Space Debris That Goes Bump in the Night

The scoop:  Just weeks after a collision of U.S. and Russian satellites added millions of pieces of space junk around the Earth, the crew on board the International Space Station experienced a near miss.

On March 12 a piece of space debris came within miles of hitting the orbital laboratory, prompting the three crew members on board to prepare for evacuation in their Soyuz spacecraft.

David Wright, co-director of the Union of Concerned Scientists, thinks enough is enough when it comes to dangerous trash in space.

Fifty years into the space age, people still view space as some sort of Wild West: a region so vast that there is little need for laws or limits -- let alone traffic management -- on dumping trash.

But as the collision between two satellites in February 2009 suggests, parts of space today better resemble the bustle of Los Angeles freeways than the wide-open Wild West.

On February 10, an Iridium communication satellite and a defunct Russian satellite collided nearly 500 miles (800 km) above the Earth at a speed of 22,000 mph (10 km/s). The force of this collision destroyed both satellites and created clouds of orbiting debris that eventually will spread out around the Earth.

This is the first known collision of two intact satellites, but the number of objects in space -- active satellites, dead satellites, old rocket bodies, and junk of all sizes -- is so large that seven other collisions are known to have occurred. And we estimate that a collision between a piece of debris larger than a marble with some active satellite in a near-Earth orbit will occur on average every two to three years over the next decade.

The February collision, as well as China's test of an anti-satellite weapon in January 2007 that destroyed a satellite near the same altitude, not only significantly increased the amount of debris in space, but added it at altitudes between 450 and 600 miles (700 and 1000 km). That's the region of space most crowded with equipment.

Because of their extremely high speeds, even small pieces of debris can damage or destroy satellites in an instant. Because atmospheric drag at high altitudes is very small, such debris can stay in orbit for decades or longer, causing it to accumulate as more is produced. As the amount grows, the risk of collisions with satellites also grows. In time, the risk could become high enough to threaten the use of this highly desirable, heavily used region of space.

There is currently no way to remove large amounts of debris from orbit, so controlling the production of debris is essential to prevent the region from being completely overrun.

Space-faring nations have taken some steps to slow the growth of debris. Starting in the mid-1990s, an international consortium of countries developed debris mitigation guidelines that the United Nations  recently adopted. The guidelines, however, are voluntary. The United Nations needs to strengthen them by making them mandatory and adding enforcement measures.

The international community must also begin to develop measures for space traffic management, similar to air traffic control around busy airports. The goal would be to avoid collisions, set up shared practices and "rules of the road," increase transparency and communication between countries on space issues, and avoid or resolve conflicts among countries over space activities.

Failing to preserve the long-term utility of space would be incredibly shortsighted. Yet creating an international consensus to take the required steps will be one of humankind's great challenges, as doing so will likely require us to change the way we view space.

David Wright is a physicist and co-director of the Union of Concerned Scientists' Global Security Program in Cambridge, Massachusetts. The views expressed are the author's alone and do not represent the official position of the Discovery Channel.

Article posted March 12, 2009.

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