Infrared astronomy is the study of heat energy known as infrared radiation emitted by objects in the universe. Everything that is above absolute freezing point, or -459.67-degrees Fahrenheit, emits infrared radiation. This type of astronomy enables scientists to see a part of the universe that the eyes cannot. Viewing the universe through infrared astronomy has brought new understanding but the study also has disadvantages.
Astronomers need large detector arrays to detect heat energy from distant objects. Detector arrays are formed by three or more 100-foot-wide energy-gathering dishes spaced miles apart focused on the same point in space. Infrared energy passes through the formation, changing the detectors' electrical conductivity. This process requires delicate equipment and time to produce one image gathered at a given point in space.
Detectors also must be placed on top of a high, dry mountain to avoid absorption of the signal from space by water vapour. Even with an advantage of altitude, infrared energy produced by the Earth is picked up in the detector. Astronomers delineate and calculate how much infrared energy is coming from Earth and space. Accurate measurements are limited to known Earth-bound infrared levels, which makes the calculation process difficult.
Infrared detectors need to be cool to avoid detection of their own emissions. This requires a separate cooling system using liquid nitrogen that must be monitored and maintained. The cost of maintaining this type of system is expensive. Sudden changes in the environment also will require renewed equipment calibration. Faint signals that are cooler than the detector will not be picked up, meaning astronomers lose part of the sky under view for more accurate observation.
The first infrared telescope was launched into orbit in 1983. It used 127 gallons of liquid helium to keep it cooled to just above absolute zero. While the telescope avoided Earth-bound interference, it only was in use for 10 months before the liquid helium ran out. Modern space telescopes last longer but remain limited in time of operation. Unlike ground-based telescopes, there also is little chance of repair upon the system failures of an infrared space telescope.