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Sirio 1, 2

Sirio 1

Sirio 1 (Satellite Italiano ricerca industriale orientato) was primarily a geostationary communications satellite. It included experiments measuring the local plasma and field environment and the flux of low-energy cosmic rays.

The satellite was launched on a Delta-2313 and was located at 15 deg w longitude.

The Sirio-2 geostationary spacecraft carried two independent payloads:

  • an S-band multichannel transponder for meteorological data dissemination ('MDD') in Africa, and
  • an laser detection/time-tag/retroreflector assembly to permit atomic clock synchronization over intercontinental distances (laser synchronization from stationary orbit - 'LASSO').

The cylindrically shaped spacecraft measured 144 cm in diameter and 240 cm in length including the apogee boost motor. The primary structural members are equipment platforms and a central thrust cone carrying conventional housekeeping electronics in addition to payloads. Attitude, orbit and spin rate control were performed using a hydrazine propulsion system including four thrusters. The spin rate would have been maintained at 90 rpm throughout the two-year nominal lifetime. A mechanically despun antenna relayed S-band telemetry (meteorological and housekeeping), while a traditional omnidirectional turnstile system supported VHF ranging and telecommands, as well as housekeeping telemetry in transfer orbit and as backup geostationary orbit.

Sirio-2 was lost in a Ariane-1 launch failure in 1982.

Nation: Italy
Type / Application: Communication
Contractors: Compagnia Nazionale Satelliti per Telecommunicaziono SpA
Equipment: ?
Propulsion: ?
Power: Solar cells, batteries
Lifetime: 2 years
Orbit: GEO
Satellite COSPAR Date LS Launch Vehicle Remarks
Sirio 1 1977-080A 25.08.1977 CC LC-17B Delta-2313
Sirio 2 1982-F06 09.09.1982 Ko ELA-1 F Ariane-1 with MARECS B