New radar technique locates lost Indian Lunar orbiter, NASA probe.
Using previously untested radar techniques, NASA has successfully located two Lunar-orbiting spacecraft, one of which has not been tracked since 2009.
Scientists from the Jet Propulsion Laboratory in California beamed high energy microwaves at the Moon from the Goldstone Deep Space Communications complex in California. The waves bounced off the Moon and were picked up by the Green Bank Telescope in West Virginia. By using the return signal to estimate velocity and distance, JPL scientists were able to locate NASA’s Lunar Reconnaissance Orbiter – which is still operating and is currently tracked by the agency.
However, the team also located India’s derelict Chandrayaan-1orbiter whose mission ended in 2009. Due to regions of the lunar surface with a stronger gravitational pull than others – known as mascons – the spacecraft’s orbit could have been radically altered or it could have even crashed into the moon.
Since the spacecraft was known to be in a Lunar polar orbit, the team directed the microwave beam just above the Lunar north pole and hoped the spacecraft would intercept it. The returned beam picked had a radar signature in accordance to what a small spacecraft wold be expected to make. Furthermore, during the four hours the Chandrayaan-1 test took place, the spacecraft crossed the beam twice in the amount of time it was predicted to make a single orbit and return to the same point. Due to the varying strength of the Moon’s gravity over regions of different composition – known as mascons – the spacecraft’s location had to be shifted by nearly 180 degrees.
Scientists were not certain if the tests, which occurred in July 2016, would be successful. Although interplanetary radar has been used to track asteroids millions of miles away using the same technique to locate a small satellite around the moon was untried. The technology demonstrated could be useful in planning future lunar missions. The Indian Space Research Organization has no intention to reactivate the Chandrayaan-1 spacecraft, whose mission ended in 2009. Chandrayaan-1 was India’s first Lunar mission, launching in October 2008.