Observations by the Hubble Space Telescope were stopped at the weekend after the fourth of the six gyroscopes on the $2 billion telescope failed. A minimum of three gyros are needed to accurately point the telescope. A emergency repair mission to Hubble was scheduled for October, after the third gyro failed earlier this year, but this was delayed by NASA. It is now scheduled for launch on December 6.
This is only the third time Hubble has been shut down since its launch in 1990. Three weeks of scientific data will be lost. During the repair mission, astronauts will replace all six gyroscopes, a fine guidance sensor, a transmitter, a spare solid-state recorder and a device that prevents batteries overheating. The crew will also install an advanced computer. A further servicing mission is planned for 2001.
