Update this morning from ESA’s Christoph Steiger, the GOCE Operations Manager at ESOC.
An important milestone has just been reached [last night – Ed.], with the pressure in the fuel system of GOCE’s ion engine dropping below 2.5 bar, which is the nominal operating pressure required to fire the engine.
We estimate that about 350g of Xenon fuel are left in the fuel tank. All eyes are now on the performance of the ion engine out of its nominal pressure range. If it kept functioning down to a pressure of 0 bar (corresponding to a completely empty tank), the orbital decay would start around 26 October. However, we expect the ion engine to terminate quite some time before that.
The ending of science operations in ‘drag-free mode‘ could essentially happen any moment now. The operations teams at ESOC are ready for the ensuing orbital decay phase, the exciting last phase of GOCE flight operations.