PARIS, March 11 (UPI) -- As Japan remembers the 18,000 people dead and missing in the March 2011 earthquake and tsunami, researchers say they found the massive quake was felt in space.
The European Space Agency's sensitive GOCE satellite detected the sound waves traveling upward from the Earth as the earthquake made the planet's surface vibrate like a drum, an ESA release reported.
Low-frequency sound -- infrasound -- that causes vertical movements that expand and contract the atmosphere by accelerating air particles were detected by the satellite while it was busy conducting is main mission of mapping Earth's gravity.
GOCE orbits at the lowest altitude of any observation satellite but at less than 170 miles up it has to periodically use its thrusters to compensate for drag from the thin upper remnants of the atmosphere.
A record of these thrusts from March 2011 was recently analyzed and showed the satellite was responding to the sound waves rising through the thin atmosphere from the earthquake in Japan.
"Seismologists are particularly excited by this discovery because they were virtually the only Earth scientists without a space-based instrument directly comparable to those deployed on the ground," Raphael Garcia from the Research Institute in Astrophysics and Planetology in Toulouse, France, said.
"With this new tool they can start to look up into space to understand what is going on under their feet."