Space Technology

NASA ground based long range sensors find lost lunar orbiter

NASA can not only hit the moon with radar and get a reflection, they can now detect a 5 ft cube orbiting the moon using only ground based radar. They proved it by finding a lost lunar orbiter from India. 

 China, Japan, India, Russia, and the US either have sent or plan to send satellites there for a bird’s-eye view of lunar features and resources. …

In Sanskrit, “Chandrayaan” means “Moon Craft.” A NASA-sponsored instrument, the Moon Mineralogy Mapper, will ride along and use an infrared spectrometer to survey the lunar terrain and give us a highly detailed picture of mineral locations. 


The moon, with an average diameter of 2,159.3 miles is 242,917 miles away at the moment, with angular diameter of 30.552 arc minutes according to WolframAlpha.  Some quick calculations… correct me if I’m wrong, but 5 ft is 0.00095 miles. So, the angular diameter of a 5ft satellite around the moon would be 2.2407e-7 Degrees, or 0.00080665199 arc seconds. At 250 miles above the earth, about the average orbit of the ISS, that same technology could find something on the surface as small as 0.0619 inches, or 1.572 millimeters. For comparison, a US Dime is 17.80 mm and 1.5 mm is the length of the average flea. Seeing a flea at 250 miles away is impressive!

India lost contact with its first lunar orbiter, the Chandrayaan-1, back in 2009. Now, NASA has revealed that the agency discovered its location in July 2016 after testing a method that can be used by future lunar missions. Chandrayaan-1 is a relatively tiny cubic probe that measures five feet on all sides, making it the perfect target for the radar experiment conducted by a team of Jet Propulsion Laboratory scientists. The team wanted to find out whether a technique used to observe small asteroids can also spot spacecraft orbiting the moon.
This method relies ground-based radar, because optical telescopes can’t see anything against the bright lunar glare. Since Chandrayaan-1 was in polar orbit around the celestial body before it got lost, the team sent a powerful beam of microwaves somewhere above the natural satellite’s north pole. They used a 230-foot antenna at NASA’s Goldstone Deep Space Communications Complex in California to accomplish the task. But they relied on the 330-foot Green Bank Telescope in West Virginia to detect the radar echoes that bounced back.

The researchers were afraid they wouldn’t find anything, since the moon has areas with higher-than-usual gravitational pull that could have caused the spacecraft to crash into it. However, the scientists were able to detect two different objects using the technique: one matched the Lunar Reconnaissance Orbiter’s well-known path. The other was a tiny object, which crossed the beam twice – the second sighting matched the time it would have taken the Chandrayaan-1 to complete one orbit.
Now that the scientists have proven that ground-based radars can be used to track probes in lunar orbit, NASA could use them for both robotic and human missions. The technique could also be used as a safety mechanism for spacecraft suffering from communication issues in the future.


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