About three weeks ago, we all awaited with abated breath as American satellite UARS hurtled back to earth - Fortunately, it crashed in such a remote area that it took scientists three days to locate the debris. Now, another satellite is making its way back and once again, scientists have no clue where the debris will end up!
The 5,300lbs (24,000kg) German Satellite called Roentgen Satellite or ROSAT is expected to re-enter the earth's atmosphere sometime between Saturday, October 22nd and Sunday October 23rd. According to the German scientists, it could land anywhere between 53° North and 53° South - Which means pretty anywhere outside of the two poles.
While the minivan-sized satellite is not as big as UARS, it is expected to be more dangerous with a 1 - 2000 chance of someone getting injured. That's because more than 30 pieces, weighing a total of 4,000lbs are expected to hit the earth's surface at a speed of about 173mph. The most dangerous part of the debris will the telescope's heat resistant mirror, which scientists believe will disintegrate into razor sharp shards as they hit the atmosphere. Having said that, based on the 50-year history of space junk landing on earth, experts are almost sure the debris will not harm anybody.
Launched in 1990 to collect data for research on black holes and neutron stars, ROSAT was initially intended to be active for only 18 months. However, the information it sent back was so useful, that it continued operating until 1999, when it finally lost contact with the scientists.
The reason behind the uncertainty surrounding falling space debris is two-fold. Since these satellites are decommissioned, they have no contact with earth, and even if they did, some like the ROSAT are not equipped with engines - Which means that experts can do nothing to change their trajectory.
The other issue is that the density of the atmosphere is different in different spots - and so the drag and therefore the ultimate destination of the debris, depends on where the satellite meets up with the atmosphere, making it very difficult to predict the exact landing site.
While scientists are developing a technology that would allow them to destroy satellites and other space junk, while still in orbit, it far from ready. Meanwhile, we just have to keep our fingers crossed that ROSAT will be as considerate as UARS and land far from populated areas.
Resources: washingtonpost.com, csmonitor.com, dailymail.co.uk