It has already been concluded and confirmed that there is some amount of water on the Moon. However, technologies indicating the presence of water are unable to tell whether it is water, hydrogen ions or hydroxyl. To fill the gap, an engineer from the US space agency NASA has developed a small but high-powered laser that could help detect water sources on our lunar neighbor. This laser could be used to develop an instrument called a heterodyne spectrometer, which would be able to zoom in at particular frequencies and confirm the presence of water on the Moon’s surface. Researchers believe the laser could power a handheld device that could be used in future missions to explore the Moon, Mars and beyond.
Spectrometers can reveal the chemical properties of matter by identifying the spectra or wavelengths of light that touch it. While most of these instruments operate over broad sections of the spectrum, the heterodyne spectrometer focuses on a specific light frequency such as terahertz or infrared.
Water and other compounds that contain hydrogen emit photons in the terahertz frequency range, which is 2 trillion to 10 trillion cycles per second. A heterodyne spectrometer combines a local laser source with incoming light and helps to measure the difference between the laser source and the combined wavelength. This measurement in turn gives accurate readings across the sub-band width of the spectrum.
Traditionally, lasers used excite electrons within the outer shell of an atom to generate light. The frequency of light depends on the energy required to excite an atom and an electron. But, these lasers fail to perform in the terahertz gap or the spectrum between infrared and microwaves.
“The problem with current laser technology is that no material has the right properties to generate a terahertz wave,” the engineer said. Dr. Bulcha,
To overcome this problem, the team of researchers used the Goddard technique. They are working to develop quantum cascade lasers that produce photons with each electron transition event, using some of the unique quantum-scale physics of layered materials the width of a few atoms.
In such materials, the laser produces photons in a specific frequency that is determined by the thickness of the alternating layers of semiconductors, rather than by the elements in the material.
In addition, the laser size is small enough to enable researchers to fit inside a teapot-sized 1U CubeSat with processor, spectrometer hardware and power supply.
