Nasa develops laser designed to detect water on the Moon
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Nasa has developed a high-powered laser which could be used to find water on the Moon, a discovery crucial for humans to further explore Earth’s closest neighbour.
Previous experiments have confirmed the existence of small amounts of water across the Moon, although most technologies cannot distinguish between water, free hydrogen ions and hydroxyl.
An instrument known as a heterodyne spectrometer could zoom in on particular frequencies to definitively identify and locate water sources on the Moon. It requires a stable, high-powered, terahertz laser - which is also small enough to take on space missions - and this has now been prototyped by Nasa.
“This laser allows us to open a new window to study this frequency spectrum,” said Dr Berhanu Bulcha, an engineer at Nasa’s Goddard Space Flight Center.
“Other missions found hydration on the Moon, but that could indicate hydroxyl or water. If it’s water, where did it come from? Is it indigenous to the formation of the Moon or did it arrive later by comet impacts? How much water is there? We need to answer these questions because water is critical for survival and can be used to make fuel for further exploration.”
Spectrometers detect spectra or wavelengths of light in order to reveal the chemical properties of matter that light has touched. Hydrogen-containing compounds such as water emit photons in a specific terahertz frequency range between microwave and infrared.
Heterodyne spectrometers combine a local laser source with incoming light and measure the difference between the laser source and the combined wavelength which provides accurate readings between sub-bandwidths of the spectrum.
Different atoms produce different frequencies of light based on the fixed amount of energy it takes to excite one electron. However, lasers fall short in a particular portion of the spectrum between infrared and microwave known as the terahertz gap.
“The problem with existing laser technology,” Dr. Bulcha said, “is that no materials have the right properties to produce a terahertz wave.”
This new tiny laser capitalises on quantum-scale effects of materials just tens of atoms across to generate a high-powered beam in a portion of the spectrum where traditional lasers fade in strength.
Bulcha hopes to continue the work to make a flight-ready laser for Nasa’s Artemis program, which aims to put the first woman and next man on the Moon by 2024.
The laser’s low size and power consumption allow it to fit in a 1U CubeSat, about the size of a teapot, along with the spectrometer hardware, processor, and power supply. It could also power a handheld device for use by future explorers on the Moon, Mars and beyond, the researchers said.
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