Scientists want to put a superlaser on the Moon. But for what?

Scientists theorize that an ultrastable laser could enable extremely precise timing and navigation on the Moon. Cold, dark craters near the lunar poles would be an ideal place to install it.

In an article earlier this month in arXivscientists announced their intention to build a laser inside one of the coldest craters on the Moon that could help lunar landers and rovers navigate with precision.

As explained by , ultrastable lasers are vital for timing and navigation systems that require extreme precision. They work by ricocheting a beam between two mirrors inside a cavity. The beam reflects between the mirrors at a highly accurate rate, in part because the chamber maintains virtually exactly the same size, rather than expanding or contracting. To maintain this stable beam length, mirrors are typically kept within a vacuum at extremely low temperatures, isolated from external vibrations.

On the Moon, there are hundreds of craters around the poles that never receive any direct sunlight because the Moon doesn’t tilt much as it rotates around itself. This makes these regions permanently shadowed and exceptionally cold, predicting some craters to reach around -253°C in the lunar winter.

Scientists now propose that these frigid conditions – along with the moon’s natural lack of vibrations and virtually non-existent atmosphere – could make these craters the perfect location for an ultrastable laserwith potential stability far greater than that of any laser on Earth.

The laser device would be similar to devices they have already built in JILA’s labs, called optical cavities, which consist of a chamber made of silicon with two mirrors.

The best optical cavity lasers on Earth can remain coherent, meaning the laser’s light waves remain synchronized for just a few seconds. However, researchers think a Moon-based laser could remain coherent for at least a minute.

This would allow it to function as a reference laser for many different lunar activities, such as maintain a time zone or coordinate satellites which fly in formation and use lasers to measure their distance from each other.

It could even be used as reference laser for activities on Earthbecause a beam takes just over a second to reach Earth from the Moon.