by Barbara Brown for ASTR 402 Spring, 2006

Kepler Mission test hypotheses: Most stars like our Sun have terrestrial planets in or near the habitable zone On an average two Earth-size planets form in the region between 0.5 and 1.5 AU

What is a habitable planet? Liquid water on planet surface--determined by size and temperature of the star and orbit of the planet Size and mass of planet--small planets don’t have enough surface gravity to hold onto a life-sustaining atmosphere Amount and composition of atmosphere Affects of moons and giant planets in the system

How are we going to do this?

Kepler Mission Scientific Objective: The scientific objective of the Kepler Mission is to explore the structure and diversity of planetary systems. This is achieved by surveying a large sample of stars to: 1.Determine how many terrestrial and larger planets there are in or near the habitable zone of a wide variety of spectral types of stars; 2.Determine the range of sizes and shapes of the orbits of these planets;

3. Estimate the how many planets there are in multiple-star systems; 4. Determine the range of orbit size, brightness, size, mass and density of short-period giant planets; 5. Identify additional members of each discovered planetary system using other techniques; and 6. Determine the properties of those stars that harbor planetary systems.

Expected Results: Based on the mission described above and assumption that planets are common around other stars like our Sun, then we expect to detect: From transits of terrestrial planets: About 50 planets if most are the same size as Earth (R~1.0 R e ), About 185 planets if most have a size of R~1.3 R e, About 640 planets if most have a size of R~2.2 R e, About 12% with two or more planets per system.

From modulation of the reflected light from giant inner planets: About 870 planets with periods less than one week. From transits of giant planets: About 135 inner-orbit planet detections, Densities for 35 inner-orbit planets, and About 30 outer-orbit planet detections.

Characteristics of a planetary transit: Period of recurrence of the transit Duration of the transit Fractional change in brightness of the star

How can we detect a planetary transit?

httphttp://planetquest.jpl.nasa.gov/transit/indexTransit.html What would a transit look like (on a graph)?

The Kepler instrument: 0.95-meter diameter photometer telescope 105 degrees 2 field of view Continuously and simultaneously monitor the brightnesses of more than 100,000 stars for the life of the mission—4 years

Scientific Operations Center at NASA Ames: William Borucki, Principal Investigator Mission Operations Center at University of Colorado LASP Data Management Center at Space Telescope Science Institute Industrial partner: Ball Aerospace, Boulder, CO Kepler Mission Team Members

Resources “Close-up on the Kepler Mission” by Jon Jenkins, “Solar transits: Tools of discovery” by Edna DeVore, “Detecting other worlds: The photometric transit or 'Wink' method” by Dr. Laurance Doyle,