Astronauts Steven Smith and John Grunsfeld train in a Goddard Space Flight Center clean room on a backup of an electrical section of Hubble in 1999. The electrical section holds transmitters, batteries, recorders and electronics that operate various parts of Hubble. The astronauts wear "bunny suits," special coveralls, hoods, gloves, boots and masks that protect the sensitive equipment from particles that could interfere with its performance.
