1997-045A
The Advanced Composition Explorer (ACE) was a Delta-class Explorer mission to measure energetic particles in near-Earth interplanetary space and study the interstellar medium. It is stationed at the Earth-Sun L1 point. Goals were:
- directly sample solar material, finding solar coronal and photospheric isotopic abundances and cosmic ray isotopic abundances.
- Determine `anomalous cosmic ray' abundances, possibly indicating isotopic composition of the ISM.
- Direct measurements of charge and mass fractionation during acceleration events (solar flares and interplanetary accelerations), and study acceleration timescales.
The spin-stablized spacecraft is based on the AMPTE-CCE bus and is built by APL for GSFC. The octagonal 2.5m long, 1.6m diameter, 752 kg satellite has 4 solar panels and two booms spanning 8.3m. It was launched 1997 Aug by Delta 7920-8. Principal investigator for ACE is E.Stone of CalTech. Total mass is 785 kg including 189 kg of hydrazine.
The Delta second stage performed a retrograde burn after insertion for disposal in an orbit with short lifetime (Ted Kawamura, Boeing, private comm. 1997 Sep 9.)
ACE entered a clockwise Lissajous orbit around L1.
| ACE | |||
| Date | Time | Event | Orbit |
|---|---|---|---|
| 1997 Aug 25 | 1439:00 | Launch by Delta 7920 | CC LC17A |
| 1440 | T+1:03 SRM 1-6 burnout | ||
| 1440 | T+1:05 SRM 7-9 on | ||
| 1440 | T+1:06 SRM1-3 sep | ||
| 1440 | T+1:07 SRM 4-6 sep | ||
| 1441 | T+2:08 SRM 7-9 burnout | ||
| 1441 | T+2:11 SRM 7-9 sep | ||
| 1443 | T+4:23 MECO | -2700 x 185? | |
| 1443 | T+4:31 Stage 1 sep | ||
| 1443 | T+4:36 Stage 2 burn 1 | ||
| 1443 | T+4:41 PLF sep | ||
| 1446 | T+7:33 SECO-1 | 185 x 185 x 28.7 | |
| 1544 | Delta burn 2 T+1:05:06 | ||
| 1548 | SECO-2 alt 233 km, T+1:09:16 | 177 x 1281969 x 28.7 | |
| 1553 | Delta sep T+1:14:47 | ||
| 1620 | Evasive burn T+1:41:27 | ||
| 1620 | SECO-3 T+1:41:32 | ||
| 1627 | Depletion burn T+1:48:07 | ||
| 1627 | Depletion cutoff T+1:48:13 | ||
| Delta orbit: | 174 x 840904 x 28.8 (B) | ||
| 1997 Aug 26 | 0000 | Range 87740 km | 182 x 1258425 x 28.7 |
| 0516 | Pass EL1:4 | ||
| 0533? | Delta pass EL1:4 | ||
| 1997 Aug 26 | MCC-1 | ||
| MCC-2 | |||
| 1997 Aug 27 | 0000 | Range 266800 km | |
| 1997 Sep 7 | Engineering burn | ||
| 1997 Sep 13 | OSM-1 | ||
| 1997 Sep 14 | OSM-2 | ||
| 1997 Sep 15 | OSM-3 | ||
| 1997 Sep 16 | 0423? | GSEx above 1.2Mkm, enter L1 region | |
| 1997 Sep 19 | OSM-4 | ||
| 1997 Sep 23 | OSM-5 | ||
| 1997 Sep 24 | OSM-6 | ||
| 1997 Sep 26? | Delta perigee, reentry? | ||
| 1997 Oct 2 | Trim burn | ||
| 1997 Dec 9 | HOI-1 (total HOI 115m/s) | ||
| 1997 Dec 10 | HOI-2 | ||
| 1997 Dec 11 | HOI-3 | ||
| 1997 Dec 12 | HOI-4 | ||
| 1997 Dec 19 | HOI trim | ||
| 1998 Jan | In L1 halo orbit | ||
| 1998 Jan 15 | SK-01 0.8m/s | ||
| 1998 Feb 20 | SK-02 3.6m/s | ||
| 1998 Mar 25 | SK-03 2.3m/s | ||
| 1998 May 1 | SK-04 0.2m/s | ||
| 1998 Jun 5 | SK-05 0.2m/s | ||
| 1998 Jul 21 | SK-06 0.3m/s | ||
| 1998 Sep 3 | SK-07 0.3m/s | ||
| 1998 Nov 11 | SK-08 0.4m/s | ||
| 1999 Jan 14 | SK-09 0.7m/s | ||
| 1999 Apr 9 | SK-10 0.5m/s | ||
| 1999 Jul 2 | SK-11 0.5m/s | ||
Payload:
- Propulsion system (10 x 4.5N MR-111 Olin mono hydrazine)
- SWIMS Solar Wind Ion Mass Spectrometer
- SWICS SW Ion Composition Spectrometer
- ULEIS Ultra Low Energy Isotope Spectrometer
- SEPICA Solar Energetic Particle Ionic Charge Analyser
- SIS Solar Isotope Spectrometer
- CRIS Cosmic Ray Isotope Spectrometer
- EPAM Electron Proton and Alpha Monitor
- SWEPAM Solar Wind Electron Proton and Alpha Monitor
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