Friday, July 17, 2009

Space Junk

Last night was another episode of The Universe and the topic was Space Junk. I have only recently heard about space junk, but it makes sense–wherever we go we produce debris. But space debris is in a category all on its own because it does come back home. That puts a whole new spin on our concept of meteors.

There are approximately 750,000 objects of debris larger than a centimeter orbiting the Earth at 17,500–28,000 miles per hour. There are an estimated 250,000+ additional objects that are too small to be detected. Space surveillance can only monitor 13,000 of these objects. Space junk consists of things like old satellites, space probes, rocket bodies, rubbish bags from the Mir Space Station, tools and even paint chips and drops of chemicals.

Space debris poses a threat to the International Space Station, Hubble Space Telescope, shuttles and satellites. The tinniest piece can put a hole in an astronaut’s suit or the exterior of a shuttle. Even NASA needs to access the locations of the debris before they launch. And the more debris produced, the higher the risk is for a catastrophic event, in space or here on Earth.

All space junk eventually falls back to Earth as its orbital speed slows from atmospheric drag and the effects of our gravity bring it down. Much of it will burn up in the atmosphere but some of it does survive and strikes the Earth. Most of it lands in the oceans since the Earth is 70% water. What does hit land is generally unoccupied as 99.9% of the Earth is not occupied by a person at any given time (hard to imagine). There is one woman from Oklahoma who is the only known person to ever be hit by space junk (she was not injured).

Around 50–200 “larger” pieces of space debris return to Earth every year. Over the past 40 years, about 12 million pounds of space junk have survived re-entering Earth’s atmosphere.

Interesting Facts: In 1965, Gemini 4 astronaut Edward White lost a glove which stayed in orbit for a month. The oldest debris still in orbit is the US satellite Vanguard I launched in 1958, which worked for only six years. Experts calculate that debris will strike one of the 900 active satellites every two or three years.

Now you’re a little smarter, Girlfriend — And so am I.

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