It’s a big Universe, that’s for sure, which means we might not necessarily cross paths with any other lifeforms that might be out there. But if we want to attract the attention of any galactic neighbours, apparently we could use laser technology we already have right now.
Today’s lasers could be repurposed to act as a beacon or a “planetary porch light” for any aliens that might be looking for us, says a team of researchers from the Massachusetts Institute of Technology (MIT).
This porch light It would be able to grab extra-terrestrial attention from as far as 20,000 light-years away, apparently.
According to the team, the infrared laser beacon could even be used to send rudimentary messages into deep space, acting as a sort of Morse code signal to let other beings know that we’re here.
“This would be a challenging project but not an impossible one,” says one of the team, astronautics graduate student James Clark. “The kinds of lasers and telescopes that are being built today can produce a detectable signal, so that an astronomer could take one look at our star and immediately see something unusual about its spectrum.”
“I don’t know if intelligent creatures around the Sun would be their first guess, but it would certainly attract further attention.”
The “feasibility study” proposes using a 1- to 2-megawatt laser focussed through a large 30- to 45-metre (about 100- to 150-foot) telescope. That would create a beam of infrared radiation powerful enough to stand out from the energy produced by the Sun – and maybe therefore powerful enough to catch the eye of extraterrestrial intelligence.
Alien astronomers in the region of Proxima Centauri (the nearest star to Earth) or TRAPPIST-1 (a potentially inhabited system around 40 light-years away) would be most likely to catch our signal, the researchers say.
All of this would be possible using laser technology already available today or within reach of scientists, the study suggests. While there are no 30-metre telescopes on Earth today, for example, a 39-metre one is being built in Chile.
The cosmic porch light would have to be built high up to minimise atmospheric interference, the team says, and might pose problems for cameras on board spacecraft that pass through it.
It would also be dangerous to look at with the naked eye.
A small price to pay, perhaps, if it means we make contact with aliens civilisations that might otherwise miss us. And within just a few short years, we could be making up plans to get together (or preparing to get blown to pieces).
“If we were to successfully close a handshake and start to communicate, we could flash a message, at a data rate of about a few hundred bits per second, which would get there in just a few years,” says Clark.
Should we need to hide from an imminent alien invasion, lasers can prove useful here too: a 2016 study detailed how laser blasts could be used to cloak Earth from view, cancelling out the dimming that would otherwise be noticed as our planet passed in front of the Sun.
It’s good to keep our laser options open, at least.
This new study also includes an analysis of whether a similar beam of laser light made from out in space could be picked up by our instruments here on Earth. A telescope 1 metre (just over 3 feet) would be enough, the researchers concluded, if it was pointed straight at the source.
Overall though, the study suggests it’s “unlikely” that we’d notice such beacon flashes from our alien neighbours, assuming they were being made – there’s just too much space to cover, which is why scientists are always looking at ways of narrowing down the search.
As yet there are no plans to get such a laser beacon built – but if we want to start advertising our existence, we know how to do it.
“In general, this was a feasibility study. Whether or not this is a good idea, that’s a discussion for future work,” says Clark.
The research has been published in The Astrophysical Journal.