NASA Spacecraft ‘Pings’ India’s Moon-based Chandrayaan-3 Lander

The US space agency said that the Vikram lander of India’s Chandrayaan-3 mission has been successfully contacted by a laser instrument on a NASA spacecraft circling the Moon.

According to NASA, a novel method of accurately detecting objects on the Moon’s surface was made possible by the transmission and reflection of a laser beam between the Lunar Reconnaissance Orbiter (LRO) and an Oreo-sized instrument on the Vikram lander.

On December 12 of last year, the lander was 100 kilometers from LRO, close to the Manzinus crater in the southern area of the Moon, when LRO sent laser pulses toward it. NASA scientists realized their method had finally succeeded when light from a small NASA retroreflector on Vikram was detected by the orbiter.

Tracking the whereabouts of Earth-orbiting satellites from the ground is a typical usage of laser pulses sent towards an object and measuring the time it takes for the light to return. On the other hand, scientists noted that there are several uses for this approach at the Moon, such as sending laser pulses from a moving spacecraft to a stationary one in reverse to pinpoint its exact position.

As part of a collaboration between NASA and the Indian Space Research Organization (ISRO), Xiaoli Sun, the project leader at NASA’s Goddard Space Flight Center, designed the retroreflector on Vikram. “We’ve shown that we can locate our retroreflector on the surface from the Moon’s orbit,” Sun stated.

In a NASA release, Sun said, “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.”

NASA’s little but potent retroreflector, known as a Laser Retroreflector Array, is just 2 inches (5 cm) wide and consists of eight quartz-corner-cube prisms arranged inside an aluminum frame in the form of a dome.

Scientists claim that the gadget is robust and easy to use; it doesn’t need electricity or upkeep and may survive for many years. According to NASA, the retroreflector’s design enables it to return light from any direction back to the source.

Retroreflectors have been utilized on the Moon since the Apollo period and have a wide range of scientific and exploratory purposes. The US space agency also said that upon returning to Earth, the retroreflectors the size of suitcases showed that the Moon is receding from our planet at a speed of 3.8 millimeters each year.

The Laser Retroreflector Array (LRA) aboard the Chandrayaan-3 lander has started working as a fiducial point—a precise location marker for reference—on the Moon, according to ISRO, which responded to the development.

On December 12, 2023, NASA’s Lunar Reconnaissance Orbiter (LRO) successfully detected signals reflected by the LRA, enabling it to estimate laser range. The Lunar Orbiter Laser Altimeter (LOLA) aboard the LRO was used for the ranging. The LRO was seen rising to the east of Chandrayaan-3 during the observation, which took place during lunar night, the Indian space agency said.