Far Ultraviolet Spectroscopic Explorer

Infobox Space telescope
name = Far Ultraviolet Spectroscopic Explorer (FUSE)


caption = FUSE in a pre-launch clean room
organization = Johns Hopkins APLNASA
major_contractors =
alt_names = Explorer 77 MIDEX/FUSE 25791 (NORAD ID)
nssdc_id = 1999-035A
location =
orbit_type = Circular low Earth orbit
height = 746 km (402.8 nmi) to 760 km (410.4 nmi)lower|0.2em|
period = 99.9 minutes
velocity =
accel_gravity =
launch_date = June 24, 1999 at 15:44 UTC
launch_location = Cape Canaveral Florida, USA
launch_vehicle = Delta II 7320
mission_length = Three years (design)lower|0.2em| Eight years (actual)lower|0.2em|
deorbit_date =
wavelength = 90.5 to 119.5 nm
mass = 1400 kg (3086.5 lb)
style = Far ultraviolet
diameter =
area =
focal_length =
coolant =
website = http://fuse.pha.jhu.edu/
as_of = September 2007
stats_ref = cite web |url=http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1999-035A |title=NSSDC Master Catalog Display: Spacecraft |work=NASA.gov |date=2007-05-18 |accessdate=2007-09-07] cite web |url=http://nssdc.gsfc.nasa.gov/nmc/tmp/1999-035A-traj.html |title=NSSDC Master Catalog Display: Spacecraft Launch/Orbital Information |work=NASA.gov |date=2007-05-18 |accessdate=2007-09-07] cite web |url=http://www.spaceref.com/news/viewsr.html?pid=25334 |title=ROSES-07 Amendment 20: Cancel FUSE Legacy Science Program |work=Spaceref.com |author=NASA HQ |date=2007-09-06 |accessdate=2007-09-07] cite web |url=http://www.n2yo.com/satellite.php?s=25791 |title=FUSE 1 Satellite details |work=N2YO.com |accessdate=2007-09-07]

The Far Ultraviolet Spectroscopic Explorer (FUSE) is a space-based telescope operated by the Johns Hopkins University Applied Physics Laboratory. "FUSE" was launched on a Delta II rocket on June 24, 1999, as a part of NASA's Origins program. "FUSE" detected light in the far ultraviolet portion of the electromagnetic spectrum, between 90.5-119.5 nanometres, which is mostly unobservable by other telescopes. Its primary mission was to characterize universal deuterium in an effort to learn about the stellar processing times of deuterium left over from the Big Bang.

"FUSE" resides in a low Earth orbit, approximately 760 km (410 nmi) in altitude, with an inclination of 25 degrees and just less than a 100 minute orbital period. Its Explorer designation is "Explorer 77".

On July 12, 2007, "FUSE"'s final reaction wheel, which is required for accurately pointing a spacecraft, failed and efforts to restart it were unsuccessful. An announcement was made on September 6 that because the fine control needed to perform its mission had been lost, the "FUSE" mission would be terminated.

Optical design

Although the original specification was to have a Wolter-type grazing incidence telescope,cite journal |url=http://adsabs.harvard.edu/abs/1994SPIE.2011...34K |title=Optical design of Lyman/FUSE |journal=Instrumentation in Astronomy VII |first=David A. |last=Content |coauthors=et al |month=July |year=1990 |pages=pp. 943–952 |doi=10.1117/12.19157 |volume=1235] the final design of the "FUSE" telescope comprises four individual mirrors. Each of the four mirrors is a 39-by-35 cm (15.4-by-13.8 in) off-axis parabola. Two mirror segments are coated with silicon carbide for reflectivity at the shortest ultraviolet wavelengths, and two mirror segments are coated with lithium fluoride over aluminum that reflects better at longer wavelengths. This optimizes performance over the entire spectral range.

Each mirror has a corresponding astigmatism-corrected, holographically-ruled diffraction grating, each one on a curved substrate so as to produce four 1.65 m (5.4 ft) Rowland circle spectrographs. The dispersed ultraviolet light is detected by two microchannel plate intensified double delay-line detectors, whose surfaces are curved to match the curvature of the focal plane.cite web |url=http://fuse.pha.jhu.edu/papers/technical/aas95/aas95.html |title=The Far Ultraviolet Spectroscopic Explorer Mission |work=JHU.edu |first=D.J. |last=Sahnow |coauthors=et al |date=1995-07-03 |accessdate=2007-09-07]

Science results

Over 400 scientific papers have been written using data from "FUSE",cite web |url=http://fuse.pha.jhu.edu/~awf/fusepubs/JHU/ |title=FUSE Publications |work=JHU.edu |accessdate=2007-09-07] with subjects ranging from cool stars to the intergalactic medium. One of the primary science goals of "FUSE" was to study the abundance of deuterium, an isotope of hydrogen. Because of the large number of atomic absorption and emission lines in the far-ultraviolet, "FUSE" enabled many studies of galactic, extragalactic and intergalactic chemistry and chemical evolution.

References

External links

* [http://fuse.pha.jhu.edu/ "FUSE" website] at Johns Hopkins University
* [http://www2.iap.fr/Fuse/ "FUSE" website] at Institut d'Astrophysique de Paris
* [http://archive.stsci.edu/fuse "FUSE" archive] at Multimission Archive at STScI (MAST)