Finding lost vehicles in deep space is no longer next to impossible, as demonstrated by how NASA successfully spotted two spacecraft including India’s lunar orbiter Chandrayaan-1.

Just what are these ground-based radar techniques and how did they end up finding the derelict spacecraft?

Details Of Lost Spacecraft

The Indian Space Research Organization launched the Chandrayaan-1 mission in 2008. The mission proceeded for around 312 days until the scientists lost contact with the orbiter in August 2009.

The satellite, according to ISRO, made more than 3,400 orbits around the moon until its disappearance on Aug. 29.

“Back then, we had predicted a two-year life for Chandrayaan-I. But we lost contact after a power system failure,” recalled Madhavan Nair, former ISRO chair and key figure behind the mission.

One of the primary challenges in recovering the lost orbiter is its small size. The Chandrayaan-1 is a mere cube measuring around 5 feet on each side, or around half the size of a smart car.

NASA Interplanetary Radar At Work

Current technologies do not offer an easy task of detecting objects orbiting the moon, revealed NASA in a statement. For one, optical telescopes are unable to spot small objects hiding in the bright lunar glare.

But a new application of NASA’s interplanetary radar made it possible. It located not just Chandrayaan-1 but also the still-active Lunar Reconnaissance Orbiter, launched back in 2009. The radar has been used for observing small asteroids a couple of million miles from Earth.

The team initially estimated the likely position of the derelict spacecraft, and then sent potent beams of microwaves toward the moon’s north pole using the 230-foot antenna at NASA’s Goldstone Deep Space Communications Complex in California. The 330-foot Green Bank Telescope in West Virginia received the radar echoes bouncing back from the moon’s orbit.

On July 2 last year, the team pointed both Goldstone and Green Bank somewhere 100 miles above the north pole of the moon. During hours of observation, something with the Indian orbiter’s radar signature crossed the beam twice, the timings between detections matching the time it would likely take Chandrayaan-1 to complete an orbit and return to the same post.

Chandrayaan-1’s orbit retained the shape and alignment expected of it, but scientists needed to shift its location by around 180 degrees or a half-cycle from 2009 orbital estimates, reported NASA scientist Ryan Park. Radar echoes from the Indian craft were received seven more times over a three-month period, all agreeing with the team’s orbital estimates.

Radar Systems: Promises And Prospects

The new application of the radar technology is deemed useful for future missions, including robotic and human missions to the moon. It is potentially beneficial for assessing collision hazards as well as a safety mechanism for space vehicles encountering communication or navigation problems.

It is not the first time that space scientists detected a missing spacecraft. Last Aug. 21, the U.S. space agency announced that it had re-established contact with the STEREO-B spacecraft, lost since October 2014. The probe was one of two almost identical spacecraft launched by NASA to orbit the sun.

More popularly known is the disappearance of the European Space Agency’s Philae lander after its historic landing on comet 67P/Churyumov-Gerasimenko. The lander, wedged into a dark crack on the comet's surface, was found by the camera aboard its mother ship Rosetta.

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