April 28, 2003
Purpose: Ultraviolet study of history of star formation
The Galaxy Evolution Explorer is an orbiting space telescope that makes observations at
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 is about 13 billion
years old, the mission will study galaxies and stars across about 10 billion years of cosmic
The spacecraft's mission is to observe hundreds of thousands of galaxies, with the goal of determining
how far away each galaxy is from Earth and how fast stars are forming in each galaxy. A
galaxy’s ultraviolet brightness tells us how fast its stars are forming. Mission scientists
will be trying to find stars that have recently formed, so they will be looking for stars
whose appearance reveals them to be young. These are the most massive stars, which are so
hot they shine in ultraviolet wavelengths.
Scientists would like to understand when the stars that we see today were formed, and when
the chemical elements that make up our Milky Way galaxy formed. We know they formed in the
interiors of stars, but we don't know when. Information gathered by the mission will fill
in one of the missing pieces of the puzzle to explain how the visible universe came to be.
Partnering with JPL on the mission are the California Institute of Technology, Pasadena,
Calif.; Orbital Sciences Corporation, Germantown, Md.; University of California at Berkeley;
Yonsei University, Seoul, Korea; Johns Hopkins University, Baltimore, Md.; and Laboratoire
d'Astrophysique de Marseille, France.
For more information, see the
Galaxy Evolution Explorer home page.