71

The biggest advantage of Mars is there are resources available on that planet. Run out of oxygen? Make your own! Same with water. Set up refining, and you can make your own metal. Large windows are more difficult in no atmosphere than Mars's thin atmosphere, which makes growing crops easier, at least according to The Case for Mars. I believe this is because ...


54

That is a UHF antenna. It was well placed on the Lab to get in the way of robotics ops during space station assembly. This is a picture of a different UHF antenna unit (this one is on the P1 truss segment) but it's clearly the same device. Fortunately this is from a credible source, NASA's ISS Flight Systems brochure (warning, pdf). I can't quite figure ...


49

The methane is produced as a by-product of the Sabatier Reaction, where Carbon Dioxide is removed from the air using a catalyst and hydrogen. The other waste product is water, which can then be split into Hydrogen and Oxygen. So basically, the amount of methane is directly related to the amount of Carbon Dioxide the astronauts breathe out. As @KeithS ...


45

The big problem is that space is empty. To build the space station, people need to haul every single gram there. Every single atom on a space station needs to be shipped there at cost--whether it's from an asteroid, planet, or elsewhere. On Mars you have the ability to use local resources. You can easily dig and build using the resources at hand without ...


41

First, I have to mention I haven't seen the movie yet. I've resisted temptation after seeing so many technical inaccuracies mentioned on Twitter by the International Space Station (ISS) astronauts that I follow. No, not the astrophysicist Neil DeGrasse Tyson, even though he was mentioned most frequently in the mass media for taking it a personal quest of his ...


37

You're right: this has issues. You can insert a station into a circular orbit halfway between Earth and Mars, but because this has an orbital period also in between those of Earth and Mars, your station won't be in a usable position most of the time. So you'd have to fill the orbit with several station to always have one reasonably close. The fuel is also ...


37

They keep the ISS at a pretty comfortable temperature and humidity level, so there's not much sweat accumulation except when they're working out. For that, they use towels. The sweat that they do produce that evaporates (along with the water vapor they exhale) gets collected as part of the water processing system and recycled into drinkable water.


32

Short answer is that there were multiple contributors: bad predictions of how long the orbit would last, schedule delays on the Space Shuttle, and cost/benefit analysis of a last minute rescue mission for an aged space station. Things to keep in mind: Skylab reentered and burned up in July 1979 the last Apollo capsule to fly was the Apollo-Soyuz Test ...


29

Salyut 7 had a active cooling system as well. The heat exchangers are the large white panels, perpendicular to the solar panels, to be seen in photographs of the station. This is necessary on all space stations in active mode as the energy produced by solar panels (apparently 4.5 kW in case of Salyut 7, an order of magnitude more in case of the ISS) needs to ...


29

It turns out that yes, there are things you can do, but they depend on things other than the astronaut's body, and they will take a long time. Physics tells us that an object's translational momentum is constant unless acted upon by an external force. If the astronaut's net momentum with respect to the room is zero, there is nothing they can do to start ...


28

Caves Any large body where you can survive on the surface to begin with can be used for caves, artificial or natural. This observation isn't off-topic because you ask about holding in atmospheric pressure. Moon caves can hold 1 atmosphere of pressure about 60 meters below the surface with no stresses on the surrounding rock. I'm using very simple math ...


27

Radiation I think this is actually the biggest concern, IMO. Astronauts aboard the ISS have a measurably increased risk of cancer due to their higher radiation exposure. Putting enough shielding on a space hab to reduce risk to earth surface levels would be unimaginably expensive. On the other hand, Mars has gigatons of surface rock which makes a pretty ...


26

We know from the nuclear power industry that spent fuel storage pools are pretty safe places to be around, radiation-wise. They're actually safe to swim in, to a point, because they're serviced routinely by human divers. They just can't get too close to the spent fuel. We use these pools for short-term storage because water is a really good radiation shield....


26

Most such spacecraft, including Skylab and the ISS, have their attitude maintained by reaction wheels. These wheel essentially convert the rotational energy of the entire spacecraft into a smaller reaction wheel. If the attitude failed while these wheels were spun up, then they would eventually slow down (In a timeframe of minutes). As the wheels slowed down,...


25

Fortunately, it turns out humans come with a nitrogen/CO₂ thruster built in... Assuming the room is filled with air, I reckon the best method is to use your breath. What you should do is, point your feet in the direction you want to go (there are quick standard techniques for this, like what cats do to land feet-down). Then breathe in deeply using your nose ...


24

The comparison rests on two pieces of evidence: Yuri Koptev's statement (possibly based on reference budget material collected by the officials of RKA and its Soviet predecessors) placing the price tag at 4.2 billion US dollars Claude LaFleur's estimates (also here). I'm going to make a glorified "Apples and Oranges" argument here. Basically, there are ...


23

Supplemental to the other answers; you are correct that the net force on the tether would be minimal, since the rotation of the counterweight would counteract the force of gravity. But, the individual components of this net force aren't being distributed evenly. Consider, say, the first kilometer of tether from the ground. This is being pulled down by ...


23

Let's look at Newton's first law: Law I: Every body persists in its state of being at rest or of moving uniformly straight forward, except insofar as it is compelled to change its state by force impressed. In modern mathematical speech, this can be stated more precise. In an inertial frame of reference, an object either remains at rest or continues to ...


22

The methane is produced as a by-product of the Sabatier reaction, where carbon dioxide is removed from the air using a catalyst and hydrogen. CO2 + 4H2 → CH4 + 2H2O The molar mass of Methane is 16.0425 (grams per mole) and the molar mass of carbon dioxide is 44.0095 (grams per mole). That means that the 1000 pounds of methane came from about 2700 ...


22

Locks aren't needed, because it is physically impossible to open the hatch from outside unless the airlock is depressurized. All airlock hatches are inward opening (the STS Orbiter side hatch was not an airlock hatch) and the air pressure inside amounts to tons of force keeping the hatch closed. For example, check out this picture of the ISS US airlock. ...


22

A 3D printer on station isn't likely to lead to direct cost savings; the range of items it can replace are limited, and it has to be supplied with feedstock mass in any case; it won't allow for significantly fewer supply launches. The primary benefit is that it can allow for the repair of a system the astronauts would otherwise have to do without until the ...


21

That 5.0 meters is the outer diameter of the payload fairing. Payloads obviously cannot be that large. In fact, they are constrained to be a bit smaller. The figures below depicts the Delta IV Heavy and Atlas V static volume (volume that a payload can occupy). http://www-eng.lbl.gov/~lafever/SNAP/OldFiles/DELTA%20PAYLOAD%20OVERVIEW_files/d4hfairings.gif ...


21

Yes. Most craft, when docking with the ISS do a fly-around to survey the docking site. They can then frequently capture images of the ISS from the top view. Here is one from the Shuttle Atlantis taken during fly around: Source: https://www.esa.int/ESA_Multimedia/Images/2008/03/International_Space_Station_seen_from_Space_Shuttle_Atlantis3 courtesy of ESA.


20

Electromagnetism To be as practical as possible, the Space Shuttle mission STS-75 experimented with a space tether. For the record, the tether did break. To be fairly exact, it did break for reasons that wouldn't have broken it if the line had been shorter. So in a certain sense (but only a limited sense), we have already seen a space tether break because ...


20

This video may help to answer your question. Starting at about 00:24, you can see an astronaut running around the "exercise wheel" of Skylab (an early NASA space station program, which followed the Apollo moon landings). Basically after some time, NASA told the astronauts to stop running around like this because it was causing more propellants to be used to ...


20

The first, experimental redocking was performed on Soyuz 29 (though by crew of Soyuz 31) with the Salyut 6 station. Afterwards, the maneuver was repeated several times, usually between different ports of a station, moving a docked craft from one port to another, in order to make room for a new arrival, although other purposes happened too - e.g. visual ...


20

Each shuttle mission had significant amounts of rope / cable / cordage aboard. tl;dr sky genies - 40 feet of rope per crewmember RMS rope reel - 80 feet of rope astrorope - 20 feet of rope per EVA crewmember (development item, not normally flown) EVA winch - 24 feet of rope EVA safety tether reel - 35 or 55 feet of cable, per EVA crewmember other ...


19

Not really. The pressure due to solar wind is approximately 1-6 nPa (See Wikipedia). The pressure due to just the light from the Sun at Earth is actually higher, at around 9 nPa (Source). The mass makes somewhat of a difference, but let's just assume somehow you can get a mass of a 1 square meter windmill at 1 gram. The effective power would be very small, ...


18

Neil DeGrasse Tyson says that Scott Kelly is now 1/100 second younger than he would have been otherwise, which almost certainly isn't enough to alter the birth order of the two; I don't know which of the two was born first.


18

The 3-D printer on the ISS is more for testing purposes than anything. The idea is that for really long duration missions, a 3-D printer will allow them to make something in case something breaks, or they realize they need something that didn't come initially with the ship. So far I can only find a few things that have been made, including a ratchet, several ...


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