The Delta II launch of NASA's fourth and final "Great Observatory" missions, the Space Infrared Telescope Facility (SIRTF), will be delayed from December 2001 for "several months" as a result of problems with the craft's Infrared Array Camera. The camera, which is one of three main instruments on SIRTF, is provided with infrared light from the craft's 850mm (33.5in) primary mirror (pictured). Following earlier budget difficulties, NASA redesigned the SIRTF to avoid cancellation. It was reduced in size from 5,700kg (12,555lb) to 950kg, while the cost was cut from $2.2 billion to $450 million. The SIRTF's mission, dictated by the amount of liquid helium it can carry to cool the infrared telescope, has been reduced to a maximum of three years.
Source: Flight International