Final answer:
The main purpose of an infrared telescope aboard an airplane is to fly above most of the Earth's atmospheric water vapor, which allows for clearer observations of celestial bodies in the infrared spectrum.
The high-altitude flight conditions also enable the cooling of telescope optics without interference from condensation, making instruments like SOFIA highly effective for astronomical observations.
Step-by-step explanation:
The purpose of an airplane with an infrared telescope on board is primarily to fly above much of the water vapor in the Earth's atmosphere.
Water vapor is the main source of atmospheric interference for making infrared observations. By flying at a high altitude, the telescope can avoid 99% of this water vapor, which is concentrated in the lower part of the Earth's atmosphere.
Moreover, this high-altitude vantage point allows for the observation of celestial bodies with minimal atmospheric distortion.
This is crucial because typical temperatures on Earth's surface lead to everything, including the telescope and observatory, radiating infrared energy, which can interfere with the detection of faint cosmic sources.
An additional advantage of airborne infrared telescopes is that they can be operated within the vacuum of the stratosphere, allowing optical elements to be cooled significantly without becoming coated with condensing gases, unlike what would happen on the Earth's surface.
The Stratospheric Observatory for Infrared Astronomy (SOFIA), for example, maximizes these benefits by operating at high altitudes, allowing astronomers to observe and study the universe in the infrared spectrum effectively.