On one hand, to be able to go from one direction in the sky to study such an object to another direction to study another object, and on the other hand to be able to maintain accurately the position in space.

You can see these boxes which are covered with metal foils for thermal reasons, and they are also, most of the time, thermally controlled inside to keep reasonable temperature inside each of these containers.

We have the Fine Guidance Sensors, one of which we will exchange out of three. Another one we changed on the last servicing mission, and on the fourth servicing mission in 2003 or 2004, the third one will be exchanged.

Claude Nicollier Quotes