Space is nothing if not vast, dark and hard to monitor. So when a small object goes missing, it can prove tricky to find. That’s what happened in 2009, when the Indian Space Research Organization’s Chandrayaan-1 lunar orbiter disappeared. But researchers weren’t about to give it up without a fight, reports The Washington Post’s Sarah Kaplan. Eight years after going rogue, Chandrayaan-1 has finally been found.
Tracking down the tiny satellite wasn’t simple. As Kaplan reports, it’s refrigerator-sized—not exactly huge in the grand scheme of space. And scientists had another enemy: the moon itself.
Blame the moon’s lumpy shape for making Chandrayaan-1 so elusive. It’s covered with mascons, which are large lumps of mass beneath the surface that make the moon’s gravity field unpredictable. Scientists have known about them since the 1960s, but only in 2013 did they discover that mascons were created by asteroids that smashed into the lunar surface long ago. The lunar crust formed around those craters, leaving mass concentrations (mascons) of gravity behind in some areas.
Those gravitational lumps can have a big impact on a spacecraft’s orbit over time, but their effect can be difficult to predict. And then there’s the bright, Sun-reflecting surface of the moon, which made it impossible to use telescopes to spot where Chandrayaan-1 had gone.
Scientists clearly needed another way to search for the lost craft. So they turned to radar. In a press release, NASA describes how researchers trained microwaves toward the moon using a 230-foot-high antenna at the Goldstone Deep Space Communications Complex in California.
The antenna acted like a massive radar gun, shooting microwaves that then bounced off of the spacecraft when it crossed near the moon’s north pole. By calculating the time it took the possible craft to orbit, they confirmed that it really was Chandrayaan-1, then adjusted their orbital estimate by about 180 degrees. Over the next three months, they observed the craft seven more times—acting just like they calculated it would inside its newly observed orbit.
As Kaplan reports, it’s not the first time NASA has used powerful radar to locate spacecraft. The agency also tested the technique on the Lunar Reconnaissance Orbiter—but that test was a bit easier since they hadn’t lost touch with the craft.
Now that scientists know where Chandrayaan-1 is, what will they do? Look toward the future. The ISRO is busy developing Chandrayaan-2, whose tenure will hopefully prove longer than the 312 days its predecessor was live. And with the help of ground-based radar, scientists now know how to find other crafts that are unlucky enough to fall out of touch.