In 1977, astronomer Jerry R Ehman detected an anomalous signal at the Big Ear radio telescope of Ohio State University.
The signal lasted for 72 seconds but has never been detected again and Ehman wrote "Wow!" in the margin of the computer printout.
"I don't know an awful lot about it to be honest, but the fact that it didn't repeat and nothing else like has been seen, makes you wonder whether it was just some curious fault with equipment or interference or something like that," Professor Jocelyn Bell Burnell told News24.
Burnell discovered pulsars as a student in 1967, but her thesis supervisor Antony Hewish shared the Noble prize in 1974 for the discovery.
She speculated that interference might have been the cause of the signal, widely regarded by some as proof of extraterrestrial intelligence.
"There's an awful lot of interference around - a hell of a lot of interference, so that's something you've got to bear in mind."
Interference in a radio telescope can render all the data obtained useless and in SA, engineers building the MeerKAT or Karoo Array Telescope in the Northern Cape province have taken extra care to prevent interference in the instrument.
"In the design of each of the components, we make sure that they don't interfere with the telescope," SKA SA project director
Dr Bernie Fanaroff told News24.
South Africa's radio telescopes are tested at every stage to eliminate interference, says Dr Bernie Fanaroff. (Duncan Alfreds, News24)
Components for the instrument are tested for compatibility and reliability at the Cape Town office before being shipped to Carnarvon to be installed in the telescopes.
"Anything that could interfere we put in an enclosure so the interference can't leak out, so we've been very careful that nothing we do can interfere with the telescope," Fanaroff added.
Burnell said that astronomers have covered the frequency most likely to be used for an extraterrestrial communication.
"If there were to be a communication it would be at what they call the Hydrogen Line - 21cm wavelength and that's been well-covered for decades and decades," she said.
The Hydrogen Line refers to the energy state of hydrogen atoms which are common in the universe.
"It's just a guess and it's based on the idea that if there are scientists on any other planet who are observing the universe, then there's a good chance that they would be observing somewhere near the Hydrogen Line because hydrogen is so common in the universe," said Fanaroff.
Intelligent alien societies would likely use the Hydrogen Line to map the universe, he added.
"If you want to map the universe, then you would be using the Hydrogen Line."
Professor Jocelyn Bell Burnell has warned that conservatism may threaten the progress made in science and technology. (Duncan Alfreds, News24)