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[Mech#4]

In July 2003, at a conference in California, it was announced that the Gamma Ray Spectrometer (GRS) on board the Mars Odyssey had discovered huge amounts of water over vast areas of Mars. Mars has enough ice just beneath the surface to fill Lake Michigan twice.[34] In both hemispheres, from 55 degrees latitude to the poles, Mars has a high density of ice just under the surface; one kilogram of soil contains about 500 g of water ice. But, close to the equator, there is only 2 to 10% of water in the soil.[35][36] Scientists believe that much of this water is locked up in the chemical structure of minerals, such as clay and sulfates. Previous studies with infrared spectroscopes have provided evidence of small amounts of chemically or physically bound water.[37][38] The Viking landers detected low levels of chemically bound water in the Martian soil.

Actual water has been discovered quite a few times.

Can ice have a surface with no moisture?

If the surface pressure is low enough, water goes straight from ice to vapour, and disappears into the atmosphere.

Ah right right, thanks.

I remember a test I did in primary school where we got a red balloon and covered one half of it with dry ice to mimic the polar ice caps on Mars. Apparently the ice on Mars actually has a layer of dry ice covering it about 8 metres thick, wonder what that could be used for.

[10ebbor10]

Extreme Skiing. The friction of skiing/ or snowboarding over it makes part of it vaporize, producing awesomely large smoke clouds as you glide down the mountain.

[wierd]

Sadly, the unbreathable atmosphere, at considerably less than 1 bar pressure, means you have to wear a pressure suit to do the slalom run, and if you manage to screw it up and get a puncture in your suit, things get hairy really quickly.

Lifewatch claims that it would take them at least 5 months to get there to evacuate you to a proper earth hospital, but more realistic time tables project close to 2 years before help can arrive.

But if you are an AWESOME skier, then BOY-- Do we have some EXTREME slopes for you! During the martian solar minimum, the northern polar region gets cold enough to snow DRY ICE. That's right, the DRIEST, FLUFFIEST powder you have ever seen! Moreover, when you ski on it, it literally just vaporizes off the skis! Come and experience the rush of being suspended by gas pressure above the ice while skiing today!

(Tickets only cost about 20 million dollars one way. Lodging and accommodations extra.)

[Another]

I think it was 20 million dollars for a week trip to ISS. Trip to the Moon is probably double or triple that and even one way to Mars is, I think, at least 20 times that. The other way to look at that is Curiosity mission cost multiplied by a few decades to keep the person alive.

[Solifuge]

On the plus side, if extracting water from the soil samples is anything like it is extracting it from lunar soil, it's as easy as lugging a kitchen microwave into space with you, throwing some dirt in there, and capturing the vapor that boils off.

Which means synthesizing hydrogen fuel, breathable oxygen, and drinkable water from the soil of Telluric planets and moons is possible with technology we have today... hell, technology that is cheep enough that almost everyone has one, and which would be easy enough to scale up to industrial-level production. That is kind of ridiculously exciting.

[MetalSlimeHunt]

I think it was 20 million dollars for a week trip to ISS. Trip to the Moon is probably double or triple that and even one way to Mars is, I think, at least 20 times that. The other way to look at that is Curiosity mission cost multiplied by a few decades to keep the person alive.

No, most of the cost of space travel is escaping Earth's gravity well. Once you're passed that, significantly less fuel is needed to get wherever you are going (which is why, for example, the lunar lander was given fuel measured in seconds for their descent).

[Another]

The problem is that you have to lift all that "significantly less" fuel all the way from our gravity well first.

[MetalSlimeHunt]

The rocket problem is irrelevant to the fact that travel costs are much lower outside the gravity well, and do not increase expoentially.

[Another]

Surely not exponentially - merely linearly from a typical week worth supplies at LEO to a year in inner Solar system.

[Descan]

If you build a rocket in outer space, it's much easier to get just the astronauts out from inside the gravity well.

So we need to nom on some asteroids~

[10ebbor10]

Actually, the cost still increases exponentially, but the amount of delta v needed is quite low, and can further be reduced by fancy gravity tricks.

Additionally, if you're willing to wait, Ion engines are very efficient.

[wierd]

Unfortunately, the longer you spend in space outside earth's nice, sexy magnetosphere-- the more likely you are to go blind and sterile, and develop all sorts of nasty cancers as a result of high energy solar radiation exposure.

Putting sufficient shielding on an ion driven space vehicle intended for humans, to make the trip safe given the long mission time it would take to use an ion engine to get to Mars, would totally negate the savings in fuel costs. (and then some.)

Putting enough shielding on to be reasonably safe when using chemical rockets is already a serious budgetary and engineering hurdle that makes a manned mission to mars quite bothersome indeed.   Anything dense enough to effectively absorb the solar particles and hold onto them, is also dense enough that it weighs epic craptons, making the orbiting of a vehicle with sufficient amounts of such shielding, VERY VERY VERY expensive.

Some engineers and Mars enthusiasts have suggesting putting a very large electromagnet and a small fission power plant on board to substitute, or reduce the need for mechanical radiation shielding, but then that runs into issues and complications with nuclear non-proliferation treaties left over from the cold war. It's basically illegal to put a fission reactor into orbit. This also makes it troublesome if you want to make REAL use of an ion thruster type engine, as without a fission power supply to drive the ionic accelerator grate with, you have to use solar energy-- and solar energy density per cubic meter of collector surface drops with the inverse cube of distance from the sun.

All these fun things have conspired to make a VERY nasty pickle for mission planners, aerospace engineers, and material scientists, trying to work on a way to get people to mars safely, without them developing leukemia shortly after arrival.

[10ebbor10]

I heard plans that involved putting the water reserves outside the ship, in order to function as a defensive layer against radiation. It works pretty well for nuclear waste storage. Additionally , Nuclear RTG's are not forbidden, and can be used to power ion drives. Besides, nuclear reactors in space are slightly problematic due to cooling troubles.

On another note, I believe that NASA once calculated that in order to get a significant amount of people to Mars, with zero chance of irradiation, would involve constructing a ship as large as the Battlestar Galatica.

[Mech#4]

I heard plans that involved putting the water reserves outside the ship, in order to function as a defensive layer against radiation. It works pretty well for nuclear waste storage. Additionally , Nuclear RTG's are not forbidden, and can be used to power ion drives. Besides, nuclear reactors in space are slightly problematic due to cooling troubles.

On another note, I believe that NASA once calculated that in order to get a significant amount of people to Mars, with zero chance of irradiation, would involve constructing a ship as large as the Battlestar Galatica.

I remember reading that they were using ice to stop the radiation leakage at the fukushima plant in Japan, could they do something similar with a rocket ship? A layer of ice between the interior and outer hull. Could also help with cooling issues.

[MonkeyHead]

Whilst a good compomise between mass and absorbtion rate, its probably not all that useful for cooling issues, as ice rapidly will end up as steam if you are not careful, which will quite quickly end up a very high pressure, requiring a bulky containment mechanism or heat sinks in a device only really designed to contain up to one atmospheres worth of pressure. There is a reason why it is often overlooked for molten salt in the heat exchangers in nuclear reactors.