We provide an overview of the Spitzer Legacy Program “ Formation and Evolution of Planetary Systems ” ( FEPS ) which was proposed in 2000 , begun in 2001 , and executed aboard the Spitzer Space Telescope between 2003 and 2006 .
This program exploits the sensitivity of Spitzer to carry out mid-infrared spectrophotometric observations of solar-type stars .
With a sample of \sim 328 stars ranging in age from \sim 3 Myr to \sim 3 Gyr , we trace the evolution of circumstellar gas and dust from primordial planet-building stages in young circumstellar disks through to older collisionally generated debris disks .
When completed , our program will help define the time scales over which terrestrial and gas giant planets are built , constrain the frequency of planetesimal collisions as a function of time , and establish the diversity of mature planetary architectures .

In addition to the observational program , we have coordinated a concomitant theoretical effort aimed at understanding the dynamics of circumstellar dust with and without the effects of embedded planets , dust spectral energy distributions , and atomic and molecular gas line emission .
Together with the observations , these efforts will provide astronomical context for understanding whether our Solar System – and its habitable planet – is a common or a rare circumstance .
Additional information about the FEPS project can be found on the team website :

http : //feps.as.arizona.edu/