The second stage of the Delta II Heavy rocket is ready for mating onto the first stage, below. The rocket will launch the Space Infrared Telescope Facility (SIRTF), currently scheduled for mid-August. SIRTF consists of three cryogenically cooled science instruments and an 0.85-meter telescope, and is one of NASA's largest infrared telescopes to be launched. SIRTF will obtain images and spectra by detecting the infrared energy, or heat, radiated by objects in space. Most of this infrared radiation is blocked by the Earth's atmosphere and cannot be observed from the ground.