Nasa finds India's lost orbiter, asleep but on track

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Scientists at Nasa's Jet Propulsion Laboratory said it required "more detective work" to find Chandrayaan-I after they spotted Nasa's Lunar Reconnaissance Orbiter (LRO).

Chandrayaan-1 was launched by Indian Space Research Organisation (ISRO) on October 22, 2008 from the Satish Dhawan space centre at Sriharikota, about 100 km from Chennai.

But nine years since its launch, a new radar technology pioneered by scientists at Nasa's Jet Propulsion Laboratory (JPL) was put into place to trace Nasa's Lunar Reconnaissance Orbiter and Chandrayaan-1. 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.

Previously scientists have tried to use optical telescopes to see objects in the moon's orbit, however the glare of the moon has been too bright for anything to be seen.

India's first unmanned lunar spacecraft which was considered "lost" in 2009 has now been located by a NASA radar. But in July, Isro officials said a star sensor -an electronic eye that helps point the spacecraft's antenna and cameras in the right directions - malfunctioned. These are caused by regions of high density, called mascons, under the lunar surface, and can act like shifting currents do on a ship to send orbiting satellites off course as they revolve around the Moon.

Despite the potential influence of mountains and other "mass concentrations", which can shift a probe's path, Chandrayaan-1 was more or less where team members expected it to be - in a polar orbit about 125 miles (200 kilometers) above the lunar surface.

She said the size of India's spacecraft, which may be compared to half a smart vehicle, made its detection even more challenging. Nasa said that the timing of the detections matched the time it would take for Chandrayaan-1 to complete one orbit and return to the same position above the moon's pole. This information was then used to update the orbital predictions for Chandrayaan-1. It had been expected to operate for two years and had been experiencing technical problems before contact was lost.

It is hoped that this new method of object detection using multiple ground-based radar antennas can be put to good use in the future. Now, after 8 years, US' space agency NASA has found the Chandrayaan 1.

In finding Chandrayaan-1 in deep space, NASA's interplanetary radar scientists have virtually spotted a 1.5 metre-sized cube travelling almost 386,000 km from the earth.

They were both orbiting the moon. Nasa explained that radar echoes from Chandrayaan-1 were obtained seven more times over three months and were in ideal agreement with the new orbital predictions.

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