Note to Mark Watney
Dig for ice on Mars but if you discover a large green humanoid you probably should try somewhere else.
Mars boffins have spotted lots of almost-pure water ice on Mars. Detailed in a Science paper titled ” Exposed subsurface ice sheets in the Martian mid-latitudes”, the find was made using the Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE) camera. The scientists who tend that instrument spotted …
Mountaineers have problems because they have very limited carrying capacity. I've used a little hand pump jobbie to make water from sea water and its not that difficult - and assuming the astronauts will be recycling I can see them getting away with a relatively small solar collector for heating and melting the stuff and PV powered purifiers for most of their needs.
Getting hold of the ice is another matter - I've tried hacking at ice before and if it gets any harder as it gets colder a couple of hours work with a pickaxe might produce more sweat than the accumulated ice cubes.
Lasers. You forget the laser guns that the Space Force™ will have with them.
Anyway what about:
"as we don't know the density of Martian ice"
Assuming no more than basic mineral contamination, surely the density will be the same as the density on earth? h2o is h2o init?
h2o is h2o however it will never be pure if frozen in an atmosphere because there are always bubbles of atmospheric gasses trapped in it - it's these that cause much of the colour of ice. From what I remember the amount of gas trapped in ice is a factor of formation speed, temperature, pressure and doubtless a few other factors not least gravity.
Right, but based on gases, we are effectively saying that that water can never be as dense as pure, controlled ice because it can only be contaminated with gasses, assuming those gases are less dense than ice (A safe assumption I feel).
It isn't the gas, per se, but the other chemicals that may affect the freezing temperature as well as the overall density. But the tone of the statement appeared to me that there would be complications from density fluctuations. The only complication would be if it was denser than terran ice.
I don't think that this can really be a factor assuming that the ice found is indeed, h2o based.
@symon - ok so you dissolve CO2 in water, what happens when you freeze the result? Not arguing that various water based diluted compounds can vary in density, but I am interested in the relative differences between density of most h2o based compounds when frozen.
As for the comet coment, (swidt), the problem wasn't about how dense water ice per se, but the underlying formation, compacted ice crystals, was it rock and ice etc. What we are talking about here on the surface of Mars (8mbar average for those that care), is really the comment that is density of the water a real consideration to how it will be utilised by our intrepid, yet thirsty, explorers?
I don't think so.
I mean it is a small point. Probably even too pedantic at this stage. But this is El Reg afterall...so if not here then where else?
"e. From what I remember the amount of gas trapped in ice is a factor of formation speed, temperature, pressure and doubtless a few other factors not least gravity."
Depends on when the ice formed. The atmospheric pressure on the Martian surface is very low now.(~0.06% Earth and mostly carbon dioxide)
Oh my, where to start. As you can see in the phase diagram, there are multiple forms of frozen ice, helpfully enumerated with Roman numbers from I to XV. But I guess for practical purposes, this type of density change is quite negligible if your water might be 90% of whatever they sell for sand up there on Mars.
Your phase diagram kind of proves the argument. We already know the temperature and pressure on Mars. It's not like we should anticipate some strange Martian form of Ice that bonds in a radically different way.
I refer you the recent incident of the probe and the comet in the night time. The designers of the probe not knowing the density of ice in said comet thought it would probably not be too dense. Probe bounced, measures to grab into the ice and hold it failed as they bounced off too. After ending up wedged less than optimally it used it's onboard stress hammer to test the hardness of the ice. It broke around the level of 'concrete'.
The ice mountains on Triton and Pluto will likely be very hard too.
"Getting hold of the ice is another matter"
A thermal ice drill should work nicely even at Mars atmospheric pressure provided you have enough power (solar or thermal nuclear) and a relatively small amount of water to start the process working. After that its a continuous process. Hot steam in, cool water vapour out which you then condense to get back more water.
@AC "Getting hold of the ice is another matter"
I would imagine at the poles there is not a huge amount of solar so I would imagine they would go and get blocks and thaw it where it was needed. It will be a while before we have pipelines up there and I'd think people will be nearer the equator.
It's not just drinking, washing, and breathing (breathing because they'll want to extract O2 from it). They will consume large amounts of water for making rocket fuel, because it's not practical to carry enough fuel for a return journey. They might also want it for shielding. Apparently it's better than regolith against radiation.
Worked so well for Bowie Base.
Note I always thought the infected humans skin texture, resembled a less green version without the carapaces & helmets of the first post. Suggesting the ice warriors might have been very different in their past.
...until you know whats in it.
I'm sure they didn't really mean the astronauts WOULD just grab a bucket but just in case...
Here on earth we've built up a tolerance to the bacteria we're exposed to regularly. Mars might potentially have had a whole ecosystem of complex microbial life at some point in it's distant past. Maybe even at a time when those glaciers were formed.
Go watch the TV series "Fortitude" or the rather good recent SCI-FI horror flick "Life" for a rather over the top view on messing with ancient bacteria.
(FWITW - Watch Fortitude anyway, cos it's awesome)
Back in the real world, I think it's highly unlikely (say the chances are a million to one) that any of the humblest things upon Mars, bacteria, minute, invisible bacteria, could have any affect on us. Directly the astronauts arrive and drink and feed, our microscopic enemies won't do anything. From that moment we are not doomed. Ulla!
FWIW, I think the science says that alien bacteria which have evolved in isolation from Earth organisms, probably pose little risk, a.k.a. zero.
"Pathogenesis requires intimacy, which is only attained through millions of years of co-evolution. The need for intimacy is apparent when you look at how bacteria and viruses cause infections and disease."
So it could be distinguished from zero with unavailable means :) Even infinitesimally small is an infinitesimally little bit bigger than 0.
He is making an assertion about all the microorganisms in the universe and assuming that they all behave in the same observable way as Earth microorganisms when he has no way of knowing that. He's saying that he knows all the unknowns, which he doesn't.
But thats taking Earth science and microorganisms and applying it to a different planet with different characteristics. The branches of evolution (if any) and pathogens may be totally different to what we have observed on Earth.
The article is taking huge leaps of logic about many unknowns, and also is contradictory -
"The chance that an alien bacteria would have evolved to stick to that protein is infinitesimally small." So not Zero as he claims after all.
Back in the real world, I think it's highly unlikely (say the chances are a million to one) that any of the humblest things upon Mars, bacteria, minute, invisible bacteria, could have any affect on us.
Ok....you first. Bottoms up!
Just because it's blue doesn't mean it's water and come to think of it, there's some nice lakes here on Earth that wouldn't want to approach much less drink it. I hope a probe will check out this "ice" before we make any plans or even think about using it.
The density of the ice will vary according to included/dissolved gases and solids but removing it just requires a heated blade. At 6 milliBar atmospheric pressure it will sublime direct to vapour. Since bacterial contamination is unlikely, you should just need to heat it up. Of course if you do that at 6 milliBar pressure yer gonna go straight to steam, but condensing it into liquid won't be difficult if you pressurise the steam, and separating out the gases and solids is child's play. Getting the energy to do all this when yer on Mars is the challenge. Gonna have to take a Nuke with ya as solar out there is weak and yer not likely to find much oil/coal. Efficient recycling will also reduce the need for vast amounts of water.
Did you actually read the article you linked to? No mention at all of shortening anyone's life, let alone by twice as much as previously thought.
All they've said is they think there is ... a two-fold or more increase in cancer risk compared to the conventional risk model for a Mars. Key word here being risk.
So that's an existing small risk that's been increased. Even two times small, is still small!
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