GALEX: Difference between revisions

{{about|the ultraviolet space telescope|the neutrino detector|GALLEX|other uses|GALEX (disambiguation)}}

{{Infobox spaceflight

| name = Galaxy Evolution Explorer

| names_list = Explorer-83, SMEX-7

| image = GALEX (transparent).png

| image_caption = Illustration of GALEX

| image_size = 225px

| mission_type = [[Ultraviolet astronomy]]

| operator = [[NASA]]{{\}}[[Jet Propulsion Laboratory|JPL]] <br /> [[California Institute of Technology|Caltech]]

| COSPAR_ID = {{cospar|2003-017A}}

| SATCAT = 27783

| website = http://www.galex.caltech.edu/

| mission_duration = Planned: 29 months<ref name="nssdc">{{cite web |url=http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=2003-017A |title=GALEX |work=[[National Space Science Data Center]] |publisher=NASA |accessdate=September 14, 2015}}</ref> <br/> Final: {{time interval|28 April 2003 12:00|28 June 2013 19:09|show=ymd|sep=,}}<ref name="jpl-missions-galex">{{cite web |url=http://www.jpl.nasa.gov/missions/galaxy-evolution-explorer-galex/ |title=Mission to Universe: Galaxy Evolution Explorer |publisher=NASA |accessdate=September 14, 2015}}</ref><ref name="decommission">{{cite press release |url=http://www.galex.caltech.edu/newsroom/glx2013-03r.html |title=NASA Decommissions Its Galaxy Hunter Spacecraft |publisher=California Institute of Technology |date=June 28, 2013 |accessdate=September 14, 2015}}</ref>

| manufacturer = [[Orbital Sciences Corporation|Orbital Sciences]]

| launch_mass = {{convert|277|kg|lb|abbr=on}}<ref name="galex-prkit">{{cite web |url=http://www.jpl.nasa.gov/news/press_kits/galex.pdf |title=Press Kit: Galaxy Evolution Explorer Launch |publisher=NASA |date=April 2003 |accessdate=September 14, 2015}}</ref>

| payload_mass =

| dimensions = {{convert|9|xx|6.5|ft|m|order=flip|abbr=on}}<ref name="galex-basics">{{cite web |url=http://www.galex.caltech.edu/about/basics.html |title=GALEX Basics |publisher=California Institute of Technology |accessdate=September 14, 2015}}</ref>

| power = 290 W<ref name="galex-prkit"/>

| launch_date = {{start-date|April 28, 2003, 12:00|timezone=yes}}&nbsp;UTC<ref name="nssdc-launch">{{cite web |url=http://nssdc.gsfc.nasa.gov/nmc/spacecraftOrbit.do?id=2003-017A |title=GALEX - Trajectory Details |work=[[National Space Science Data Center]] |publisher=NASA |accessdate=September 14, 2015}}</ref>

| launch_rocket = [[Pegasus (rocket)|Pegasus XL]]

| launch_site = ''[[Stargazer (aircraft)|Stargazer]]'', [[Cape Canaveral Air Force Station|Cape Canaveral]]

| launch_contractor = [[Orbital Sciences Corporation|Orbital Sciences]]

| entered_service = May 28, 2003<ref name="jpl-missions-galex"/>

| disposal_type = Decommissioned

| deactivated = {{end-date|June 28, 2013, 19:09|timezone=yes}}&nbsp;UTC<ref name="decommission"/>

| decay_date = <!--when craft re-entered the atmosphere, not needed if it landed-->

| orbit_reference = [[Geocentric orbit|Geocentric]]

| orbit_regime = [[Low Earth orbit|Low Earth]]

| orbit_semimajor = {{convert|7065.55|km|mi|abbr=on}}

| orbit_eccentricity = 0.0003629

| orbit_periapsis = {{convert|684.85|km|mi|abbr=on}}

| orbit_apoapsis = {{convert|689.98|km|mi|abbr=on}}

| orbit_inclination = 28.9986°

| orbit_period = 98.5167 minutes

| orbit_RAAN = 50.7756°

| orbit_arg_periapsis = 189.3734°

| orbit_mean_anomaly = 229.9485°

| orbit_mean_motion = 14.6178 rev/day

| orbit_epoch = September 13, 2015 13:13:39&nbsp;UTC<ref name="heavens-above">{{cite web |url=http://www.heavens-above.com/orbit.aspx?satid=27783 |title=GALEX - Orbit |work=Heavens Above |date=September 13, 2015 |accessdate=September 13, 2015}}</ref>

| orbit_rev_number = 66130

| apsis = gee

| telescope_type = [[Ritchey–Chrétien telescope|Ritchey–Chrétien]]<ref name="nssdc"/>

| telescope_diameter = {{convert|50|cm|in|1|abbr=on}}<ref name="nssdc"/>

| telescope_focal_length= <!--focal length of telescope-->

| telescope_area = <!--collecting area-->

| telescope_wavelength = 135–280 [[Nanometre|nm]] ([[Ultraviolet]])<ref name="nssdc"/>

| telescope_resolution = <!--resolution of telescope-->

| programme = [[Small Explorer program]]

| previous_mission = [[Reuven Ramaty High Energy Solar Spectroscopic Imager|RHESSI]]

| next_mission = [[Aeronomy of Ice in the Mesosphere|AIM]]

}}

The '''Galaxy Evolution Explorer''' ('''GALEX''') is an [[orbit]]ing [[ultraviolet]] [[space telescope]] launched on April 28, 2003, and operated until early 2012.

==History==

An airlaunched [[Pegasus (rocket)|Pegasus]] rocket placed the craft into a nearly circular orbit at an [[altitude]] of {{convert|697|km}} and an [[inclination]] to the [[Earth]]'s equator of 29 degrees.

The [[First light (astronomy)|first observation]] was dedicated to the crew of the [[Space Shuttle Columbia]], being images in the [[constellation]] [[Hercules (astronomy)|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 [[Christopher C. Kraft Jr. Mission Control Center|NASA Mission Control Center]].

After its primary mission of 29 months, observation operations were extended to almost 9 years with NASA placing it into standby mode on 7 Feb 2012.<ref>[http://www.universetoday.com/93409/galex-mission-comes-to-an-end/ GALEX ends]</ref>

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 $150.6 million. The [[California Institute of Technology]] 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 of 1980|Stevenson-Wydler Technology Innovation Act]]. Under this Act, excess research equipment owned by the US government can be transferred to educational institutions and [[Nonprofit organization|non-profit organizations]].<ref>{{cite news |author=Stephen Clark |title=NASA, Caltech mull over unique satellite donation |url=http://www.spaceflightnow.com/news/n1202/10galex/ |work=Spaceflight Now |date=10 February 2011 |accessdate=2010-02-17}}</ref> In May 2012, GALEX operations were transferred to Caltech.<ref name=woo>[http://phys.org/news/2012-05-nasa-ultraviolet-space-telescope-caltech.html Marcus Woo - NASA lends ultraviolet space telescope to Caltech (May 17, 2012) - Phys.org]</ref>

On June 28, 2013 NASA decommissioned GALEX. It is expected that the spacecraft will remain in orbit for at least 65 years before it will re-enter the atmosphere.<ref>[http://www.galex.caltech.edu/newsroom/glx2013-03r.html NASA Decommissions Its Galaxy Hunter Spacecraft]</ref>

==Science mission==

[[File:GALEX Field of View.jpg|thumb|left|GALEX field of view compared to a full Moon]]

During its initial 29-month mission, which was extended, it made observations in [[ultraviolet]] 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 13.8 billion years old,<ref>{{cite web |last= |first= |title=Cosmic Detectives |url=http://www.esa.int/Our_Activities/Space_Science/Cosmic_detectives |authorlink= |work= |publisher=The European Space Agency (ESA) |date=2013-04-02 |doi= |accessdate=2013-04-26}}

</ref> the mission will study [[galaxy|galaxies]] and stars across about 10 billion years of cosmic history.

The [[space observatory|spacecraft's]] mission is to observe hundreds of thousands of [[galaxy|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]].

The observatory participated in GOALS with Spitzer, Chandra, and Hubble.<ref name=goals>[http://arxiv.org/abs/0904.4498 GOALS: The Great Observatories All-Sky LIRG Survey]</ref> GOALS stands for ''Great Observatories All-sky LIRG Survey'', and [[Luminous Infrared Galaxies]] were studied at the multiple wavelengths allowed by the telescopes.<ref name=goals/>

==Specifications==

The telescope has a 50&nbsp;cm diameter aperture primary, in a Richey-Chretien f/6 configuration.<ref name=astro>[http://www.astronautix.com/craft/galex.htm Encyclopedia Astronautica - GALEX]</ref> It can see light wavelengths from 135 nanometers to 280&nbsp;nm,<ref name=astro/> with a field of view of 1.2 degrees wide<ref name=astro/> (larger than a full moon). It has gallium-arsenide solar cells which supply nearly 300 watts to the spacecraft.<ref name=astro/>

==Pre-launch images==

{{Gallery|lines=3|width=150

|File:Galex PIA04264.jpg|GALEX at the pre-launch tests

|File:GALEX Pegasus.jpg|GALEX being mated to a [[Pegasus XL]] Rocket

|File:GALEXRollout.jpg|GALEX's [[Pegasus&nbsp;XL]] being attached to the [[Lockheed Martin|Lockheed]] [[Lockheed L-1011 TriStar|L-1011]] ''[[Stargazer (aircraft)|Stargazer]]''

|File:GALEXLaunch.jpg|The L-1011 ''Stargazer'' take-off with GALEX attached under-belly <!--

|File:A-Mira-Full down sampled and cropped.jpg|An image of [[Mira]]'s bow shock and tail of hydrogen gas.-->

}}

==Examples of results==

<!--{{wide image|A-Mira-Full down sampled and cropped.jpg|1500px|align-cap=center|[[Mira]]'s bow shock and hydrogen gas tail in ultraviolet.}}-->

[[File:A-Mira-Full down sampled and cropped.jpg|thumb|699px|center|[[Mira]]'s bow shock and hydrogen gas tail in ultraviolet.]]

{{-}}

[[File:Ultraviolet image of the Cygnus Loop Nebula crop.jpg|thumb|center|420px|Ultraviolet view of [[Cygnus loop]]]]

{{-}}

==See also==

{{Portal|Spaceflight}}

*[[GALEX Arecibo SDSS Survey]]

*[[Arecibo Observatory]]

==References==

{{reflist}}

==External links==

{{Commons category|GALEX}}

*[http://www.galex.caltech.edu GALEX website] by the [[California Institute of Technology]]

*[http://www.jpl.nasa.gov/missions/galaxy-evolution-explorer-galex/ GALEX website] by the [[Jet Propulsion Laboratory]]

*[http://galex.stsci.edu GALEX data archive] by the [[Space Telescope Science Institute|STScI]]{{\}}MAST

*[http://galex.stsci.edu/GalexView/ GALEXView Search Tool] by the STScI{{\}}MAST

*[http://wikisky.org/?object=M31&img_source=GALEX GALEX Ultraviolet Sky Survey] at [[Wikisky.org]]

{{Explorer program}}

{{Space observatories}}

{{Jet Propulsion Laboratory}}

{{Orbital launches in 2003}}

{{Use American English|date=January 2014}}

{{DEFAULTSORT:Galex}}

[[Category:Artificial satellites orbiting Earth]]

[[Category:Explorers program (NASA)]]

[[Category:Space observatories]]

[[Category:Ultraviolet telescopes]]

[[Category:Spacecraft launched in 2003]]

[[Category:Spacecraft launched by Pegasus rockets]]