FRESIP - A MISSION TO DETERMINE THE CHARACTER AND FREQUENCY OF EXTRA-SOLAR PLANETS AROUND SOLAR-LIKE STARS

FRESIP (FRequency of Earth-Sized Inner Planets) is a mission designed to detect and characterize Earth-sizes planets around solar-like stars . The sizes of the planets are determined from the decrease in light f rom a star that occurs during planetary transits, while the orbital pe riod is determined from the repeatability of the transits. Measurement s of these parameters can be compared to theories that predict the spa cing of planets, their distribution of size with orbital distance, and the variation of these quantities with stellar type and multiplicity. Because thousands of stars must be continually monitored to detect th e transits, much information on the stars can be obtained on their rot ation rates and activity cycles. Observations of p-mode oscillations a lso provide information on their age and composition. These goals are accomplished by continuously and simultaneously monitoring 5000 solar- like stars for evidence of brightness changes caused by Earth-sized or larger planetary transits. To obtain the high precision needed to fin d planets as small as the Earth and Venus around solar-like stars, a w ide field of view Schmidt telescope with an array of CCD detectors at its focal plane must be located outside of the Earth's atmosphere. SMM (Solar Maximum Mission) observations of the low-level variability of the Sun (similar to 1:100,000) on the time scales of a transit (4 to 1 6 hours), and our laboratory measurements of the photometric precision of charge-coupled devices (1:100,000) show that the detection of plan ets as small as the Earth is practical. The probability for detecting transits is quite favorable for planets in inner orbits. If other plan etary systems are similar to our own, then approximately 1% of those s ystems will show transits resulting in the discovery of 50 planetary s ystems in or near the habitable zone of solar-like stars.