FUSE

 1999-035A

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The Far Ultraviolet Spectroscopic Explorer was originally the last Delta explorer. It was descoped in the mid 1990s and a revised, smaller spacecraft was built by Orbital/Germantown for JHU. The new FUSE is a MIDEX class mission. The bus is the medium LeoStar bus derived from the Fairchild MMS.

The spacecraft has a mass of 1130 to 1220 kg. Launch vehicle is a Delta 7320-10. Bus mass is 580 kg; instrument mass is 780 kg. Total mass is 1360 kg. The 0.35m telescope has four off-axis parabolas with an effective area of 80 sq cm and 1.5 arcsec resolution. Wavelength range covered is 905-1195A. The satellite is 1.2 x 1.8 x 5.5m in size with about a 6.0m solar panel span.

The effect of FBC was apparent as understaffing meant less prelaunch testing and more small teething troubles on orbit. Initially large slit observations were done as the channel alignment and wavelength calibration were refined. In early 2000 the D/H measurement with the narrow slit was begun.

On 2004 Jun 6, nine debris objects were emitted from FUSE at the time of a sensor door closing in safemode; they were probably pieces of insulation.

FUSE
Date	Time	Event	Orbit
1999 Jun 24	1544:00	Launch by Delta 271	CC LC17A
		T+1:03 SRM burnout
		T+1:06 SRM sep
		T+4:24 MECO
		T+4:37 SES-1
		T+4:58 Fairing sep
	1554	T+10:17 SECO-1	185 x 855 x 28.8
	1652	T+1:08:22 SES-2
	1653	T+1:09:07 SECO-2	100.08 754 x 769 x 25.0
	1700	T+1:16:05 Stage 2 sep
	1714	Stage 2 depletion burn	95.63 182 x 915 x 19.1
1999 Nov		Science operations begin
2001 May 31		Wheel failure 1
2001 Dec 10		Reaction wheel failure (2nd of 4)
2002 Mar 2?		FUSE restored to operation
2003 Jul		Zero gyro mode installed
2004 Jun 6		Safemode, debris objects
2004 Dec 27		Safemode,reaction wheel problem
2005 Nov		Resumed operations
2007 Jul 12		Last reaction wheel fails, end of science ops
2007 Oct 18		Decomissioned

Payload:

• HRS High Resolution Spectrograph