Two satellites collide in orbit

It’s been all over the news – Two satellites collided in orbit.

It happened on the 10th February 2009 at 16:56:00 UTC.

The satellites involved were the out of order Russion Kosmos 2251 (93-036A) and the still working Iridium 33 (97-051C) satellite. They collided 789km above the Siberian arctic. There is now a cloud of debris quickly growing in size.

The interesting thing is that the satellites were almost at 90 degrees to each other (see image below). At that altitude, orbital velocity is around 7.4 Km/sec (27,000 Km/hour). At this speed, the chances of two objects the size of a car colliding is very slim….. but chances are chances…


I’m keeping an eye on the Space Track orbital data lists to see how much debris comes out of it.

Back in 2007, the Chinese destroyed one of their own satellites (FENGYUN 1C 99-025A). Each part of debris is catalogued and so far they are now up to 2242 pieces of debris from it’s destruction – Each piece is monitored daily to make sure it won’t collide with anything else.

The real problem is that scientists have come to agree that the number of objects in orbit has surpassed a critical mass. in scientific terms, they call it the critical spatial density. This is the point at which one collision creates debris which, through an exponential chain reaction even more collisions happen.

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