With all of these debris like dust loating around in space, how do satellites remain clean? How are they able to capture clear photos despite no means to clean the lens?

Question

With all of these debris like dust loating around in space, how do satellites remain clean? How are they able to capture clear photos despite no means to clean the lens?

In: Planetary Science

Answer 1

There’s actually not that much dust in space. Space dust is a real thing, but we are talking about a couple tiny particles in such a massive area, that the chance of it hitting a satellite is negligible to non-existant.

The density of the dust cloud through which the Earth is traveling is approximately 0.000006 dust grains/m3

Essentially a one in a million chance of it hitting a satellite, and even then the dust grain is so tiny that it’s more like a particle of smoke than what we think of as dust.

Answer 2

Space is big. Really, really big. While there is a lot of rubbish and debris out there that we’ve caused, it is absolutely insignificant to the physical volume of space overall, and even in the near-earth orbits in which most satellites sit, it is still quite an insignificant volume. So chances are low enough to begin with.

Space agencies track as much as they can, including when some poor astronaut drops a space-wrench and sends it into orbit. So there’s a good map of where things are in orbit, which is taken into account whenever a satellite is put into orbit to reduce the chances of something hitting them. There is a *lot* of orbits to work with, so we can put quite a few satellites up there without them ever colliding or crossing paths with each other or the debris we do track, so reduces those chances further.

Collisions do occur. It’s not like Earth where dust will “settle” on things due to gravity. Everything is moving with some speed, so dust won’t settle but will instead impact. Those impacts happen and are predicted to happen, so anything put into orbit has a certain level of “defence” against such things – essentially, armoured/strengthened as best possible. More complicated pieces of kit will also have redundancies built in as well.

The risk of something hitting a camera or telescope precisely enough to cause damage is therefore very small, but not impossible, and is an accepted risk of space travel and exploration.[The James Webb Space Telescope took micrometeor damage to one of their mirrors within months of being launched.](https://www.livescience.com/james-webb-space-telescope-micrometeoroid-picture) But that is why redundancies, back-ups etc are built it.