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An account of the rescue of Olympus in 1991, following loss of signal. The video includes the following:
0:12 It is in the innovative nature of space technology that problems arise and remarkable solutions are sometimes found. The story of the rescue of Olympus is a classic of the genre.
0:29 Olympus, the world’s largest and most powerful 3-axis stabilized communication satellite was launched into a geostationary orbit by Ariane 12 July 1989., and has been in continuous operation ever since.
0:57 Animation of Olympus being in space . On the 29 May 1991, the satellite lost its Earth present signal and switched automatically to a emergency sun acquisition mode
1:10 Pierre Kaufeler, Spacecraft Operations Manager, ESOC, explains (in French) what happened.
01:38 The emergency sun mode is a safety mode for most 3-axis stabilised spacecraft. It is normal that the spacecraft goes into this pre-programmed safety mode in case of a failure. Until this happened Olympus had been in an ordinary geostationary orbit, 36 000 km above the Earth, 19 degrees west longitude. But the satellite problems with its two infrared Earth sensors, which had become unreliable. On 29 May an un-validated operational procedure was used to try to recover from this problem, and the control of the satellite was lost.
2:58 Pierre Kaufeler speaks (in French) explains what happened.
3:41 With the loss of control from Fucino, Italy, the satellite was spinning in such a way that the solar panels were virtually supplying no power. The temperature dropped to minus 60 degrees Celsius. Olympus was effectively dead in space.
4:04 Alan Smith, Olympus Flight Operations Director, ESOC: The spacecraft was out of control, the batteries were flat, the spacecraft was tumbling with one revolution every 90 seconds. We were not able to tele command the spacecraft and we did not get any telemetry from it.
4:21 Also it was beginning to move out of its geostationary orbit moving circa 5 degrees a day, out of range of the Fucino tracking station.
4:46 Alan Smith, continued: With the spacecraft drifting 5 degrees per day, it would soon be out of contact with out ground station Fucino. Everybody’s feeling were quite pessimistic, and the change for recovery was not very high.
5:12 Jean-Marie Luton, ESA Director General (DG), instructed ESOC to do whatever was possible to recover the spacecraft. But never before in the history of space had such a rescue been attempted.
5:39 David Wilkins, Chief of Operations for the Olympus Recovery Mission, ESOC: ESOC took over the recovery task following the issue of the DG’s instructions. Wilkins explains all the difficulty, e.g. with very little power and only sometimes during the day, very little telemetry, and the spacecraft was rotating.
7:35 Felix Garcia-Castaňer, Director of Operations, ESOC: We managed to exercise our corporate agreements with other space agencies, with NASA and CNES in order to use the ground stations in California and in Kourou, and this has been vital in the success of the mission operation. I also must stress the very good cooperation with industry, and this case with British Industry, resulted in the possibility to put together a very good integrated team.
8:55 B y June the recovery plan had been worked out: First getting telemetry data, second shutting down any system not needed to save energy, third getting adequate solar array power to charge the batteries, and forth to stop the spinning.
10:09 On the 19 June came the first indications that the plan might work.
10:14 David Wilkins, we had to wait until 19 June, when we managed to get commands in.
10:35 Olympus started to indicate it had accepted some commands from ESOC.
10:47 Pierre Kaufeler speaks (in French) explains the problematic and how the control of the spacecraft worked out.
11:27 ESOC and ESTEC experts doubled their efforts working long into the night, ignoring weekends. The initial calculations proved correct. By July the sun angle had improved sufficiently to charge the batteries.
11:58 With only limited charge of the batteries, tele command and telemetry start becoming continuous.
12:08 Pierre Kaufeler speaks (in French) explains.
11:45 On the 29 July, the preparation was completed and a series of burn commands were send, to ignite the thrusters to de-spin the satellite, and stop the drifting.
13:08 On 6 August a command corrected the orbit inclination. On 9 August a engine burn reduced the drift to 0.9 degrees. Then on 13 August a final burn repositioned Olympus at 19 degrees east. It was back where it should be.
13:35 Alan Smith explain a bit of the result of the recovery.
14:22 Olympus recovery team had written history by the Olympus recovery.
15:20 The End