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 towards it.

The Vikram lander of India’s Chandrayaan-3 mission has been successfully contacted by a laser instrument aboard a NASA spacecraft orbiting the Moon, according to the US space agency.

According to NASA, a new method of precisely detecting targets 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, 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 towards it.

NASA scientists realized their method had finally succeeded when light from a tiny NASA retroreflector aboard Vikram was detected by the orbiter.

Tracking the whereabouts of Earth-orbiting satellites from the ground is a typical usage of laser pulses sent toward an object and measuring the time it takes for the light to return.

However, scientists noted that there are numerous uses for the process in reverse, which involves sending laser pulses from a moving spacecraft to a stationary one to pinpoint its exact location, on the Moon.

The team at NASA’s Goddard Space Flight Centre led by Xiaoli Sun stated, “We’ve demonstrated that we can locate our retroreflector on the surface from the Moon’s orbit.” The retroreflector on Vikram was built as part of a collaboration between NASA and the Indian Space Research Organisation (ISRO).

“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,” Sun stated in a statement from NASA.

NASA’s small yet powerful retroreflector, known as the Laser Retroreflector Array, is only 2 inches (5 centimeters) wide and consists of eight quartz-corner-cube prisms mounted within an aluminum frame in the shape of a dome.

Scientists claim that the gadget is robust and easy to use; it doesn’t need electricity or upkeep and can 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 era and have a wide range of scientific and exploratory purposes.

The US space agency also stated that the retroreflectors, which are the size of a suitcase, demonstrated that the Moon is receding from Earth at a speed of 3.8 centimeters annually.

The Laser Retroreflector Array (LRA) on 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) on 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 continued.

SOURCE: https://www.ndtv.com/india-news/nasa-spacecraft-pings-indias-chandrayaan-3-lander-on-moon-4913940