The Indian Space Research Organization (ISRO) lost communication with its first ever lunar mission Chandrayaan-1 on August 29, 2009. Scientists at the US space agency NASA reported Thursday that they had successfully located Chandrayaan-1. The spacecraft is still circling the moon in a polar orbit 200 kilometers above the lunar surface. The probe was the size of a small car.

NASA India Chandrayaan-1
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NASA used a new technique to find Chandrayaan-1

Researchers at NASA’s Jet Propulsion Laboratory (JPL) used a new ground-based radar technique to locate the lunar probe. Objects like Chandrayaan-1 are difficult to find because the mountains and other “mass concentrations” on the moon with high gravitational pull can significantly change a spacecraft’s orbit. The Indian lunar spacecraft was more or less where NASA scientists expected it to be.

Optical telescopes cannot find such small objects because the moon’s immense brightness would overwhelm the view of objects passing in front of it. That’s why astronomers at NASA used the “interplanetary radar” technique to locate the object. The interplanetary radar is used to find small asteroids millions of miles from our planet. But scientists were not sure whether it could locate a tiny lost probe orbiting the moon.

NASA also locates LRO

Ryan Park, the manager of the Solar System Dynamics group at JPL, said in a statement that they had to shift the location of the spacecraft by roughly 180 degrees from the old estimates from 2009. The probe was in polar orbit, so it was expected to cross above the poles on each orbit. In July 2016, NASA pointed the Goldstone Solar System radar to beam microwaves.

Using the Green Bank Telescope, scientists analyzed the radar beam echoes that bounced back to the Earth, reports Space.com. Astronomers were able to detect both the Chandrayaan-1 and NASA’s own Lunar Reconnaissance Orbiter (LRO). The detection team said finding LRO was easy because they had its precise location data. The LRO was launched in 2009 to collect data that could be useful for future manned missions to the moon.

Finding Chandrayaan-1 was a major challenge

Locating Chandrayaan-1 was far more challenging because of its small size and the fact that the last successful contact with the spacecraft was made in August 2009. JPL said the rediscovery of the Indian lunar spacecraft was proof that its interplanetary radar technique works. It can detect even small objects in the lunar orbit. Chandrayaan-1 was launched in October 2008, and it is estimated to have made more than 34,000 orbits around the moon.

ISRO’s mission was concluded before the spacecraft lost contact. It had found the evidence of water ice on the moon’s surface. ISRO is working to launch its second lunar mission Chandrayaan-2 next year. It would include three objects: an orbiter, lander, and rover.