US Military Satellite Explodes Over Earth, ESA Assesses Risk

The United States Air Force and space industry media have revealed that a satellite which had been orbiting the Earth for the greater part of two decades exploded in early February, strewing debris that is worrying some experts. Now, the European Space Agency (ESA) has released a hasty assessment of this danger.

The explosion in question, which occurred within the core of the US Air Force's Defense Meteorological Satellite Program Flight 13 (DMSP-13), was first reported by the industry trade publication Space News on Feb. 27. It was reportedly the oldest continuously operational satellite in the DMSP network, having been launched back in 1995, with the National Weather Service and military agency both reporting that the satellite hadn't been involved in any crucial operations for a very long time.

Since then, the Air Force announced that the explosion that ripped the satellite apart likely occurred because its battery-fuel system had overheated.

T.S. Kelso, a senior research astrodynamicist at the Center for Space Standards & Innovation, added that it once was not uncommon for batteries to overheat and eventually explode mid-orbit.

"We spent a lot of time on battery management and thermal maintenance to avoid these types of problems," Kelso told SpaceNews on Tuesday. "The fact that we're seeing this in old DMSP satellites - that were built long before we appreciated the need to passivate energy sources like these - is not too [surprising]."

So we won't be seeing any newer satellites suddenly exploding anytime soon. Still, there remains one significant worry: the debris. The Air Force has identified 46 pieces of debris of trackable size following the incident. (Scroll to read on...)

And while they are too small to penetrate our atmosphere, small debris could still cause significant damage to spacecraft and orbiters while hurtling around the Earth at tens-of-thousands of mph. That's where the ESA has stepped in, hastily assessing the trajectory and threat of each piece. What they found was encouraging.

"The event is not considered major," Holger Krag of ESA's Space Debris Office said in a release. "Should the reported number of fragments stabilize at this level, we can consider it to be within the range of the past 250 on-orbit fragmentation events."

"We do not expect any meaningful risk due to the event," he added.

Still, the agency presses that this is a strong reminder of the risk that aging satellites pose. Later this month, experts will meet at ESA's ESTEC technical centre at Noordwijk, the Netherlands, to discuss debris mitigation technologies - methods to ensure that satellites can remove themselves from key low-Earth orbits well in advance of a repeat problem like this.

As things stand, the ESA often resorts to harpooning space debris that can get in the way of a mission, while NASA and various independent research partners have been investigating ultra-fast robotics to catch hurtling space junk.

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