Plans for weekend – avoid falling satellite

Yes. Really. Because the European Space Agency’s GOCE satellite, launched in 2009 to measure the Earth’s magnetic field, is falling back to Earth. This is because it has run out of fuel, which was the only thing keeping it up in a rather tenuous 280km orbit. Now, already having fallen to about 190km above us by yesterday, it’s expected to fall out of the sky completely by Sunday or Monday.

Should you be worried? Well, no.
Not according to Dr Stuart Clark anyway. He says it’s likely that the one tonne unit is “likely to fragment into 25-45 pieces en route”. And although “No one knows exactly when or where it will smash down”, we’ll probably be ok. That’s because those pieces (each weighing an absolute minimum of 22.22kg if his assumptions are correct) will likely burn up before they touch down.
Much like most other meteorites:

According to Cornell University’s Ask and Astronomer webpage, between 18,000 and 84,000 meteorites bigger than 10 grams hit the Earth every year. Not all of these survive to strike the ground.

The total amount of mass contained in a year’s worth of meteorites is about 37,000-78,000 tonnes, or 101–214 tonnes per day. So, another tonne from GOCE represents an increase of just 0.5-1% on the day.

To put the numbers into clear context, the Chelyabinsk meteor that struck Russia on 15 February 2013, injuring people and causing wide-spread damage, is estimated to have been 12,000–13,000 times more massive than GOCE.

All of which is very reassuring, until 20 kilos of hot metal ruins your Sunday evening braai.

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