How Telescopes Work

Launched on August 25, 2003 from Cape Canaveral, Florida, the Spitzer Telescope has provided infrared observations of objects as close as our solar system and as far away as the most distant reaches of the observable universe. Now celebrating its fourth anniversary, the telescope has exceeded the wildest expectations of NASA scientists who attribute the spectacular success to the efficiency and smooth performance of the spacecraft.

Spitzer’s technical performance is just as stellar, being the first infrared space telescope to achieve the low temperatures needed for infrared observations by using a sun shield for passive cooling and an Earth-trailing orbit. The efficient cooling techniques made it possible to use a smaller tank of coolant, liquid helium, to chill the instrument, thereby cutting the cost of the project.

As if to celebrate the observance of its fourth anniversary, Spitzer has mapped the outer structure of the Helix Nebula, a dying star scattering its remnants into space. The nebula is a six light years across and offers a spectacular view for stargazers. The probing of the telescope into the inner regions of the nebula around the dead star in the center has shown what appears to be a planetary system which survived the star’s chaotic demise.

Spitzer also recently, for the first time, detected water vapor on a planet orbiting another star. The planet, known as HD199733b, hurtles around its sun about every two days. Astronomers refer to this class of planets as “hot Jupiters”, and had predicted the presence of water vapor in their atmospheres, although finding it was difficult. Spitzer made it possible to verify the presence of water by providing measurements of changes in infrared light from the star as the planet passed by.

During a recent survey of distant galaxies, Spitzer also revealed images of the largest galactic collision ever recorded. The telescope observed an unusually large stream of light emerging from four elliptical galaxies, and further analysis of the information indicated that the light was from stars which had been thrown out by a titanic collision. In addition, the telescope recorded the lack of gas in the merging galaxies, unusual in that most mergers are gas-rich, providing the materials to create new stars. Gas-poor mergers do not support the formation of new stars.

The Spitzer Telescope’s anticipated lifetime was initially two-and-a-half years, but since its coolant is expected to last longer, the increased usefulness is projected to be more than five-and-a-half years, with many more spectacular discoveries to be made.