Growing water droplets on Phoenix's legs? (NASA)

Has Liquid Water Been Detected On Mars?

Article Updated: 24 Dec , 2015

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Liquid water may have been discovered by the late Phoenix Mars Lander. This astonishing (and controversial) claim comes from some very intriguing images of the lander’s leg shortly after Phoenix landed on the Red Planet last year. The series of black and white images appear to show droplets of water hanging off the robot’s bodywork in the shade; it seems possible that the water droplets were splashed from the surface during Phoenix’s rocket-assisted landing. Far from being static blobs, they appear to grow, much like water droplets here on Earth as water vapour is absorbed from the atmosphere.

But wait a minute, isn’t the Martian atmosphere too thin and too cold to accommodate liquid water? That’s where the perchlorate comes in

If liquid water has been found to exist on the surface of Mars, there will be huge implications for our understanding of the planet. Most tantalizingly, liquid water, on or near the planet’s surface, could aid the survival of microbial life, reinvigorating the search for extraterrestrial life on out interplanetary neighbour. But on a planet where the atmospheric pressure is 100 times less than on Earth, and temperatures reached a maximum of -20° Celcius during the Phoenix mission, why isn’t this “liquid water” candidate frozen?

The perchlorate discovery in the Martian soil was announced by the Phoenix team in August 2008, after an explosion of intense Internet conjecture caused by the “potential for life” announcement by an Aviation Week article days earlier. It turned out that the Phoenix instrumentation had found quantities of a toxic chemical called perchlorate known to be a hindrance to life as we know it. Although follow-up reports were slightly more positive about the presence of the chemical (a possible energy source for microbial life), the mood was fairly sombre. On a planet as unforgiving as Mars, any bad news is a severe knock for the hope of finding life.

However, regardless of perchlorate’s toxic effects on life, it may be helping out another one of life’s resources to stay in liquid form. If perchlorate is dissolved in significant quantities, water could remain as a liquid down to temperatures as low as -70°C. So could it be that the dissolved perchlorate salt is acting as a very impressive anti-freeze?

Nilton Renno from the University of Michigan and Phoenix team member, thinks it could be. “According to my calculations, you can have liquid saline solutions just below the surface almost anywhere on Mars,” he said.

Renno’s team carried out a series of laboratory experiments and found that the lander’s thrusters would have melted the top millimetre of ice in the regolith. The resulting water droplets may have been splashed onto the landers leg. If the concentration of perchlorate was high enough, the water could have remained in a liquid state during the Mars daytime. As time progressed, atmospheric water vapour may have been absorbed, hence the growing and shifting blobs of liquid on the leg. There is also the possibility that the droplets were splashed from pools of perchlorate-rich water already in a liquid state on the surface.

However, not everyone is convinced. Fellow Phoenix team member Michael Hecht from NASA’s Jet Propulsion Laboratory in Pasadena, California, thinks that the photographs actually show water ice, not liquid water. The “frost” changed shape as vapour from the air coalesced and froze to the leg. Renno points out that this is unlikely as any ice on the leg would be more likely to sublime, rather than grow, but Hecht believes this could happen if the leg was colder than its surroundings.

Renno’s team will be continuing tests on samples of perchlorate-rich water under Mars-like conditions for the next few months to understand the dynamics of water under these extreme conditions. What makes this even more interesting is that some microbial life on Earth has the ability to survive in very salty fluids, perhaps microbial alien life on Mars evolved in a similar environment where there were pools of liquid water maintained at extremely low temperatures by high concentrations of perchlorate salt

Source: New Scientist


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Aaron Slack
Guest
Aaron Slack
February 18, 2009 7:46 AM

Provocative…fascinating… too bad it’s inconclusive sad

s0l
Guest
s0l
February 18, 2009 3:49 AM

Once we set foot there we will find life. I doubt machines will, they’re stupid, slow and un-living.. Good for taking pictures and doing chemical analysis but that’s about all they’re useful for really..
To each his own… smile

mewo
Member
mewo
February 18, 2009 4:34 AM

Frost doesn’t normally form big round chunks like the ones in the photos, does it? From my experience (which amounts to scraping the stuff off my windshield) it forms thin crystals. Of course, frost might well behave differently if it’s made of perchlorate-laden water in a low pressure environment well below zero degrees, but those blobs sure do LOOK like water droplets to me.

David R.
Member
David R.
February 18, 2009 6:29 AM

The Great Perchlorate Debate resumes.

Conic
Guest
February 18, 2009 7:40 AM

A small piece of dust appears, then goes away.

300 million down the drain.

Never has a mission produced so little data with so many great instruments. The atomic force microscope has returned hardly any information at all… What is the deal?

How is it that when the last two rovers did so well, are still working after all this time, we dont just send the same rovers to new locations? Would it not save money to use the same design over again? Would it not save money to use the same teams to run all 4 rovers?

Eric Near Buffalo
Guest
Eric Near Buffalo
February 18, 2009 7:48 AM

I think you could probably use the Rover design over and over. You could at the same time put additional instruments with higher technology on board.

starman
Member
starman
February 18, 2009 10:22 AM

I wonder if the team considered electrodeposition.

The perchlorate/water conjecture should be easy to determine with some perchlorate, water and an environment chamber – better than a calculation.

Manu
Member
Manu
February 18, 2009 10:50 AM

@ Conic:
Really? Ice, Perchlorate, Carbonate, Silicate, not to mention snow: aren’t these news? The atomic force microscope probably found clay particles: not GREAT news?
The data is just beginning to be studied; I’ll bet we’ll hear about it for years if not decades.
Yes, the rovers are fantastic. But a rover sent there instead of Phoenix would be just as dead now, for the very same reason. And rovers don’t dig, don’t do chemistry. They never will, unless they get bigger (MSL).
Any mission raises questions it can’t answer, the next mission is designed to answer these questions, and raises more.
Just be patient!

Conic
Guest
February 18, 2009 10:59 AM
Manu… We already knew there was ice on Mars. Touching it is, in astronomy, hardly a requirement. The rovers could have carried all of the instruments found on this sessile lander, and it could have moved them around. Rovers can dig, and drill (they have already done the latter), and anything else. Obviously any polar lander should have had an RTG based power system, or at least a way to stay dormant and come back to life after the winter. Just one season of science, at this cost, and at a time when money for probes is very hard to get, is inexcusable to me. Sorry to be this way. I love all missions, and in a perfect… Read more »
Manu
Member
Manu
February 18, 2009 1:37 PM
@Conic: Yes I see, but then the rover you describe is precisely the next rover! Phoenix’s instruments could never fit on a MER, let alone an RTG. Phoenix is way heavier than MERs, and MSL is way heavier than Phoenix. MERs don’t dig, they don’t drill, they scratch. That’s great, but we need more, don’t we? Even MSL won’t drill, only ExoMars will (maybe). Also, contrary to other regions of Mars, there was no reason to move around where Phoenix landed, because it’s all of the same for 100s of miles. That was a strong factor in mission design, which probably allowed packing in more instruments instead of wheels and motors. Besides, Phoenix has learned a few hard… Read more »
Aqua
Guest
Aqua
February 18, 2009 3:39 PM

I am curious about the Phoenix lander’s legs. What material were they made from? I will assume aluminum with some sort of protective coating – anodize or other? Might one of these materials have reacted with Perchlorate? or water vapor? And if so, how and what would such an oxidation look like? We’ve all witnessed how oxidized aluminum degrades here on Earth. Given there may have been out-gassing or melting caused by the lander’s exhaust, what chemical reations might take place? Another contributing factor may be tribo-electric charges, i.e. electrostatic field induction.

Astrofiend
Member
Astrofiend
February 18, 2009 3:48 PM

@Manu & Conic:

Throughout the entire Phoenix mission and even to this point, I’ve shared and swung between both of your viewpoints, sometimes on a daily basis. I’ve gone from being completely underwhelmed by Phoenix to being stoked on it’s achievements to being disappointed by the amount of science being done and back again. I still have mixed feelings about it! In the end, it has done some great science, but I feel like it could have been so much more. But then again, you live and learn. But then again… Arrrghhh!

Chris Coles
Guest
February 19, 2009 1:37 AM

If it were a water droplet that had almost immediately frozen onto the leg and then, during the heat of the day, (the leg is in direct sunlight, the droplet is on the opposite side of the leg, out of direct sunlight), the warmth heats the surface of the leg sufficiently that the still frozen droplet has now a surface layer, perhaps an atom thick that has melted such that the droplet, still frozen, slides across the surface of the leg.

That will give you the appearance of a liquid droplet with pure water and no need for any antifreeze.

Food for thought?

Chris Coles
Guest
February 19, 2009 1:40 AM

Oh! And you could try this out for yourselves with your home freezer and a aluminium tube splashed with water. Once frozen, take it out into sunlight on a very cold day and see if it works.

John Davis
Guest
John Davis
February 19, 2009 6:03 AM

I also notice that with many fuels (I do not know the fule that powers the lander) Water is a product of combustion.

InvaderXan
Member
February 19, 2009 6:43 PM

Didn’t the lander have some trouble getting soil into its analyser because it was “too clumpy”? Soil on Earth tends to be clumpy when it’s damp. Could this have any significance?

What’s more, the lander finally shook the soil in after a few days. It’s conceivable it was only able to do so because it had sufficiently dried out.

Mind you, ice (or dry ice) crystals could likely have a similar effect…

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
February 20, 2009 12:22 PM
Ah, cool! (Or wet? I remember Emily Lakdawalla over on Planetary Society blog speculating about those blob after their discovery, only to oversee the report on their putative liquid status when she linked to the 40th Lunar and Planetary Science Conference program. I was miffed at the time. Soil on Earth tends to be clumpy when it’s damp. IIRC one abstract from the above mentioned cementing as a possibility, from detected in abundance carbonates or so. It turned out that the Phoenix instrumentation had found quantities of a toxic chemical called perchlorate known to be a hindrance to life as we know it. I’m not a chemist, but I don’t get why Ian O’Neill persists in claiming “hindrance… Read more »
Aqua
Guest
Aqua
February 20, 2009 5:31 PM

The location of each of the little ‘blobs’ in the lander images, whatever they are, may be where micrometeors impacted during transit? Those impact sites then exposing raw metal to the Martian atmosphere… Tribo electric chemical oxidation anyone?

Paul Scott Anderson
Member
March 29, 2009 2:57 PM
There is another new update on The Planetary Society Blog, including comments on why the Phoenix team et al, think the droplets were salty water brines and not just ice or frost and unlikely to be the result of hydrazine, etc. from the engine thrusters mixing in with melted ice: http://www.planetary.org/blog/article/00001890 Excerpt: “The first question that comes to mind is “Why don’t they think the spheroids are made of ice, not liquid water?” They argue that ice particles wouldn’t have formed in spheroids, they would have formed a thin, uniform layer, much like the frost coating seen later in the mission. For the spheroids to be ice at the observed weather conditions, the humidity would have to be… Read more »
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