photo shows STS-82 astronaut Scott Horowitz with a multi-layer
insulation (MLI) repair patch. During the Second Servicing Mission,
astronauts detected damage to insulation on the outside of Hubble.
Astronauts working inside the shuttle created repair patches
with the materials they had on hand. MLI covers 80 percent of
Hubble's exterior. This insulation, coupled with supplemental
electric heaters, maintains the temperature of the equipment
and optics within safe limits.