Asuka

 1993-011A

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The ASTRO D satellite was Japan's most ambitious astronomy satellite to date and involved extensive collaboration with the United States. Four foil-mirror X-ray telescopes from NASA-Goddard were installed on a folding optical bench which extended after launch, to give X-ray images of limited quality over the 30 x 30 arcmin field of view (although the resolution was around 2 arcmin, the point spread function of a single source covered much of the field of view). The mirror outer diameter was 0.34m and focal length was 3.50m. Two traditional proportional counter imagers (GIS) were carried, as well as two X-ray CCD detectors known as SIS. The SIS detectors, developed at the Massachusetts Institute of Technology in the USA, provided unprecedented spectral resolution without the use of dispersive gratings and could provide low resolution information on emission lines in the 0.5 to 10 keV range; the same technology was later used for the ACIS camera on NASA's Chandra.

The 420 kg satellite was 3m long at launch, the telescopes extending its deployed length to 4m. Spacecraft diameter is 1.2m.

After launch, ISAS renamed ASTRO D as `Asuka', after a mythical bird and an important historic region. To avoid confusion for English speakers ISAS also officially gave the satellite another name with identical pronunciation for use in scientific publications and in non-Japanese speaking countries: ASCA, an acronym for Advanced Satellite for Cosmology and Astrophysics. Control was from ISAS/Kagoshima.

The mission was very successful, with the unique CCD detectors attracting research interest from astronomers around the world. Some astronomers outside of Japan had begin to participate in the ISAS X-ray astronomy program with Ginga, but it was with ASCA that widespread foreign guest observer and archival research became standard.

On 2000 Jul 14 an enormous solar flare triggered a large geomagnetic storm and increased drag. ASCA safemoded and because the increased atmospheric drag exceeded the momentum wheel torque, lost attitude control. ASCA still transmitted in daylight when the solar panels are illuminated, spinning at 0.3 rpm. ASCA reentered on 2001 Mar 2 near the Solomon Islands.

Asuka (ASCA)
Date	Time	Event	Orbit
1993 Feb 20	0220	Launch by Mu-3S-II	KAG
		T+0:40 SOB sep
		T+1:24 Stage 1 cutoff, sep
		T+1:26 Stage 2 start
		T+2:36 Stage 2 cutoff, coast
		T+2:35 Fairing sep
	0223	T+3:15 Stage 3 spinup
	0224	T+4:00 Stage 2 sep
	0227	T+7:13 Stage 3 burn 87s? at 570 km
	0228	T+8:40? M3B rocket cutoff
	0229	T+9:30 M3B sep
	0229	T+9:40 Yo-yo despin
			515 x 606 x 31.1
2000 Jul 15		Safemode, lost attitude
2000 Jul 16		Batteries depleted
2001 Mar 2		Reentered