A new coat for the telescope

The thermal blankets covering Hubble's exterior when it was launched (called Multi Layer Insulation - MLI) were showing signs of deterioration by the time of Servicing Mission 3B. This damage was due to debris orbiting the Earth.

Space debris has both a natural and an artificial origin. Naturally arising space debris has dimensions ranging from a thousandth of a millimetre to a few centimetres and resembles tiny stones. The artificial debris is of human origin and includes used rocket parts, small pieces of old satellites and fragments from explosions. To protect critical systems, Hubble and other satellites are placed at safe altitudes that minimise the risk of microcollisions.

Nevertheless, some deterioration is inevitable, so the Multi Layer blankets must be repaired to keep the Telescope thermally insulated and protected.


The Multi Layer Insulation has flaked in places and there is some concern that the particles might find their way into the Telescope and cause a contamination problem. Repairs to this blanket began during Service Mission 3A and continued during Service Mission 3B.

Pieces of Multi Layer Insulation protects the telescope. They look like ordinary household aluminum foil.

Pieces of Multi Layer Insulation protects the telescope. They look like ordinary household aluminum foil.