Quick Facts: Kepler

Mission Introduction

Kepler spacecraft

One goal of the Kepler mission is to estimate the number of planets that exist in multiple-star systems. (Courtesy NASA/Wendy Stenzel)

The centuries-old quest for other worlds like our Earth has been rejuvenated by the intense excitement and popular interest surrounding the discovery of hundreds of planets orbiting stars beyond our solar system.

Kepler was specifically designed to survey a portion of our region of the Milky Way galaxy to discover planets in or near the habitable zone of their stars and determine how many of the billions of stars in our galaxy have such planets. Results from this mission will allow us to place our solar system within the continuum of planetary systems in the Galaxy.

There is now clear evidence for substantial numbers of three types of exoplanets; gas giants, hot-super-Earths in short period orbits, and ice giants. Astronomers have recently discovered the first Earth-size planet orbiting a star in the “habitable zone”—the range of distance from a star where liquid water might pool on the surface of an orbiting planet. The discovery of Kepler-186f confirms that planets the size of Earth exist in the habitable zone of stars other than our sun.

The scientific objective of the Kepler Mission was to explore the structure and diversity of planetary systems. This objective was achieved by surveying a large sample of stars to:

  1. Determine the abundance of terrestrial and larger planets in or near the habitable zone of a wide variety of stars
  2. Determine the distribution of sizes and shapes of the orbits of these planets
  3. Estimate how many planets there are in multiple-star systems
  4. Determine the variety of orbit sizes and planet reflectivities, sizes, masses and densities of short-period giant planets
  5. Identify additional members of each discovered planetary system using other techniques
  6. Determine the properties of those stars that harbor planetary systems


Kepler’s loss of a second spacecraft reaction wheel in May 2013 effectively ended data collection in the original Kepler field after 4 years of continuous monitoring. However, all other Kepler assets remain intact and can be used for the K2 mission. The K2 mission provides an opportunity to continue Kepler’s ground-breaking discoveries in the field of exoplanets and expand its role into new and exciting astrophysical observations.

Both missions are founded on the proven value of long-baseline, high-cadence, high-precision photometry and exploit a large field of view to simultaneously monitor many targets. On two reaction wheels, K2 is limited to pointing near the ecliptic plane, sequentially observing fields as it orbits the sun. This observing strategy regularly brings new, well-characterized target fields into view, enabling observations of scientifically important objects across a wide range of galactic latitudes in both the northern and southern skies. K2 will perform a series of long, ecliptic-pointed campaigns to collect data for the astrophysical community that will inform their understanding of planet formation processes, young stars, stellar activity, stellar structure and evolution, and extragalactic science.

LASP Roles

LASP managed Mission Operations for Kepler and continues to do so for the K2 mission.

LASP Instruments

LASP did not provide any instruments for the Kepler mission.

For more information about the Kepler and K2 missions and mission operations at LASP, see:

Kepler Field of View

Kepler is looking at just one large area of the sky in the constellations Cygnus and Lyra. (Courtesy Carter Roberts)

Quick Facts

Launch date: March 6, 2009
Launch location: Kennedy Space Center, Cape Canaveral, Florida
Launch vehicle: Delta II
Mission target: Earth-trailing orbit
Mission duration: 3 1/2 years (extended for two years; K2 mission extended through the end of FY2019)
Other organizations involved:

  • NASA Ames Research Center
  • NASA Jet Propulsion Laboratory
  • Ball Aerospace
  • SETI Institute
  • Lawrence Hall of Science
  • Smithsonian Astrophysical Observatory
  • Space Telescope Science Institute

KeplerClick on the image to view a PDF (672 KB) of Kepler FAQs.