NASA’s Lunar Reconnaissance Orbiter (LRO) has achieved a significant milestone in space exploration by successfully shooting a laser at India’s Vikram lander on the Moon. Contrary to what some may believe, this laser shot was not the beginning of a space war, but rather a meticulously planned scientific experiment. The laser, which traveled an impressive distance of about 100 kilometers (62 miles) from orbit to the Moon’s surface, hit a target that was just 5 centimeters (2 inches) wide. This groundbreaking achievement marks the first time a laser has been shot from around the Moon to a target on its surface.
The target in question is a Laser Retroreflector Array, roughly the size of an Oreo cookie, which was placed on the Vikram lander by the Indian Space Research Organization (ISRO). The laser beam bounced off the retroreflector and was then detected by NASA as the LRO orbited the Moon. This technique of bouncing light to and from satellites is commonly used on Earth to determine their precise location in orbit. Now, scientists are exploring the possibility of using this approach on the Moon to accurately locate stationary objects.
Xiaoli Sun, the mission leader from NASA’s Goddard Space Flight Center, expressed excitement about the successful experiment. “We’ve shown that we can locate our retroreflector on the surface from the Moon’s orbit,” Sun stated. “The next step is to improve the technique so that it can become routine for missions that want to use these retroreflectors in the future.”
The Laser Retroreflector Array developed by Sun’s team consists of eight quartz-corner-cube prisms arranged in a dome-shaped aluminum frame. This innovative device has the ability to reflect light from any direction and does not require any power or maintenance. Consequently, it can be used repeatedly over an extended period to precisely locate Vikram or other stationary objects on the Moon. While Vikram is no longer functional, this technology will be crucial for future lunar missions where knowing the exact location of spacecraft will be of utmost importance.
Interestingly, the main challenge in this experiment was not the target itself. Retroreflectors the size of a suitcase have been utilized on the Moon since the Apollo era, providing valuable information about the Moon’s movement away from Earth at a rate of 3.8 centimeters (1.5 inches) per year. The real difficulty lay in using NASA’s Lunar Orbiter’s altimeter, known as LOLA, to hit such a small target. LOLA, which has already exceeded its primary mission by 13 years, was originally designed to aim for an area 10 meters wide. However, with eight attempts, LOLA eventually succeeded in hitting the Vikram retroreflector.
The successful laser shot by LOLA opens up exciting possibilities for future lunar missions. Specialized lasers could be developed to make retroreflectors an essential technology for upcoming expeditions to the Moon. In fact, NASA has already placed a retroreflector on Japan’s SLIM, which recently landed on the Moon. The hope is that LOLA will be able to replicate its impressive feat and hit the target consistently.
As we continue to explore and expand our presence in space, experiments like these pave the way for advancements in scientific research and technological innovation. The successful laser shot from the LRO to the Vikram lander demonstrates the collaborative efforts between NASA and ISRO, pushing the boundaries of what we can achieve in our quest to unravel the mysteries of the Moon and beyond.