We have over 2,000 satellites hovering, spinning, and orbiting Earth. Once these come to the end of their lives, they aren't removed but simply burn up if they reenter the stratosphere. Others, however, continue circling Earth known as "zombie satellites", neither dead nor alive.
How do you find a zombie satellite?
"Most zombie satellites are satellites that are no longer under human control, or have failed to some degree," explained Scott Tilley to NPR.
In 2018, Tilley's passion for hunting satellites led him to find a signal from a NASA probe called IMAGE, which the agency lost track of in 2005. Thanks to Tilley, NASA now has reestablished contact with the probe.
This isn't the only probe Tilley's encountered, some are even older than IMAGE. "The oldest one I've seen is Transit 5B-5. And it launched in 1965." Transit 5B-5 was a nuclear-powered U.S. Navy navigation satellite that still orbits Earth.
Well folks, here's what appears to be a new ZOMBIE SAT!— Scott Tilley (@coastal8049) March 25, 2020
LES-5 [2866, 1967-066E] in a GEO graveyard orbit.
Confirmation will occur at ~0445 UTC this evening when the satellite should pass through eclipse.
If so this is definitely the oldest emitting GEOsat I know of. pic.twitter.com/QFSRb5bT1I
More recently, Tilley went on the hunt for LES-5, a communications satellite he believed may still have life left in it, and he was right. LES-5 was built by MIT's Lincoln Laboratory and was propelled up into Space in 1967.
What pushed Tilley to look for LES-5 was that if it was still functioning, this would make it the oldest functioning satellite still remaining in geostationary orbit.
He gathered as much information about how to find the satellite and went about building what he needed to do so: "This required the building of an antenna, erecting a new structure to support it. Pre-amps, filters, stuff that takes time to gather and put all together."
On March 24, Tilley hit the jackpot. "The reason this one is kind of intriguing is its telemetry beacon is still operating," explained Tilley of LES-5.
So, even though LES-5 was meant to stop operating in 1972, it is still going on in 2020. As long as its solar panels are in the Sun, the satellite's radio keeps working.