The European Space Agency said one of four of its Cluster mission satellites, intended to work together in studying Earth's space environment and its interaction with the solar wind, failed to switch on a vital scientific instrument in March, jeopardizing the entire mission.
Even worse, no status information could be coaxed out of the satellite's instruments, an ESA release said Thursday.
"With no status data and no response from the instrument, we suspected either that the device's five power switches were locked closed or a failure caused by an electrical short circuit, one of the most dangerous faults on any satellite," ESA's Jurgen Volpp, Cluster operations manager said.
After eliminating a short circuit as a possible fault, controllers were faced with the task of trying to activate the power switches.
Tests in 1995 had simulated what might happen if three of the five switches locked close, but no one ever considered how to recover from all five being locked or even thought such a situation possible.
The team painstakingly designed a recovery procedure and tested it on one of the functioning sister satellites.
"The solution was based on a 'dirty hack' -- jargon referring to any non-standard procedure -- but we really had no other option," Volpp said.
A series of commands was radioed up June 1 from a very tense control room, Volpp said.
To immense relief, he said, these successfully flipped the power switches to "on" and the recalcitrant satellite came back to life, putting the entire Cluster mission back on track.