FUSE

Far Ultraviolet Spectroscopic Explorer

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General

Designation	25791 / 99035A
Launch date	24 Jun 1999
Country of origin	United States
Mission	Scientific: Astronomy
Perigee/Apogee	800 km
Inclination	25°
Period
Launch vehicle	Delta 2 #271

FUSE will access the wavelength below 1180 Angstroms (the HST STIS cutoff) with high resolution astronomical spectroscopy in the far-ultraviolet spectral region. No long-term observatory since Copernicus (1972) has possessed this capability.

Total project cost: $171 million including $120 million for the satellite. Funded by NASA. French and Canadian space agency share observation time. French CNES paid 6 million EUR.

On 10 Dec 2001 the satellite went into safe mode when the second of 4 reaction wheels stopped. In Feb 2002, partial usability was restored with the use of the magnetic torquer. Full operations were restored in March 2002.

In July 2003 we learn that the gyroscopes are ageing and that software to operate in gyroless mode was uploaded in April 2003. In this mode, the science data is to remain the same quality.

On 27 Dec 2004 the third reaction wheel stopped. The satellite went into safe mode. Observations resumed in November 2005 and were back to original quality in Jan 2006. The control system has been modified again to use magnetic control on two axes, which provides a tenuous but acceptable level of control.

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End of life

Out of service	Jul 2007
Cause	Last reaction wheel failed
Decay

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External resources

http://fuse.pha.jhu.edu/

sat-index articles

Technical data

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Specifications

Prime contractor	OSC
Platform
Mass at launch	1360 kg
Mass in orbit
Dimension	1.2 x 1.8 x 5.5 m
Solar array
Stabilization
DC power
Design lifetime	3 years

Carries a telescope with 4 mirrors. It explores in the 912 to 1187 angstrom range. The instrument is provided by the John Hopkins University.

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