NASA's Spitzer Space Telescope, the youngest member of the "Great Observatory" programme, has completed 15 years in space. The Great Observatories are four big-ticket space telescopes -- Spitzer, Hubble Space Telescope, the Compton Gamma Ray Observatory (CGRO), and the Chandra X-ray Observatory -- designed to view the universe in different and complementary wavelengths of light.

Launched into solar orbit on August 25, 2003, Spitzer was initially scheduled for a minimum 2.5-year primary mission. But the space telescope has lasted far beyond its expected lifetime, the US space agency said in a statement. "In its 15 years of operations, Spitzer has opened our eyes to new ways of viewing the universe," said Paul Hertz, director of the Astrophysics Division at NASA Headquarters in Washington.