Sand grains in space - a threat?
If tiny particles of solid material (the size of sand grains, for instance) were flung into space, would they pose a danger to anything they hit?
I'm no physicist, but my understanding is that objects in space do not reach terminal velocity, and, once in motion, continue to accelerate until acted upon by another force (e.g. a gravitational pull, or colliding with something). This leads me to speculate that such tiny particles would effectively become vicious little bullets that could threaten satellites, spaceships etc.
Can someone with space knowledge confirm/refute this?
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1 answer
You are incorrect.
There is no "terminal velocity", that is a term used with air resistance (or it can apply to fluid resistance) when the amount of acceleration (due to gravity) is matched by the resistance of the medium through which something is falling; like air. Pointed objects like arrows will have a higher terminal velocity than something flat. A skydiver in "dive" position will move faster than a skydiver in "spread-eagle" flat position; their terminal velocity depends upon the amount of surface area that must push air out of the way.
However, in space, there is no resistance medium; but there is also no automatic propulsion system. Objects can be attracted by gravity, but otherwise will just continue to move at whatever speed they were moving; or continue to just sit there if there is no gravitational gradient and no initial motion. They do not automatically accelerate at all.
Sand and dust, just sitting there, can be a problem for anything that is traveling at high speed and hits them: That is the equivalent of them traveling at high speed and hitting an object at rest. Since high speed does increase the energy of such a particle, you are correct in intuiting they could cause damage: But it is not because everything in space accelerates.
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