Page 8 - Trashing the Planet: Examining Our Global Garbage Glut

TRACKING ORBITAL DEBRIS

An estimated twelve hundred active commercial satellites are orbiting
Earth. Some of them relay telephone or television signals. Others aid in
weather forecasting, national defense, navigation, and scientific research.
Satellites cost anywhere from $20 million to $3 billion each, and all active
satellites together are worth around $1 trillion. Because satellites are so
important, government agencies spend a great deal of time and money
tracking space debris. When trackers see that a piece of debris is headed
toward an active satellite, they notify satellite controllers on the ground,
who remotely maneuver the satellite to avoid a collision.
In the United States, the task of tracking space junk falls to the Space
Surveillance Network (SSN), operated by the US Department of Defense.
Using radar, telescopes, and high-powered cameras, the SSN can track
objects as small as 2 inches (5 cm) across. The SSN often consults with
space-tracking agencies from other nations, such as Australia’s Space
Environment Research Centre, a world leader in tracking space debris.
CLEANING UP SPACE JUNK

Some scientists say that to remove the threat to satellites and other space
vehicles, we must devise methods for removing space junk from orbit.
NASA researchers have proposed arming the ISS or satellites with lasers
that could shoot down large pieces of junk. The lasers would fire ten
thousand pulses per second, partially melt pieces of space debris, and push
them into Earth’s atmosphere. There, as the debris fell toward Earth, it
would grow extremely hot as it rubbed against the air. It would disintegrate
and burn up before hitting the ground. A laser debris-removal system has
yet to be built, but if it were, it could potentially destroy one piece of debris
every five minutes, cleaning up one hundred thousand pieces of space junk
each year. In little more than four years of deployment, the system could
remove the most troubling debris circling Earth.
The European Space Agency (ESA) has another idea for removing
clutter from orbit. The agency’s first debris removal mission is scheduled

86 TRASHING THE PLANET