David Charbonneau
Harvard University
The Fast Track to Finding an Inhabited Exoplanet
When exoplanets are observed to transit their parent stars, we are granted
direct estimates of their masses and radii, and we can undertake studies
of their atmospheres. Such systems have profoundly impacted our
understanding of giant exoplanets akin to Jupiter or Neptune, but the
study of smaller rocky exoplanets has only just begun. The NASA Kepler
Mission is conducting a space-based transit search for rocky planets
orbiting large, Sun-like stars. Alternately, by targeting nearby low-mass
stars, a ground-based transit search using modest equipment is capable of
discovering planets as small as 1.5 Earth radii in their stellar habitable
zones. The discovery of such planets would provide fundamental constraints
on the physical structure of planets that are primarily rock and ice in
composition. Moreover, by differencing spectra gathered when the planet is
in view from those when it is occulted by the star, we can study the
atmospheric chemistry of potentially habitable worlds.