Low Earth Orbit

When a satellite circles close to Earth we say it's in Low Earth Orbit (LEO). Satellites in LEO are just 200 - 500 miles (320 - 800 kilometers) high. Because they orbit so close to Earth, they must travel very fast so gravity won't pull them back into the atmosphere. Satellites in LEO speed along at 17,000 miles per hour (27,359 kilometers per hour)! They can circle Earth in about 90 minutes.

Space Junk The LEO environment is getting very crowded. The United States Space Command keeps track of the number of satellites in orbit. This is a graphic display of the objects in low earth orbit. According to the USSC, there are more than 8,000 objects larger than a softball now circling the globe. Some people worry about the number of items now in low earth orbit. Not all of these things are working satellites. There are pieces of metal from old rockets, broken satellites, even frozen sewage. At 17,000 mph, even a small bolt can hit a space shuttle with the impact of a hand grenade. Which is exactly why the US Space Command keeps track of these things!