been there for much longer. Does somebody know if the location of the fresh craters has been released?

Posted by: nprev Jan 6 2007, 04:07 AM

Glad you mentioned this, Climber; been wondering about the implications for landing/settlement.

The big question seems to be whether the amount of risk incurred for surface installations on Mars is significantly above the Earth background level. Our atmosphere conveniently disposes of many otherwise dangerous meteors, but will we have to deeply bury any future Martian colonies?

Posted by: dvandorn Jan 6 2007, 08:36 AM

I don't know that the impact rate is enough to cause huge problems for individually pressurized buildings and facilities. On Earth, there are several hundred lightning strikes per second, many of which occur close to buildings and people. And yet, while there is a certain amount of damage (mostly to trees) from lightning strikes every year, rather few people are injured or killed by lightning each year.

Now, compare the frequency of lightning strikes to the frequency of impacts on Mars, and factor in the percentage of those which are large enough (those that make craters of, say, 100m or more in size) to blast you even if they don't hit you directly, vs. those which create craters of only 10 or so meters or less in size (which could land 100 meters away and not damage your habitat), and I bet you're far less likely to get hit by a meteor, or have your domicile destroyed by a close impact, on Mars than it's likely you would get hit by lightning on Earth.

Also, look at the number of pieces of the space shuttle Columbia which fell onto a couple of towns in Texas. Out of all of those pieces, very few actually hit buildings, and *none* hit any human beings. Heck, I don't think there were any documented cases of any pieces hitting any animals, even. So, you can drop a good number of objects onto a fairly densely populated area without actually hitting anyone.

Now, I grant you, if you built big transparent pressure domes on Mars, you'd increase the probability of a meteor causing a depressurization event... but I'd bet you're not going to see anything beyond relatively small metal tubes in Martian colonial building styles for quite a while...

-the other Doug

Posted by: AlexBlackwell Jan 9 2007, 04:39 PM

Did anyone happen to listen to this http://planetary.org/radio/show/00000218/? I did and discovered a couple of things for first time during the Huntress interview:

1. MGS was the first spacecraft to use aerobraking, not Magellan.
2. THEMIS was an MGS payload and not, as I always suspected, on 2001 Mars Odyssey.

Posted by: djellison Jan 9 2007, 05:09 PM

Yeah - I spotted that...I put it down to misscommunication between Wes and Matt.

Doug

Posted by: AlexBlackwell Jan 9 2007, 05:31 PM

Undoubtedly, and poor THEMIS. It and 2001 Mars Odyssey get no respect, except as a workhorse relay for MER. I remember when Christensen was a http://planetary.org/radio/show/00000213/ several weeks ago, when during the intro THEMIS was assigned to Mars Express (an error which was corrected in the next broadcast).

Aside from that, though, this latest broadcast and Huntress's whole discussion of water on Mars (and even the brief discussion of the new crater results) had a strange tilt to it, at least to me. I guess following Christensen and Edgett and their ultra-precise descriptions of the latest science results has its drawbacks.

Posted by: Greg Hullender Jan 9 2007, 06:32 PM

Meteor strikes on Earth aren't unheard of.

http://astro.wsu.edu/worthey/astro/html/im-meteor/strikes.html

Mrs. Hodges apparently never completely recovered from being hit by one.

--Greg

Posted by: climber Jan 9 2007, 07:59 PM

I guess he considers Magellan aerobraking as a test, which, IIRC, it was at the origin since aerobraking was not used to get to primer orbit. May be not that accurate but far from the BBC's stuff.

Posted by: AlexBlackwell Feb 21 2007, 01:38 AM

I just noticed that a preprint of this paper is now available (http://www.gps.caltech.edu/~tglotch/2006je002863_inpress.pdf).

Posted by: AlexBlackwell May 30 2007, 06:16 PM

FYI, the final version of this paper should be published online tomorrow in http://www.agu.org/journals/je/.

Posted by: marsbug Aug 30 2007, 01:36 PM

Sorry to resurrect a long dormant thread but it seems like the best place to ask this question: In the http://www.planetary.org/blog/archive blog Doug reported on a hypothesis that bacteria on mars could survive by using an intracellular fluid of water mixed with hydrogen peroxide. As an idea this makes some sense as at atmospheric pressure at least (I've not been able to locate a temperature-pressure curve for H2O2) a 60%-40% H2O2-H2O mix has a boiling point of 120 deg C and a freezing point of -50 degC. In other words its stable over nearly twice the temperature range of water. So (finally gets to the point) has it been considered anywhere that the liquid flowing down the gullies could be bleach? Google hasn't thrown up anything on the idea, although it has been convincingly argued that H2O2 could be produced in the martian atmosphere during storms and be coating the surface.

Posted by: djellison Aug 30 2007, 02:08 PM

And at 6 mbar? That's the crucial point. You can mix all sorts of things with water to change the boiling point and freezing point - H2O2 is one of the more unpleasent ways of doing it - particularly on the UV soaked surface of Mars.

Doug

Posted by: ugordan Aug 30 2007, 02:13 PM

Not to mention the required quantities of H2O2 for the gullies. We'd be past talking about minute amounts but really significant quantities.

Posted by: marsbug Aug 30 2007, 02:48 PM

Both good objections! I suppose if the peroxide is produced during storms, and has been doing so for a long time it could have reached quite high concentrations in some regions, mixed in with soil and ice. As to the question of how it behaves at 6mbar thats up in the air (pardon my bad pun), I can't find anything on it. Theres no reason to supppose hydrogen peroxide over any other possible candidate, other than the argument for its production on mars has already been put foward in detail. Personally I'd favour H2O2, or something like, as 'antifreeze' for the gully water over salts ,which are frequently suggested, because it lowers the freezing point by an extra 30 degC, which would make high latitude polar gullies easier for me to accept as water related. I've not done any legwork on the idea, it just caught my imagination. I'll do some more digging and see if I can come up with some numbers.

Posted by: tty Aug 30 2007, 06:08 PM

If - and it's a very big if - there are appreciable quantities of H2O2 on Mars it could have important consequences for future exploration if it could be extracted. H2O2 at high concentration decomposes catalytically into H2O and O2 at fairly high temperatures. Imagine having a steam turbine that also produces water and oxygen!
H202 is even a fairly good rocket monopropellant as the germans demonstrated with Me163B.

Posted by: paxdan Aug 30 2007, 06:41 PM

Doug i appreciate that the 6 mbar point has been made, and made well with regard to liquid on the surface. However, i wonder how much depth of regolith/permafrost you need before the pressure of overlaying material allows H20, H202 etc to exist as a liquid? Is it 10s of meters or kilometers.

Do we have accurate modelling of the heat flow of hte martian crust to asses this?

Posted by: dvandorn Aug 31 2007, 03:07 AM

Also proven by the American Mercury capsule spacecraft. Its reaction control system fuel was H2O2.

-the other Doug

Posted by: dvandorn Aug 31 2007, 03:10 AM

No. One of the datasets that is most wanting about Mars is its crustal heat flow, both average and regional. Thermal emissions instruments (TES, infrared imagers, etc.) give a rough idea, but what I wouldn't give for a set of 20 or 30 heat flow probes scattered across Mars. I'd *almost* like that more than I'd like a seismic network.

-the other Doug

Posted by: marsbug Aug 31 2007, 10:58 AM

Well I couldn't find much on either the behavoir of hydrogen peroxide at ten mbar or less, or a copy of the paper on hydrogen peroxide snow theorized to form during dust storms that I could access. I suspect that these are moot points, as the martian soil is 20% iron sulfate, which a friend in the chemistry department assures me would cause H2O2 to decompose far to quickly for it to build up in significant amounts! So to answer my own question, no its not likely the gullies on mars flow with concentrated bleach!