The US satellite LES1, build from Massachusetts Institute of Technology (MIT), was launched into space on February 11, 1965, from Cape Canaveral, Florida. He finished only a few of the mission objectives, before terminating transmission in 1967. The satellite was lost in the space because of failure in its circuitry.
After 50 years, the satellite starts transmitting signals again. In 2013, an Amateur Astronomer called Phil Williams, from Cornwall, United Kingdom, retrieves a signal from LES1, but needed three years to confirm it. The “ghostly sound” within the signal was the reason many to believe that alien civilization catch the satellite and it is trying to communicate with the Earth. However, the astronomical community was surprised how the lost satellite comes back online again.
Component failure is thought to be the reason why satellite transmitter starts working again. The transmitter receives power from onboard solar panels. The satellite needs four seconds to rotate on itself, and the signals send on 237MHz oscillates every time when the solar panels are shadowed.
This isn’t the first time NASA to lose satellite in the space which reappears later. The Solar and Heliospheric Observatory spacecraft lost contact with NASA in 1998, before connecting again 22 months later.