Chandrayan was found when JPL discovered new technology to find small objects in space, JPL said, "Optical telescopes are unable to search for small objects hidden in the bright glare of the moon".
The Indian spacecraft, Polar Sattelite Launch Vehicle -C11 (PSLV) takes off carring India's first lunar probe Chandrayaan-1 at the Satish Dhawan Space Centre in Sriharikota, around 110KM north of southern Indian city of Chennai on October 22, 2008.
Optical telescopes can not find such small objects because the moon's vast brightness would overwhelm the view of objects passing in front of it.
Whilst interplanetary radars have been used to see small asteroids millions of miles from Earth, they have never been used to see such a small item at a distance as far as the moon. The orbiter is a cube about five ft (1.5 m) on each side, which makes it a very tricky target.
In addition to the Indian satellite, NASA's lunar reconnaissance orbit (LRO), which is still active, has also been accurately located. Apparently, it was easy for the new radar technology to detect LRO because astronomers were working with the navigators of the spacecraft and, thus, they had the correct orbit data where it was located. Indian Space Research Organisation (ISRO), who was the owner and operator of the lunar mission later declared the spaceship as "lost" after it mislaid communication with the spacecraft on 29th August 2009.More news: US Private Sector Employment Jumps Much More Than Expected In February
"Radar echoes from the spacecraft were obtained seven more times over three months and are in ideal agreement with the new orbital predictions", the team wrote.
The interplanetary radar has found that Chandrayaan-1 is still circling some 200 km above the lunar surface.
To find the spacecraft, the team used NASA's 70-meter antenna at the agency's Goldstone Deep Space Communications Complex in California to send out a powerful beam of microwaves directed toward the moon. While the latter was an active one, Chandrayaan was a hard bet as the contact with it had been lost for nearly a decade now. The radar echoes bounced back were received by the Green Bank Telescope in West Virginia.
Through calculations, the Chandrayaan-1 was known to be in an orbit taking it past both poles every two hours and eight minutes. The spacecraft's instrument readings yielded signatures of water molecules on the moon. This made researchers uncertain whether they could locate it using the radar. The Moon's mascons (regions with higher-than-average gravitational pull) were an added risk as they "can dramatically affect a spacecraft's orbit and even cause it to have crashed into the moon", the statement said. "This new technique could assist planners of future moon missions", a recent NASA report said. The mission will consist of an orbiter, lander and rover.