Hitomi

2016-012A

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Hitomi (

\uni{ ひとみ}{ }

or

\uni{ 瞳}{ }

- eye pupil) was the ASTRO-H mission, originally NEXT (Next X-ray Telescope for JAXA). a followon to Astro-E2 with a hard X-ray imaging telescope and a very long focal length.

Orbit 550 x 550 km x 31 deg. Size 4.5m long, 12m deployed, 2.2m dia. Mass 2700 kg. Launch by H-2A 202 with a 4S fairing.

The three HXT telescopes are 30-60 arcsecond resolution, 750 sq cm area, 8 arcmin field of view, 0.5-80 keV spectral range. The `super-mirror' coating and multilayers allow the hard X-ray imaging. Each HXT has a WXI Wide band X-ray Imager with an SXI CCD array (12 arcmin field of view) and an HXI CdTe detector (6 x 9 arcmin field of view). The single SXT has the SXS microcalorimeter at the focal plane, while the SGD is a Compton telescope for soft gammas.

SXS has 6x6 pixel array 28" pixels, 4 eV res at 3-12 keV in 12 m long spacecraft. Dewar operates at 50 mK.

By mid March the SXS had begun taking data, although not with its full energy range. The results were reported to be scientifically excellent, in preparation for the calibration observation phase due to begin in April. But on Mar 25 disaster struck - at 1910 UTC the satellite started tumbling and then at 0140 UTC Mar 26 the spacecraft partly disintegrated. US tracking found ten debris objects in orbit.

During the next scheduled passes, the first at 0740 UTC, JAXA received only a short burst of telemetry later determined to be from a different satellite. JSPOC reported:

Breakup Notification: SL-12 R/B (SCC# 33472) at approximately 0145z, 27
Mar 16. 21 associated pieces as of 1400z 27 Mar 16. ASTRO H (SCC# 41337)
at approximately 0820z, 26 Mar 16. 5 associated pieces as of 1400z 27
Mar 16. The events are not related. All objects have been added to
conjunction assessment screenings.

ASTRO-H
Date	Time	Event	Orbit
2016 Feb 17	0845	Launch by H-IIA F30	TNSC
		Azimuth 104 deg
		T+1:39 SRB MECO
		T+1:48 SRB sep
		T+4:15 Fairing sep
	0851	T+6:38 MECO 311 km 4.8 km/s
		T+6:46 St 1 sep
		T+6:52 SEIG-1
	0858	T+13:24 SECO-1
	0859	T+14:14 St 2 sep	575 x 575 x 31.0
	0907	T+22:34 Chubu2 sep
	0912	T+27:34 Chubu 3 sep
	0917	T+32:34 Horyu-4 sep
2016 Feb 28		EOB extended
2016 Feb 29		Begin Initial Func. Verif. Phase
2016 Mar 25	1910	Attitude anomaly over S atlantic
	2049	MSP pass, only partial telem
	2231	MSP Santiago pass
2016 Mar 26	0052	MGN W Aus pass
		JAXA last comm pass, problem
2016 Mar 26			96.11 563 x 581 x 31.0
2016 Mar 26	0137	Debris event, over Mexico, orbit change	96.07 560 x 580 x 31.0
	0740	scheduled pass over W Aus
	1449	Beacon signal for 3 minutes over Japan
	1623	Beacon signal for 4 minutes over Japan
2016 Mar 28	1306	Beacon for 10s over Japan
2016 Mar 28	1533	Last beacon signal intercepted for 6s, Santiago

Payload:

• SXT-1 Soft X-ray imaging system with SXI at focus, f= 5.6m

• SXT-2 Soft X-ray Telescope - spectrometer with SXS detector, f = 5.6m, 0.3-12 keV

• HXT-1 Hard X-ray Telescope (2) on extensible bench, focal len 12m (Nagoya/) 300 cm2 at 30 keV, 5-80 keV

• HXT-2 Hard X-ray Telescope (2) on extensible bench, focal len 12m (Nagoya/) 300 cm2 at 30 keV, 5-80 keV

• SXS Soft X-ray spectrometer, 0.3-10 keV, 0.45m outer dia mirror with XCS (X-ray Calorimeter Spectrometer).

• SXI Soft X-ray imager, CCDs

• HXI1 Hard X-ray imager, Si DSSD (Double Sided Si Strip)/CdTe cross-strip detectors 9' FOV at end of 6m extensible optical bench

• HXI2 Hard X-ray imager, Si/CdTe cross-strip detectors 9' FOV at end of 6m extensible optical bench