2006-005A
ASTRO-F, the Infrared Imaging Surveyor (IRIS), has a 0.7m telescope cooled to do a 50-200 Mu m far infrared sky survey. It was named Akari ('light') after launch.
The spacecraft mass was 952 kg at launch. Its bus module supports cryostat and star trackers on a truss. The cryostat is 1.5m dia and 2.5m high, while the full satellite is 3.7m long, 1.8m dia, 5.7m span with 2 panels. The telescope has a SiC mirror, a focal plane cooled to 6K with FIR detectors cooled to 1.8K. The telescope beam was 21" at 60 microns.
Orbit 750 x 750 km x 97 deg.
The M-V-8 launch vehicle also carried CUTE-1.7 and a solar sail experiment 15.6m span, the Solar Sail Subpayload (SSP, soraseiru sabupeirodo). There were problems with the Sun sensor that delayed initial operations of Akari, and cover ejection was delayed to Apr 13. The ejectable telescope lid was 2.0m dia 0.4? high.
After initial checkout Akari began a sky scan which lasted 550 days and surveyed 94 percent of the celestial sphere. On 2007 Aug 26 the satellite used up its 170 liters of liquid helium and the 68-cm main telescope began to warm up from its 6-Kelvin operational temperature. In 2008 the Akari infrared observatory began a new phase of its mission. On the ground an international team began production of the source catalogs, which would supersede the 20-year-old IRAS point source catalog and serve as finding lists for new observatories like Herschel. Meanwhile, in space, Akari's shorter wavelength detectors were still operating well thanks to mechanical coolers which keep the focal plane at about 40 Kelvin. The Infrared Camera system developed by a team led by the University of Tokyo takes images in the traditional K, L and M bands as well as the MIR-S and MIR-L bands at 7-11 and 15-25 microns. Akari's other instrument system, the Far IR Surveyor, which was developed by Nagoya University, had four channels returning brightness and spectral information between 50 and 180 microns; it was retired after cryogen depletion.
| ASTRO F | |||
| Date | Time | Event | Orbit |
|---|---|---|---|
| 2006 Feb 21 | 2128:00 | Launch by M-V-8 | USC |
| T+1:15 St 1 sep, 50 km? | |||
| T+1:15 St 2 burn | |||
| T+2:31? St 2 burnout 150 km | |||
| T+3:06 Fairing sep | |||
| T+3:20 St 2 sep | |||
| T+3:22 St 3 nozzle extend, spring jettison | |||
| T+3:25 St 3 burn 225 km? | |||
| 2133 | T+5:09 St 3 burnout 305 km | ||
| T+5:57 180 deg pitch begins | |||
| T+7:02 Pitch complete | |||
| Spinup? | |||
| 2136 | T+8:39 St 3 sep | ||
| 2145 | T+17:20 CUTE-1.7 sep from St 3. | ||
| 2146 | T+18:20 Sail deploy from St 3 | ||
| T+1:50:00 Solar panels deployed | |||
| 94.82 301 x 781 x 98.2 | |||
| Orbit raise | |||
| 2006 Apr 13 | 0755 | Cover jettison | |
| 2007 Aug 26 | 0833 | LHe depleted | |
| 2011 May 24 | Power supply malfunction | ||
| 2011 Jun | Science ops ended | ||
| 2011 Nov 9 | 98.8 693 x 706 x 98.3 | ||
| 2011 Nov 11 | 97.71 596 x 701 x 98.3 | ||
| 2011 Nov 24 | 96.08 441 x 700 x 98.3 | ||
| 2011 Nov 24 | end of ops | ||
| 2012 Jan 17 | 96.05 439 x 698 x 98.3 | ||
Payload:
- 0.67m telescope
- Cryostat with 170 liters of LHe
- IRC IR cameras (3): NIR (K,L,M), 10 mu, 20 mu
- IRC/NIR 10' FOV, 1.5" pixels
- IRC/MIR-S, 256 x 256 Si:As at 7-11 mu
- IRC/MIR-L, 256 x 256 SiAs at 15-25 mu, 10' FOV, 2"/pix
- FIS, Far IR Surveyor, 50-200 mu.
- 60-micron channel, 30"/pixel, 20x2
- Wide-S channel, 50-100 mu for FTS
- Wide-L channel, 100-200 mu with FTS
- 170-micron channel, 50"/pix, 15x2
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