Combined observations using the ALMA in conjunction with spacecraft will greatly enhance studies of the planets and their satellites. Millimeter continuum observations probe the deep atmospheres of the giant planets or the surface layers of the terrestrial planets. Millimeter heterodyne spectroscopy allows the detection of narrow spectral lines and measurement of small molecular abundances.
Temporal monitoring reveals composition changes as a function of season and climate.
Asteroids and Comets The ALMA can study the size and albedo of asteroids, and probe their sub-surface temperatures. ALMA continuum observations of comets will explore dust sizes not accessible to optical or radio observations. Spectroscopic observations will determine the molecular composition of the nuclear ices sublimating into the coma, and search for new molecular species. Comparisons with molecular cloud cores will provide clues to the origin of comets. The ALMA may play an important role in the search for extrasolar planets through accurate astrometry, possibly even direct detection.