March 13, 2017
NASA finds India’s long-lost lunar orbiter
Eight years after it went missing, the location of India’s first lunar orbiter has been discovered, thanks to a new NASA radar technique which the space agency believes could be used to locate previously hard-to-find orbiting object while planning future missions to the moon.
According to Engadget and Science Recorder, India lost contact with its Chandrayaan-1 lunar orbiter back in 2009, eventually abandoning hope that the lost spacecraft would ever be found. However, NASA officials revealed late last week that they had discovered the probe’s location last July using a radar-based technique previously designed to track tiny asteroids.“We have been able to detect NASA's Lunar Reconnaissance Orbiter [LRO] and the Indian Space Research Organization's Chandrayaan-1 spacecraft in lunar orbit with ground-based radar,” the project’s principal investigator Marina Brozovic, a radar scientist at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, said in a statement.
“Finding LRO was relatively easy, as we were working with the mission's navigators and had precise orbit data where it was located,” she added. However, finding Chandrayaan-1 “required a bit more detective work, because the last contact with the spacecraft was in August of 2009” and the probe itself was rather small – “cube about five feet (1.5 meters) on each side” or “about half the size of a smart car,” according to NASA.
Technology could make future moon missions safer
To detect the two spacecraft, Brozovic and her colleagues used ground-based radar systems, as optical telescopes are unable to search for relatively small objects in the moon’s bright glare. To find probes located 237,000 miles (380,000 km) away, the they used the 70-meter antenna at the NASA Goldstone Deep Space Communications Complex in California’s Mojave Desert.
They fired a series of microwaves from the Goldstone Complex antenna towards the moon, and the radar echoes were received by the 100-meter Green Bank Telescope in West Virginia, NASA explained. Since they knew that Chandrayaan-1 was in polar orbit around the moon, and that the spacecraft would always cross above the lunar poles on each orbit, they focused their attention to the moon’s north pole on July 2, 2016, and were able to locate the missing orbiter.
“It turns out that we needed to shift the location of Chandrayaan-1 by about 180 degrees, or half a cycle from the old orbital estimates from 2009,” said Ryan Park, manager of the Solar System Dynamics group at JPL, who helped calculate its orbit for the NASA radar team. “But otherwise, Chandrayaan-1's orbit still had the shape and alignment that we expected.”
Over the three months that followed the initial detection, the technique was able to obtain radar echoes from Chandrayaan-1 seven more times, including during follow-up observations made by the powerful Arecibo Observatory in Puerto Rico. Having successfully demonstrated that radar can be used to detect and track spacecraft in lunar orbit, the researchers now intend to use these arrays as a hazard assessment tool in future manned and unmanned missions to the moon.
Image credit: Dan Roam