UIDAlexD
  • Member for 5 years, 6 months
  • Last seen more than 1 year ago
  • REDACTED, United States
Why does the Falcon 9 use RP-1/LOx and not LH2/LOx?
27 votes

To make a long story short, liquid hydrogen has a very low density of just 70 kg/m3. RP1, on the other hand, has a density very close to that of water - about 1000 kg/m3. This means that for the same ...

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Tiny emergency propulsive device if stuck floating in a large volume in microgravity
10 votes

For comparison's sake, SAFER is what 3m/s-dV of compressed gas looks like. I doubt you'd be able to hide that. Hand fans are your best bet, because unlike all your other options they don't carry ...

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Making propellants on Mars: Why not just LH2/LOX instead of methane?
9 votes

As briefly mentioned in the previous answer, H2 is very tricky to deal with. The temperature is one thing, but what he didn't mention was its extremely low density. If I recall correctly the LH2 tanks ...

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Can the James Webb Space Telescope basically manage its own orbit if necessary?
Accepted answer
9 votes

I don't have too much time to research as I'm about to head off to work, but a quick investigation of the JWST doesn't show anything that could be used for Astrogation. Curiosity can do its own ...

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Is it possible for something to fall straight down to earth? What are the requirements?
8 votes

Obligatory XKCD Forgive me for assuming this, but it seems like you don't quite understand what an orbit is. As XKCD Puts it "Space is not up, space is sideways very, very fast." To put it another ...

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Are and should satellites use wireless communication internally, rather than cables?
6 votes

Alright, let's put on our engineering caps. To have a wireless connection, we need: Wires connecting the subsystem to the wireless transmitter Wires connecting the transmitter to the power supply An ...

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Never reducing propellant for space propulsion
5 votes

Everyone has this idea at some point, and every time it doesn't work. However, you came to the right place if you want to learn. Antzi explained it very well, but I think there's something deeper to ...

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Power requirements for zapping debris with lasers from ISS
3 votes

Several things, actually 1: Power As others have said, you need to power this monster. Lasers are very power hungry and inefficient weapons. For every watt of heat you put towards vaporizing your ...

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What limits the speed of space probes currently?
2 votes

Very generally speaking, a reaction engine works by throwing energy out the back to get motion towards the front. Now, according to high-school physics, the energy we get for throwing a chunk of mass (...

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Are the Boeing CST-100 Starliner and Orion MPCV interchangeable at any level?
2 votes

Short principle-based answer: Yes They both use a Low Impact Docking System, so what one could dock with the other could too. For that matter, they could dock with eachother. Here's the principle ...

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Could cosmic rays be produced by alien propulsion systems?
1 votes

Asdfex did an absolutely superlative job explaining why it's probably just background stellar emissions we're seeing, but let me ask you this: Who said a sun can't be an engine? If you're willing to ...

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Would reusability affect the performance of a rocket engine compared to a single launch version of that rocket engine
0 votes

I think you're asking the wrong question. Reusable engines will certainly have inferior performance to expendable ones, at least for a given cost/mass/size/TWR/ect. Just think about how cheap and ...

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