GALEX Retired After a Decade of Service to Space Science

The Andromeda galaxy, M31, observed by the now-retired ultraviolet space telescope GALEX. This composite image is false-colored with blue representing far ultraviolet and orange representing near ultraviolet.

The Andromeda galaxy, M31, observed by the now-retired ultraviolet space telescope GALEX. This composite image is false-colored, with blue representing far ultraviolet and orange representing near ultraviolet. Image Credit: NASA/JPL – Caltech.

GALEX, the Galaxy Evolution Explorer, was recently decommissioned by NASA after more than 10 years of operation. GALEX was a space telescope with the primary goal of mapping galaxies in ultraviolet light, gathering observations from relatively close and quite distant galaxies. Since the light from those distant galaxies was up to 10 billion years old, GALEX has been able to provide astronomers with new insights into the evolution of galaxies over the last 10 billion years.

GALEX under construction at JPL prior to its 2003 launch. Image Credit: NASA/JPL.

GALEX under construction at JPL prior to its 2003 launch. Image Credit: NASA/JPL.

NASA used a Pegasus XL rocket to launch GALEX in April 2003, using a similar approach to that used to launch IRIS last week. Pegasus rockets can carry lightweight payloads with good fuel efficiency by virtue of being launched from a carrier aircraft at an altitude of about 12,000 meters (40,000 feet).

Since its launch, GALEX has remained in a low-Earth orbit of nearly 700 kilometres altitude, and it is expected to now continue in that orbit, non-operational, for another 60 years or more until its orbit decays and it burns up in Earth’s atmosphere.

GALEX carried a 20-inch Cassegrain (specifically, a Ritchey–Chrétien) telescope which was optimised for the reception of wavelengths from 135 to 280 nanometers. GALEX’s primary mission of 29 months was extended for several years more, overseen by NASA’s Jet Propulsion Laboratory (JPL) in partnership with the California Institute of Technology, Orbital Sciences Corporation, University of California, Berkeley, Yonsei University, Johns Hopkins University, Columbia University, and Laboratoire d’Astrophysique de Marseille, France.

A-Mira-Full_down_sampled_and_cropped posted on AmericaSpace

Mira A, a red giant star moving fast relative to the interstellar medium, has left a trail of ejected matter over a period of 30,000 years. Like other red giants, Mira will lose a large fraction of its mass in the form of gas and dust. In fact, Mira ejects the equivalent of the Earth’s mass every 10 years. It has released enough material over the past 30,000 years to seed at least 3,000 Earth-sized planets or nine Jupiter-sized ones. Image Credit: NASA/JPL.

NASA decided to suspend financial support for operations of GALEX in early February 2011. What followed was an inspiring example of public/private partnership in astronomy and exploration when, in May 2012, GALEX operations were transferred to Caltech, which managed to keep the telescope operating for another year with the help of public donations.In its final year investigators from around the world used GALEX to study everything from stars in our own Milky Way galaxy to hundreds of thousands of galaxies more than five billion light-years away.

Caltech and JPL have reported that data from the last year of the mission will be progressively made public in the coming year. “GALEX, the mission, may be over, but its science discoveries will keep on going,” said Kerry Erickson, the mission’s project manager at JPL.

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