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29
votes
6answers
2k views

Why are rockets so big?

I'm curious why rockets are so big in their size. Since both the gravitational potential one need to overcome in order to put thing into orbit, and the chemical energy burned from the fuel, are ...
14
votes
4answers
857 views

NASA's “Impossible” Space Engine

Recently, there was some news that said that the researchers at NASA have come across some impossible kind of space engine which does not require any fuel. I have read at a few places like here, here ...
2
votes
3answers
320 views

How does the solar sailing concept work?

Wikipedia describes solar sailing as a form of spacecraft propulsion using a combination of light and high speed ejected gasses from a star to push large ultra-thin mirrors to high speeds. I ...
1
vote
2answers
2k views

Difference between deltaV and specific impulse

When reading any literature regarding space propulsion, I keep getting about these terms deltaV and ISP or specific impulse. I know specific impulse is supposed to be the velocity the propellant mass ...
4
votes
1answer
78 views

thermodynamics of a dual-face surface in space

This question is a continuation from this one. A material disk have two sides, one that is reflective and another absorptive of electromagnetic radiation in the range where the background cosmic ...
6
votes
2answers
243 views

relativistic spaceship, CMB radiation and thermodynamics

Scenario: a spaceship is travelling at a high fraction of $c$. The interstellar gas and CMB radiation has blueshifted significantly and we are facing a possible melting of the front radiation shield! ...
3
votes
6answers
5k views

Ion Drive Propulsion Top Speed

I would like to know if there is some formula / graph which would provide / show the efficiency of a certain type of propeller in space. Specifically, I'm interested in the acceleration attainable at ...
5
votes
0answers
257 views

Mirrors and light beam divergence technology limits

There are many applications for orbital space mirrors in astronomy (better telescopes) and space propulsion (solar power for deep space probes), but this is limited by the minimum beam divergence ...
4
votes
1answer
243 views

Could this fountain, under the right conditions, technically be able to lift me up?

There is a big fountain in a lake in my city. I was talking with a friend and we were wondering whether it would be able to lift me up. I sent a few emails and obtained information about the ...
1
vote
2answers
184 views

How can thrust be generated in space which is a vacuum?

Since thrusters have no matter to push off of, how can a spacecraft generate thrust in the vacuum of space?