Earth orbit is messier than most teenagers' bedrooms. Since the start of space exploration in the late 1950s, dozens of countries and corporations have left thousands of hunks of junk screaming through space. At last count, there are more than four million pounds and 110,000 useless objects streaking through space at a speed of 17,500 mph. It's like a high-tech junkyard 300 miles up in space.

Nuts and bolts, used rockets, screwdrivers, lens covers, gloves and many, many other discarded items continue to orbit the Earth. Add to that list of stuff in space a whopping 2,674 satellites and 90 probes. Of course, these objects are designed to be there!

Since most objects gradually slow down and fall out of orbit, space would eventually clean itself if no new stuff were added. (Some weather and communications satellites are exceptions, as they orbit at 22,300 miles and may remain in orbit for centuries.) A 1996 study found that about one-third of all the junk strewn in space is still there. The United States and the former Soviet Union combine to account for about 90 percent of all the stuff.

Photo courtesy NASA

Photo courtesy NASA

Even something as small as a paint chip can cause a problem. In 1983 a paint fleck that was too small to be tracked by NASA actually cracked the windshield of the space shuttle. (Click here to see a picture.) In fact, more than 80 windshields have been replaced due to space debris.

Photo courtesy NASA

Major Space Junk Contributors United States: 741 satellites 46 probes 2971 pieces of debris Former Soviet Union: 1335 satellites 35 probes 2571 pieces of debris European Space Agency: 24 satellites 2 probes 233 pieces of debris

Engineers also worry about the International Space Station (ISS). Designed to last 20 years, it's the largest object ever to orbit in space. When its size and time in space are considered, the odds are high that something will hit it. Fortunately, the ISS can be maneuvered to miss objects that are large enough to be detected from Earth -- which means objects the size of a melon or larger. However, it's the smaller objects that pose the greatest hazard because they are difficult, if not impossible, to track.

Fortunately, NASA is working on several projects that could solve the space junk problem. One of the programs is called the Orion Project. It features high-powered laser beams that will redirect objects away from a spacecraft and toward the Earth where they will burn up in the atmosphere. Tests are planned for a special laser system based in Hawaii. While promising, these systems are years away from being practical. Scientists have even considered installing "laser-brooms" directly on spacecraft to clean up the debris directly from space. However, such a system is currently impractical because it requires much more energy than can be supplied by a spacecraft.

So the best way to reduce space junk is to limit its amount in the first place. Currently, about 200 objects are added to the cosmic scrap pile each year. Engineers at NASA and other space organizations are designing spacecraft to leave less junk in space and to "de-orbit" space junk faster. Much like on planet Earth, aerospace engineers are trying to reduce waste and recycle more stuff in space. Unfortunately, that recycling truck does not yet have curbside pickup.

What Do You Think? Engineers are currently looking at methods to reduce space junk. At the present time, what do you think is the most practical way to clean up space? Install laser "space brooms" directly on spacecraft to destroy useless objects Fire high-powered laser beams from Earth to redirect objects so they will burn up in earth's atmosphere Design spacecraft so less stuff is left in space in the first place Design objects so they slow down and fall out of orbit faster Launch a series of super magnets that attract and hold metallic space junk