continued:
The Earth's lower atmosphere absorbs most infrared rays (IR) coming from above so that few reach the surface. However, an airplane flying in the stratosphere at 40,000 feet or higher has most of the atmosphere below it and can see the sky in the infrared. While satellites have also made infrared measurements, an aircraft can carry a crew and much more equipment and can be modified and reused. The Kuiper aircraft has been flying over 20 years.

The Kuiper aircraft is a Lockheed C-141 transport modified to carry an infrared telescope. The telescope is mounted in the aircraft so that it can move independently. An automatic system keeps the telescope pointed at the selected astronomical object even when the aircraft moves in turbulence. Liquid nitrogen and other cryogenic liquids cool the mirrors of the telescope so they don't create infrared radiation themselves. The telescope mirrors gather infrared from a large area, a circle about one yard in diameter, and concentrate it on a detector. Various detectors may be attached and these are also cooled.

*engineering *science

Adding video to channels (Engineering, Science) - requested by kulpims.