The first ORFEUS mission was launched on September 12, 1993 at 7:45 am (EDT) with Shuttle Mission STS-51 (Discovery) for its flight to space. On the first day in space the main payload, the Advanced Communications Technology Satellite (ACTS), was released. On the second day the ASTRO-SPAS satellite was released and captured again after 6 days. On September 22, Discovery landed at night at 3:56 am (EDT) at Kennedy Space Center.
The ASTRO-SPAS satellite as well as all instruments on board the satellite were controlled by a specially equipped control center (SPAS Operations Center - SPOC) operated at the Kennedy Space Center. Also the Echelle Spectrometer was operated by the Tübingen Team with its own ground control station.
Before the finally successful launch there were three launch attempts which had to be scrubbed:
- On July 17, the launch was scrubbed due to problems with the pyrotechnic initiator controller, which triggers the release of the solid rocket boosters from the mobile launcher platform.
- On July 24, the launch was scrubbed due to problems with a hydraulic power unit in one of the solid rocket boosters.
- After the next launch date was shifted due to further technical problems and because of the Perseid meteor shower to August 12, also this launch attempt had to be scrubbed at the T-3 seconds mark, when the shuttles main engines had ignited already. One of 4 sensor signals which measure the fuel flow had failed, causing an immediate shutdown of the main engines. After this, the main engines had to be replaced, causing a further delay of several weeks.
The two spectrometers on board the ORFEUS telescope should be operated alternately. Therefore a movable mirror was mounted in the telecope (see page telescope). This mirror stuck during its second actuation, but luckily it stopped at a position, where an unobstructed observation with the Berkeley spectrometer still was possible. For this reason there exist no Echelle spectra from the first ORFEUS mission.
Links
Wikipedia: STS-51
NASA Space Shuttle Archive: STS-51
Kennedy Space Center: STS-51
JSC image gallery STS-51
NASA STS-51 video highlights with comments of the astronauts
