US and Russia: Space Clash
No, not a headline from the Cold War but a reference to the first known satellite collision in space. Space is apparently becoming crowded with debris, but what is it and where does it come from?
Somewhere, high above planet earth, a US satellite hurtled towards a defunct Russian satellite at nearly 780km/h. The resulting collision produced massive clouds of debris, and added hundreds of pieces of wreckage to the space debris already orbiting earth. This disused Russian satellite was just one of thousands of pieces of so-called ‘space junk’ suspended above our planet.
What is Space Debris?
Orbiting around the earth are thousands of pieces of space junk, ranging in size from nuts, bolts and gloves, to outdated satellites. Some of them are racing along at 17,500 miles an hour! The oldest debris still in orbit is the US satellite, Vanguard I, which was launched in 1958 and stopped working after 6 years. It is still up there. The Mir Space Station put out over 200 pieces of debris during its first 10 years of operation, most of which were bags of rubbish. There are currently more than 600,000 objects larger than 1cm in orbit.
Polar view showing tracked objects in lower earth orbit and the geosynchronous region
Is it Dangerous?
Basically, unless you are an astronaut, you are very unlikely to find yourself in danger from a piece of space junk. There has only been one recorded incident of a person being hit by re-entering debris – in 1997, Lottie Williams of Oklahoma was hit on the shoulder by a piece of a Delta II rocket.
The greatest perceived danger is to space shuttles, to astronauts on space walks and to the Mir space station. A speck of paint from a satellite once dug a quarter-inch-wide pit in the space shuttle window. The effects of a direct hit from a baseball-sized piece would be devastating.
A propellant tank which landed near Georgetown, TX in 1997
What is Being Done?
NASA’s Orbital Debris Program Office is responsible for monitoring and attempting to mitigate the problem of space debris. Based on their recommendations, the US Government developed a set of standard practices for managing space debris, and other countries soon followed. By 2002, there was an international set of guidelines which provided a consensus on how to limit the growth of orbital debris.
The larger pieces of debris are constantly tracked, and many are allowed to re-enter the earth’s atmosphere either from orbital decay (uncontrolled entry) or with a controlled entry. Although much of the debris will burn up on re-entry, a controlled entry aims to encourage surviving pieces to land in uninhabited areas. However, even objects on an uncontrolled re-entry are unlikely to cause significant damage as nearly three-quarters of the planet is covered in water, and the majority of the dry land is uninhabited, so there’s a good chance that most objects will land far from the nearest unsuspecting populace.