1995-065A
The Solar and Heliospheric Observatory was launched on 1995 Dec 2. The satellite was built by Matra Marconi Space for ESA, which managed the SOHO project in collaboration with NASA. It is 3.65m long, 3.65m wide and has a mass of 1864 kg (ESA web page) or 1875 kg (AWST). SOHO, together with CLUSTER, formed part of the Cornerstone 1 (CS1) mission, the first element of the Horizon 2000 program to be launched.
SOHO was the second L1 mission and entered a counterclockwise (Class 2) halo orbit of radius 600000 km around the Earth-Sun L1 point 1.5 Mkm from the Earth. (ISEE had used a clockwise, Class 1, orbit).
In Jun 1998, SOHO went out of control during a momentum management maneuver. Errors in commanding the satellite meant that the emergency sun re-acquisition procedure failed and contact was lost. Goldstone radar detected the spacecraft a few weeks later, and intermittent contact was restored on Aug 4.
145 kg of fuel remained in mid-1999; original loading was 240 kg meaning the dry mass is 1624 kg. A later report gave 1863 kg full with 251 kg prop.
| SOHO | |||
| Date | Time | Event | Orbit |
|---|---|---|---|
| 1995 Dec 2 | 0808:01 | Launch by Atlas IIAS Centaur (AC-121) | CC LC36B |
| 0808:01 | Atlas and first pair SRB on | ||
| 0808:57 | First pair SRB burnout | ||
| 0808:59 | Second pair SRB on | ||
| 0809:09 | First pair sep | ||
| 0809:56 | Second pair burnout and sep | ||
| 0810:43 | BECO | ||
| 0810:47 | Booster jettison | ||
| 0811:33 | Fairing sep | ||
| 0813:07 | SECO | ||
| 0813:09 | Atlas sep | ||
| 0813:26 | Centaur MES1 | ||
| 0817:49 | Centaur MECO1 | 175 x 183 x 28.8 | |
| 0932:44 | Centaur MES1, 1:57 over E Pac. | ||
| 0934:42 | Centaur MECO1 | ||
| 1009:42 | Centaur sep | 177 x 1115746 x 29.72 | |
| Centaur sep burn | |||
| 1030s | Centaur blowdown | ||
| 2310 | Pass EL1:4 | 174 x 1110172 x 29.72 | |
| 1995 Dec 3 | 2300s | TCM-1, 243000 km range | |
| 1995 Dec 15 | 1 Mkm range | 3500 x 1290200 x 29.2 | |
| 1995 Dec 22 | s | TCM-2 | 9180 x 1345592 x 29.5 |
| 1995 Dec 23 | 0750 | GSEx above 1.2Mkm, L1 region | |
| 1996 Feb 14 | 1700 | Halo orbit insertion | 238000 x 666672 x 54.4 |
| 1996 May 23 | SK-1 0.3k/s | ||
| 1996 Aug 1 | 290000 x 1568000 x 22.7 | ||
| 1996 Sep 1 | 881024 x 1326562 x 23.9 | ||
| 1996 Sep 11 | SK-02 0.5m/s | ||
| 1997 Jan 14 | SK-03 0.04m/s | ||
| 1997 Apr 11 | SK-04 0.19 m/s | ||
| 1997 Sep 4 | SK-05 1.9m/s | ||
| 1997 Nov 29 | SK-06 0.04m/s | ||
| 1997 Dec 19 | SK-07 0.40m/s | ||
| 1998 Apr 17 | SK-08 1.4m/s | ||
| 1998 Jun 24 | Momentum management mvr | ||
| Safemode | |||
| 2100 | Emergency sun re-acq | ||
| 2330 | Safemode | ||
| Emergency sun re-acq | |||
| 1998 Jun 25 | 0340 | Safemode, contact lost | |
| Net dV 1.42 cm/s | |||
| 1998 Jul | Contact by Arecibo | ||
| 1998 Aug 3 | DSN contact, Recover control | ||
| 1998 Sep 16 | Operations resume | ||
| 1998 Sep 25 | RM-01 6.2m/s | ||
| 1998 Oct 16 | RM-02 1.9m/s | ||
| 1998 Nov 13 | RM-03 2.3m/s | ||
| 1998 Dec 21 | Safemode, gyro failed | ||
| 1999 Jan | Observations resume | ||
| 1999 Jan 7 | RM-04 8.1m/s | ||
| 1999 Jan 10 | RM-05 8.6m/s | ||
| 1999 Jan 26 | RM-06 4.0m/s | ||
| 1999 Feb 1 | RM-07 0.3m/s | ||
| 1999 Feb 14 | Safemode again | ||
| 1999 Feb 18 | Out of safemode | ||
| 1999 Mar 5 | RM-08 0.1m/s | ||
| 1999 Jun 17 | SK-09 0.5m/s | ||
| 2013 Jan | UVCS retired | ||
Payload:
- Service module with hydrazine thrusters
- CDS (Coronal Diagnostic Spectrometer) o CDS from Rutherford Appleton Laboratory, United Kingdom. Effective geometric diameter about 20 cm?; Wolter II telescope 150-800A
- CELIAS (Charge, Element, and Isotope Analysis System) o CELIAS from the University of Bern, in Switzerland.
- COSTEP (Comprehensive Suprathermal and Energetic Particle Analyzer) o COSTEP from the University of Kiel, Germany (in German).
- EIT (Extreme ultraviolet Imaging Telescope) o EIT from the NASA/Goddard Space Flight Center, USA. 12 cm tel.
- ERNE (Energetic and Relativistic Nuclei and Electron experiment) o ERNE from the University of Turku, in Finland.
- GOLF (Global Oscillations at Low Frequencies) o GOLF from the Institut d'Astrophysique Spatiale, France.
- LASCO (Large Angle and Spectrometric Coronagraph) o LASCO from the Naval Research Laboratory, USA. o LASCO from the Max Planck Institute for Solar System Research, Germany.
- MDI/SOI (Michelson Doppler Imager/Solar Oscillations Investigation) o MDI/SOI from Stanford University, USA.
- SUMER (Solar Ultraviolet Measurements of Emitted Radiation) o SUMER from the Max Planck Institute for Solar System Research, Germany. ; 13 cm telescope-spectrograph
- UVCS (Ultraviolet Coronagraph Spectrometer) o UVCS from Harvard-Smithsonian Center for Astrophysics, USA. 7 cm mirror in spectrograph
