At a Glance

LES1 never reached its intended orbit due to a launch failure.It remains a mystery why the satellite resumed sending signals after 46 years.

An American satellite left for dead as space junk almost 50 years ago has come alive again, transmitting signals back to earth.

According to NASA, — LES1 through LES9 — designed and built by Lincoln Laboratory between 1965 and 1976.

The purpose of the unmanned space crafts was to test techniques for military satellite communication, NASA says.

Because of several launch failures, LES1 through LES4 did not reach their intended orbit but still produced "remarkable results," according to NASA.

LES 5, 6, 8, and 9 all ended up in their intended orbit and performed as expected, while LES7 was scratched due to a lack of funding and the termination of the project known as West Ford.

In 2013, an amateur radio astronomer from North Cornwall, UK, picked up a signal that was later determined to come from LES1.

The satellite was built by the Massachusetts Institute of Technology and launched from Cape Canaveral on Feb. 11, 1965.

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The amateur radio astronomer, Phil Williams, said in an article for Southgate Amateur Radio News that the . Scientist determined that the odd signal was attributed to the satellite "tumbling end over end," hiding the solar panels as it tumbled through space. As the satellite's solar panels received light from the sun, the signal grew stronger.

“This gives the signal a particularly ghostly sound as the voltage from the solar panels fluctuates,” Williams told Southgate Amateur Radio News.

It's unknown what caused LES1 to resume sending signals. Williams notes that there must be some other explanation why it 237 Mhz transmission resumed as it's likely the onboard batteries had disintegrated after 46 years in space.

The "zombie" satellite poses no threat as it will likely be years before it eventually tumbles to the Earth's surface, Williams noted.

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