There is currently a great interest in the discovery of exosolar systems,
with the eventual interest in discovering planets in the habitable region
about a star. In the U.S. this is a part of the origins program of NASA and
has been, in part, the justification for maintaining the NASA budget.
Currently planets have been discovered by accurate radial velocity
measurements and these discoveries are biased by observational selection
factors and cannot reach Earth sized planets. There are other possible
detection methods, such as astrometry, imaging, and Fourier Transform
Spectrographs (FTS).
There are a number of plans for space missions to be able to discover
and image Earth size planets in habital regions about stars. The programs
FAME, SIM, GAIA, and Terrestrial Planet Finder (TPF) use astrometry and SIM
and TPF would also use imaging. FAME is a survey instrument to observe
40,000,000 stars over 5 years to determine positions, proper motions, and
parallaxes at 40 microarcseconds level. This will detect Jupiter size
planets and indicate problem stars. There needs to be efficient and accurate
methods to characterize the non linear proper motions and make solutions for
companions. The use of Bayesian statistics and other techniques will be
considered.
Based on the discoveries and observations of exosolar systems, the
evolution of solar systems can be investigated. There are two competing
explanations for the method of forming planets, and observations by FAME,
SIM, and GAIA may be able to distinguish between these methods.