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.

Claude Nicollier (born 2 September 1944 in Vevey Switzerland) is the first astronaut from Switzerland and has flown on four Space Shuttle missions. He took part in two servicing missions to the Hubble Space Telescope (called STS-61 and STS-103). Nicollier retired from ESA in April 2007.