A coded message called “A Sign in Space” has been sent from a spacecraft orbiting Mars to simulate potential communication from an advanced alien civilisation.
A message has been sent from a spacecraft orbiting Mars back to Earth, to simulate potential communication from an advanced alien civilisation.
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| SETI’s Allen Telescope Array in California has picked up a message sent back from a spacecraft orbiting Mars Seth Shostak/SETI Institute |
On 24 May, a European Space Agency (ESA) spacecraft at Mars, the Trace Gas Orbiter (TGO), was used to send a small coded message a few kilobytes in size to our planet. Picked up by radio receivers on Earth, groups of astronomers and enthusiasts then set to work decoding it, a potential dry run for first contact.
“This kind of experiment is long overdue,” says Franck Marchis from the SETI Institute in California, who helped to coordinate the event. “We have been searching for extraterrestrial signals for more than 60 years, but we never really thought about what receiving and decoding such a signal would be like.”
The project, called “A Sign in Space”, was set up by artist Daniela de Paulis in Rome, who was put in touch with ESA to use the TGO spacecraft. The goal was to assess how, if we ever picked up a radio signal from an alien civilisation, humans might respond. “Having a Martian source makes the project immediately more relatable,” she says. “The source of the signal is truly in outer space.”
It took 16 minutes for the transmission to get from Mars to Earth owing to the current distance of nearly 300 million kilometres between our two planets. The data was picked up by several radio telescopes on Earth including the SETI Institute’s Allen Telescope Array in California and the Green Bank Observatory in Virginia.
Groups on Earth then set to work trying to decode the message, the contents of which were kept closely under wraps. Neill Sanders, from the astronomy group Go Stargazing in the UK, was one of those involved in trying to decipher the message. “It’s fascinating,” he says. “It gives us a little sense of what would happen if we really did get a signal, everything from capturing the signal to processing the data.”
The science mission of TGO, which studies the atmosphere of Mars from 400 kilometres above its surface, wasn’t affected by the project says Tiago Loureiro at ESA’s European Space Operations Centre in Germany. “We explored options on how this could be done without disturbing the spacecraft’s operations,” he says.
Message have been sent by humans into space before in attempts to make first contact, such as the Arecibo message in 1974 that was beamed to a nearby galaxy cluster. NASA’s twin Voyager spacecraft – both now beyond the solar system – also contain a “golden record” with information about planet Earth. Despite the suspected billions of planets in our galaxy, however, we have never encountered a message coming the other way – until now.
The message has yet to be decoded, but when it has been, de Paulis hopes it will encourage discussion of what it might mean to make first contact. “How would we make sense of such a thing?” she says. “The project is really a way to highlight this very human philosophical process of making meaning around something.”