# Tag Info

85

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 goal, and there are numerous smaller groups. For the Moon, there is the Google Lunar X prize, Shackleton Energy Corp, and OpenLuna, and again numerous other ...

65

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 flying those missions accepted that dose of radiation with the health risks that come with it. A manned Mars mission will take, at minimum, months of travel. For ...

65

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 shielding but shielding was considered undesirable. There are two main radiation threats in space: cosmic rays and solar flares. Their "defense" against solar ...

54

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 to their station or capsule. When you are inside an object which is in orbit, you are in orbit too! The Earth pulls on the station with nearly 1 g and it pulls ...

44

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 designed to float at 54 km from the surface, in the most active layer of the Venusian cloud system. The instrument pack had enough battery power for sixty hours of ...

36

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 muzzle velocity of a rifle. There is nothing in the vacuum to slow them down, other than eventually hitting something, or the ground. 1 km/s is already a good ...

35

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 these down one at a time. Atmosphere The thin atmosphere allows aerobraking, and can be useful in the production of oxygen. Electricity + Martian atmosphere ...

33

Part of this is also discussed in the How can Mars have dust storms with such a thin atmosphere? thread, but yes it would be abrasive, and direct evidence for this can be appreciated in all kinds of aeolian formations on the Martian surface, like the dunes of the Nili Patera region or the ones in the Lyot Crater, just to name a few of the most well know ...

32

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 equipment to exist on Mars. Venus is a swirling hell. The "atmosphere" is a sea of incredibly hot, ultra-boiling, 800+ F° sulfuric acid (!!!) (Indeed, Venus is ...

30

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 gravitational acceleration constant. We can also neglect air resistance to make it simpler, since we're more interested in a safe height to jump off on the Moon, than that ...

26

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 colonisation, most groups really do not want their test subjects to die because we couldn't get to them in an emergency. Deserts are actually much more forgiving in ...

26

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 because of pressure differential, basically the pressure due to gravity counteracts the pressure from the air. Without gravity, the air would simply push the ...

23

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 to only allow 1 part in 40,000 of the base radiation to make it through. The website linked indicates you want a mass of about 375 pounds/square foot to only ...

22

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 and sufficient for bacteria to survive, at least. Probable chlorinated salts, e.g. perchlorates, which are likely and wide-spread in Martian soil, don't ...

22

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 force from the lunar gravity would be F=ma, = 62kg x 1.622m/s2 = 100N (almost exactly). lift force = 0.5 x density x lift coefficient x area x velocity^2 This ...

21

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 for transit time. BepiColombo launched in 2018 and won't be able to enter orbit until the end of 2025. MESSENGER similarly launched in 2004 and didn't enter ...

18

If long-range navigation is necessary, a combination of inertial navigation with occasional position fixes using stars gives reasonably accurate navigation. Inertial navigation has a few drawbacks: high cost and these systems become less accurate over time (hence the need for occasional position fixes). For short-range navigation, dead reckoning may be ...

18

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 nuclear reactors, we have the technology and engineering to provide sufficient power to a base to provide heating and the power necessary to break ice into ...

17

The higher plants are less efficient, so the entity will probably be not a bush, but a jar of algae. 30-40 liters of Сhlorella suspension could provide for a gaseous exchange of a single person. Grishin Yu. I. "Artificial Space Ecosystems" Cosmonautics, Astronomy 7/1989

17

There are a few things that could be done (Using pretty heavily "A Case for Mars" second edition): There will not be full constellation of satellites, but undoubtedly there will be satellites orbiting Mars at that time that are functioning. Each Mars orbiter since Mars Global Surveyor has included some sort of a beacon which could be heard. Measuring ...

17

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 hard surface. Paresthesia, or the sensation of having arms and limbs falling asleep, would be a good standard to measure against to answer this question. The ...

17

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 energy to break the bone with a fall in the first place. The body should naturally do a reasonable job of balancing the muscle strength needed to do tasks against ...

17

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 negligible, being about two orders of magnitude down from the gravity effect. Time passes about 0.66 parts per billion faster on the Moon than on Earth, due to not ...

16

There have been several experiments with fish in space; as far as I can tell, all have used water rather than humid air as the habitat. While there is no definitive answer available as of 2013 (lack of empirical research), present research suggests fish cannot really live in space without water. It appears difficult to keep fish alive and healthy in a ...

16

The key material to produce to make plastics is the production of ethylene, which is $C_2H_4$. According to The Case for Mars, this can be produced by the reaction $2CO+4H_2 \rightarrow C_2H_4+2H_2O$, with the presence of an Iron catalyst.. And the carbon monoxide comes from $6H_2+2CO_2 \rightarrow 2H_2O+2CO+4H_2$. Thus, the key to making plastics on Mars is ...

16

Yes, they would be more stable, but there is a big issue as to where you'd want it to be. There's a paper on this very subject. The paper states that at specific rings around Mercury near the poles, that just below the surface the temperature is constant and near room temperature, making them quite ideal for colonization. Bottom line, it is entirely possible,...

16

I've done a fair deal of spelunking (caving) and one of the first things you realize when you've visited several caves is that their inner air temperature tends to be at roughly the yearly average of the outside temperatures. They might produce their own climatic system if they're deep enough or have any connection with the outside temperatures, like both ...

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This answer is outdated. The Dawn flyby in February 2015 added a lot of information which was not known at the writing of this answer. We don't actually know much about Ceres. All we know about it is from earth-based or earth-orbit-based observation. Until now it wasn't visited by a probe, but the Dawn spacecraft will do so in February 2015. This will ...

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