Isro's Chandrayaan-1, once thought lost, still orbiting the Moon: Nasa

India's first lunar mission – the Chandrayaan-1 spacecraft, which was generally considered lost – is still orbiting the Moon, NASA scientists have found with new technological application of their interplanetary radar.

The Indian Space Research Organisation (ISRO) lost communication with Chandrayaan-1 on August 29, 2009, barely a year after it was launched on October 22, 2008.

Chandrayaan-1 is still circling some 200 kilometres above the lunar surface, the scientists determined.

In addition to finding Chandrayaan-1, the scientists also located NASA's Lunar Reconnaissance Orbiter around the Moon.

"We have been able to detect NASA's Lunar Reconnaissance Orbiter (LRO) and the Indian Space Research Organisation's Chandrayaan-1 spacecraft in lunar orbit with ground-based radar," said Marina Brozovic, a radar scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, and principal investigator for the test project.

"Finding LRO was relatively easy, as we were working with the mission's navigators and had precise orbit data where it was located. Finding India's Chandrayaan-1 required a bit more detective work because the last contact with the spacecraft was in August of 2009," Brozovic said in a NASA statement on Thursday.

Finding derelict spacecraft and space debris in Earth's orbit can be a technological challenge.

Detecting these objects in orbit around Earth's Moon is even more difficult.

Optical telescopes are unable to search for small objects hidden in the bright glare of the Moon.

However, with the new technological application of the interplanetary radar, the scientists at JPL successfully located the two spacecraft orbiting the Moon.

The researchers believe that the new technique could assist planners of future Moon missions.

Add to the mix that the Chandrayaan-1 spacecraft is very small, a cube about 1.5 metres on each side — about half the size of a smart car.

Although the interplanetary radar has been used to observe small asteroids several million miles from Earth, researchers were not certain that an object of this smaller size as far away as the moon could be detected, even with the world's most powerful radars.

Chandrayaan-1 proved the perfect target for demonstrating the capability of this technique, the researchers said.