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We can breathe pure oxygen for unlimited time if the pressure is not too high; about 0.4 bar is okay. Breathing pure oxygen at 1 bar is possible for some hours, but a longer time may damage the lungs.
A mix of oxygen and helium is also breathable and is used for deep diving. Xenon cannot be used due to its narcotic effect on the body. Argon is less ...
133
I believe the discovery was made by orbiting satellite, but I'm not sure which one.
That is not the case.
Look at the author affiliation for the article to which you linked. The three authors of that paper were from the British Antarctic Survey. These scientists were part of a larger expedition to Antarctica. They pointed a cheap instrument (extremely cheap ...
119
(*) Jupiter, for all intents and purposes, doesn't have a solid surface to stand on. Not any more than you could say that Earth's atmosphere has it, before you hit Terra Firma. It's an enormous ball composed of mostly Hydrogen and Helium, but also other heavier elements in smaller parts, and it's so massive that its own gravity compresses these gases into ...
74
Am I not considering something?
Yes. You are not considering Mir, Soyuz, and the Space Shuttle.
The International Space Station is a multinational program, jointly led by the US and Russia. While the US and Russia had to compromise on many design decisions, the makeup of the breathing atmosphere was not one of them. The decision to pressurize the ISS to ...
64
Although the temperature at altitude can be several thousands of degrees, the atmosphere is so thin it does not transfer heat efficiently. Wikipedia explains it very well -
The highly diluted gas in this layer can reach 2,500 °C (4,530 °F) during the day. Even though the temperature is so high, one would not feel warm in the thermosphere, because it is ...
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I've done a lot of work on this subject with researchers and engineers at JPL, NASA Langley, and NASA Ames. There are some interesting things that come out of high-fidelity CFM (Computational Fluid Mechanics) modeling of entries or re-entries, and also from flight experience. This FAA tutorial segment is a good general reference for the principles involved.
...
53
“Bouncing off the atmosphere” is a misleading turn of phrase.
When returning to the Earth from the Moon, a spacecraft is on an elliptical orbit with the high end somewhere around the moon’s altitude and the low end just grazing the top of Earth’s atmosphere. The concern around a too-shallow reentry angle is that it won’t slow the spacecraft enough for a ...
44
Not much research has been done on this question in recent years, but some researchers are worried enough to research into wooden satellites.
The question on the environmental impact of deorbiting satellites burning up in the upper atmosphere was partly addressed in a 1994 report (warning: not peer reviewed) by the Environmental Management of the Space & ...
40
TFB's answer is correct that both Vikings made barometric measurements (and it is what the question asked for!), but it's worth noting that the atmosphere had been measured before surface instruments were available, and seems to have got pretty close to the current value.
In 1965, Mariner 4 carried out radio-occultation experiments, where the probe's signal ...
37
It can keep an atmosphere, and in fact does. The atmosphere is something akin to a high grade Earth-based vacuum. But that's probably not what you are looking for.
Okay, so what would happen with, say, an Earth sized atmosphere on the Moon? A lot of really interesting things would happen actually. First of all, in longest days of the night, the atmosphere ...
33
The mass of Earth's atmosphere is 5E+18 kg and the Troposphere alone has 3/4's of that. With an average height of 13 km that makes its volume $4 \pi r^2 h$ or about 6.6E+18 m^3.
If we break up one thousand 100 kg satellites into semi-porous PM2.5 particles that works out to be 1.5E-08 micrograms per cubic meter, and we generally worry about tens of ...
32
It's not the temperature that matters, it's the heat transfer.
The density of the atmosphere up in the thermosphere is very very thin. There simply isn't nearly enough mass to transfer any significant amount of heat from the thermosphere to a spacecraft travelling through it.
Spacecraft do need heat protection to survive re-entry, but that is because they'...
31
Rockets are much faster than airplanes for most of their flight.
Here's a graph of a Space Shuttle launch:
The red line is speed. It's in ft/s, 1000 ft/s is 1097 km/h. So At about 45 seconds, the Shuttle flies 1000 km/h which is faster than an airliner.
At about 1:40 it crosses 3000 ft/s which is about Mach 3 (the speed of the fastest aircraft). ...
30
The short answer is no -- an internal combustion engine needs to pull oxygen from the air to operate, and no solid bodies in the solar system have that kind of atmosphere.
Venus' atmosphere is mostly carbon dioxide with a small amount of nitrogen; neither of those is combustible.
Mars, similarly, has a mostly inert atmosphere; there's a trace of oxygen ...
27
Buoyancy is a big problem. To stay aloft, the average density of the balloon envelope, lifting gas and gondola must be <= the density of the surrounding atmosphere.
The pressure inside a balloon must be equal to or slightly greater than the surrounding atmosphere, otherwise the balloon will collapse. If you look at the ideal gas law you'll see that see ...
27
The Chelyabinsk meteor was travelling at over 65,000 km/h when it hit the brunt of the atmosphere 23 km high in the air. This is 60 times the speed on sound! NASA estimates that the meteor's mass at this point was 10,000 tonnes, and it had a diameter of 20 meters.
At these incredible speeds, the body is placed under immense stress. Colossal pressure is ...
26
I think it's fairly safe to assume that Mars has plenty of nitrogen locked in its mineral deposits, since it's one of the most abundant elements of the Solar system and the planet formed out of the same protoplanetary disk as Earth has. Some nitrogen rich minerals are a safe bet, especially the ones of magmatic origins that might be easily accessible in top ...
26
Rory mentions oxygenation rate which is an excellent point but there's additional reasons why not keep ISS atmosphere at a lower pressure - thermal convection and air cycling. Pressure at roughly one atmosphere means that the ventilation system on the station works better and no pockets of carbon dioxide or even carbon monoxide build up, which would be ...
26
In order for a combustion process to happen, you do not only need fuel, you also need an oxidizer. On Earth, that is usually the oxygen in the air. In Titan's atmosphere, there is no oxygen. This applies to other atmospheres too, like the hydrogen dominated atmospheres of Jupiter and Saturn. Hydrogen, just like the methane in Titan's atmosphere, is flammable ...
answered Mar 6 '16 at 21:53
SE - stop firing the good guys
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26
No, unless your structure is located directly on the equator and your satellite follows a perfectly circular orbit, atmospheric "orbits" aren't possible, even in a vacuum tunnel.
Because the Earth is on an axis of ~23 degrees and rotates every day, it is not possible to create an orbit which has no ground track precession except for equatorial ...
25
Short answer: Yes. Mars is not windy enough to properly wave most flags.
Long answer: In storm conditions, a flag constructed out of a very light material would be able to properly wave.
If we take a standard flag, say 3'x5' that's made of 200g Nylon
$\ell= 1.5$ meters
$h_f = 0.9$ meters
$W = A * 0.2 * g_{Mars}$, $W = 1$ Newton
Going off the calculations ...
23
Based on saturation diving operations, it looks like the limits are as follows:
Compressed air: Nitrogen narcosis limits you to around four times Earth's atmospheric pressure.
Any gas mix: Hydreliox was used for the current depth record; insomnia and fatigue issues appear to limit you to around 65 times Earth's pressure regardless of gas mix.
Neither Titan ...
23
Yes, a capsule cannot literally bounce off the atmosphere and its kinetic energy must be reduced by an encounter with the atmosphere, rather it would just pass through the atmosphere and back into space, having failed to lose enough velocity to stay in the atmosphere. After going partially around the planet it will reenter the atmosphere, that is actually ...
23
Intravehicular spacesuits are worn inside the cabin in case of emergencies, particularly during ascent and descent. The Mercury suits were manufactured by Goodrich. Nearly all other IV suits have been manufactured by the David Clark Company: Gemini, Apollo 1, Shuttle ejection seat suit, Shuttle LES, and Shuttle ACES (all an evolution of the Gemini design).
...
22
I would argue that no specific level of molecular or atomic oxygen in atmosphere is indicative of carbon-based life (i.e. life as we know it on Earth). A planet could have oxygen rich atmosphere which could be due to naturally occurring thermo-chemical reactions (e.g. Sabatier/Bosch reaction), loss of hydrogen in water vapor through atmospheric escape and ...
22
Nearly all balloons that have been constructed have been for flights from the surface to altitude. That requires a structure that can survive tethered at the surface in a range of wind speeds in high-density air, then expand to several times their original size in order to maintain lift as the air density decreases. The minimum density ends up being ...
22
The mass of Titan is 1,345 · 1023 kg, but the mass of the Moon is 7,349 · 1022 kg. The gravity at the surface is 1,35 m/s² for Titan and 1,62 m/s² for the the Moon.
But the surface temperatures are very different, 94 K for Titan but the mean surface temperature of the Moon is 218 K and the peak about 300 K.
Due to the high surface temperature of the Moon,...
22
This is being done with biosphere 2 and several similar projects and found to be very complicated. Specifically in a small sealed system there is little buffering or inertia available if one element is over or under producing or just having a seasonal change so die offs are hard to avoid.
For this reason the plants on the ISS and proposed future projects ...
21
Yes, humans definitely have been to outer space.
The easiest proof I can think of immediately is this video of commander Chris Hadfield demonstrating wringing of a wet towel on the ISS.
Or this one — it contains more than 200 seconds long uncut shot of a̶b̶s̶e̶n̶t̶ micro-gravity. It also shows vast interiors of the ISS, which are technically challenging to ...
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