I have some minority interests. One of them is strange lights in the sky (both causing and enjoying), so a couple of days ago I was intrigued to read about an odd glowing cloud -- with twinkly bits -- that scuttered across the Milky Way above the night skies of Western Australia. At first, it was a complete mystery: whatever it was, it made itself known a few thousand kilometres above the Earth and lasted a few hours before fading away.
There was a suspicion that it was some sort of anti-satellite weaponry testing, similar to that carried out by the Chinese last month. That deposited some five hundred pieces in orbit big enough to be tracked by radar (now up to seven hundred or so), and a rather larger number of apoplectic people on the ground shouting about debris and further collisions.
Now, the truth is -- probably -- known. The object in question was -- almost certainly -- the mortal remains of one stage from a failed satellite launch of last year. From the excellent Space Weather site:
One year ago, the Briz-M sat atop a Russian Proton rocket that left Earth on Feb. 28, 2006, carrying an Arabsat-4A communications satellite. Shortly after launch, the rocket malfunctioned, leaving the satellite in the wrong orbit and the Briz-M looping around Earth partially-filled with fuel. On Feb. 19, 2007, for reasons unknown, the fuel tanks ruptured over Australia.
It then shot off in a random direction, scattering bits, until it finally fell apart in that glowing, glittering cloud to the delight and consternation of the Western Australian amateur astronomy community. That cloud is now up to over a thousand trackable fragments, and growing.
Why did it go bang? Nobody knows. The most popular theory is that the corrosive fuel left in the thruster finally ate through to the outside, but there's also the chance that something else hit it. There's a lot of junk up there, and as of tonight there's nearly two thousand more than there were a month ago.
Space is a big place - you may think it's a long walk down to the chemist, etc - so even thousands of bits don't guarantee more trouble tomorrow. But a lot of that stuff's going to stay up there for a long time. So far, we've been lucky. Still, don't assume your GPS or your HD film channel beamed down from geosynchronous orbit is going to be there forever.