When Satellites Collide

The big space news this week is the unprecedented collision of two major satellites in orbit: Cosmos 2251, a long-defunct Russian communications satellite, and an Iridium satellite, one of several communications satellites launched by Motorola in the late 1990s/early 2000s....The big space news this week is the unprecedented collision of two major satellites in orbit: Cosmos 2251, a long-defunct Russian communications satellite, and an Iridium satellite, one of several communications satellites launched by Motorola in the late 1990s/early 2000s. There have been occasional accidental collisions among smaller bits of space debris before, but this is the first time two large objects have collided, producing a cloud of wreckage. (Phil Plait has a nice analysis of the math behind the collision here and here.)The debris is expected to burn up in the Earth's atmosphere -- eventually. The question is, will that happen before some bit of debris collides with, say, another military or civilian satellite, or even the International Space Station? This is not a new problem. Many years ago, while chatting with a few space scientists about
various missions, I innocently asked, "So, how do we get all that stuff
back down again once we're done with it?" The answer ...