It's known that Mars has both ice and water vapor, and that further, summertime temperatures are warm enough to sustain liquid water.
It's the atmosphere that makes this a bit surprising. Martian atmospheric pressure is less than 1% that of earth in the deepest valleys, and about .006 atm on average. If you look at a phase diagram for water [0], you can see that at .006 atm and below, water goes directly from solid to gas ("sublimation"). Even slightly above that pressure, there's only a tiny temperature range in which liquid water will exist.
I would guess that's why they've theorized very salty water. Its lower freezing point is going to allow for liquid water in a bigger temperature range at typical Martian atmospheric pressures.
IIRC, Mars's global atmospheric pressure is about 25% higher in the southern summer than in the southern winter, due to differential sublimation and condensation of carbon dioxide, from the southern ice cap as well as from the soil at lower latitudes, and southern hemisphere summer temperatures can range all the way above zero celsius -- so there's quite a range of weather conditions to which any briny water would be subjected, especially in the southern hemisphere.
Edit to add, the Martian southern hemisphere seasons are more extreme because the effects of its significant eccentricity and its axial tilt are additive there, while they counteract each other to moderate the seasons in the north.
Three cheers for the science journalism in this link. The reporter clearly conveys the facts of the announced findings, includes images of candidate flowing water on Mars with captions as they appear in the original paper in the journal Science, and does a Q&A with a third party scientist who gives knowledgable further analysis. Anyway, this is really exciting.
Whose internet law is it that says that any sufficiently advanced idiot is indistinguishable from a troll? Or is it that any sufficiently advanced troll is indistinguishable from an idiot?
On each planet is something ice on one, sand, lava, on another, etc., This is where we get our weather from in some ways. Our Earth is in the solar system of these other planets revolving around them.
I think it is the general population's consensus that there is no life on mars. With the minuscule amount of area we have explored, I think there is ample opportunity to still discover life. Considering most landing sites have been selected for their ease of touchdown and not possibility of life, I'd day we still have a fair chance of finding it. This is especially true in light of these new findings.
Great point that most people don't get. As Robert Zubrin said, you could drop 100 Spirit/Opportunity level rovers into the Rocky Mountains and probably never find prehistoric fossils, while a team of four human scientists would easily find a lot. The probes are amazing and important, but no substitute for sending humans.
I think there's also an element of the scientific bias for assuming the mundane leaking into the public. Which is fine, but scientists have learned to temper that by maintaining a strong sense of curiosity and determination.
Personally, my gut instinct is that the chances of life having existed on Mars at some point are quite high, above 90%. But the evidence for such may be very hard to come by. What if all life on Mars had never advanced beyond a unicellular level? What if most/all life died out one or two billion years ago? How challenging will it be to find evidence of that life? Especially when we only have a few robotic explorers to work with?
Personally I couldn't care less about finding microbial life. I want to find animal-sized life or heavy vegetation. That Mars might house single-celled life does nothing for my excitement.
Finding any life outside our planet would be a huge discovery; even if it's billions of years away from growing legs, we could learn so much about life in its early stages, which could answer some big questions about our own evolution.
Most importantly, if life was found on Mars and it was convincingly shown to have had a separate origin to life on Earth (i.e. no panspermia) then this would severely impact upon our understanding of how common life in the universe is.
When we've only got one example and it's us, our estimate of the probability of life evolving on a given planet (given suitable conditions) could literally be anything from 100% to any arbitrarily low number you might like to think of.
If we check two life-plausible planets and find separate life on both, the probability is suddenly way biased towards the high end of the scale. (A statistician can figure that one out for me.)
True, but I'd rather send a fleet of robots over there and bottle 1000 different soil samples for later study, and then get on with terraforming the place, perhaps by crashing a comet into it. 'But what if we contaminate this otherwise pristine natural environment' seems to get trotted out in every discussion of Martian exploration and is (IMHO) slowing us down.
The International Space Station is the most expensive object humanity has ever built. You think that the reason we are slow at terraforming Mars is because we're debating about life there?! No. The reason we're slow is because it would take millennia and incomprehensible amounts of money.
I say we land there with humans, spend a few decades checking the place out, then begin with the terraforming.
You misunderstand me. The non-contamination argument is offered reflexively to any proposal for work on Mars - from sending more landers to manned exploration. It's an obstruction to funding and research, rather than to terraforming directly - just as news like this is an encouragement.
I do not think terraforming need be terribly expensive, incidentally. We already map a great number of asteroids and comets out of awareness that if a sufficiently large one were to hit the Earth its impact would be devastating. Our best understanding at present of how to deal with the possibility of such an impact is to give the item a slight nudge that will alter its trajectory during a non-terminal interaction with Earth's gravitational field. We have already matched speeds with and made very close observations of asteroids, and our observational abilities are constantly improving. So to begin the work of terraforming Mars, I would begin looking for asteroids with large quantities of ice (or ammonia or other appropriate compounds) that are likely to intersect closely with Mars' orbit, and give them an encouraging nudge.
It annoys me that since the two rovers we've sent so far have worked so well, our response is to spend years developing a New and Better Rover at great expense, rather than launching launching a large number of rovers that use the existing design which is already known to work, and which can be done without any additional research whatsoever.
I was under the impression that Mars once had an atmosphere, but its lack of a strong magnetic field means that the solar winds sweep that all away. If true, that means that terraforming would have to involve 'jump-starting' Mars' magnetic field, which would probably involve a great deal more difficulty.
Wait that tin can floating around above us is the most expensive thing we've built? Wow, that's sort of kills all the dreams of things like building an enterprise size ship in space for a long while.
I guess it's a function of cheap transport to LEO. If we get that, other things will follow. Go Space X!
I remember brining up a theory on reddit about how rice agriculture had a profound influence on Japanese culture, and this idiot chimes in with "Japanese like to cooperate because they had AGRICULTURE?" Basically, his entire concept of agriculture was a point in a tech tree in a strategy game. (Hence no differentiation between agriculture in the wheat fields of Western Europe vs. rice paddies in Japan.)
In some ways, modern life does leave us out of touch with the complexities of the world and nature.
Rice was a lot more labor intensive in that it required more time in the field per food-for-one-person than wheat. It also doesn't store as well nor have bumper crops. So, if you have a bad year, it's hard to have a buffer with which to get by. As a result, the vast majority of the population had to get over themselves, cooperate and comply with spending most of their lives taking care of the rice or else people would starve. Troublemakers who did not cooperate were putting everyone else in clear, near-term risk and were dealt with harshly.
It may be an indication for salt water, but there are other explanations. For example, also sand can have something similar to fluid dynamics. You need to take the low gravity and thin atmosphere into account and do real calculations or simulations to gain further insights.
There is likely to be a lot more info shortly as there's currently a live press conference going on (encouragingly, the BBC has interrupted its normal news coverage to cover the entire thing).
Why do people feel the need to quote this whenever Europa is mentioned? congratulations, you have good taste in science-fiction, and now it would be nice to move on to the science part and dispense with the fiction bit. Enough with the space hippy act already.
The hive mind disagrees with my sense of humour today. Or maybe it was the ALLCAPS. I would have quoted Tom Swift but since we were talking about why we might not go to Europa (and I don't recall what book it was where he went to the moons of Jupiter)... shrug oh well.
It's closer and we have so much evidence already on other phases of water (vapor and ice). This excites people since it will be the closest source of water outside of Earth and could be the motivation to send Man over there.
Europa is so much further and just to look for the fish would require equipment to penetrate the surface for the off chance there is water underneath.
It's the atmosphere that makes this a bit surprising. Martian atmospheric pressure is less than 1% that of earth in the deepest valleys, and about .006 atm on average. If you look at a phase diagram for water [0], you can see that at .006 atm and below, water goes directly from solid to gas ("sublimation"). Even slightly above that pressure, there's only a tiny temperature range in which liquid water will exist.
I would guess that's why they've theorized very salty water. Its lower freezing point is going to allow for liquid water in a bigger temperature range at typical Martian atmospheric pressures.
[0] http://www.cims.nyu.edu/~gladish/teaching/eao/week2.html - top of the page