The engine constantly throttles up and down, not only to counter the drag on the satellite from residual air molecules in near space but also to smooth the flight of the vehicle to minimise the noise in the gravity measurements.

BBC: Goce gravity mapper surfs atmosphere

"All they do is put an ID card down and pick up a phone, " says Bill Knight, who stands behind a counter giving out the phones.

CNN: Volunteer greeters offer hugs, applause for troops