Sometime in the next two hours, one of my favourite satellites*, GOCE, will fall to Earth. GOCE stands for Gravity field and steady-state Ocean Circulation Explorer and is the European Space Agency’s gravity measuring mission. It flies in a low earth orbit measuring tiny variations in the earth’s gravitational field to help measure ocean circulation patterns and sea-level. It also mapped the Mohorovicic Discontinuity, the boundary between crust and mantle, which I reported on here. Because it is flying so low (about 280km), it encounters a lot more air resistance than other boxy satellites, and so it was designed to be a sleek and beautiful machine. Being so beautiful, and built in Italy, it is often referred to as either the Ferrari or Supermodel of satellites.
However, this air resistance also limits its lifespan, as more fuel is needed to keep it on its trajectory. Launched in 2009, the end of its lifespan is now, and sometime between now (9:56 am Australian Time) and the next two hours it is expected to plunge into the Indian or Pacific Oceans. It will be an interesting experiment, as there hasn’t been an uncontrolled satellite re-entry for quite a while**. New materials make for a robust construction in GOCE, and so about 25% of the satellite is expected to make the surface of the Earth, once it breaks apart and begins to burn up at 80km.
In its last few hours, engineers have been downloading all the final remains of data, helping to predict its final trajectory as it bids us its farewell.
Slate’s Phil Plait on GOCE here.
Good BBC article from a month ago here.
* not geeky at all
** better than leaving it uncontrolled in space where it might cause an accident, we’ve all seen the documentary Gravity right!