Has anyone heard of our satellites being hit by the floating debris?

Question

With so many satellites and so many debris (and UFOs?) floating above the Earth's spheres, how come we never heard of any of those hitting any of our satellites?

Answer 1

Space debris are being tracked and to date it is estimated that there are roughly 9,000 catalogued objects (catalogued by USSPACECOM radar) in orbit with a size larger than 10 cm, of which only about 600 are functioning satellites and the remaining 8,400 classified as space debris.

Spacecraft and satellites can avoid collisions by maneuvering around the larger debris. For example, when a space shuttle is in orbit, the USSPACECOM regularly examines the trajectories of orbital debris to identify possible close encounters. If a catalogued object is projected to come within a few kilometers of the space shuttle, it will normally maneuver away from the object.

Answer 2

NASA's LDEF satellite was in orbit for 68 months and was used, in part, to measure meteoroid and debris collisions. Data from this experiment is at:
http://setas-www.larc.nasa.gov/LDEF/MET_DEB/md_enviro.html

[ See also: http://en.wikipedia.org/wiki/LDEF ]

The problem with collisions with two or more satellites is especially problematic in geosynchronous orbit (about 25,000 miles above the earth's surface). The geo orbit is popular because satellites there remain fixed over one spot on the earth's surface. Further, there are gravitational "wells" in these orbits due to gravitational variations in the earth. When multiple satellites are co-located near a well, the probability of them colliding goes up. Satellites have control centers on earth that are manned 24/7 so that position readjustments can be made. Their sub-systems are also monitored (e.g. electrical, thermal, etc.).

Hope this helps!

Answer 3

It's almost impossible for them to hit.

You'd almost have to plan it (and then be real lucky if they actually hit - it would be like to people trying to hit 2 marbles together when they're standing on opposite sides of a football field).

There isn't actually that much up there, and it's an awfully big area.
Plus your working in 3 dimensions, so they can go over and under each other.

--Old satellites usually don't stay up there either, they burn up in the atmosphere on their way back to earth.

Answer 4

Yes usually they will calculate the speed and distance and collision area and time as for space station (mir) they will drive apart.

Answer 5

It is calculated.