If you've seen Gravity, you know how it goes: Even a tiny speck of paint shooting through space at 18,000 mph can be catastrophic. So when a hand-sized piece of space debris was going to fly by the International Space Station last week, the European Space Agency fired up the thrusters on a resupply ship docked at the station, making it the first time an ESA ship pushed the ISS out of harm's way.

Top image: The ATV docked on the ISS

The rescuer was an Autonomous Transfer Vehicle (ATV), an unmanned cargo ship that brings supplies and fuel to the space station. Once docked at the station, the ATV has a second important function: giving the space station boosts to keep it from slowly falling back down to Earth. These boosts are meticulously planned to keep the ISS in a steady orbit.

But on October 27, the ATV was called upon for an emergency boost. A hand-sized piece of an old Russian satellite was going to pass within 2.5 miles of the station. In just hours, the ATV Control Centre team did the math and decided to fire the docked ATV's thrusters for 4 minutes, raising the ISS by just over half a mile into the sky. Although a Russian supply ship has pulled off an emergency boost before, it was the first time the ATV's system was tested on such short notice.

As for the ATV, it's designed to burn up on reentry into Earth's atmosphere after it undocks from the space station in February. That way, it won't turn into space junk itself. [ ESA]


ATV-5 approaching the International Space Station. All images via ESA.