Given the critical role of water in supporting life, it is not surprising that almost all planetary missions are examining ice in the solar system. These include, but are not limited to:
NASA Cryospheric Science Missions
Part of NASA's mission is to develop an understanding of the total Earth system; our oceans and ice shelves are important indicators of changes in the world's climate and weather. Today there are several ocean- and ice-observing satellite missions and an extensive scientific research community studying these data and participating in active fieldwork.
After successfully completing the first in-depth, up-close study of Saturn and its realm from orbit, Cassini is on an extended mission to follow up on the many discoveries made during its primary 4-year mission. Among the most surprising discoveries were geysers erupting on Enceladus and its effects on the Saturnian environment, giant ice ridges on Iapetus, ice dunes on Titian, and dynamics between mini-ice moons and Saturn's rings.
Lunar Reconnaissance Orbiter
The instruments on this mission are studying and mapping the Moon globally; one of its key objectives is to map the locations and amounts of water on the Moon. It has discovered polar cold traps with low temperatures and radar data consistent with the presence of water ice in permanently shadowed regions in polar craters.
Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter is designed to track changes in the water and dust in Mars' atmosphere, look for more evidence of ancient seas and hot springs and peer into past Martian climate changes by studying surface minerals and layering. Among the mission's major findings is that the action of water on and near the surface of Mars occurred for hundreds of millions of years, and observations of layering within Mars' polar ice caps and polar processes across its surface.
This mission is on its way to study Pluto and its environment in the Kuiper Belt. Pluto is now classified as a dwarf planet, and appears to be primarily composed of rock and ice. New Horizons will be the first mission to explore this distant world.