Editing GALEX (section)

== Science objectives ==
The primary objective of the Galaxy Evolution Explorer was to learn what factors trigger star formation inside galaxies; how quickly stars form, evolve and die; and how heavy chemical elements form in stars. Additional goals include:<ref name="galex-presskit">{{cite web|url=http://www.jpl.nasa.gov/news/press_kits/galex.pdf|title=Galaxy Evolution Explorer Launch|publisher=NASA|date=April 2003|access-date=3 December 2021}} {{PD-notice}}</ref>

* Determining how fast stars are forming inside each galaxy
* Determining when and how the stars we see today formed
* Creating the first map of the ultraviolet universe
* Helping scientists find and understand ultraviolet bright quasars. These objects can serve as background sources for the Hubble Space Telescope and FUSE as it probes the gases from which galaxies form stars

To accomplish its objectives, the Galaxy Evolution Explorer conducted eight surveys, grouped into two broad categories – a local universe investigation and a star formation history investigation. The local universe investigation includes the following four surveys:<ref name="galex-presskit"/>

* All-sky imaging survey – will look at the entire sky and develop a comprehensive catalogue of ultraviolet galaxy images, useful to map the distribution of star formation within the local universe
* Nearby galaxy survey – will study about 150 nearby galaxies that are familiar to scientists to understand how stars formed in individual galaxies
* Wide-field spectroscopic survey – will analyze the light wavelengths of galaxies in a wide swath of the sky
* Medium spectroscopic survey – will examine the light properties of galaxies within a narrower portion of the sky

The star formation history investigation will take information gathered by the local universe investigation and apply it to more distant galaxies by looking further back in time. It includes the following four surveys:<ref name="galex-presskit"/>

* Deep imaging survey – will look at a portion of the sky to study the distribution of star formation in the deep universe
* Deep spectroscopic survey – will look for the most distant galaxies
* Ultra-deep imaging survey – will look as deep as possible at a very small portion of the sky
* Medium imaging survey – will study star formation in galaxies beyond our local cosmic neighborhood, but not as deep as the deep imaging survey