| Hubble's second set of Solar Panels flew with Hubble until 2002 and consists of two large rectangular wings of solar cell blankets. These panels (also called Solar Arrays) rotate so that each wing faces the Sun. The solar cells absorb energy from the sunlight and convert it into electrical energy. The solar cell blankets are mounted in a frame and unfurl from a cassette in the middle of the wing. The tension is maintained by a spreader bar at the end of each side of the wing. During the First Servicing Mission a new set of Solar Panels was mounted on Hubble to replace the first set which had been oversensitive to temperature variations during Hubble's orbit. The second set had a more advanced system of springs to reduce vibrations induced by temperature differences when Hubble was moving from the bright side of the orbit to the dark side and vice versa. After the installation of the new Solar Panels the vibrations were reduced dramatically. Each Solar Panel wing has 10 individual panels consisting of 2438 solar cells. The panels are less than 0.5 mm thick. The Solar Panels were exchanged during Servicing Mission 3B for more rigid arrays (of the same type which are used on the Iridium Satellites). | 
