Heads up! Space Junk Falling to Earth

There's no need to get too worked up about it, but you may want to keep an eye on the sky for the next day or so, just in case. NASA says the odds of a person getting hit by a piece of space debris is 1 in 3,200.

A U.S. research satellite is expected to plummet back to Earth sometime tomorrow and although much of the bus-sized satellite will burn up upon re-entry into the Earth's atmosphere, about 26 significant-sized chunks are expected to remain.

"There is a lot of space junk out there and continually there are satellites and other pieces of space junk that are entering Earth's atmosphere," she says, adding that a piece of this size returns to Earth about once a year.

NASA's website states there have been no confirmed reports of injury or significant property damage due to falling satellites thus far. An Oklahoma woman was apparently hit on the shoulder by a small piece of a rocket in 1997, but was not hurt.

NASA says there are about 21,000 pieces of "orbital debris" - man-made objects in orbit which serve no useful purpose - that are larger than 10 centimetres (four inches). It estimates there are about 500,000 pieces of space junk sized between one and 10 centimetres (0.4 and four inches) and probably tens of millions that are smaller than one centimetre (0.4 inches).

Since the space program started, about one piece of space junk falls to Earth each day. NASA predicts the 26 pieces of space junk expected to hit the Earth from this satellite will have a combined weight of 532 kilograms (1,173 pounds), the largest of which is expected to weigh 158 kilograms (348 pounds).

"You might expect there to be some damage if (a piece) fell on some property. It would probably damage it significantly,"

Given that, it would be nice to know if one should stay inside tomorrow or not, but not only is it difficult to predict the time the satellite debris will land, it's pretty well impossible to pinpoint with any accuracy where it will land.

"If there was a trajectory that this hunk of metal was travelling through and it was unimpeded, then we would be able to predict very well (where it will land), but there are all sorts of influences it may experience," Edwards says, including wind.

NASA expects the chunks will all land within 800 kilometres (500 miles) of each other - it's just not quite sure where that 800-kilometre stretch will be. Even within about two hours of the expected re-entry time, the best it will be able to do is predict within about 12,000 kilometres (7,500 miles) of the landing point.

In other words, if you happen to get hit by a piece of the landing satellite, you are very, very unlucky indeed. This particular satellite was launched in 1991, but was decommissioned in 2005.