GALEX
Encyclopedia
The Galaxy Evolution Explorer (GALEX) is an orbit
ing ultraviolet
space telescope launched on April 28, 2003. A Pegasus rocket
placed the craft into a nearly circular orbit at an altitude
of 697 kilometres (433.1 mi) and an inclination
to the Earth
's equator of 29 degrees.
The first observation was dedicated to the crew of the Space Shuttle Columbia
and images the sky in the constellation
Hercules, taken on May 21, 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.
wavelengths to measure the history of star
formation in the universe
80 percent of the way back to the Big Bang
. Since scientists believe the Universe to be about 13.7 billion years old, the mission will study galaxies
and stars across about 10 billion years of cosmic history.
The spacecraft's
mission is to observe hundreds of thousands of galaxies
, with the goal of determining the distance of each galaxy from Earth and the rate of star formation
in each galaxy. Near- and far-UV emissions as measured by GALEX can indicate the presence of young stars, but may also originate from old stellar populations (e.g. sdB stars).
Partnering with the NASA Jet Propulsion Laboratory
(JPL) on the mission are 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.
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
ing ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
space telescope launched on April 28, 2003. A Pegasus rocket
Pegasus rocket
The Pegasus rocket is a winged space launch vehicle capable of carrying small, unmanned payloads into low Earth orbit. It is air-launched, as part of an expendable launch system developed by Orbital Sciences Corporation . Three main stages burning solid propellant provide the thrust...
placed the craft into a nearly circular orbit at an altitude
Altitude
Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
of 697 kilometres (433.1 mi) and an inclination
Inclination
Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...
to the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
's equator of 29 degrees.
The first observation was dedicated to the crew of the Space Shuttle Columbia
Space Shuttle Columbia
Space Shuttle Columbia was the first spaceworthy Space Shuttle in NASA's orbital fleet. First launched on the STS-1 mission, the first of the Space Shuttle program, it completed 27 missions before being destroyed during re-entry on February 1, 2003 near the end of its 28th, STS-107. All seven crew...
and images the sky in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Hercules, taken on May 21, 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.
Science mission
During its 29-month mission, which was extended, it will make observations in ultravioletUltraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
wavelengths to measure the history of star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
formation in the universe
Universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...
80 percent of the way back to the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...
. Since scientists believe the Universe to be about 13.7 billion years old, the mission will study galaxies
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
and stars across about 10 billion years of cosmic history.
The spacecraft's
Space observatory
A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects...
mission is to observe hundreds of thousands of galaxies
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
, with the goal of determining the distance of each galaxy from Earth and the rate of star formation
Star formation
Star formation is the process by which dense parts of molecular clouds collapse into a ball of plasma to form a star. As a branch of astronomy star formation includes the study of the interstellar medium and giant molecular clouds as precursors to the star formation process and the study of young...
in each galaxy. Near- and far-UV emissions as measured by GALEX can indicate the presence of young stars, but may also originate from old stellar populations (e.g. sdB stars).
Partnering with the NASA Jet Propulsion Laboratory
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...
(JPL) on the mission are the California Institute of Technology
California Institute of Technology
The California Institute of Technology is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering...
, Orbital Sciences Corporation
Orbital Sciences Corporation
Orbital Sciences Corporation is an American company which specializes in the manufacturing and launch of satellites. Its Launch Systems Group is heavily involved with missile defense launch systems...
, University of California, Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
, Yonsei University
Yonsei University
Yonsei University is a Christian private research university, located in Seoul, South Korea. Established in 1885, it is one of the oldest universities in South Korea, the top private comprehensive universities in South Korea, and is widely regarded as one of the top three comprehensive...
, Johns Hopkins University
Johns Hopkins University
The Johns Hopkins University, commonly referred to as Johns Hopkins, JHU, or simply Hopkins, is a private research university based in Baltimore, Maryland, United States...
, Columbia University
Columbia University
Columbia University in the City of New York is a private, Ivy League university in Manhattan, New York City. Columbia is the oldest institution of higher learning in the state of New York, the fifth oldest in the United States, and one of the country's nine Colonial Colleges founded before the...
, and Laboratoire d'Astrophysique de Marseille, France.