Q&A with Steve Clarke, deputy associate administrator for exploration in NASA’s science division (members only)

The satellite awaiting launch early Saturday from California aboard the final flight of the venerable Delta 2 rocket should allow scientists to more precisely track changes in our planet’s ice sheets, using six green laser beams to chart the height and slope of polar ice and glaciers, providing a key input into climate change research.

NASA has selected two satellite missions for launch on the same rocket in 2022 to investigate the origins of the solar wind and explore the interaction between magnetic fields around Earth with those from the sun.

A Russian cosmonaut, a German flight engineer and a NASA astronaut undocked from the International Space Station and plunged back to Earth overnight Wednesday, landing on the snowy steppe of Kazakhstan to wrap up a six-month mission.