Earth fills the background behind Hubble in its position in the space shuttle's cargo bay. Two astronauts work in the cargo bay, one partially obscured by the shuttle's robotic arm.

Astronauts Foale and Nicollier During Servicing Mission 3A

C. Michael Foale (left) and Claude Nicollier (partially obscured by the Remote Manipulator System (RMS) hover above Discovery's aft cargo bay during their spacewalk to perform servicing tasks on the Hubble Space Telescope (HST) during the third servicing mission.

Credits: NASA