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NASA radar finds India's lost lunar spacecraft Chandrayaan-1 orbiting the moon

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Chandrayaan-1’s orbit profile. But after a few more trips around the moon who knows where it might have gotten

NASA's Jet Propulsion Laboratory (JPL) was testing its features and Chandrayaan was a flawless choice. Sunlight reflecting off the surface of the moon makes optical telescopes pretty much useless, and microwave radar-based systems require operators to point a beam of energy in just the right spot to find what they're looking for. In the year 2008, Chandrayaan-1 was launched from Sriharikota on October 22.

DSS-14 - NASA's 70-meter antenna which found Chandyaan-1.

The JPL team says that tracking of the two spacecraft by ground radar opens up new possibilities for lunar exploration with such stations providing future missions to the Moon with a new tool to asses the danger of collisions and for an extra level of safety for spacecraft that experience issues with navigation or communication.

The craft was reportedly located a total of seven times in three months since July 2016.

Eight years after it was considered "lost", India's first lunar spacecraft, Chandrayaan-1, has been "re-discovered" by Nasa's ground-based radars, the American space agency announced on Friday.

Chandrayaan-1 was India's first mission to the Moon. "We have been able to detect NASA's Lunar Reconnaissance Orbiter (LRO) and the Indian Space Research Organisation's Chandrayaan-1 in lunar orbit with a ground-based radar", said Marina Brozovic, a radar scientist at JPL and principal investigator for the test project. Finding LRO was less of a challenge and more of a proof of concept; it's an active spacecraft, so precise location data from the mission's navigators guided the search, detection team members said.

Although the technique has been used before to observe small asteroids several million miles from Earth, researchers were not certain that the radar could detect an object the size of Chandrayaan-1, a small cube spacecraft about 1.5 meters on each side - about half the size of a smart vehicle - in orbit around the Moon.

They were both orbiting the moon. Nasa points out that the orbiter was also very small.

NASA uses giant radar dishes to detect things like asteroids millions of miles away, and it's pretty easy to track satellites in Earth's orbit, but there are awkward middle distances that aren't so easy to monitor. On July 2 a year ago, the scientists pointed two antennas, one in California and the other in West Virginia, to a location about 160km above the Moon's north pole.

"There's not much atmosphere over the Moon, nearly as good as vacuum, so the spacecraft has not lost energy due to friction, and so continues in the same orbit". They then studied the radar "echoes" that bounced back to Earth using the 330-foot (100 m) Green Bank Telescope in West Virginia. It had found the evidence of water ice on the moon's surface.

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