If it hasn't been run across already, this article, reproduced from Melosh's contribution to the july 94 planetary report, has some interesting ideas that might apply to a mars impact, particularly in the updates down the bottom where he talks about how spallation might not operate alone to launch particles , but in combination with the impact plume.

Very sad words stu, although well crafted as ever! I hope that before anyone here gets much older things will begin to change. EDIT: I was born in the early 1980's so perhaps I dont feel as betrayed as some here might. I remember school teachers telling me how all space travel would be over by 2000 because there was nothing out there worth the effort. And I see today how nothing much has changed out there, and how many hold the same point of view as my teacher, and how we are still dreaming of space and still striving to make the dream happen.
Part of me is surprised that my teacher was wrong, the rest of me is just very glad that he was!

Well done one and all working on that launch!

Gullies have been observed on slopes too shallow to support a dry flow, which argues for some kind of volatile. But I dont know much about the mechanics of dust slides, perhaps a violent event (an impact?) could trigger a dust slide on a slope otherwise to gentle. Also; would it be possible for anyone to confirm or deny that CRISM would not pick up chloride salts? I agree that the CRISM data puts a dent in the gullies=water argument but I'm a long way from being convinced its dead. And although I dont give it much credence personally we've yet to see anything that kills the 'exploding CO2' theory.( Minor rant incoming) Press releases on mars water seem to fall into two camps: 'mars is bone dry' or 'mars is soaking wet'. I'd like to see one that falls into the 'mars is definately icy and may be slightly damp' catagory!

A bit more than I was expecting but I've no complaint! However it would help my understanding a lot if you could point me in the direction of a detailed explanation of frost leaching, as I've got only a vague idea of how it works and hence only a very vauge understanding of your reply!

Edit: I've no wish to turn this thread into an undergraduate geology classroom, but my usual sources (wikipadea and google) have let me down a bit on this one.

While this may be a blow to hopes of water flowing down gullies right now, the morphological evidence for formation by liquid water, in the last few million years, maybe the last few tens of thousands, is stronger than ever. Dry slides may be running down the gullies today but the evidence from HIRISE suggests very strongly that dry slides did not form them. So the party doesn't have to be over, gullies were still likely formed by liquid water on mars in the (geologically) recent past, and as Andyg points outthere are still questions about the gullies that need answering.

Ice above -20 often contains veins of liquid water kept liquid by impurities, this is the first stage of Dburts eutectic brine formation. If a piece of dark coloured rock is included in a piece of ice near the surface then sunlight will warm the rock, which will lead to these veins becoming larger and more numerous near the rocks surface. Many people here probably know this already, but if surface ice was present at home plate or meridiani in the past could this provide a source of rock altering 'dampness'? Wouldn't steam condensing onto a rock surface form ice (not right away perhaps but fairly quickly) at martian temperatures anyway? If this has already been discussed could someone point me in the right direction?

No argument there! hence the 'even if'.

I don't think there's much of a 'somehow' about it julius, an icy mars warmed very occasionally by impacts or volcanism has seemed a likely scenario for a while now. I wouldnt ever count liquid water out of the equation entirely though, theres so much ice on mars that even if conditions were right for melting only occasionally and briefly it could make an impact on martian geology and history.

What about the five million dollar secound prize? that seems acheivable, the question is would $5000,000 be enough of an incentive to make it worth while?

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!

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.

Sorry to resurrect a long dormant thread but it seems like the best place to ask this question: In the planetary society 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.

My thinking exactly nprev. It's an interesting piece of speculation, and I'm glad to hear that the originators at least have been responsible and presented it as just that, no more or less. I'd be very interested to see if they can come up with some predictions that might be tested by pheonix. It would be a long shot, but if they found some supporting evidence who knows?

Certainly, but whats the answer? I thought that with it being in wide use the temperature-pressure curve for H2O2 would be widely available, but I cant find it anywhere!

Thanks Doug and AndyG! This makes it seem a bit more plausable, and use of gettering answeres the objection of how to maintain a vacuum (shoulda thought of that!). Fifty days still seems like a long time to me, but a long term venus lander; what an idea! Going a bit off topic here but what science objectives could you fulfill with one?

I usually try to avoid numbers but this intruiged me so heres a quick and dirty attempt:
Assume the thermal isolation system consists of a double walled shell with a good vacuum in between (say 10^-4 mbar) so that convection and conduction between the walls is close to zero, and that the shell is constructed of a low vapour pressure material such as tungsten, or is being actively pumped to keep it at that level. Assume also that connections between the walls are minimised (could fairly low tech heat tolerant machinery outside the shell be operated entirely by remote by an electronics package inside?) to ten square centimetres of cross sectional area, made of material with a low thermal conduction , say equal to aerogel at 0.03 w/m/k. As a random figure lets say the separation between walls is 10 cm, and the water starts at a temperature of 273 degrees Kelvin. The amount of heat transmitted through the connections would then be:


0.03= q/t * (L/(A*ΛT)
wher q/t is joules per secound, L is the length of the conducting connection, A is the total csa of the connections and ΛT is the temperature difference in kelvin.

So:
q/t= 0.03/ (0.1/(0.01*400)= 1.2 watts. Which looks ok.
BUT:
The major source of heat into the inner vessel will be radiation from the outer wall. Assuming that the outer wall reaches the same temperature as the venusian atmosphere fairly quickly, and that it can be approximated as a black body it will be radiating heat onto the inner wall at
W= σ*A*T^4
Where W is heat transfer in watts, σ is the Stefan-Boltzmann constant, A is the internal surface area of a sphere with an internal radius of 40 centimeters and T is the temperature of the outer wall in Kelvin (673 deg):
A= 4πr^2 = 4*π*0.4*0.4 = 2.01 meters square (ish)
W= σ*2.01*673^4= 23797.24 watts falling onto the inner shell? Or roughly 24 Kj per secound.
So water has specific heat capacity of 4.2 kJ.kg^-1.K^-1, so for 100 kg to reach 373 Kelvin from just above freezing requires 4.2kj*100*100= 42000 Kj. Assuming it heats linearly (which I know it doesn’t but can’t remember how to work it out properly) 42000/24 = 1750 seconds, or just under half an hour.
That doesn’t look very promising! Where did I go wrong anybody (bet its something very simple!)?. But it does assume one atmosphere of pressure, not ninety! Any chance I could look at how you worked it out for that figure doug?

Edit: Even if it works at ninety atmospheres I'd be impressed by a container that would hold a good vacuum for fifty days under those conditions without an active pump. I'd also be impressed by an active pump that would run for fifty days under venus surface conditions. Not saying it can't be done, just that I'd be impressed!

Well done!

Doug just posted this on the previously reported VIMS bright spot on the planetary society weblog- although if everyone else is like me you've probably checked it out already! Cheers Doug!

Here is a link to the letter in nature describing the results of the huygens analysis of the aerosols (apologies if its been linked elswhere) I'm not a nature subscriber and I have no problem accesing it, however I'm using my universities network. Something which should be remembered is that when applied to organics mass spectrometry requires a certain amount of educated guesswork for interpretation. The guys doing this are unlikely to guess wide of the mark but i'd advise anyone to read the letter and satisfy themselves of the reasoning presented before basing a paper on these results! Unlikely as they may be there are other interpretations, and titan is as alien as it is fascinating. For the record I now consider myself a titan convert , and I've bored loved ones almost to tears with it I'm sure!
P.S Belleraphon 1 nice snaps!
edit: I should probably be clear that I'm not trying sound patronising to those who do know a lot about mass spectrometry, but not everyone who reads this post will.

Just having fun with an idea that may be utter rubbish: I read many moons ago an article on emergent complexity which suggested that an already very complex system could spontaneosly jump to a new level of complexity by synthesising something not native to itself. The last week I've been flipping through the National Academies report Limits to Organic Life in Planetary Systems ( like to add my thanks to rlorenz for that) and then I re-read this esa article which describes how the pyrolisis products of the aerosols on titan were hydrogen cyanide and ammonia. The thought occcured to me this afternoon that the ammonia, which is suggested as a potential biosolvent and is not naturally present in titans atmosphere, might possibly possibly be the result of emergent behavoir in titans atmospheric chemistry. Thats not to suggest that the aerosols are 'alive' or the chemistry that produced them is, but that the aerosols might be a step along the way slightly further than the organics around them. If you can have a complex titan, could you have an emergent one? Or possibly five hours of taking down numbers of a broken vacuum chamber has just made my brain leak

Since we dont have an accepted definition of alive yet that would probably cause a 'vigorous' debate on our place in the universe, characterised by the sound of breaking crockery . It would be fascinating to dig through layers of surface material on an old piece of titan terrain (such as the sand seas)and see how it has changed (evolved? ) over geologic time.

This caught my attention a few minutes ago and here seemed the best place to post it. Not sure if it counts as a private mission, but apparently nasa supervision will be at arms length at least.

Apart from heat due to radioactive materials, are there any other potential heat sources that far out? For example (picks an idea out of the air) could there have been a recent impact large enough to have liquified the interior? I know any ideas would be pure speculation, but thats all we'll have until june 2015 . The ammonia in the (possible) water might allow for heat sources ordinarily to feeble to be considered to have an impact. Would anyone care to speculate?

Um.. I hate to be the dense one yet again but am I looking at gullies or dark streaks here? I may just have missed something but I see dark streaks running down the slopes on a lot of these pictures, rather than gullies with heads incised chanels and debris aprons at the bottom. Sorry but could someone clarify this for me or just point out what we're looking at?