Voyage To Mars Word Search: Fill & Download for Free

When US astronauts went to the moon during the Apollo program, later missions included a rover so the crews could visit more sites during their short stays. They never traveled farther from the LM than they could safely walk back from in the event of an emergency or rover failure. The LRV (Lunar Roving Vehicle) design was reminiscent of a pair of folding lawn chairs bolted to the deck of a go-cart.When Elon Musk starts to build a community on Mars, travel on the open surface will be facilitated by various land vehicles.Van, or truck-like vehicles will move people and equipment over distances impractical to walk. Open rovers will carry suited astronauts and colonists on short to moderate distances, on trips that may include several stops to work on the surface.NASA has been testing manned rover prototypes for more than a decade. Two of them are based on the same chassis. Though NASA initially called them Lunar Rovers, they have since been re-branded Space Exploration Vehicles (SEV), so they may be used on Mars as well. There’s even a chassis-less, cabin-only variant for zero-G exploration operations in close proximity to an asteroid. I have read that the SEV is designed to support a crew of two for two weeks and, in contingency mode, accommodate up to four persons. The images of these exploratory vehicles conjures the adventuristic romanticism of popular fictions like the 1977 movie, Damnation Alley , or the mid-70's Saturday morning serial, Ark II, or maybe the more recent epic of Mark Watney's solo trek across Mars in The Martian.So far, all the vehicles I've shown and discussed are (or will be) designed, built, and tested here on Earth, then sent to Mars. Because of the bottleneck imposed by the expense of interplanetary spaceflight, these vehicles will be as light and compact as possible. The first concern for every gram of its mass will be safety and reliability. Creature comforts won't even make the list.Think of teaming up with your favorite travel buddy, loading up all your perishable necessities, then striking out on a two-week road trip… one on which you cannot leave the car… not even for a shower or restroom break. Such a trip would be so stressful. Your friendship may be taxed past survivability. Imagine having to stay focused on mission functions and goals, all while keeping a lookout for the unexpected discovery or pitfall. Such austere conditions would be suboptimal for such a mission. It takes “are we there yet?” To a whole new level.It's a good thing you asked the question the way you did. The advantage Mars colonists will have over a “penants, pictures, and boot prints” mission that is destined to end at the opening of the Earth-return window, is resources. A colony will come complete with engineers, fabrication tools, and a whole world of raw materials. Also, time: Vehicle builders won't have the looming crunch of a fixed return date. Iron from meteorites or hematite spherules (blueberries), along with plastics and carbon fiber made from processing Mars' CO2 atmosphere (In-situ Resource Utilization - ISRU) will be the lions share of materials used to build a Colonial Exploration Vehicle. Such a vehicle could be orders of magnitude more massive and spacious than anything Earth could loft to Mars. It could accommodate a crew large enough to permit specialization, to meet multiple mission goals, while keeping them safe, healthy, comfortable, and relaxed enough to do a superior job, and even an enjoyable one, over a months-long mission duration. When I think of that kind of vehicle, my thoughts go to the Halley VI. As the suffix implies, it is the latest in a series of research stations operated by the British Antarctic Survey.As you can see, it's huge!… and mobile! In the first image, the modules' skids can clearly be seen mounted beneath the support pylons. Though it is not self-propelled, it is accompanied by a fleet of very powerful, very capable tracked dozers which provide the locomotion to relocate the mobile station to nearly any destination in its study range along the Antarctic Brunt Ice Shelf.Halley VI was designed to operate continuously, and accommodate a peak crew of 70 scientists and support staff, including a chef, physician, communications officer, vehicle mechanic, generator mechanic, electrician, plumber, field assistant, two electronics engineers, a meteorologist, data manager, and mission commander.If that seems like overkill, we can agree. A Mars Colonial Exploration Vehicle might accommodate a crew of 12 - 15 scientists and support staff for a three to six month tour of duty away. It’s staff might be comprised of a medical officer, two powerplant operators, two engineers, the mission commander and his executive officer. Five to eight researchers would complete the complement. Such a vehicle might look a lot like this.I am proud to introduce you to the LRUP (Long-Range Utility Platform). These images have been used on Quora with the artist's concent. He goes by 600V, or Rust Shake and he has been a friend to me. My thanks to him for graciously permitting my usage. In a brief word about this concept art, Rust Shake submitted his original design to a contest commissioned by General Electric. I understand he won the contest, but was never rewarded the cash prize. I discovered the images during an online search some time back, while contemplating this very question, and struck up a conversation with him.There are two common chassis units seen coupled together here. The first has a Command and Control Cab Section and a Habitation Section. In the depicted configuration, this particular LRUP has a second, self-propelled common chassis loaded with two cargo trucks, each carrying a compact fission powerplant. This arrangement might be useful in long distance ground transit of cargo between distant settlements. The common chassis units can be custom configured and combined in greater numbers for other missions, like off-base construction or long range exploration.The Mars Colonial Exploration Vehicle variant of the LRUP might have four common chassis units. The first might have multiple Habitation Sections behind the CnC Cab Section. The second common chassis unit may be outfitted with fission powerpacks. The third and fourth may be loaded with scientific instrumentation, probe drones, a core drill array, and mission consumables.Such an exploration mission might consist of one or more days at a site to conduct core drilling, seismic and ground penetrating radar soundings, sample collection, drone operations, and panoramic or detailed look-down photography, composition laser spectroscopy, and meteorological measurements. Placement of instrument array pallets, ROV's or communications relays may occur before the LRUP gets underway. Multiple such stops, each separated perhaps by several kilometers will allow researchers to characterize the region's terrain, geology, resource mineralogy, and geographical way-finding.Crew change-out, consumable replenishment and emergency evacuations can be conducted in the field with suborbital hopper flights.Thanks for posing your cool question on Quora. Ad Astra!If you found this interesting or thought-provoking, please consider taking a moment to share or leave an upvote.I am interested in your ideas, critiques, and reflections on the LRUP and it's Mars Colonial Exploration Vehicle variant, so I encourage you to leave them for me in the comments section. I look forward to discussing this with everyone.Voyage o/t BlackSeaTiger.

No. Unless their aim is just to be delivered to Mars and die there, dead on arrival or soon after, that could be done on that budget perhaps, though it is very optimistic.You've sold your house on Earth - to pay for your trip - but you still need somewhere to live on Mars. Is he going to provide free houses on Mars for all his colonists? Surely not. A house on Mars would be vastly more expensive than one on Earth. He would no longer be making a profit on every colonist, but rather, an immense loss. Even Elon Musk couldn't sustain a business shipping a hundred colonists to Mars at a time while making a loss of millions of dollars per colonist.Also, it's not much use being on Mars without a spacesuit. A spacesuit will set you back $10 million. That's not including the design cost, just the cost for someone to make it, a months long job involving many complex intricate components, not unlike building a spaceship. Basically it is a very small mobile spaceship with its own independent life support. It also will need to be maintained and repaired, which itself is a tricky job, and it has a finite life too.Suitsat - a Russian Orlon suit that reached the end of its useful life, discarded as a satellite experiment. With current technology at least, your "Mars suit", as complex as a small spaceship, would probably cost around $10 million to build, would need a lot of maintenance, and after using it for a while it would need to be discarded and replaced by a new one.Elon Musk and Robert Zubrin are hopeful that Mars colonists could pay for their spacesuits, and everything else they need, through their inventions and other intellectual property, which they sell back to Earth.Then, to survive in your habitat you need complex life support too. It's not like an aqualung with an endless supply of air. You need to have carbon dioxide scrubbed all the time as we can't survive long if levels build up to as high as 1% of the atmosphere, which doesn't take long in a small enclosed habitat. Many other noxious gases like hydrogen sulfide and sulfur dioxide will build up in the habitat too, like "sick building syndrome" to the nth degree. You can't just open a few windows to air your house.How are you going to pay for all that technology, which also is likely to need a fair bit of servicing? You need solar power, you need batteries, or nuclear power to survive dust storms that blot out the sun. Then you have to have a habitat that can hold in the atmosphere at a pressure of ten tons per square meter outwards pressure. You also need radiation shielding meters thick covering it to protect from cosmic radiation and solar storms. How much does that kind of a "house" cost to build? You can't build it on Mars, except the shielding, the rest has to be imported from Earth. Also if it is anything like the ISS, it has a finite life. After a few decades you will need to import a new "house" to replace the old one which is now aged so much in the harsh space environment, surrounded by vacuum, huge temperature changes every day, that it is no longer worth repairing.Nothing grows there. You are suddenly in the middle of a desert, with no water, maybe ice but it has to be melted to be used, a few rocks, and most difficult of all, no air to breathe. You never need to think about how to get air to breathe when colonizing on Earth. Without a pressurized spacesuit you can't even go outside to repair your habitat, so the spacesuit is vital. The average temperatures are the same as Antarctica, but it's much worse than that sounds, because the temperature swings are so extreme between day and night. It's so cold that carbon dioxide freezes out as dry ice / water ice frosts in the morning for 100 days of the two Earth year long Mars year even in the tropics. You get dust storms every two years which sometimes blot out the sun completely for weeks on end. If you somehow could take one of the coldest driest deserts on Earth, the Atacama desert, and elevate it to a height of 30 kilometers on Earth, you'd have the same atmospheric pressure as the lowest points on the Mars surface, that is still far more habitable than Mars (still a little oxygen in the atmosphere, more sunlight, no dust storms, easy access from Earth, ozone layer and magnetosphere to protect you somewhat), The top of Mount Everest (at 8.848 km above sea level) is far more hospitable than Mars. And how do you pay for it? Elon Musk's idea is that the colonists pay through inventing things.Perhaps, as he says, Mars would have a labour shortage with jobs in short supply - but what job is going to apy you hundreds of millions of dollars to pay for your habitats and spacesuits on Mars, and their maintenance and repair and replacements when they wear out? And what exports will Mars have to pay for all those imports?Well, Elon Musk shares Robert Zubrin's ideas that the Martian colonists in such tough situations will be so inventive they will invent a stream of inventions that transform life on Earth and earn them huge amounts of money to pay for their colony. I suppose it is understandable that he'd find this idea compelling ,considering his own inventiveness. It's based on analogies with the technological inventiveness of early settlers in the US. Again this seems bordering on fantasy to me. Surely it will be mainly the other direction, that with all their complex technology, which they will need just to survive at all, they will depend tremendously on the many discoveries we made on Earth? Even Elon Musk with all his inventiveness and business nous would not be able to pay to support everyone in a Mars colony, and he hasn't suggested that he hopes to do so.If you've only read the articles and books, and listened to Mars colonization enthusiasts, as they wax lyrical in realms of fantasy about future Mars cities and a terraformed Mars, you may not realize that there are others who are profoundly skeptical about it all, bringing a perhaps sobering dose of common sense. Paul Spudis, senior staff scientist at the Lunar and Planetary institute in Houston, and author of The Value of the Moon: How to Explore, Live, and Prosper in Space Using the Moon's Resources. is particularly scathing about these ideas of a Martian colony in the near future. If you haven't come across these views before, his Delusions of a Mars Colonist may give you an interestingly different perspective."So aside from the inconvenient facts that we don’t know how to safely make the voyage, how to land on the planet, what the detailed chemistry of the soil is, or if we can access potable water, whether we can then grow food locally, or how to build habitats to shield us from the numbing cold and hostile surface environment, don’t know what protection is needed due to the toxic soil chemistry, or how to generate enough electrical power to build and operate an outpost or settlement – in spite of these annoying details that make this idea prohibitive, the creation of a Mars colony within a decade is marketed to the public as if the plans had already been drawn up."..." With flashy artwork depicting futuristic cities, sleek flying cars, and lush green fields resplendent under transparent crystal domes (in startling contrast to the red-hued surrounding desert of the martian surface) it is simply assumed that a human colony on Mars will evolve into some kind of off-Earth utopia.""But how will these future Mars inhabitants make a living? And by that, I mean what product or service will they offer that anybody on Earth will want? If you think that the answer is autarky (complete economic isolation and self-sufficiency), then you are imagining an economy (and likely, a political state) in which North Korea is a free market, pluralistic paradise by comparison. People who migrate to Mars need more than food and shelter – they will need imports from Earth, material and intellectual products designed to enrich and refine life on the frontier. What will they have of value to trade or to sell for these imports?"..." Much is made of the possible economic value of “information,” but it is not clear that Mars is particularly rich in factual data marketable to those back on Earth, although a martian pioneer might have desperate need of it – which would make them their own “customers” and exacerbate the economic disparity of the colony to an even greater degree."The Mars enthusiasts' plans get particularly sketchy when they cover the economics of a Mars colony (while Moon firsters tend to cover lunar economics in great detail). There is only one short, and perhaps not very convincing chapter on this in Case for Mars. This relies on that idea of exports of intellectual property rights by the inventive Mars colonists as one of the most important ways to pay for the colony.Zubrin also covers the idea of exporting deuterium which is an idea that doesn’t really work when you look at it closely. Yes deuterium is valuable, but the Mars deuterium is only concentrated five times relative to the deuterium on Earth, it’s only present at a concentration of r 0.078% in Mars ice, and you have a target of 99% concentration. This would save just one step out of many in a deuterium enrichment plant.Heavy water plant near Arroyito, photograph by Frandres This plant produces most of the world’s deuterium, at a rate of 200 tons per year, and is powered by a nearby hydroelectric power station at Arroyito dam with a power output of 128 MW. (I'm not sure how much of that power output is used for the plant, do say if any of you know).The equipment for extracting deuterium weighs 27,000 tons including the support structures and includes 250 heat exchangers, 240 pressure vessels, 90 gas compressors 13 reactors and 30 distillation columns. (Statistics from Arroyito Heavy Water Production Plant, Argentina)Other ideas for economic benefit from Mars are equally sketchy.The Moon is a bit different. Though life would be very expensive there also, authors like Paul Spudis etc do pay a lot of attention to the commercial case. The big advantage the Moon has is its nearness to Earth, making exports far easier and tourism possible. It's not quite "day trip" but you could visit it, and be back within a week. Also there are various ideas that could reduce costs of transport to Earth hugely, which wouldn't work for Mars. It's only two days away also, with easy access any time of the year (not just every two years), and far far easier to get back in an emergency, which makes it much safer for humans. Far easier to leave the surface than for Mars, reducing export costs. Also there's the possibility of ice at its poles, combined with solar power available 24/7 year round as a source of abundant power. Paul Spudis and others believe it will be economic to supply this ice as water and rocket fuel to LEO, outcompeting water sent from Earth. Water is vital to humans in space and very expensive to send to orbit at present.So, the "Moon firsters", though optimistic at times about the commercial value of the Moon, do tend to be far more realistic than the "Mars firsters". They are not so involved in these ideas that seem to belong more in science fiction than in real life, of just setting up home as if you could build a log cabin on Mars and live off the land. You may be interested in my Is there a fortune to be made on Mars, the Moon or anywhere else in space? in my "MOON FIRST Why Humans on Mars Right Now Are Bad for Science" (it was also featured as an article in Forbes magazine). It compares the economic case for Mars and for the Moon.In “We Need to Stop Talking About Space as a ‘Frontier’.” by Lisa Messeri she suggested that language helps and that perhaps we need to stop thinking about space as a "Frontier" with its unfortunate connotations of damage to the environment of North America, and the destruction of American Indian peoples and cultures."Comparing outer space to the frontier is so prevalent that it’s sometimes hard to remember that it is a metaphor, not an accurate portrayal of what lies beyond Earth. The commercial space industry prides itself on newness and novelty, and yet the reliance on the same old metaphor both limits the imagination of humans in space and glosses over the social and historical problems of imagining a frontier that is empty and beckoning."..." But mobilizations of the frontier metaphor from Turner to today don’t just ignore the historical reality of war, disease, and environmental destruction. The Americanness of the frontier metaphor is also at odds with the need for international cooperation in the new era of space exploration. While the frontier might inspire Tumlinson and his fellow American baby boomers, does it have salience more broadly? As we try and move from a model of space competition to space cooperation, does the frontier, which necessarily pits “us” against “them,” undermine the peaceful expansion many imagine?"Steven Lyle Jordan put it rather well, I thought, in his blog post: Space is not a frontier, commenting on her article - why not refer to space as our "environment" rather than our frontier?"There is lots of room for expansion in the Environment… but absolutely no guarantee that we can, in fact, expand beyond this oasis and thrive. Most of the Environment is downright hostile to us. Intelligence might allow us to figure out a way… but the uncontrolled elements of that vast Environment may eventually doom us to non-existence anyway. Once more… we have no way to know. But there’s nothing stopping us from trying; only the incredible difficulty and unlikelihood of succeeding.""The word “environment” embodies the knowledge of science and nature, the desire to experience it and learn what is learnable… but not to desecrate, strip-mine or destroy it for personal gain. If that’s not a noble-enough reason to explore new environments, I don’t know what is.""This way of thinking about space probably gives us the best and most accurate image of the universe and our place in it. It will also serve us best in imagining our future activities in space: How we should treat the vast Environment; and how we should act when or if we discover others out in the Environment. (It probably wouldn’t have hurt if we’d considered Earth this way, instead of seeing it as empty spaces to exploit. Just saying.)"So, this focus on colonization for its own sake really narrows our vision, I think. Everything we do becomes a step on the way to the aim of eventually attempting to colonize a place with freezing temperatures, frequent dust storms, water only in the form of ice, and a near vacuum for an "atmosphere". Well that's how I see it at least.So, I don’t see us colonizing any of these places for their own sake, any time soon. Rather there has to be some other reason to be there. The Moon is the most likely place to provide such a reason because it is so close to Earth and also so little gravity, and books on the Moon settlement have many chapters about the economic value of the Moon, unlike books on Mars that skim over this in a single chapter typically with rather sketchy ideas about how it just possibly might be economically worth while if .... Also, the lunar lava tube caves could potentially give huge low maintenance enclosed spaces. If we build closed system habitats like that, eventually, perhaps they could even be as economic to live in as Earth through economies of scale and because the Moon has no weather to speak of and is tectonically very quiet. But that's a bit of a way into the future.Mars could provide such a reason too, for scientific study, search for present day life or past life, and its two moons also. Lockheed Martin looked into Phobos and Deimos as intermediate destinations for their "Stepping Stones to Mars" and they remain destinations of great scientific interest, both in their own right, and as a base for studying Mars from orbit. Deimos also is a type of meteorite that may well have abundant water ice. They are tiny worlds so we also need to consider the potential of negative scientific impact of humans building a base on them. Perhaps we might eventually have settlements there of some sort too. I cover this in detail in I cover this in the sections Interesting flyby and orbital missions for Mars.Anyway I argue strongly that Moon is the obvious place to start our experiments in sending humans to somewhere else other than Earth, for safety reasons and nearness to Earth too as well as all the other reasons.For more about this see my OK to Touch Mars? Europa? Enceladus? Or a Tale of Missteps? (This answer is mainly an extract from it).and Case For Moon FirstSee also my answer to Is there anything of economic value on Mars that would allow trade to finance a colony on Mars?

It is not lack of interest. The polar regions are of great interest, for instance the Martian dry ice geysers in Richardson crater, one of the most interesting dynamic processes on Mars and the polar regions also have astrobiological interest too. There are potential habitats there that might even have fresh liquid water within 20 cms of the surface of the ice - of all things to find on Mars with its near vacuum atmosphere.As far as I know the only suggested habitats that might have fresh water on Mars are in polar regions, a layer of fresh water only a few cms thick, 10 to 20 cms below the surface in transparent ice. Thin though that layer may be by Earth standards, it is of extraordinary interest on Mars where any fresh water on the surface would evaporate almost immediately. It is a process that happens beneath clear ice in Antarctica and models show it should happen in the Martian ice sheets too, so long as there is similarly clear ice there.The main potential habitats, which I’ll look at in detail in this answer, are:Flow like features in Richardson Crater that form after the Martian dry ice geysers have erupted (not the same as the ones in the northern hemisphere or the ones in Russell’s crater - there are three different similar looking features that form in different conditions - only the ones in Richardson Crater are of special interest for astrobiology)Liquid water forming around sun warmed grains in snow or icePerchlorate salts lying on layers of ice forms liquid water droplets in tens of minutesLiquid water can exist permanently below 600 meters of ice (100 meters of rock) kept warm by the heat of Mars itself, if it once forms, e.g. after an impactIce fumaroles can mask the heat signature of venting of hot moist gas and make good habitatsAnywhere there is clear ice in polar regions, then fresh liquid water can form at a depth of around 6.5 cms by the solid state greenhouse effect.So it’s exciting for astrobiology, also for geology too, but they are also habitats the Earth microbes could contaminate and by the Outer Space Treaty we have an obligation to prevent “harmful contamination” in the words of the treaty. It also just makes sense. If you are searching for native life on Mars, and most people agree that is one of our top science objectives there, the last thing you want to do is to just find life you brought there yourself.So, before we developed this modern understanding of the potential vulnerability of the polar regions to Earth microbes, NASA made two attempts, the Mars Polar Lander which crashed, and Phoenix which succeeded. However it was as a result of unexpected observations by Phoenix that scientists were lead to the realization that actually there could be habitats there for modern native Mars life - and so since then any landers sent there have to be sterilized to a high standard.We could not send Curiosity there, or a second copy of Phoenix either, because it is now not thought to be sterilized sufficiently. Hopefully it has not contaminated the region of Mars around it with Earth life, but I think the Phoenix landing site might be a great site to visit to get ground truth on how effective our planetary protection measures have been on Mars - but with an appropriately sterilized lander of course.WHY IT IS HARD TO STERILIZE TO THE LEVELS OF THE VIKING MISSIONS IN THE 1970SThe current “gold standard” for Mars is set by the Viking landers.Viking Lander being prepared for dry heat sterilization – this remains the "Gold standard" of present-day planetary protection.After preliminary cleaning similarly to the levels used for Curiosity, they were then heat-treated for 30 hours at 125 °CFive hours at 125 °C would be enough to reduce the population of microbes by ten, so this was enough for a millionfold reduction - that’s including enclosed parts of the spacecraft. It would still have a maximum of 30 spores and so several thousand dormant microbes as the spore count used undercounts the number present by a factor of a hundred or so. But in addition the numbers are reduced by the journey out there, the harsh conditions on Mars, and then a microbe would have to be pre-adapted to the conditions there to have a chance of surviving once there.They didn’t achieve certainty but to a high chance no microbe from Viking was able to replicate and spread on Mars.According to modern planetary protection rules then you could send a spacecraft sterilized like this to the Phoenix landing site.But the problem is that modern equipment is much more miniaturized than for Viking, and made up of thin layers only a few atoms thick and delicate materials including epoxy attachments. Even when space hardened, it tends to be more sensitive and so would not stand being baked in an oven for days like Viking. The components would come unglued and instruments also would go out of alignment.WE HAVE ALSO MADE GREAT PROGRESS IN HIGH TEMPERATURE INSTRUMENTS SINCE VIKINGIt’s not all bad news however, for heat sterilization. Since Viking, while commercial equipment for most purposes have got more sensitive to high temperatures, we have also had many advances in high temperature technology too. The commercial equipment is not built to withstand high temperatures not because it can’t be, but because it doesn’t need to be.High temperature electronics and instruments are used where they are needed and are more capable than in the 1970s. We have them for oil wells as they drill deeper to regions where the temperatures go above 200 C. For planes where they can reduce weight by putting sensors closer to the engines, and for electric cars for similar reasons.NASA has also been working for some time to develop a rover able to withstand Venus surface conditions and drive around and study the surface. With high temperatures, high pressures and sulfuric acid too. Very sterilizing for Earth life.In 2007 they developed a silicon chip capable of 17,000 hours of continuous operation at 500 °C.For their Venus rover, we need cameras to operate at high temperatures, we need mechanisms, we need instruments such as a Raman spectroscopy, we need communications and so on. In their 2010 study they thought all of those were possible for the future. Though they couldn’t build it yet, they saw a way to it as a future roadmap.If the aim is to reach a high temperature for sterilization, the job may be easier to some extent, as the instruments don’t have to actually function at those high temperatures. They have to withstand being heated to high temperatures for a considerable period of time - but will then operate at normal temperatures.So, if you choose the right components for your lander / rover, we actually have the capability to go beyond what they could in the 1970s and I do think that if we went all out with a major program, as for the Venus rover - that we could design a 100% sterile lander in the near future. It would probably need to use RTGs for the power source - and perhaps also as the heat source for sterilization during the journey to Mars, as these have no problem working at high temperatures. Heat your lander at 500 C for six months on the voyage out to Mars and there would be no life left on it at all. Nothing viable. You can also use techniques like CO2 snow which could be done on the surface of Mars to remove even the dead organics from the outside of the lander.There is one plan already for a sterile probe to descend into the Europan ocean by Brian Wilcox.I think myself that designing a 100% sterile rover / lander should be a top priority. It would be expensive to start with, but well worth it.Once we have built the first one and developed the understanding we would have a basic design there that could be used to explore regions such as the subsurface oceans of Europa and Enceladus and the senstiive sites on Mars even if they have cms thick liquid water or more, and yet not have any concerns about introducing Earth life.The long term pay off would be huge.It would obviously take a lot of ingenuity for the astrobiologists, to redesign instruments to be able to be heat sterilized. They did however succeed for Viking, at the temperatures used there. With the Viking sterilization, tenfold reduction every 5 hours, at a dry heat of 125 °C, in theory you wouldn’t need to continue for that long to have pretty much 100% certainty that there is no life left at all.If anyone knows of any work on this apart from Brian Wilcox’s proposed mission, do say!CURRENT PLANETARY PROTECTION RULESAnyway the current rules are not as strict as that. But they do require a lander to be sterilized to Viking levels or higher if they target regions where there is ice within 5 meters of the surface. The reasoning is that a crash could end up melting the ice.So first here is a map of special regions as updated in 2016, but they also decided that even outside of those regions you need to do case by case studies before landing there.There Are Regions On Mars That It's Forbidden To ExplorePOTENTIAL FOR LIQUID WATER HABITATS IN THE POLAR REGIONS - CALCIUM PERCHLORATE SALTS IN LAYERS ON TOP OF ICEDespite what other answers say here, polar regions do have the potential for liquid water. Even fresh, not salty, water.First the Phoenix lander actually spotted droplets forming on its legs.Unfortunately, it wasn't equipped to analyse them but the leading theory is that these were droplets of salty water. They were observed to grow, merge, and then disappear, presumably as a result of falling off the legs.Nilton Renno, who was on the team for Phoenix and also runs the REM “weather station on Mars” for Curiosity was one of several who investigated various ways for thse droplets to form.He found that liquid water can form very quickly on salt / ice interfaces when the salt is on top of the ice. By “salt” there he means calcium perchlorate salts similar to the salts they found in the Phoenix site.Within a few tens of minutes this salt on top of ice formed droplets of liquid brines in Mars simulation experiments. This is striking as it could open large areas of Mars up as potential sites for microhabitats that life could exploit. The professor says"If we have ice, and then the salt on top of the ice, in a few tens of minutes liquid water forms. Our measurements clearly indicate that. And it's really a proof that liquid water forms at the conditions of the Phoenix landing site when this salt is in contact with the ice."Based on the results of our experiment, we expect this soft ice that can liquefy perhaps a few days per year, perhaps a few hours a day, almost anywhere on Mars. So going from mid latitudes all the way to the polar regions." This is a small amount of liquid water. But for a bacteria, that would be a huge swimming pool - a little droplet of water is a huge amount of water for a bacteria. So, a small amount of water is enough for you to be able to create conditions for Mars to be habitable today'. And we believe this is possible in the shallow subsurface, and even the surface of the Mars polar region for a few hours per day during the spring."(transcript from 1:48 onwards)That's Nilton Renno, who lead the team of researchers. See also Martian salts must touch ice to make liquid water, study shows . He is a mainstream researcher in the field - a distinguished professor of atmospheric, oceanic and space sciences at Michigan University. For instance, amongst many honours, he received the 2013 NASA Group Achievement Award as member of the Curiosity Rover " for exceptional achievement defining the REMS scientific goals and requirements, developing the instrument suite and investigation, and operating REMS successfully on Mars" and has written many papers on topics such as possible habitats on the present day Mars surface.MOHLMANN’S FRESH WATER FORMING AROUND DUST GRAINS IN SNOW OR ICEThis is another suggested habitat for life in the Mars higher latitudes based on processes that happen in the Antarctic ice. Dust grains in the ice often produce tiny melt ponds around them in the heat of the summer sunshine. The dust grains absorb the heat (preferentially over the ice), and so heat up and melt the surrounding ice. Then this heat gets trapped because of the insulating effect of the solid state greenhouse effect, because ice traps heat radiation, so forming tiny melt ponds of a few millimeters thickness or more. This could happen on Mars too, so is another possible habitat with fresh water.It's just a few millimeters of fresh water, but that could be significant on Mars. Another example of this process, then meteorites in Antarctica are often found associated with gypsum and other evaporates - minerals that can only form in the presence of liquid water and must have formed after they fell in Antarctica. Sometimes the researchers find capillary water, or thin films of water, and sometimes they even find evidence of a rather large meltwater pond which formed around the meteorite, or find the meteorites in depressions filled with refrozen ice.A similar process could be at work in the Martian icecaps too. This process could melt the ice for a few hours per day in the warmest days of summer, and melt a few mms of ice around each grain. Indeed, if I can venture a speculation of my own, perhaps just as in Antarctica, there could be larger melt ponds around meteorites embedded in the ice too - as Mars must have many meteorites embedded in the polar ice sheets.This could explain another puzzle. Particles of gypsum (the same material that is used to make plaster of paris) have been detected, first in the Olympia Undae dune fields that circle the northern polar ice cap of Mars, See this paper for details. Later on, they were detected in all areas where hydrated minerals have been detected, including sedimentary veneers over the North polar cap, dune fields within the polar ice cap, and the entire Circumpolar Dune Field. There's strong evidence that the gypsum originates from the interior of the ice cap. See this paper for details. Gypsum is a soft mineral that must have been formed close to where it has been discovered (or it would get eroded away by the winds) and as an evaporite mineral, it needs liquid water to form. Opportunity later found veins of gypsum in the equatorial regions, in 2011, a clear sign of flowing water on ancient Mars. But these polar deposits are more of a mystery because they are found in the dust dunes on Mars, so must be produced locally, but where?.Losiak, et al, modeled tiny micron scale dust grains of basalt (2-2 microns in diameter) exposed to full sunlight on the surface of the ice on the warmest days in summer, on the Northern polar ice cap. They found that these tiny dust grains were large enough to provide for five hours of melting which could melt six millimeters of ice below the grain. They say that with pressures close to the triple point, on windless days, you should get a significant amount of melting. They speculate that this might possibly explain the deposits of gypsum in the polar regions. Could it have formed in a similar way to the gypsum that sometimes forms around Antarctic meteorites?Möhlmann did a similar calculation. This time he was looking at the possibility of liquid water forming inside snow on Mars. The snow would be exposed to the vacuum, but as the ice melted it would plug all the pores in the snow and eventually form a solid crust of ice on the snow, and so protect it from further evaporation. It would trap the heat as well and so encourage melting. This could happen anywhere between a few centimeters depth down to ten meters below the surface.THIN FILMS OF UNDERCOOLED WATER WRAPPED AROUND INDIVIDUAL MICROBESThis is an interesting suggestion by Möhlmann in an article in Cryobiology magazine, that life may be able to make use of thin film monolayers of the " ULI water" (Undercooled Liquid Interfacial water) wrapped around a microbe, even in tiny nanometer scale layers of liquid water only two monolayers thick."In view of Mars it should be mentioned, that there is water ice in the permanent polar caps. At mid- and low-latitudes, ice can form, at least temporarily, via adsorption and freezing in the soil. There, the adsorbed and frozen water overtakes the role of ice, as described above. So, ULI-water can be expected to, at least temporarily, exist also in martian mid- and low-latitudinal subsurface soil. A similar environment can be expected to exist in isolation heated parts of icy bodies in the asteroidal belt, and analogously in the internally heated icy moons of Jupiter and Saturn. It is thus a current and challenging question if ULI-water can act as supporting life in environments with temperatures clearly below 0 °C by delivering that water, which is necessary for metabolic processes, and by permitting transport processes of nutrients and waste. It is the aim of this paper to demonstrate the potential importance of ULI water in view of the possible biological relevance of nanometric undercooled liquid interfacial water."He cites research suggesting life can remain active in the presence of just two monolayers of water wrapped around a microbe.If there is just a small thermal gradient in the ice, of one degree centigrade per meter, then enough liquid water will form to fill a micrometer sized microbe once a month. Enough will form to fill it once a day if there is a locally steeper gradient of one degree centigrade per 10 cm. This can lead to a constant transport of fresh water to bring fresh nutrients to the microbe, and to remove wastes. The main question is whether this is a sufficient flow of water to sustain life. For more details of this intriguing idea, see his article.SOUTHERN HEMISPHERE FLOW-LIKE FEATURES - MAY INVOLVE FRESH WATER CMS THICK!There are two main types of these flow-like features. For a technical overview of them, see the Dune Dark Spots section in Nilton Renno's survey paper. These ones in the southern hemisphere which form in Richardson crater are particularly promising because all the current models involve liquid water in some form and what's more, in the models, these features start off as fresh water trapped under ice.The more interesting ones, for habitability, are in the south. The southern ice cap consists mainly of dry ice. It is colder, and higher up (at a higher altitude). It stretches as far as forty degrees from the pole in winter (so spanning over 4,700 km), but it reduces to just 300 km across in summer, Richardson's crater is 17.4 degrees from the south pole (that's over 1,000 km).So though the features resemble each other in appearance, the conditions in which they form are very different and not directly comparable. The southern hemisphere features from at much higher surface temperatures than the northern hemisphere features, and they appear late in spring, after the rapid disappearance of a vast and thick layer of dry ice that covered the entire southern polar region, and beyond. In the summer then surface temperatures at Richardson crater can actually get above the melting point of ice at times in daytime, as measured by the Thermal Emission Spectrometer on Mars Global Surveyor. (See figure 3 of this paper)..This map shows where the crater is. It is close to the south pole - this is an elevation map showing the location of Richardson crater in Google Mars, and I’ve trimmed it down to the southern hemisphere. You can see Olympus Mons as the obvious large mountain just right of middle, and Hellas Basin as the big depression middle left. Richardson crater is about half way between them and much further south.Here is a close up - see all those ripples of sand dunes on the crater floor?Link to this location on Google MarsWell it’s not the ripples themselves that are of special interest, Mars is covered in many sand dune fields like that planet wide. What interests us are some tiny dark spots that form on them which you can see if you look really closely from orbit.And, would you ever guess? Although it's one of the colder places on Mars, there's a possible habitat for life there in late spring? It is due to the "solid state greenhouse effect" which causes fresh water at 0°C to form below clear ice in Antarctica at a depth of up to a meter, even when surface conditions are bitterly cold.The Warm Seasonal Flows often hit the news (probable salty brines on sun facing slopes). But for some reason, the flow-like features in Richardson crater are only ever mentioned in papers by researchers who specialize in the study of possible habitats for life on Mars.I first learnt about them in the survey of potential habitats on Mars by Nilton Renno, who is an expert in surface conditions on Mars (amongst other things, he now runs the Curiosity weather station on Mars). You can read his survey paper here, Water and Brines on Mars: Current Evidence and Implications for MSL. The models I want to summarize here are described in his section 3.1.2 Dune Dark Spots and Flow-like Features under the sub heading "South Polar Region". But it's in techy language so let's unpack it and explain what it means. I will also go back to the papers he cited, and some later papers on the topic.In the case of Richardson's crater, both models involve liquid water in some form, and also potentially habitable liquid water. One of the two main models involves relatively thick layers of fresh water below optically clear water ice, up to tens of centimeters thick, and so is very promising for microhabitats. The other model involves microscopically thin layers of fresh water that join together to make a larger stream and pick up salts on the way out. That's very promising too. So let's now look at these two ideas in detail.First, early in the year, you get dry ice geysers - which we can’t image directly, but see the dark patches that form as a result and are pretty sure this is what happens:Geysers which erupt through thick sheets of dry ice on Mars. Clear dry ice acts as a solid version of the greenhouse effect, to warm layers at the bottom of the sheet. It is also insulating so helps keep the layers warm overnight. Dry ice of course at those pressures can't form a liquid, so it turns to a gas and then explosively erupts as a geyser. At least that's the generally accepted model to explain why dark spots suddenly form on the surface of sheets of dry ice near the poles in early spring on Mars.So that would be cool enough, to be able to observe them, video them and study them close up. I hope the rover would be equipped with the capability to take real time video. These geysers are widely known and many scientists would tell you how great it would be to look at them up close, and see them actually erupt.But most exciting is what happens later in the year, when it is getting too warm for the thick layers of dry ice needed for geysers. These layers of dry ice vanish rather quickly in spring. You would think that the dark spots that you get in the aftermath of the geysers would just sit there on the surface and gradually fade away ready to repeat the cycle next year. But no. Something very strange happens. Dark fingers being to form and creep down the surface as in this animation. Very quickly too (for Mars). I haven't been able to find a video for this, as the papers just use a sequence of stills, so I combined together some of the images myself into an animation to show the idea:Flow-like features on Dunes in Richardson Crater, Mars. - detail. This flow moves approximately 39 meters in 26 days between the last two frames in the sequenceAll the likely models for these features, to date, involve some form of water. Alternatives that one might try to use to model them might include a second ejection of material by the dry ice geyser, or dust deposition, but researchers think these are unlikely to produce the observed effects.SIMILAR LOOKING FEATURES NOT TO BE CONFUSEDThe Richardson crater flow-like features should not be confused with two rather similar looking features, the dark streaks in Russell crater, 55 degrees from the south pole (compared to 17.4 degrees for Richardson crater).These are braided, divide, recombine and cross each other's tracks. They flow down the slopes channeled by wind formed ridges in the dunes, and most distinctive of all, they are able to rush up over small features of up to two meters high and down the other side.These seem to be dry features associated with defrosting and small dust avalanches as they are episodic, moving rapidly at speeds of 2-4 meters per second like an avalanche. The authors call them "dark flows". For details see this paper.They also should not be confused with the Flow-like features in the Northern polar dunesThe two Martian ice caps are rather different. The northern cap is low lying, mainly ice, with a thin layer of dry ice that disappears in summer. The flow like features in the northern hemisphere form at 12.5 degrees from the pole at surface temperatures of about -90°C, which is low enough for dry ice to be stable on the surface. Their models involve either extremely cold salty brines or dry ice and sand. These features are far too cold to be habitable to Earth life and may not even involve liquid waterThey are easily confused because they are so similar in appearance, and because both are referred to as "flow like features".These are thought to form at much lower temperatures. Some of the models for these also involve liquid water but there are other hypotheses as well, some of them involving dust and ice slipping down the cliff faces.Perhaps one reason the Richardson crater flow-like features get so little attention is that it is easy to confuse them with these other features and assume they have been proved to be dust flows or to form at temperatures to low to be habitable.But they form in different conditions at different temperatures and the explanations used for these other features don’t work for them. Currently the only models for them involve fresh liquid water beneath the ice, either as layers cms thick, or as thin undercooled liquid water layers, then combining with salts to form the flows on the Martian surface.MORE ABOUT THESE FEATURES AND WHY THEY ARE SO INTERESTING FOR HABITABILITYSo, these southern hemisphere flow like features seem very promising. That’s not as surprising as you might think. The same thing happens in Antarctica - if you have clear ice, then you get a layer of pure water half a meter below the ice.The water is trapped by the ice so stays liquid. And what’s more, if they model it assuming clear ice like the ice in Antarctica they find that the ice there gets enough heat from the sun in the day to keep it liquid through the night to the next day so the layer can actually grow from one day to the next (ice is an excellent insulator). Also the Mars atmosphere is so thin that it doesn't matter at all that the air above the ice is very cold in these regions. The atmosphere is a near vacuum and works as a great insulator. Better in some ways than Antarctica.Inuit village, Ecoengineering, near Frobisher Bay on Baffin Island in the mid-19th century - ice and snow are very insulating on Earth or on Mars. Just as you can be snug and warm inside an igloo, a layer of fresh water can stay warm a few tens of cms below the surface, warmed by the sun every day beaming through th clear ice. The near vacuum of the Mars atmosphere helps if anything.Möhlmann's model is pretty clear (abstract here). If Mars has transparent ice like the ice in Antarctica, then it should have layers of liquid fresh water 5 - 10 cm below the surface and a couple of cm in vertical thickness in late spring to summer in this region. His model doesn't involve salt at all, so the water would be fresh water.The only question here is whether clear ice forms on Mars in Mars conditions and whether the ice is sufficiently insulating. We can’t tell that really from models, the only way is to go there and find out for ourselves.Blue wall of an Iceberg on Jökulsárlón, Iceland. On the Earth, Blue ice like this forms as a result of air bubbles squeezed out of glacier ice. This has the right optical and thermal properties to act as a solid state greenhouse, trapping a layer of liquid water that forms 0.1 to 1 meters below the surface. In Möhlmann's model, if ice with similar optical and thermal properties forms on Mars, it could form a layer of liquid water centimeters to decimeters thick, which would form 5 - 10 cm below the surface.In his model, first the ice forms a translucent layer - then as summer approaches, the solid state greenhouse effect raises the temperature of a layer below the surface to 0°C, so melting it.The melting layer is 5 to 10 cm below the surface. In the model, then the ice below the surface is first warmed up in the daytime sunshine, due to a greenhouse effect, the infrared radiation is trapped in the ice in much the same way that carbon dioxide traps heat to keep Earth warm. Then because the ice is so insulating, the heat is retained overnight, and the water remains liquid to the next day. To start with it would be only millimeters thick but over several days, gets to thicknesses of centimeters.He found that subsurface liquid water layers like this can form with surface temperatures as low as -56°C.CREATES POTENTIAL FOR FRESH LIQUID WATER FLOWING ON MARS!This should happen on Mars so long as it has ice with similar properties to Antarctic clear ice.If there is a layer of gravel or stone at just the right depth, the rock absorbs the infrared heat and that can speed up the process. In that case, a liquid layer can form within a single sol, and can evolve over several sols to be as much as several tens of centimeters in thickness. That is a huge amount of liquid water for the Mars surface.The fresh water of course can't flow across the surface of Mars in the near vacuum conditions, as it would either freeze back to ice, or evaporate into the atmosphere. But the idea is that as it spreads out, it then mixes with any salts also brought up by the geyser to produce salty brines which would then remain liquid at the much lower temperatures on the surface and flow beyond the edges to form the extending dark edges of the flow-like features.Later in the year, pressure can build up and cause formation of mini water geysers which may possibly explain the "white collars" that form around the flow-like features towards the end of the season - in their model this is the result of liquid water erupting in mini water geysers and then freezing as white pure water iceThis provides:A way for fresh water to be present on Mars at 0 °C, and to stay liquid under pressure, insulated from the surface conditions.5 to 10 cm below the surface, trapped by the ice above itDepending on conditions, the liquid layer is at least centimeters in thickness, and could be tens of centimeters in thickness.Initially of fresh water, at around 0°C.They mention a couple of caveats for their model, because the surface conditions on Mars at these locations is unknown. First it requires conditions for bare and optically transparent ice fields on Mars translucent to depths of several centimeters, and it's an open question whether this can happen, but there is nothing to rule it out either. Then, the other open question is whether their assumption of low thermal conductivity of the ice, preventing escape of the heat to the surface, is valid on Mars.The process works with blue ice on Earth - but we can't say yet what forms the ice actually takes in these Martian conditions. The authors don't go into any detail about this, but ordinary ice can take different forms even in near vacuum conditions. As an example of this, the ice at the poles of the Moon could be "fluffy ice""We do not know the physical characteristics of this ice—solid, dense ice, or “fairy castle”—snow-like ice would have similar radar properties. [then they give evidence that suggests fluffy ice is a possibility there] "(page 13 of Evidence for water ice on the moon: Results for anomalous polar)That's the main unknown in their model, whether the ice is blue ice like Antarctic ice, or takes some other form. The ice should at least be in the same hexagonal structure crystalline phase as ice is on Earth - Mars is close to the triple point in this ice phase diagramPhase diagram by Cmglee, wikipedia. Ice outside of Earth can be in many different phases. For instance in the outer solar system it is often so cold that it is in the very hard orthorhombic phase, where it behaves more like rock than what we think of as ice. However ice on Mars is likely to be in the Ih phase similar to Earth life. The Mars surface is close to the triple point of solid / liquid / vapour in this diagram.So, the ice is likely to be of the same type as the blue ice in Antarctica. Not likely to have bubbles of air in it. But it could still take a different forms. The model shows that Mars should have layers of liquid water ten to twenty centimeters below the surface if there are any areas of clear blue ice as in Antarctica.This solid state greenhouse effect process favours sun facing slopes (equator facing). Also, somewhat paradoxically, it favours higher latitudes, close to the poles, over lower latitudes, because it needs conditions where surface ice can form on Mars to thicknesses of tens of centimeters. (The examples at Richardson crater are at latitude -72°, longitude 179.4°, so only 18° from the south pole. There is no in situ data yet for these locations, of course, to test the hypothesis. Though some of the predictions for their model could be confirmed by satellite observations.ALTERNATIVE - THIN LAYERS OVER SURFACES MELTING AT WELL BELOW O CAnother model for these southern hemisphere features involves ULI water (Undercooled Liquid Interfacial water) which forms as a thin layer over surfaces and can melt at well below the usual melting point of ice. In Möhlmann's sandwich model, then the interfacial water layer forms on the surfaces of solar heated grains in the ice, which then flows together down the slope. Calculations of downward flow of water shows that several litres a day of water could be supplied to the seepage flows in this way.The idea then is that this ULI water would be the water source for liquid brines which then flow down the surface, mixing with dust, to form the features. That would still be interesting as you end up having flowing liquid water on Mars, several litres a day what’s more. Here is a paper from 2016 describing the idea.See also Möhlmann's paper The three types of liquid water in the surface of present MarsThose are the only two models so far. So it does seem very likely that there is liquid water here, and even with the interfacial liquid layers, the water starts off as fresh water beneath the ice, or possibly salty (in either model) if there are salt grains in the ice for the water to pick up. Either way the features start out as a flow of fresh water trapped beneath a layer of ice. This is one of the least publicized types of habitat on Mars, seldom mentioned outside the specialist literature. Yet in some ways it's one of the most interesting, if it exists, because of the potential for fresh water at 0 °C.This liquid water is hard to observe because the features are so small, beyond the resolution of CRISM. However, analysis of the larger spots, at around the spring equinox, produced a signal that just possibly could be liquid water, where the ice is in contact with the dark material of the dune spots." In the gray ring area the water ice 631 surrounds darker surface, where liquid interfacial water layer or brine (Möhlmann 2004, 632 2009, 2010) may form. We found no firm evidence for the presence of liquid water in near-IR 633 spectra, although linear unmixing results show that the data are not inconsistent with a 634 possible slight contribution (a few %) of liquid water in the dark core unit." page 26 of this paper.MORE WIDESPREAD LIQUID WATER AT DEPTH OF ABOUT 6.3 CM BELOW OPTICALLY CLEAR ICEMöhlmann has also suggested that his process could be a more widespread phenomenon in the Mars ice caps, not just associated with the geysers, as for Antarctica. Just more noticeable for the flow-like features because of the conditions in which it forms there.Liquid water could form at a depth of around 6.3 cm wherever there is optically clear ice on Mars in snow / ice packs, just as it does in Antarctica. In summer, it could form layers from centimeters to tens of centimeters in thickness.Results of Mohmann's modeling of the solid state greenhouse effect in clear ice on Mars. The plateaus show temperatures that get above the melting point of water regularly every Martian sol, at depths of about 6.3 cms. L here is 11.4 cm. Ice at this level will melt periodically, and especially in summer can stay liquid overnight, leading to subsurface liquid water in layers of from cms to tens of cms in thickness. This should happen on Mars not just in the flow-like Features of Richardson crater, but also, anywhere where there is optically clear ice.In another paper he writes "This liquid water can form in sufficient amounts to be relevant for macroscopic physical (rheology, erosion), for chemical, and eventually also for biological processes. "His models seem clear enough. The air temperature hardly matters, because the Mars air is so thin it's a near vacuum, insulating the ice, like a thermos flask. The only unknown here is whether Mars does have optically clear ice like this, which is common on Earth in cold conditions like this in Antarctica.Before I go on to the last couple of examples of possible habitats in the polar regions, let’s just revisit the Phoenix lander site. I think it would be a great place for a mission that’s both interesting for astrobiology and also for ground truth for planetary protection.LIFE IN ICE TOWERS HIDING VOLCANIC VENTSSo, this is another suggestion, that we could find habitats on Mars inside ice fumaroles. It's a nice idea, and perhaps ice fumaroles do form on Mars from time to time. So far we haven't found any on present day Mars. But it may well be worth keeping a look out for them, as it would be a very interesting habitat if we find one, or one of them starts to form, around a volcanic vent on Mars. If Mars does have any volcanic vents which vent water rich gases through a fumarole, they are likely to form ice towers like this, as happens in Antarctica.Let's look at the idea in some more detail. This photo shows an ice fumarole - an ice tower that forms around a vent of volcanic gases in the extremely cold conditions right near the top of Mount Erebus in Antarctica.+One of the numerous Ice Fumaroles near the summit of Mount Erebus in Antarctica. If these also occur on Mars, they could provide a habitat for life, and would be extremely hard to spot from orbit due to the low external temperatures. Image credit Mount Erebus Volcano ObservatoryFor more photos of ice fumaroles see "Ice Towers and Caves of Mount Erebus",They were originally discovered by the Antarctic explorer Shackleton during his 1908 Nimrod expedition, when he and a few others set out to climb Mount Erebus.Photograph from Shackleton's Mount Erebus expedition with a fumarole in the backgroundHe described them like this."The ice fumaroles are specially remarkable. About fifty of these were visible to us on the track which we followed to and from the crater, and doubtless there were numbers that we did not see. These unique ice-mounds have resulted from the condensation of vapour around the orifices of the fumaroles. It is only under conditions of very low temperature that such structures could exist. No structures like them are known in any other part of the world."Ice caves form below the fumaroles, and these are especially interesting as a habitat for life.Entrance to Warren Cave on Mount Erebus. Credit Brian Hasebe. Volcanically heated, the temperatures inside their three study sites were 32, 52 and 64 degrees Fahrenheit (2,11 and 18 degrees Celsius), far warmer than the surroundings.These ice caves on Erebus are of especial interest for astrobiology, as analogues for habitats outside of Earth, because they are so biologically isolated. Most surface caves are influenced by human activities, or by organics from the surface brought in by animals (e.g. bats) or ground water. These caves at Erebus. are high altitude, yet accessible for study. There is almost no chance of them being affected by photosynthetic based organics, or of animals in a food chain based on photosynthetic life. Also there is no overlying soil to wash down into them.As described in this paper, these ice towers eventually collapse and then rebuild themselves, but though temporary features, they persist for decades. The air inside has 80% to 100% humidity, and up to 3% CO2, and some CO and H2, but almost no CH4 or H2S. Many of the caves are completely dark, so can't support photosynthesis. Organics can only come from the atmosphere, or from ice algae that grow on the surface in summer, which may eventually find their way into the caves through burial and melting. As a result most micro-organisms there are chemolithoautotrophic i.e. microbes that get all of their energy from chemical reactions with the rocks. They don't depend on any other lifeforms to survive. They survive using CO2 fixation and some may use CO oxidization for their metabolism. The main types of microbe found there are Chloroflexi and Acidobacteria.This makes them very interesting as an analogue for Mars habitats. If Mars is currently geologically active, then in such cold conditions, it may well have ice fumaroles around its vents, and if so they would be only a few degrees higher in temperature than the surrounding landscape and hard to spot from orbit. We haven't found these yet. The closest we have got so far is that the silica deposits in Home Plate which Spirit found, might have been formed by ancient fumaroles on Mars, (not necessarily ice fumaroles) though they could also have been formed by hot springs or geysers.This article Martian Hot Spots in NASA's Astrobiology magazine presents Hoffman's ideas. He explains that ice fumaroles on Mars could be up to 30 meters tall in its lower gravity and 10 to 30 meters in diameter, circular or oval in shape. So, potentially these things could grow to be huge on Mars, as high as a nine story high skyscraper, and potentially some of them could be as wide as they are high.He suggests searching for them on Mars from orbit, and he wondered if some temperature anomalies in Hellas Basin could be ice fumaroles. They wouldn't need to be in polar regions because the fumaroles themselves would bring large quantities of water vapour to the surface to keep replenishing the ice towers as they sublime away in the thing Mars atmosphere. They might be quite easy to spot as white circles or ovals, probably in permanently shadowed regions, and they would be slightly warmer than their surroundings. This shows one of his candidates.Daytime infrared from Odyssey IRAnomalous warmth in infrared at night as well on all nine infrared bands, so not a chemical signature.That candidate is in Hellas Planitia and is from 2003. Despite a search of high resolution visual images they were unable to find anything visual corresponding to them, they were only visible in infrared. But it shows the sort of thing they would be looking for. Lots of small dots around 10-30 meters in diameter each, clustered around a potential fracture. For details see their paper.The idea is that just as on Earth, volcanic action could bring water vapour and other gases from below. The water vapour, as in Antarctica, would freeze out to form these ice towers. If these environments do occur on Mars, they would provide a warm environment, high water vapor saturation, and some UV shielding. The ones we have on Earth don't have significant amounts of liquid water. However, as they have close to 100% humidity inside, that doesn't matter. They sustain microbial communities of oligotrophs, i.e. micro-organisms that survive in environments that are very poor in nutrients. The same could be true of Mars.Though we haven't found ice fumaroles on Mars yet, we have found recently formed rootless cones, which are the results of explosive contact of lava with water or ice. This shows that ice (or water) and lava were in close proximity as recently as around ten million years ago.This shows rootless cones on Mars (to the left) and in Iceland. They are the locations of small explosions of steam, when lava surges over the surface over water or ice. These rootless cones on Mars formed around ten million years ago which shows that Mars has had ice and lava in close proximity very recently. They range in diameter from 20 meters to 300 meters.So, could there be other ways that volcanic processes on Mars produce habitats by interacting with ice, such as the ice fumaroles? From this 2007 paper:Hoffman and Kyle suggested the ice towers of Mt. Erebus as analogues of biological refuges on Mars. They combined the idea of still existing near surface ice deposits with the assumption that there is still some localized volcanic activity on Mars today.There are several examples from Mars that show a direct interaction between lava and ice in the geological history of Mars. The most obvious cases are the rootless cones seen in the northern lowlands. HRSC images show direct and violent interaction in the relatively recent geological history, for example at the scarps of Olympus Mons. Mars today is in relatively dormant phase, and any interactions which might be occurring today are presumably on a much less dynamic scale. Nevertheless, they may be driving local hydrothermal systems. Studying the geothermal processes in the first few tens to hundreds of meters below the surface of Mars today might thus uncover a wide variety of new habitats where biological activity may survive on this cold and dry planet.For more about this topic see Volcano-Ice Interaction as a Microbial Habitat on Earth and Mars. These ice fumaroles would be of great interest, but of course, being open to the surface, would easily be contaminated by Earth life from surface explorers or brought in to them through dust from the Martian storms.So far we've been looking at habitats deep below the surface of Mars, though perhaps connected to the surface. But what about habitats on the surface itself? They would make planetary protection even more of an issue, so it's important to look at the possibility. First we need to look at the question, is surface life possible there at all. Just a decade ago, most scientists (with the exception of Gilbert Levin) would have answered with a resounding "No". But that's all changed.There might also be habitats for native Mars life below the surface similar to lake Vostok in Antarctica - well within reach of drilling. Searches so far have turned up a blank but they could still be there if the lakes are small up ot a few kilometers in size. They could be as close to the surface as only 100 meters deep below rock, or 600 meters deep below ice and remain liquid indefinitelyICE COVERED LAKES HABITABLE FOR THOUSANDS OF YEARS AFTER LARGE IMPACTS - OR INDEFINITELYWhen comet Siding Spring was discovered in 2013, before they knew its trajectory well, there was a small chance that it could hit Mars. Calculations showed it could create a crater of many kilometers in diameter and perhaps a couple of kilometers deep. If a comet like that hit the martian polar regions or higher latitudes, away from the equator, it would create a temporary lake, which life could survive in.Artist's impression of Mars as seen from comet Siding Spring approaching the planet on 9th October 2014. It missed, by less than half the distance to our Moon. But sometimes comets will hit the Mars ice caps or higher latitudes. If that happens, it will create lakes and hydrothermal systems that last for thousands of years.These lakes can last for a surprisingly long time, insulated by the ice and heated from below by the rock. The models suggest that large craters of 100 - 200 km in diameter in the early solar system would have made lakes that stayed liquid for as long as one to ten million years. This happens even in cold conditions, so it is not limited to early Mars. A present day comet a few kilometers in diameter could form a crater 30 - 50 km in diameter and an underground hydrothermal system that remains liquid for thousands of years. The lake is kept heated by the melted rock from the initial impact in hydrothermal systems fed by water from deep underground.Also, there's another way to keep water liquid. Any ice deep enough below the surface, only 100 meters deep, can actually stay liquid indefinitely if covered by an insulating layer of gravel. There'd be enough heat from below, just from the heat of Mars itself and enough insulation above from the gravel, to keep the water permanently liquid. See section 2.2.3 of Niton Renno's article. This is also one theory for the Martian "dry gullies" that they formed through liquid water suddenly flowing out of a subsurface aquifer like this. This was the most popular theory for them at one point, though there are other explanations for them now.It's much harder to keep water liquid below ice, since rock is much more insulating than ice. It's especially hard for water to form below an ice sheet. If the ice cap was four to six kilometers deep, then you'd expect the base of it to be liquid water, melted from below just through the heat of Mars itself. Though Mars does have ice at both poles, its ice sheets aren't quite as deep as that. But it could still have liquid water at the base of its ice sheets, if there's localized geothermal heating from below.Also, if a lake formed, originally by geothermal melting or a meteorite impact, it's much easier to keep the lake liquid than it was to melt the water in the first place. In one model, then if a lake forms at a depth of over 600 meters below the ice (originally open to the surface) then it can remain liquid indefinitely from the heat flux from below, even without local geothermal heating.We'd be able to detect this water using ground penetrating radar because of the high radar contrast between water and ice or rock. MARSIS, the ground penetrating radar on ESA's Mars Express is our best instrument for the job. After several searches, it hasn't found anything yet. See page 191 of this paper. Their resolution isn't that great, however, around a kilometer.From the searches done to date, we can say with reasonable certainty that Mars doesn't seem to have an equivalent of our Lake Vostok (250 km by 50 km by 0.43 km deep) beneath its ice caps at present. It could however still have small subglacial lakes of up to a kilometer or so in diameter. They were looking for water liquid through geothermal heating, but their search would surely have found impact lakes too.So, Mars doesn't seem to have any large lakes created from impacts just now. Nor does it have any major lakes formed through geothermal activity below glaciers or ice caps, though it could have smaller lakes.So in short there are lots of exciting prospects to explore in the polar regions for astrobiologySo far we haven’t even made a start at looking for life there. Or anywhere on Mars except briefly in the 1970s with the Viking landers which produced ambiguous results and have never been followed up.See also myIs This Why We Haven't Found Life On Mars Yet? Value Of Actually LookingLet's Make Sure Astronauts Won't Extinguish Native Mars Life - To Jupiter's Callisto, Saturn's Titan And Beyond - Op EdModern Mars habitability - WikipediaTouch Mars? (book, around 2,000 pages, in a single web page, give it time to load) - this article is based mainly on sections of this bookRemoved section of this answer about the idea of using the Phoenix lander site to test planetary protection ideas - it was long enough anyway and that made it rather long :)