85 votes

Why are we trying to build a base on Mars before the Moon?

At the moment, there are a few groups trying to reach Mars, and a few groups who are trying to reach the Moon. Mars One has grabbed headlines lately, SpaceX states Mars colonization as its long term ...
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  • 20.8k
66 votes
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Why can't we use the same radiation shielding in Mars that we used when going to the moon?

Radiation exposure is a cumulative risk. The more radiation you receive, the more likely you are to develop cancers. The Apollo missions took no more than two weeks to complete; the astronauts ...
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66 votes

Why can't we use the same radiation shielding in Mars that we used when going to the moon?

In addition to what Russell Borogove says about cumulative risk you're operating under a false assumption--that there was shielding on the Apollo capsules. Not only did the Apollo capsules not have ...
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54 votes
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Could a space colony 1g from the sun work?

Interesting but no, it wouldn't work for the same reason that astronauts in the International Space Station, other space stations, or orbiting shuttles or capsules do not "feel" gravity with respect ...
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  • 148k
47 votes
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When will we send floating probes to Venus?

When will we send? We already did. In 1985 and 1986 the Soviet Union sent two Vega probes to Venus. Both included a robotic balloon (usually called aerobots). The two balloon aerobots were ...
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  • 920
36 votes

Flung debris in lunar landing

Great question. The exhaust velocity from typical landing engines is about 3 km/s. You can imagine good-sized particles being accelerated to a significant fraction of that, say 1 km/s, which is the ...
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  • 57.5k
35 votes

What are the advantages of building a human colony on Mars vs the moon?

There are three big advantages to Mars over the Moon for a longer term settlement. There is a thin atmosphere. The days are approximately 24 hours The gravity is about twice as high. Let's break ...
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  • 118k
34 votes

When will we send floating probes to Venus?

Why are people so fascinated about Mars and not about Venus at all? The trivial answer - Mars is moderate place. A human could easily get around with a spacesuit, and it is trivial for robots and ...
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  • 1,584
30 votes
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How far can you fall on the Moon without injury?

The simplest would be defining some arbitrary impact velocity that is at the limit of being fatal, and we then consider everything else (surface properties, subject's physique,...) except ...
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  • 75.3k
28 votes

Could liquid airlocks work?

The diagram you show would work only for specific instances. A few things that it relies on: Gravity is required for this to work, or else all of the liquid will escape. The diagram you show works ...
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  • 118k
26 votes
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Would colonising Antarctica be a good test for colonising Mars?

There are a number of problems with this idea. The top two I can see are: The Antarctic is an incredibly difficult place to work and live. While that might sound like an excellent test for Mars ...
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  • 13.4k
24 votes

If colonists burrowed far enough under the ice on Ganymede or Europa, would the ice provide adequate protection for them from Jupiter's radiation?

Yes, it absolutely would! The radiation on Europa is about 5.4 Sv (540 rem) of radiation per day. Looking at this guide, and assuming you want to meet OSHA standards of 5 rem per year, you would need ...
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  • 118k
23 votes
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Mars versus the poles of Mercury WRT colonization

Your delta-v analysis doesn't account for the landing delta-v. On Mars, only a fraction of a km/s has to be done propulsively, on Mercury the entire landing will be propulsive. You also don't account ...
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22 votes
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Is it possible to grow plants on Mars?

Some of the rocks on Mars aren't too bad for growth of plants or bacteria. They contain a considerable amount of clay minerals (about 20%), and several other minerals which are considered as essential ...
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  • 996
22 votes

Could you fly on the Moon, in Earth's atmospheric pressure, by flapping wearable wings?

The lift force you would need to produce would have to be equal (stable flight) or greater (take off) than the force pulling you back towards the moon. If your mass is average for a male at 62kg, the ...
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  • 4,361
18 votes
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Would a Moon resident age differently than someone living on Earth?

The time dilation of the Moon relative to Earth is dominated by not being as deep in the gravitational field of Earth. Not so much the velocity of the Moon. Though the velocity effect isn't ...
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  • 57.5k
18 votes
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If we got to Mars right now and landed at the poles (where there is a lot of water ice) how long would we be able to stay there?

There's really no limiting factor on how long we could stay there if we brought enough supplies with us and we had regular resupplies. Humans really only need food, water, and oxygen to survive. Via ...
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  • 1,319
17 votes
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Do you need a mattress on the Moon?

Probably not. A good measure of comfort is how much external body pressure is induced from laying on a hard surface. Earth gravity is enough to cause an adult considerable discomfort when lying on a ...
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  • 1,308
17 votes

How far can you fall on the Moon without injury?

Going away from the scientific answers, and more towards the psychological answers, I'd like to approach how one makes a mistake bad enough to break a bone. The first step involves getting enough ...
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  • 1,814
16 votes

Would colonising Antarctica be a good test for colonising Mars?

When I think of (non-political) challenges when settling the Antarctic, two things come to my mind: Long winter nights Snow Any self-sustained facility will probably be solar powered1. The long ...
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16 votes
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Could ozone be used in a biodome on Mars?

If we have $O_2$ lighted with UV, we have actually many reactions working together: $O_2 + \gamma \rightarrow 2O$ $O_2 + O \rightarrow O_3$ $O_3 + \gamma \rightarrow O_2 + O$ $O + O_3 \rightarrow 2 ...
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  • 3,234
16 votes
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How many plants would be needed to produce oxygen enough for 20 humans?

This article addresses much the same question. The quick summary is about 300 to 500 typical domestic houseplants per person, with significant caveats, more like 700 to be safe. So 6-14 thousand such ...
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  • 18.9k
16 votes

Could a space colony 1g from the sun work?

Have the object tidally locked into its orbit around the sun This way we would get the 1g gravity from the sun on the opposite side of the asteroid Interesting idea, but you missed something in your ...
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16 votes

Is there dirt or its structural equivalent on Mars?

The fine regolith on Mars is regarded as being the closest equivalent to an Earth like soil. It contains sand and dust. Clay deposits have been found. The two could be mixed to produce a more graded ...
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  • 10.6k
15 votes

When will we send floating probes to Venus?

No, there is no space race to Mars. The original space race was to orbit, for entirely military reasons. Sputnik was simply a demonstration of "we can drop a nuke anywhere we want, any time". The ...
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  • 1,728
14 votes
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How efficient would it be for an outpost to use human-powered vehicles?

Human powered vehicles used within domed or cavern cities would seem to be extremely plausible. One way to look at it is a simple bicycle is less complex than a powered vehicle. The power source (aka ...
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  • 4,133
14 votes

Flung debris in lunar landing

Damage to existing equipment from exhaust plumes is indeed an issue for lunar outpost planning. The best information currently available about this is from the Apollo 12 mission that landed close (...
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  • 141
14 votes
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How deep a valley or trench would be needed on Mars to provide the same atmospheric pressure as 6 km above sea level on Earth?

Mars' atmosphere scale height is, depending on who you ask, 10.8 to 11.1 km. Pressure at the bottom of Hellas Planitia: 1.16 kPa Earth sea level: 101.3 kPa Earth 6km altitude: ~50 kPa. So we need ...
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