In brief: A satellite that weighs more than a large car is set to crash back to Earth sometime tomorrow (Wednesday, February 21), almost 30 years after it was launched. But don’t worry about being hit by part of it: the satellite will break into fragments and the chances of being injured by one are under 1 in 100 billion.
The European Space Agency (ESA) launched the European Remote Sensing 2 (ERS-2) satellite on an Ariane 4 rocket back in April 1995. In 2011, after 16 years of operations, the ESA decided to end ERS-2 operations and deorbit the satellite. Following 66 deororbting maneuvers, which included draining the propellant tanks and lowering its altitude from 785 km (488 miles) to 573 km (356 miles), the mission officially came to an end on September 5, 2011.
Deorbiting satellites at the end of their life helps keep space highways clear, preventing collisions in orbit and reducing the risk of creating more space debris. In the case of ERS-2, the process allowed the satellite to safely re-enter the Earth’s atmosphere sometime within the next 15 years.
Tomorrow is believed to be the day the satellite will re-enter the atmosphere. As this is an uncontrolled re-entry, the ESA doesn’t know exactly where ERS-2 will land, which sounds worrying for a satellite that weighed 5,547 pounds at lift-off and is still 5,057 pounds without fuel.
The good news is that ERS-2 will break up into fragments about 80km (49.7 miles) above the Earth’s surface and the vast majority will burn up in the atmosphere. But the size of the satellite means that chunks weighing up to 115 pounds could come crashing down to the surface.
Thankfully, the fact that water covers about 70% of our planet’s surface means that what remains of ERS-2 will most likely land in the Ocean. The ESA says the 1 in 100 billion chance of being injured by falling space debris is 1.5 million times lower than the risk of being killed in an accident at home, or 65,000 times lower than the risk of being struck by lightning. The agency also adds that the pieces contain no toxic or radioactive substances.
The ESA predicts that reentry will take place at 5:14 am CT (11:14 UTC) tomorrow, with an accuracy of within 15 hours.