How is it when we launch spacecraft out to orbit other planets or eventually to go to the moon, the craft don’t collide with all the space junk up there?

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The ISS is under constant threat of being destroyed by debris, so when we (eventually) launch astronauts to go to the moon or when we launched like Juno or New Horizons, how did they not get destroyed by the space junk?

In: Engineering
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Sometimes things do collide. We track the orbits of much of the debris satellites that are up there and manage the orbits of new items so as not to collide. This has to be done very carefully as there are many items something could collide with. Last I saw there was around 10,000 debris satellites so it is a lot of work. As I recall the sbirs system was supposed to track all the items in orbit.

Almost all large items are tracked (both intentionally places satellites and debris). There’s over 17000 items that are tracked, which helps avoid collisions.

Smaller items that cannot be tracked do pose a huge risk, and cause damage to satellites. Collisions occur relatively frequently, but don’t tend to cause horrific consequences yet – there’s a fear that the orbit may become impassable in future.

There is very little space junk out there compared to how much space there is, most of the junk is in certain locations notably where we want to put many of the satellites, the probes spend very little time in the danger area – https://youtu.be/Km2uemAqbbM

As others have stated, we do track everything that we can that is orbiting the Earth, but another thing to remember is that the Earth simply is huge compared to what’s orbiting it. You could easily put 20,000 pennies evenly spaced in a large parking lot and most of them wouldn’t even be close to each other. It’s a bit like that, but imagine that the parking lot is much much bigger, and the pennies are much much smaller.

The ISS is not “under constant threat of being destroyed by debris”. There’s always some risk, but it’s not as if the station is always mere moments away from destruction, or anything close to that. First, most debris is too small to do serious damage. We’re talking about grains of dust or flecks of paint. These things hit the ISS and other spacecraft all the time, but they have shielding to protect them. The ISS is also at an altitude where debris will fall back to Earth and burn up pretty quickly, so any debris large enough to pose a risk doesn’t stay around for long. Second, large debris is tracked, so if there is a collision risk, the station’s orbit can be adjusted to avoid it.

Third, you have to understand just how huge space is. Even the space near Earth, which is the most crowded, is just mind-boggling huge, and almost entirely empty. The odds of a spacecraft transiting this space or leaving it to go to another planet being hit by debris large enough to cause serious damage are staggeringly low. No spacecraft has ever been damaged or destroyed doing this.

So, in short, space is really really big and really really empty. There’s always some risk of debris but it’s managed.