Галактики в ультрафиолете: Космический телескоп GALEX

NASA UV space telescope of the Explorer program, operated 2003 2013
the ultraviolet space telescope

The spacecraft was three axis stabilized, with power coming from four fixed solar panels. The satellite bus is from Orbital Sciences Corporation based on OrbView 4. The telescope was a Modified Ritchey–Chrétien with a rotating grism. GALEX used 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 diameter. The target orbit is circular and inclined at 29.00° to the equator.

An air launched Pegasus launch vehicle, launched on 28 April 2003 at 11:59:57 UTC, placed the craft into a nearly circular orbit at an altitude of and an orbital inclination to the Earth's equator of 29.00°.

The Galaxy Evolution Explorer (GALEX) which explored 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 conducted an all sky imaging survey, a deep imaging survey, and a survey of 200 galaxies nearest to the Milky Way galaxy. As well, GALEX performed three spectroscopic surveys over the 135–300 nanometre band. GALEX had a planned 29 month mission, and is a part of the Small Explorer (SMEX) program. The first observation was dedicated to the crew of the Space Shuttle Columbia, and was images in the constellation of Hercules taken on 21 May 2003. This region was selected because it had been directly overhead the shuttle at the time of its last contact with the NASA Mission Control Center, Houston, Texas. After its primary mission of 29 months, observation operations were extended. In 2009, one of its detectors, which observed in far ultraviolet light, stopped functioning. NASA cut off financial support for operations of GALEX in early February 2011 as it was ranked lower than other projects which were seeking a limited supply of funding. The mission's life cycle cost to NASA was US$150.6 million. The California Institute of Technology (Caltech) negotiated to transfer control of GALEX and its associated ground control equipment to the California Institute of Technology in keeping with the Stevenson Wydler Technology Innovation Act. Under this Act, excess research equipment owned by the U. S. government can be transferred to educational institutions and non profit organizations. On 17 May 2012, GALEX operations were transferred to Caltech. On 28 June 2013, NASA decommissioned GALEX. It is expected that the spacecraft will remain in orbit until at least 2068 before it will re enter the atmosphere.

GALEX carries a single f/6.0, Ritchey–Chrétien telescope, with a diameter primary, and a secondary mirror. Beam splitters direct the Near UV (NUV) and Far UV (FUV) components to separate photoelectric detectors of diameter In each, the photoelectrons are multiplied by a microchannel plate, and detected by the anode grid. The grid enables determination of the exact position of electron impact, by the time delay of each pulse at the two ends. The telescope has a field of view (FoV) of 1.2°, and a resolution of five arcseconds, and enables either imaging or spectral composition of a single star/galaxy, by a rotatable wheel containing a clear window and a grism (a cross between a grating and a prism).