Wed October 19, 2011
Watch Out! More Space Debris Coming Our Way
It's happening again: This time instead of a NASA satellite, it's a German satellite that will burn through the Earth's atmosphere and crash somewhere unknown. If you remember, in September a decommissioned weather satellite fell into the South Pacific.
It'll be same drill for ROSAT, which the German Aerospace Center says is scheduled to re-enter Earth's atmosphere sometime between October 22 and October 23.
National Geographic reports that the risk of ROSAT injuring someone on Earth is about third higher than UARS was. ROSAT, reports National Geographic, has a 1 in 2,000 chance of injuring someone.
NatGeo adds some more caution:
Debris could come down anywhere between 53 degrees north latitude and 53 degrees south latitude, an area that includes most of Earth's land mass, the German Aerospace Center's Roland Gräve said via email.
That could be a worry, because the satellite's 1.5-ton mirror is likely to survive the superheated trip through the atmosphere all the way to the ground, where it could make a major dent in whatever it strikes.
By contrast, the biggest piece of NASA's UARS spacecraft thought to hit the planet was a 300-pound (150-kilogram) chunk of the craft's frame.
The satellite will face a violent return. Here's how the German Aerospace Center describes it:
In the final phase, ROSAT will be 'caught' by the atmosphere at which point it will not even complete an orbit around the Earth: instead, it will go into 'free fall'. The rate of this free fall encounters the powerful braking effect of residual atmosphere, causing the speed of the satellite to decay. This process of slowing down consumes vast amounts of energy that is released in the form of heat. The maximum heating takes place at an altitude of 80 kilometres. Shortly thereafter, maximum retardation takes place.
The Aerospace Center adds that it's unlikely that anyone on Earth will be able to see the re-entry. Odds are, they say, that it'll "come down over the sea or over uninhabited regions where there are no human observers and no radar stations."