Note: incredibly beautiful and hi-res images to go with this blog post can be found on the HiRISE Science in Motion page.
Late last year, NASA released results that indicated a strong possibility of liquid water on Mars. Gullies formed in the steep sides of craters looked very much like liquid water had erupted from underground, evaporated, and left a deposit of minerals behind. The features were bright, veined streaks that appeared in images.
Now, though, that’s being rethought. New evidence indicates that the deposits may be from dry flows; basically minor landslides. As the scientists themselves say in their paper (subscription required):
Bright gully deposits identify six locations with very recent activity, but these lie on steep (20° to 35°) slopes where dry mass wasting could occur. Thus, we cannot confirm the reality of ancient oceans or water in active gullies
In other words, the slopes are steep enough that even in Mars’ light gravity, solid matter can tumble down. In the original images, some lighter material can be seen upslope of the gullies, and perhaps the streaks came from those deposits. Spectra taken don’t show the kinds of materials expected for evaporational deposits. The gullies may have formed millions of years ago from flooding of water, but that time is long past.
Bummer. That was a very cool story, but now it’s looking less like water.
And then things get worse! The Vastitas Borealis Formation is a large area on Mars thought to have been an old ocean, or maybe was the result of catastrophic flooding. That looks less likely to be the case now too! New images show large (1-2 meter) boulders in the area, when it was thought to be mostly fine-grained sediment:
The origin of the Vastitas Borealis Formation (VBF), covering the lowest portions of the extensive northern plains, has been the subject of much debate, including (among other hypotheses) that it is the fine-grained residue of an ancient ocean or that it represents frozen deposits of sediment-laded water from giant outflow channels.
Here’s an image of the boulders. Note the scale bar; both images are at the same scale.
The paper goes on to say:
The more than 200 HiRISE images of this unit show that rocks ranging in size from the limits of resolution (~0.5 m) to ~2 m in diameter are ubiquitous… Boulders are concentrated around circular structures of probable impact origin, but they are present over most of the VBF at uniform densities. In addition, we have seen no light-toned layered deposits within the VBF; such deposits elsewhere are thought to be of aqueous sedimentary origin. The boulder distribution and absence of light-toned layered deposits are difficult to reconcile with the hypothesis that the VBF primarily consists of a thick (~100-m) deposit of fine-grained materials deposited from suspended sediments in an ocean.
In other words, the rocks indicate that the area was not an ocean or from outflow. Bummer again.
The final blow: a region thought to have been an old dried up sea turns out to be ponded lava when it flowed over a channeled region. In other words, the smooth lava fooled the scientists when it was seen in lower-res images, but new data show the reality of the lava flows.
Wow. Bummer3.
This is a pretty big setback for those looking for sources of liquid water on Mars (frozen water — ice, duh — is not hard to find, especially at the poles). It would be nice to think that liquid water could be found, but we have to go where the data tell us. Right now, they’re saying that liquid water, even subsurface deposits of frozen water, may be rarer than we thought.
September 20th, 2007 at 6:48 pm
That’s annoying. My field is physical chemistry of water- guess I don’t get a trip to Mars after all.
September 20th, 2007 at 6:58 pm
I agree, bummer cubed. But, on the plus side, that HiRISE image is beautiful!
September 20th, 2007 at 7:09 pm
0_0 Half a metre resolution? Wow!:D I didn’t realize that it could see things that small! That’s awesome.
September 20th, 2007 at 7:29 pm
Awww man, I thought the possibility of liquid water on Mars was one of the most interesting things about it!
Oh well, it’s still a cool planet!
September 20th, 2007 at 7:31 pm
Greetings from Germany
Late last year, NASA released results that indicated “a strong possibility of liquid water on Mars”
Its an invalid Link Dr. Plait
And does this mean that the Phoenix Mission wont deliver any results?
September 20th, 2007 at 9:30 pm
The “strong possibility of liquid water on Mars” reference and bad link was probably to this BA Blog entry, LIQUID WATER ON MARS!:
http://www.badastronomy.com/bablog/2006/12/06/liquid-water-on-mars/
September 20th, 2007 at 9:35 pm
I wonder what this means for the Orion program?
September 20th, 2007 at 9:35 pm
Oh well. If it wasn’t for the search for water on Mars, think of the things we might never had known and those awesome pictures we’d not have seen. Someone somewhere will be learning something from these photos, right?
So, it’s still exciting to me.
September 21st, 2007 at 12:20 am
It is possible to get large boulders into the middle of an otherwise sedimentary sea bed. Ice bergs calving off glaciers arising on land can carry boulders out into the middle of the sea where they melt and the boulders sink wherever they happen to be.
So I don’t think the mere presence of boulders necessarily disproves that it was once a sea. (Boulders clustered around craters could be ejecta from impacts after the sea dried up.)
September 21st, 2007 at 1:03 am
Well, hey, I have Good News for all you! Liquid Water is a Truth! Just have Faith that it exists and rejoice in its liquescent transcendence!
Well maybe let’s not.
This does suck. Maybe if we planted a bunch of cows and SUVs on Mars we’d get liquid water in a century or six. Global Warming For Mars!
September 21st, 2007 at 1:30 am
Well what a pity that a planet can only apparently be considered interesting if it has/had liquid water.
September 21st, 2007 at 3:57 am
Nice example of how science works. Nobody is clinging to old hypotheses in the face of new evidence. Very refreshing.
September 21st, 2007 at 5:41 am
I guess it is who you ask about water. I see visible signatures of water on Mars even at the Rover site.
I am disappointed we have not got anything from the MRO from the frozen sea.
http://www.esa.int/SPECIALS/Mars_Express/SEMCHPYEM4E_0.html
This came out yesterday from the MRO. Lots of signatures there in the discussion
http://hirise.lpl.arizona.edu/PSP_004085_1420
dfrank
September 21st, 2007 at 6:18 am
Nuts; I was really hoping for more evidence of water flow. But in science, unlike mysticism, you have to follow the data wherever they lead to gain knowledge.
September 21st, 2007 at 6:31 am
While fundamentalist Christians have their God of the gaps, planetary scientists studying Mars have water of the gaps. It seems that liquid water, even though it has never actually been observed on Mars, is the first resort for any Martian feature that cannot readily be explained, only to be replaced later by a mundane explanation when more data come to light.
September 21st, 2007 at 7:54 am
If I may express a similarly curmudgeonly view – it does sometimes seen that the fervent wish for water on Mars (biological implications and all that implies for news coverage and finding) can very easily color our interpretations. It’s an alien world, not to be judged by terrestrial standards – and I suspect that repeatedly doing so has harmed more than helped the improveent of our understanding.
September 21st, 2007 at 8:24 am
Here are some great images and discussions.
http://www.lpi.usra.edu/meetings/7thmars2007/pdf/3001.pdf
dfrank
September 21st, 2007 at 8:54 am
No, Walter; I disagree. Whilst no one is denying that we in fact want to see liquid water still extant on Mars, it is by no means a “god of the gaps” situation.
For one thing, many physical features of Mars, from its channels to its “blueberries” are, at least on Earth, formed in conjunction with water. It is not unreasonable to start with that as an hypothesis.
But the really important bit is that, as evidence indicates that liquid water is not present, we do not cling to the idea that it must be so. Rational folk follow the evidence where it leads.
The “god of the gaps” idea simply takes what is unknown, and makes a statement of irrational faith about it, without providing any impetus for further research. When rational inquiry reduces the gaps of ignorance, “god” retrenches in his/her/its new and shrunken territory. There is no desire on the part of the irrational to seek out anything that might dethrone their god.
September 21st, 2007 at 9:05 am
[sarcasm]
Yeah, whatever. I want to know what Ted Hoagland thinks about this.
[/sarcasm]
September 21st, 2007 at 9:11 am
Well said, Rav. Scientists’ abilities to address errors and revise theories are some of their greatest strengths.
September 21st, 2007 at 9:53 am
Regarding the boulders, not only can glaciers carry them out into an ocean, but massive flooding can supposedly move very large boulders great distances.
I cannot remember what part of this US this happened in, but I was watching PBS a few months ago and they had a special about an area in the Western half of the US that is filled with a bunch of small crater like holes and many boulders around. The theory that PBS was pushing for explaining how this happed were massive ice damns that were created during the last ice age. When the ice damns finally broke it was a flood of “biblical” proportions that supposedly not only carved away the landscape, but also carried massive boulders hundereds of miles.
If I can remember that show that I saw this on I will post again.
September 21st, 2007 at 10:06 am
[...] the BA himself, even the mainstreamers hopeful of "Martian Water" disappointed: http://www.badastronomy.com/bablog/2…-liquid-water/ __________________ "I have this theory that the Apollo missions were faked when NASA found [...]
September 21st, 2007 at 12:18 pm
Well, if there’s no liquid H2O on Mars. then what the heck did I mix in my Scotch the last time I was visiting there???
Hmmm, perhaps my mind was wandering to Jupiter???
Gary 7
September 21st, 2007 at 1:14 pm
Small nitpick – I thought that the maximum angle of slope is independent of the strength of a planet’s gravity?
September 21st, 2007 at 1:56 pm
Moving glaciers transports stones and gravel, and AFAIK not only at the rock interface. In any case when the ice melts you can see boulder fields.
September 21st, 2007 at 2:00 pm
Is there liquid water or isn’t there? Make up you’re mind, NASA! We’re at war!
September 21st, 2007 at 2:01 pm
*your* mind…
[curses the lack of preview]
September 22nd, 2007 at 12:37 am
I can’t remember which specific programs I’ve seen (many years ago) which have the footage, but I’ve seen footage of huge (say, 8-10 feet across or so; “atuomobile sized” and larger) bolders being carried along by floodwaters from flash flooding. I also recall seeing massive (house-sized) bolders moved by galcial outflow; the people filming the event were almost stranded by the outlow washing around the area they were standing. Anyway, it’s certainly possible for water to move large boulders.
September 22nd, 2007 at 3:27 pm
Eric, Torbjörn and CR… Yes, but it gets more complicated…
Glaciers can certainly transport and drop huge boulders long distances, leaving them strewn about the surface (ask me, I live in New England
but getting them to sit on the surface of sediment is a little trickier. That’s where the ice bergs floating on a sea idea comes in. A glacier would tear up the surface destroying any sedimentary layers and then when it melts, deposit everything (sand, mud, rocks, boulders) in a big jumble. A sea might deposit uniform or seasonal sediments for millions of years building up a deep layer of sedimentary rocks. When the climate is right, ice bergs floating on the sea can then deposit large boulders on top of the undisturbed sediment. So it depends on what we are looking at. If the boulders are on the surface of the sediment, then it might mean a surge of ice berg formation as the climate cooled and glaciers formed, before everything froze up solid. If the boulders are partially buried in sediment, then it could be there was a prolonged period of ice bergs with seasonal deposits (spring or summer runoff transporting mud to the sea which forms sedimentary layers, everything freezes (at least at the surface in the fall and winter, so little happens, then in the spring the glaciers at the edge of the sea melt back some releasing another crop of ice bergs that drop more rocks and boulders, repeat for a few million years.) If the boulders are resting on or in a jumble of other material, then no sea or ice bergs are involved, just a glacier or floods.
BTW Eric, I think you are thinking of the Spokane Flood in the Grand Coulee region of Washington State (12-18000 years ago according to the USGS web site.)
BTW, I’m not a geologist, just watch a lot of TV.
September 22nd, 2007 at 5:07 pm
Just as I thought ..no liquid H2O
Now lets see what Phoenix Mission will bring us
September 22nd, 2007 at 5:13 pm
[...] Plait from Bad Astronomy writes about the new results of Mars research. Last year scientists announced that most probably there has been liquid water on Mars. Now they [...]
September 22nd, 2007 at 11:52 pm
andy said – Well what a pity that a planet can only apparently be considered interesting if it has/had liquid water.
There is a certain context you are missing here. This whole website has a subtext and agenda in which any the existence of a supreme creator, the validity of the biblical creation account (no matter how metaphorical) and Intelligent Design, must be undermined and ridiculed in every single blog entry. The existence of water on Mars opens the possibility of life developing outside of the biblical narrative, which in turn downgrades the insanely miniscule statistical probability of the development of life processes to within the random range.
That is why every time a microscopic bubble is located in a rock that MIGHT have originated from Mars in some wildly improbable meteoric cataclysm, it is trumpeted that this MIGHT have originated from a metabolic degradation of Martian bacterial doody, which in turn obviously means that life can develop any old damn place without a god, whether on Mars or on that outdated applesauce in your refrigerator.