What Goes Up…
I spent most of September 23rd waiting for a bus. No ordinary bus, you understand. This one was special. It was apparently going to fall out of the sky. Even in these days of congested highways such a detour seemed a little drastic, but it must be true because it was on the breakfast news. I wish I could say that I waited all day and then three came along at once but, in fact, the bus never materialized.
When I got back home I turned on the news only to discover that I’d picked up on the back-end of a story. It wasn’t a bus at all, it was a satellite the size of a bus. That made a lot more sense. And, the good news is, it was not going to land in my back garden. The latest prediction was that it was likely to come down on some South Pacific islanders. Phew! That’s lucky! But how much of a threat is space junk?
Satellites, rockets and bits of spacecraft fall to Earth all the time. Mostly they come to a spectacular fiery end high in the atmosphere and are a thrill to watch, should you be lucky enough to see one. Every now and then, however, a huge satellite decides to come home and some of it makes it all the way. Last September it was, somewhat ironically, the turn of UARS, NASA’s Upper Atmospheric Research Satellite, which eventually made a harmless splashdown near the islands of Samoa. Back in 1978, Canada was not so lucky. On January 28th the Soviet RORSAT satellite crashed near Great Slave Lake scattering radioactive material over 124,000 square kilometers – an areas about the size of the state of Mississippi. The bulk of it was never recovered, nor was most of the $15 million clean up bill: the Soviets reimbursed Canada less than half the amount. Other notable falls have included parts of NASA’s 85 ton Skylab landing in Western Australia in 1979, a spent fuel tank from a Russian Zenit 3 rocket ending up in Colorado last March, the nose cone of an Ariane 5 rocket found washed up on the beach at Corpus Christi, Texas in 2000 and fragments of the 40 ton Salyut 7 space station scattered over the town of Capitan Bermudez in Argentina.
And then there was Lottie Williams of Tulsa, Oklahoma. Lottie was walking with friends early one morning in January 1977 when she felt a tap on the shoulder. It wasn’t one of her friends but a fragment of a Delta II rocket launched the previous year, according to a report by CORD, the Center for Orbital and Re-entry Debris Studies. Fortunately, it did no harm to Lottie.
Strange as it may seem, satellites crashing to Earth are the least of our worries. Nowadays about 200 bits of spacecraft bigger than a basketball re-enter the atmosphere each year, well down on 1989 when the figure peaked at more than 1,000. Better spacecraft design and management, including a greater use of “graveyard" orbits high above the Earth have resulted in fewer objects plunging into the atmosphere. But it is the stuff that’s left up there that is causing headaches for the space agencies.