Scientists have proposed building an “ultrastable laser” in one of the Moon’s darkest craters to provide GPS-level navigation on the lunar surface.
Many craters in the Moon’s south pole never receive direct sunlight and lie in permanent shadow, which makes them an ideal place to construct the laser technology.
Highly stable lasers provide a source of coherent light that has a nearly unwavering frequency, or colour that could provide a master time signal in a GPS-like lunar navigation system. Multiple copies of these lunar lasers could precisely measure the distances between objects and potentially detect exotic physics phenomena such as ripples in spacetime.
To construct a lunar laser, astronauts would first install a key component known as an optical silicon cavity – a block of silicon that permits only certain frequencies of light to bounce back and forth between mirrors on each end of the block. The distance between the two mirrors determines the frequencies that are allowed to resonate...