Mary Cleave left the NASA astronaut corps in the early 1990s to make a rare jump from human spaceflight to Earth science. She was going to work on an upcoming mission to measure gradations in ocean color something she had actually seen from low-Earth orbit with her own eyes. From space, differing densities of phytoplankton and algae and floating bits of plant life reveal themselves as so many blues and greens. For Cleave, a former environmental engineer, the attraction was simple.
"We were going to measure green slime on a global scale," said Cleave, now retired from her varied NASA career.That is exactly what SeaWiFS Sea viewing Wide Field of view Sensor did for over 13 years, until it recently stopped communicating with ground-based data stations and after several months of intensive efforts at recovery, was declared unrecoverable in February.