Two satellites to be rescued

At the moment, two very different satellites are currently being rescued by their ground controllers. The first, GOCE, is central to a scientific mission by the European Space Agency (ESA). Responsible for accurately measuring variations in Earth's gravity field, this satellite has experienced two successive failures in two onboard computers (in February then July 2010). The satellite is operating normally, but can no longer transmit the data that it collects. On the ground, engineers are hoping that a software update sent to GOCE will allow this failure to be resolved. To date, the mission has however already collected two thirds of the expected data and provided a first map of the variations in Earth's gravity field (see this Enjoy Space article). The second is an American military telecommunication satellite, AEHF-1.  Successfully launched from Cape Canaveral Air Force Station on 14 August, it should provide secure high-level communications between United States military staff, their theatres of operations and even the president!  However, due to a failure in its main propulsion system, AEHF-1 has not been able to reach its operating orbit. The American military has announced that that the best specialists are working on the issue and that by using the altitude thrusters (much less powerful and normally used to keep the satellite in its orbit), ground controllers will “drive” AEHF-1 to its intended location within several months. Despite this unexpected fuel consumption, the operational life of 14 years could still be achieved.

Published 31 August 2010