A New Mexico State University research team has been working on a lunar laser project to help place humans on the moon again for the first time in over 50 years.
Under NASA, the Lunar Laser program uses telescopes out of New Mexico State University’s Apache Point Observatory, south of Alamogordo, to emit laser pulses to the moon and measure the distance based on how long it takes the laser to come back.
Originally made to study gravity, the program was taken up by NASA in 2020 and has been focused on laser technology since then.
This project is made possible by small retroreflectors, which are mirrors made with the specific purpose of reflected lasers back to earth. The lasers have been on the moon since the first mission to place mankind there in 1969.
At the observatory, a small laser is sent out into space. It is shot for 100 picoseconds 20 times over the course of a second. A picosecond is one trillionth of a second.
The laser travels from a telescope at the Apache Point Observatory to the moon. Russet McMillan, night operations manager of the telescope, said the importance of the laser is that it is very short.
“The shorter [the laser], the more accurately we can measure it,” McMillian said. “We measure the timing to high accuracy, and that way we can measure the distance in the instant that this pulse of light reflected off the reflector on the moon.”
By the time the laser reaches the moon it is around a mile long; however, the mirrors can be as small as four inches wide.
The light that manages to hit the mirror is then sent back to earth. From the observatory, the team can then measure the moon’s distance from how long it takes the laser to return to earth.
However, the reflectors have become less effective as they have collected lunar dust, which covers them and makes them less effective. Before 2025, the last of the five lunar retroreflectors to be placed on the moon was positioned in 1971, to ensure success for the future of the Lunar Laser project more had to be placed.
March marked the first mission to place a new retroreflector on the moon in over 50 years.
“I think one of the things that's so fascinating about this, that's really highlighted by the new reflector is the way that it really ties together the old moon missions with new fresh science that we're doing today,” McMillan said. “Now we're going to be able to connect that to new reflectors, the one that they landed on the moon in March and other ones that will be upcoming. We're going to be continuing the legacy of those original moon missions that started with one small step and continuing to get new science that will be more valuable because of having a continuous record going back 56 years now.”
Projects that are going to use the technology researched at Apache Point Observatory have already been planned including projects called Artemis II and III. Artimis III is set to launch some time in 2027 and will be the first project to put humans on the moon since Apollo 17 in 1972.
Laser measurements have an integral role in assuring safe landing for the spacecraft, McMillan said, by assuring astronauts have the most accurate information on the orientation and motion of the moon.
