CNN/News 8 Austin

Space Debris Near-Miss Prompts Tracking Questions

March 13, 2009 01:00 PM
by Emily Coakley
Another space junk close call, which forced a space station to evacuate, begs the question of how NASA tracks such tiny pieces of debris.

Crew Scurries to Safety

The three astronauts comprising the space station crew sought safety in a "Russian escape capsule," fearing that their own craft would be hit by the "piece of space junk," reported CBS News. NASA told the press that the object was actually "a small piece of an old spacecraft motor" measuring less than one inch. Despite passing only "within three miles of the station," the debris could have caused "a fatal loss of air pressure" inside the station.

Space junk is tracked by radar, according to CBS, but how exactly are such tiny objects accounted for?

The Spacebook blog, led by NASA astronaut Sandra Magnus, touches on the tracking of space debris. According to Magnus, the Air Force monitors the junk from a Colorado-based facility, which takes action if "anything is projected to enter" an "imaginary box" that has been drawn around each space station.

According to a 2005 CNN article, tracking is done at the Space Control Center at Cheyenne Mountain Operations Center in Colorado Springs, and is led by the Airforce's "1st Space Control Squadron." The team monitors, identifies and catalogs "all manmade objects orbiting Earth larger than 10 centimeters (4 inches) long."

But NASA space debris scientist Mark Matney told the Associated Press that this week's incident was the "closest call" he'd seen since joining NASA in 1992. And Harvard astrophysicist Jonathan McDowell called it "yet another warning shot that we really have to do something about space debris now ... on an international level."

Related Topic: Texas fireball

In February, many Texans saw a flash of light streak through the sky and heard a sonic boom. Officials in one central Texas county got so many calls about the light "that it sent deputies out in a helicopter to look for a plane crash," the Associated Press reported.

Federal Aviation Administration officials said the Texas fireball was most likely a meteor. Several news outlets reported that the fireball was likely debris from two satellites that had collided in space last week, though an astronomer told the AP that wasn't the case.

The incident, along with a collision of two satellites the week prior, signaled the growing problem of space junk.

"There are an estimated 300,000 objects of more than 1cm in diameter orbiting the Earth, including roughly 12,000 satellites, of which only 6% are still functioning," Sky News reported.

The satellite collision prompted the European Space Agency to start work on its own space junk detection system. Right now, the agency uses NASA radars, Deutsche Welle  reported.

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Historical Context: Cosmic collisions; asteroid detection system

Although small space debris hitting the earth often causes no major damage, collisions with larger objects could be devastating.

One of the most famous incidents of an asteroid hitting the earth is thought to have occurred near Tunguska in Siberia. A fireball erupted 12 miles into the sky on June 30, 1908, flattening an area of more than 2,100 square kilometers, though there was no crater or fragments of meteorites. The conditions led scientists to form several theories. According to findingDulcinea though, “The most widely accepted explanation is that a small comet or asteroid exploded 6 to 8 kilometers above the Earth’s surface.” The resulting explosion was approximately 1,000 times more powerful than the atomic bomb dropped on Hiroshima.

This past autumn, an asteroid about the size of a bus hit the atmosphere above Africa, renewing calls to create a system that would detect asteroids, meteoroids and other space debris before they hit the earth’s atmosphere.

Some scientists are concerned that an asteroid called Apophis is going to hit Earth in 2036. Apophis was first noticed in 2004, and is expected to pass within 20,000 kilometers of Earth in 2036, though the risk of it actually hitting the Earth is thought to be small.

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