Firstly, is it correct that for travel in outer space, the distance that can be travelled with a given amount of fuel is determined by the energy required to overcome the following forces: gravity from nearby objects, drag?
Assuming this is correct, what (roughly) is the difference in the magnitude of these forces, and how does this change for interplanetary, interstellar, and intergalactic space?
I am trying to work out whether the amount of mass being transported is of significance, or is only the amount of drag important.
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1$\begingroup$ Vacuum of space = extremely low drag, practically none. Coasting along at constant speed costs nothing. Suggest you look into the "rocket equation" and the "relativistic rocket equation" for more info. $\endgroup$– StephenG - Help UkraineCommented Mar 21, 2020 at 17:02
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2 Answers
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Firstly, is it correct that for travel in outer space, the distance that can be travelled with a given amount of fuel is determined by the energy required to overcome the following forces: gravity from nearby objects, drag?
Actually, when it comes to deep space probes once you are free of Earth's gravity, the gravity of other planets becomes your friend, not foe. Deep space probes take advantage of gravity. Some of the terms used are "gravity assist", "gravitational sling shot", and gravity "swing by".
Probably your best resource for this question is the NASA website.
Hope this helps.
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The distance you can travel in space is mostly set by the velocity you have and time. It is not like on the surface of Earth, where the distance is largely set by the amount of fuel.
The reason is that friction and drag are almost completely absent in space. If you fire your rocket engine the amount of fuel determines the velocity you get. But in free space that just means you will now coast forever with that velocity, and the distance is set by the amount of time you wait.
An obvious complication is starting from a planet, where a fair bit of the fuel will be spent on overcoming gravity (and some air resistance). If you do not have enough fuel to reach escape velocity from the planet the distance is also going to be limited by the size of your orbit. If you have a moon or other planets within reach you can do clever gravity assist manoeuvres to coast with very little fuel between them, including getting escape velocity from the planetary system. This has less to do with fuel than clever navigation and timing.
answered Mar 21, 2020 at 18:31
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$\begingroup$ A space probe needs enery. Is the temperature low enough in space to build a superfluid fountain turbine for current generation ? (Oops there is no gravity so thishould not work) $\endgroup$ Commented Dec 19, 2021 at 8:47