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56 votes
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If an astronaut threw a cup of coffee into space, would it freeze, or boil off into gas?

This was tested nearly sixty years ago. Using a very large cup filled with 95 tons of water. An empty second stage of a Saturn I under test was used. Only the first stage should be tested but with ...
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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 ...
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36 votes

Could there be any use with importing vacuum from space to Earth?

There are multiple problems with this idea. The first and most obvious problem is that the sealed container which has a perfect vacuum inside (seller claims so at least) is not of much use until you ...
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36 votes
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Was the ship decompression scene in the movie Aliens realistic?

I did a quick extrapolation from Organic Marble's data (1.5" diameter hole = lose 1500 lbs of air per hour from 14.7 psi; flowrate proportional to the square root of the pressure differential) and my ...
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31 votes

If an astronaut threw a cup of coffee into space, would it freeze, or boil off into gas?

It would not freeze into a block. It would quickly expand and boil, but not in a rolling boil. Without pressure, bubbles would form throughout the coffee and expand rapidly, causing it to spray out of ...
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27 votes
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How come we don’t put a huge windmill-like machine in space?

As far as I understand you want the "windmill" to drive a dynamo. Have you ever tried turning a dynamo? It takes some force to do so, and that force is then (partially) turned into electricity. So the ...
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24 votes

Was the ship decompression scene in the movie Aliens realistic?

As much as I love this movie, it's not very realistic. Here are some cabin leak numbers for the shuttle Orbiter. At an initial 14.7 psi cabin atmosphere, a 1.5 inch diameter round hole was projected ...
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23 votes
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How are vacuum optimized engines tested without disintegrating them?

Flow separation can occur in a rocket nozzle that is overexpanded. This can cause quite severe turbulence and thus buffeting of the rocket nozzle. The SSME used a special rocket nozzle shape to ...
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22 votes
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Could the void of space act as a good refrigerator for food in long journeys?

On planet earth, food spoils for several reasons: Oxidation Dehydration Microorganisms Oxidation is a reaction with the oxygen in the atmosphere. You can witness this when you cut an apple in half ...
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21 votes
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Is it real to patch an opening to the vacuum with plastic tarp and duct tape as in Martian?

The fix as show in the movie wouldn't work. To seal off the atmosphere in a more permanent manner, one would need to have something much stronger than Duct tape, or any tape. That wouldn't hold a seal....
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19 votes
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Would unpainted iron or steel rust in space?

"Rusting", or more chemically correct "oxidation", is a reaction with oxygen in the atmosphere. Iron reacts with oxygen and turns into iron oxide, the reddish-brown substance commonly referred to as "...
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  • 9,136
17 votes

Could there be any use with importing vacuum from space to Earth?

According to WP, at the upper end of Earth thermosphere -- that's LEO, somewhere above the orbit of ISS -- the pressure goes to around $1 \times 10^{-7}$ Pa. This level of vacuum is regularly ...
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16 votes
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What would happen if I throw a grenade in space?

Yes, it would explode. Most hand grenades are nowadays triggered chemically, electrically or contain a fuze enclosed within the assembly, so they don't require atmospheric oxygen to ignite, are ...
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16 votes
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How do the roll-rings at the ISS work?

The ISS Utility Transfer Assemblies (UTAs) are located in the center of the Solar Alpha Rotary Joints (SARJs) - the continuously rotating interface between the outer truss segments that support the ...
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14 votes
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Is it possible to bring "nothing" back from space?

Space is not quite as empty as you might think, and your average jam jar is easily strong enough to hold atmospheric pressure against an internal vacuum. More to the point, there wouldn't be any need ...
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14 votes
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What is the ring at the bottom of the Merlin vacuum engine?

The nozzle of the Merlin Vacuum is very large, to help get better expansion ratios since it only ever fires in a vacuum, unlike the 9 sea level optimized Merlins that have smaller nozzles. This is ...
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12 votes

Do electronics and mechanical components work in a vacuum or require a sealed controlled atmosphere?

Generally speaking, all "air-tight" containers leak to some small degree. On Earth this manifests itself as an inability to maintain a vacuum indefinitely; in space, it manifests itself as an ...
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12 votes

How come we don’t put a huge windmill-like machine in space?

Consider the windmill as a system. If there is no wind blowing on the windmill, there is no energy being input into the system. If you pull power out of the windmill, energy is being output from the ...
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12 votes
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Would a spaceplane be able to softly land on an airless planet?

Yes But... This only works if your craft can generate enough thrust to reduce orbital velocity to zero quickly enough that acceleration due to gravity does not produce a crash landing, since you are ...
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12 votes
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Does the Merlin vacuum engine on SpaceX's Falcon 9 gimbal?

According to the Falcon Payload User's Guide posted on the SpaceX website, the 2nd stage engine gimbals. (Emphasis mine)
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11 votes

Could the void of space act as a good refrigerator for food in long journeys?

The effect of the void of space is not so much cold, rather it is an insulator. Though heat radiates away, there is no convection nor conduction. Many spacecraft take precautions not to overheat in ...
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11 votes
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What does the exhaust plume of a rocket look like in vacuum?

Sorry, no bulb-shaped exhaust plume, at least not in true vacuum. But you might see something similar to an incandescent light bulb shaped exhaust plume at high altitudes that first stages reach, up ...
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11 votes

How are vacuum optimized engines tested without disintegrating them?

There are several test stands with altitude capability of up to 100 K ft (30.5 km or 8 Torr) for engine firings using the steam ejector system and up to 250 K ft (76 km) non-firing capability with ...
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10 votes
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What are the considerations for smelting iron and aluminum in space?

Iron is generally used for steel and I will address iron in the question as referring to steel. You need a phenomenal amount of electricity to smelt aluminum in the most commonly used method here on ...
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10 votes

In the absolute vacuum of Space, will an electric dynamo still work?

Unless the lubrication system fails in the dynamo that is in vacuum, electrical generation will work. Magnetic fields are unaffected by air or the lack of, at least at the level under consideration. ...
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10 votes
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Are galvanised steel parts safe to use in space?

It's not just zinc. Pure tin coatings and cadmium coatings are also prohibited, at least in the vicinity of electronics. See the Prohibited Materials Section of the NASA Parts Selection List (NPSL). ...
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9 votes

What are the considerations for smelting iron and aluminum in space?

Current iron and aluminium processes rely on gravity: Impurities (which are lighter than the metal being processed) are skimmed off the top of the molten metal. Molten metal can be relied on to stay ...
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  • 121k
9 votes

near space vacuum balloon

But would it be possible to create one that floated near space with almost no air pressure? Possibly, depending on what material(s) you use to make the balloon. If so how much could it lift? what ...
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9 votes
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Mars Vacuum-blimp Feasability

For the sake of this answer I'm going to use the numbers I get from NASA and Wolfram Alpha. These are: ...
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9 votes
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Why were some early interplanetary probes pressurized?

This was done to simplify thermal management. In a pressurized container, you can use air cooling. In a vacuum, you have to use heat pipes or liquid cooling to transfer heat to a radiator. This also ...
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