89 votes

What led NASA et al. to decide the ISS should be a zero-g station when the massive negative health and quality of life impacts of zero-g were known?

Reliability. Any rotating station needs non-rotating components: solar panels need to face the Sun, radiators need to be shadowed, docking points need to be non-moving, and so on. Making a rotating ...
  • 11.8k
70 votes

Why Mars instead of a space station?

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 ...
  • 119k
54 votes

Why does there appear to be a 180-degree stereo microphone array outside the ISS?

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 ...
54 votes

What led NASA et al. to decide the ISS should be a zero-g station when the massive negative health and quality of life impacts of zero-g were known?

I'll add one or two more items to Mark's excellent list. Stability - large rotating platforms (and they have to be large to produce useful artificial gravity) are subject to all sorts of precession. ...
45 votes

Why Mars instead of a space station?

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 ...
  • 15.1k
41 votes

What led NASA et al. to decide the ISS should be a zero-g station when the massive negative health and quality of life impacts of zero-g were known?

It's a good question, followed by many relevant responses so far. I'll focus on the physiology aspects. Research had been conducted for decades prior to ISS launch on creating artificial gravity ...
37 votes

Is a midspace space station between Earth and Mars practical?

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 ...
  • 122k
37 votes
Accepted

What happens to astronaut sweat on the ISS?

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 ...
  • 16.9k
32 votes
Accepted

Why was Skylab allowed to fall, instead of being pushed into a higher orbit and preserved for the future?

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 ...
  • 7,116
31 votes

What led NASA et al. to decide the ISS should be a zero-g station when the massive negative health and quality of life impacts of zero-g were known?

There was a proposal to add an experimental rotating habitat: Nautilus-X. One of those wonderfully tortured backronyms: Non-Atmospheric Universal Transport Intended for Lengthy United States ...
  • 7,906
29 votes
Accepted

Why did Salyut 7 freeze over, while ISS requires massive cooling system?

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 ...
  • 13.5k
29 votes
Accepted

How best to maneuver inside a large room within a space station using only arm and leg motion?

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 ...
28 votes
Accepted

Astronauts make a lot of CH₄ and some H₂ as well; do space capsules and space stations have systems to remove these?

For the ISS, the relevant bit of kit would be the Trace Contaminant Control System, which is part of the Air Revitalisation System. A Trace Contaminant Control System ensures that over 200 various ...
27 votes

Why Mars instead of a space station?

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 ...
26 votes
Accepted

When Mir's attitude control computer failed, why did the station immediately start rotating?

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 ...
  • 119k
25 votes

How best to maneuver inside a large room within a space station using only arm and leg motion?

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 ...
24 votes

Why was the ISS so much more expensive than Mir?

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 ...
  • 11.4k
24 votes

Does the speed of ISS slow down at the time of a spacewalk or does it become stationary?

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 ...
  • 6,830
23 votes

Is there no physical security in space, other than being in space?

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 ...
23 votes

Why does the material for space elevators have to be really strong?

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 ...
  • 331
23 votes

What can the ISS do that a SpaceX Starship could not?

ISS has a lot of truss constructions to attach equipment, such as power plants or scientific apparatuses. Starship would need these as well. ISS has many docks for visiting spacecrafts. Starship, ...
  • 3,067
22 votes

Do 3D printers in space stations mean a significant cost reduction?

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 ...
21 votes
Accepted

Why is Bigelow BA330 expandable instead of fitting fairings?

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 ...
21 votes

Are there any photo(s) of International Space Station (ISS) captured from above its altitude?

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 ...
20 votes

Has a spacecraft ever docked with the same space station twice in one mission?

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 ...
  • 52.9k
20 votes

Just how much rope have different crewed missions been given?

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 ...
20 votes
Accepted

Have space station occupants always had a return vehicle ready?

Yes, all human occupied space stations to date have had a return vehicle for every crew member. To my knowledge (and general consensus), that includes Skylab, Salyut, Mir, Almaz and China's Tiangong. ...
  • 76.9k
19 votes

Do 3D printers in space stations mean a significant cost reduction?

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 ...
  • 119k
19 votes
Accepted

Cyanobacteria as Life Support?

Why this wouldn't work? It works for the Earth; the reason why it is not implemented in space is purely in the engineering limitations. Cyanobacteria live in water, humans live in air. Gravity is ...
  • 1,692
18 votes
Accepted

Scott Kelly age vs Twin's

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 ...

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