NASA telescope uses moonlight to enhance accuracy of satellites

NASA has sent a telescope in space that will measure the amount of light reflected off the Moon in order to improve the accuracy and consistency of measurements among Earth-observing satellites. The airborne Lunar Spectral Irradiance, or air-LUSI, flew aboard NASA's ER-2 aircraft to accurately measure reflected moonlight.

By using the Moon as a "tuning fork," scientists can more easily compare data from different satellites to look at global changes over long periods of time, the US space agency said in a statement late on Monday.

"The Moon is extremely stable and not influenced by factors on Earth like climate to any large degree. It becomes a very good calibration reference, an independent benchmark, by which we can set our instruments and see what's happening with our planet," said air-LUSI's principal investigator, Kevin Turpie from the University of Maryland in the US.

NASA has more than 20 Earth-observing satellites that give researchers a global perspective on the interconnected Earth system. The air-LUSI is a telescope that measures how much light is reflected off the lunar surface to assess the amount of energy Earth-observing satellites receive from moonlight.

In order to improve the accuracy of lunar reflectance models, air-LUSI measurements are accurate with less than 1 per cent uncertainty. This airborne approach has the advantage of studying moonlight during different phases of the Moon while being able to bring the instrument back between flights for evaluation, maintenance, and, if necessary, repair, according to NASA.

"Once air-LUSI measurements are used to improve the accuracy of the total amount of light coming from the Moon, we can take extensively more accurate measurements of Earth using current and future space-borne observatories," said Turpie.