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The Galaxy Evolution Explorer (GALEX) is an orbiting space ultraviolet telescope, which explores the origin and evolution of galaxies, and the origins of stars and heavy elements over the redshift range of z between 0 and 2. GALEX will conduct an all-sky imaging survey, a deep imaging survey, and a survey of 200 galaxies nearest to the Milky Way Galaxy. As well, GALEX will perform three spectroscopic surveys over the 135-300 nanometer band. GALEX has a planned 29 month mission, and is a part of the Small Explorers (SMEX) program.

The spacecraft will be three-axis stabilized, with power coming from four fixed solar panels. The spacecraft bus is from Orbital Sciences Corporation based on OrbView 4. The telescope is a 50-cm Modified Ritchey-Chretien with a rotating grism. GALEX uses the first ever UV light dichroic beam-splitter flown in space to direct photons to the Near UV (175-280 nanometers) and Far UV (135-174 nanometers) microchannel plate detectors. Each of the two detectors has a 65 millimeter diameter. The target orbit is 670 km circular and inclined at 28.5 degrees to the equator.

Alternate Names

  • 27783
  • Explorer 83
  • Galaxy Evolution Explorer
  • Small Explorer/GALEX

Facts in Brief

Launch Date: 2003-04-28
Launch Vehicle: Pegasus XL
Launch Site: Cape Canaveral, United States
Mass: 280 kg
Nominal Power: 290 W

Funding Agency

  • NASA-Office of Space Science (United States)


  • Astronomy

Additional Information

Questions and comments about this spacecraft can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Dr. Christopher R. MartinMission Principal InvestigatorCalifornia Institute of
Dr. James L. FansonProject ManagerNASA Jet Propulsion
Dr. Peter FriedmanProject ScientistCalifornia Institute of

US Active Archive for GALEX Information/Data

The GALEX Archive at MAST (STScI)

Other Sources of GALEX Information/Data

GALEX Home Page

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