It’s a moment that’s been depicted countless times in science fiction – but what would actually happen if aliens made contact via a signal picked up on Earth?
The moment could come as early as the end of this decade: if aliens receive signals sent, for example, by NASA’s Deep Space Network (DSN) to the Pioneer 10 satellite in the 1970s.
When the time comes, the signal will most likely be received by large ground-based telescopes such as FAST in China, the Very Large Array (VLA) in New Mexico and the Parkes Telescope in Australia, says former NASA expert Sylvester Kaczmarek.
Day one
There is no universally agreed-upon rule about how scientists or governments would respond — or on questions like whether aliens would have rights.
But extraterrestrial-oriented organizations, including the Search for Extraterrestrial Intelligence (SETI), established a framework in 2010.
Rather than immediately announcing the find to the world, scientists would work to confirm that it was real – first by ruling out interference from Earth, such as satellites and radio transmissions.
In the 1990s, a mysterious signal was discovered at the Parkes Radio Telescope indicating it was a microwave in the staff canteen.
Kaczmarek says: ‘For a signal to be considered potentially extraterrestrial, researchers typically need multiple layers of confirmation and analysis, often over several weeks or months.
The signal will likely be received by large ground-based telescopes such as the Parkes Telescope in Australia (pictured)
‘The signal should exhibit properties inconsistent with natural astrophysical sources and man-made interference.’
In SETI’s ‘Declaration of Principles Concerning the Conduct of the Search for Extraterrestrial Intelligence’, published in 2010 with the International Academy of Astronautics (IAA), the guidelines suggest that explorers should work with other institutions to ensure that the signal is real is.
Nothing would be announced until confirmed, although the scientists would respond to media inquiries if news ‘leaked’.
Week one (after confirmation)
Scientists at the observatory would notify organizations such as the International Academy of Astronautics (IAA) and the International Telecommunication Union (ITU).
Kaczmarek says that while organizations like SETI have their own strategies for first contact in the event of sudden contact, organizations with expertise in space communications like NASA and the ESA would almost certainly become involved.
WEEK ONE: Once scientists are confident, the discovery would be shared – likely via a public announcement, including a press release and scientific publication, telling the world that aliens have been discovered
Seth Shostak of SETI, who has a plan for what will happen if an alien signal is received
Kaczmarek says: ‘Governments would also quickly become involved, especially those with advanced space programs or defense capabilities, such as the US Space Force or equivalent agencies.
“In such a scenario, however, there would likely be confusion and competing interests before a unified global strategy emerged.”
Once scientists are confident, the discovery would be shared – likely via a public announcement, including a press release and scientific publication, Kaczmarek says:
Kaczmarek says: “This transparency may be delayed depending on geopolitical or security considerations, especially if governments or defense agencies become involved.”
But once the secret is out, it will undoubtedly leak, so governments will likely try to avoid the panic and confusion that would ensue.
Week two
One of the first things that would happen would be to ‘protect’ the frequency on which the signal was received, to ensure that more signals could be received.
WEEK TWO: Chaos breaks out around the world after we hear about the alien signal
Scientists would use emergency procedures within the International Telecommunication Union’s World Administrative Radio Council.
SETI guidelines suggest the creation of a Post-Detection Study Group to analyze the signal and initiate discussions on how to respond.
At this point it is likely that the United Nations would become involved in deciphering the signal and figuring out how to respond.
Kaczmarek says: ‘In principle, the United Nations would play a central role in any coordinated global response.
Sylvester Kaczmarek is a former NASA space and AI expert
‘The United Nations Office for Outer Space Affairs (UNOOSA) is the most likely body to provide leadership because it oversees the peaceful uses of space and has existing treaties, such as the 1967 Outer Space Treaty, that cover international cooperation in space.’
Scientists and governments would work together at this point to understand where the signal came from, what it means – and whether or not to respond to it.
Week three
The response to extraterrestrial contact would vary depending on the form it took: a visit from a spacecraft would require an immediate response, Kaczmarek says.
But a signal received from the depths of space requires long-term planning.
It is likely that responding to such a signal would be a global decision, according to the Declaration of Principles Concerning the Conduct of the Search for Extraterrestrial Intelligence.
Instead of the scientists or any other group formulating an answer, the scientists would seek guidance from global groups such as the United Nations.
The document says: “In the event of the confirmed detection of a signal, the signatories to this statement will not respond without first seeking the advice and consent of a broadly representative international body, such as the United Nations.”