Meet the scientists who are still searching for E.T.

The press agent’s answerphone message was unusually spicy. ​“Robin does not want to do an interview,” she trilled breathlessly down the line. ​“We’ve had 143 requests and she has decided not to do any of them.”

The agent had received messages from The Times, The Guardian, ​“about eight” enquiries from different parts of the BBC. Robin – a well-known astronaut to whom I’ve given a pseudonym – had declined them all.

The mistake she had made was to talk freely to a magazine journalist about extraterrestrials – comments that were ​“taken massively out of context”, according to her exasperated agent. ​“Aliens exist, there’s no two ways about it,” Robin had said. ​“There are so many billions of stars out there in the universe that there must be all sorts of different forms of life.”

I’m not naming Robin out of respect for her inbox. But the controversy raises an interesting point: a lot of scientists seem to think that it is unlikely that we are alone in the universe. Few are willing to say so publicly – and even fewer are actively engaged in the search for intelligent alien life.

Despite a steady drip-drip of headlines, as government agencies and private organisations around the world have plunged huge amounts of cash into ever more sophisticated satellites (most recently it was the $100 million Breakthrough Listen project), the fact remains that many serious-minded scientists don’t want to tell their peers they’re searching for ET. Perhaps their reluctance makes sense. The mere mention of the word ​“aliens” is enough to trigger visions of twirling lightsabers, Scarlett Johansson picking up humans in her truck in Under The Skin and that wobbly little fellow trying to phone home.

And yet: this is a field of scientific research long-enough established to have its own acronym: SETI, or the Search for Extraterrestrial Intelligence.

“There has been an attitude that SETI is not ​‘proper science’, and that getting involved in something like that would likely be the end of one’s career,” says Erik Zackrisson. A 45-year-old Associate Professor in Astronomy at Sweden’s Uppsala University, he founded the Swedish arm of SETI in 2014. ​“But the ​‘are we alone?’ question has always intrigued me, so I was eager to get into this as soon as I got my PhD. But I still put it off for many years.”

And no wonder. Not so long ago SETI was a no-go area in science, despite the field having an on-off, six-decade backstory.

What is regarded as the first serious conference on SETI took place in 1961, held by a small group of astronomers and other scientists at the Green Bank Observatory in West Virginia. But it took until 1992 for NASA to launch a radio astronomy programme called SETI, which was allocated US taxpayer funding of $100 million over ten years.

Less than a year later, however, that federal funding was pulled. The project was ridiculed by Nevada Senator Richard Bryan, who tabled the amendment that killed the programme. As the Senator’s press release put it: ​“This hopefully will be the end of Martian hunting season at the taxpayers’ expense.

“Millions have been spent,” he added, ​“and we have yet to bag a single little green fellow.”

Nonetheless, research has continued via private funding in a handful of academic institutions around the world. Yet the fear of marginalisation remains. Zackrisson discovered that his own supervisor had abandoned the idea of setting up a Swedish SETI 20 years ago, ​“due to similar issues related to the scepticism of the national astronomical community”. But he was convinced of the value of the research and, undaunted, continued with his investigations – albeit discreetly. Zackrisson ran SETI as a side project to his primary research on the first stars and galaxies in the universe, corralling support from PhD students who helped out in their free time.

Only ​“a very small number” of people worldwide are engaged in SETI full-time, according to the Swedish academic. In the US, where the memory of Senator Bryan’s humiliation still stings, he thinks there have been ​“no more than five” scientific PhD dissertations with a primary focus on SETI.

This hasn’t stopped the few scientists in the field taking creative new approaches. In the early ​’90s SETI researchers were predominantly concerned with detecting a cosmic ​“hello”: some kind of radio or other signal from an alien civilisation. This was their only option, as technology was not sufficiently advanced to look for ​“exoplanets”, possibly inhabitable worlds that orbit a star beyond our own solar system.

Almost 30 years on, modern telescopes have been able to detect thousands of exoplanets. We still can’t see them at a high enough resolution to detect signs of alien civilisation so, a few years ago, Zackrisson started to wonder what kind of alien structures we actually might be able to detect.

An intelligent alien civilisation would probably need a lot of energy, he reasoned. And what better energy source in the solar system than the stars themselves?

An efficient means of harnessing solar energy could be by encasing the stars with a huge array of solar panels, which could be distributed on drones. These would form ​“Dyson spheres”, which would be like giant shrouds around the stars, collecting energy and, in the process, serving to reduce the visible brightness of the galaxy.

Following this theory, if he could find a galaxy that was dimmer that it was supposed to be, perhaps he could find an alien civilisation that was sucking up the energy from the stars. Zackrisson’s conclusions are, so far not massively optimistic: there are very, very few galaxies that meet his criteria. The search for alien life is rich with ​“wild and creative ideas”, however, and he remains committed.

“In terms of technological capabilities, we certainly have a better chance at discovering signs of intelligent life than all of the generations that have come before us. But this doesn’t mean we will be successful, because this depends on how difficult this task really is – that is, how rare intelligent life is in the universe. And really we have no idea.”

It turns out the question of how rare intelligent life might be is a very tough one to answer. It’s one with which Caleb Scharf, director of New York’s Columbia Astrobiology Centre, is currently grappling.

“Certainly I think most [scientists] would say that there’s a good chance that there is other life of some kind somewhere,” says Scharf, ​“just because of the number of planets out there and the ubiquity of carbon chemistry throughout the cosmos. Unless life is crazily improbable – and it might be – there should be other living stuff somewhere.”

Scharf is an astrobiologist. It’s a discipline that combines astronomy and systems science, one that sometimes involves ​“trying to ask the craziest ​‘what if?’ questions. [It] is actually super difficult, if ​‘crazy’ has to nonetheless still fit into the realm of what is just conceivably possible.”

Scharf has spent a lot of time mulling something called the Fermi paradox. This is an idea that was conceived over lunch in 1950 by physicist Enrico Fermi, and it goes like this: humans are very late to the cosmic party. The Milky Way assembled at least ten billion years ago, which should be more than enough time for aliens to evolve in another corner of the galaxy and show up on all inhabitable worlds. But there are no traces of them anywhere.

A host of explanations have been put forward for the Fermi paradox. These range from the theory that an alien species just might not be all that into interstellar exploration to the ​“great filter”. This is the ominous suggestion that a species tends to implode and extinct itself before it can become sufficiently technologically advanced to spread through the cosmos.

Scharf came up with his own idea over lunch at Bernheim and Schwartz, a now-closed pub in New York. It had large wooden tables in booths on which he could spread his notebooks and mull over ideas with friend and fellow scientist Adam Frank.

What if, they wondered one afternoon, Earth was actually like a remote South Pacific island, too out-the-way for aliens to bother visiting very often?

This ​“galactic archipelago” hypothesis could explain why there is no trace of alien life on earth, while also retaining the possibility that the galaxy is teeming with life beyond our observational capabilities. It could also mean that aliens have already paid us a visit, but all traces have been lost.

“A million or a few million years would erase all trace of life on Earth but for some funky chemical and isotopic signatures,” says Scharf. ​“Give a pyramid a few million years and it will be dust again. And fossils are useless, they’re so incredibly a rare, [which is] a fact we tend to forget.”

If we want to find alien planets we might be better off changing the search terms. Rather than look for Earth-like planets, let’s focus on galactic regions where the distribution of stars might mean there are entire clusters – or archipelagos – of neighbouring interstellar species. And the best way to do that is by creating the most detailed maps of space possible.

One scientist doing that is Timo Prusti. He’s the Gaia Project Scientist at the European Space Agency in Paris. The Gaia Project was a five-year mission to map all currently visible stars in the Milky Way. This amounts to about two billion stars. That mission is complete but the Gaia satellite launched into space is still functional, so Prusti is overseeing a project that could help locate extraterrestrial life. And it involves massive planets.

“A specific contribution to extraterrestrial life search is in the importance of massive planets in planetary systems,” he says. ​“In our solar system we believe that Jupiter has an important role in cleaning small asteroids from the inner solar system so that a planet like Earth is not too frequently bombarded by asteroids.”

According to Prusti, Jupiter may be a part of a planetary ecosystem that helps maintain life on earth. So, find massive planets like Jupiter orbiting a star, the reasoning goes, and perhaps you can find another inhabitable world. The signature to look for is called a ​“wobble”, which is a tiny deviation in the location of a star caused by an orbiting planet.

“Gaia is the best way to find those stars that have a Jupiter-like planet far away from the stars. Gaia cannot tell if there are smaller [Earth-like] planets closer to the star in these systems. But Gaia can identify the systems where a massive planet is around in a far-away orbit helping inner planets – if they are there – to have a more favourable environment.”

Eventually Gaia will provide data on around 100 billion objects in the universe, which is just one of the reasons why the task of searching for extraterrestrial intelligence is vastly more expansive in 2020 than it was in 1993.

But perhaps the world is waking up to the potential results of this technological advancement. In the US, the House of Representatives recently proposed legislation for NASA’s future that included ten million dollars a year allocated for the ​“search for technosignatures, such as radio transmissions”. That is, effectively, alien signals. The return of federal funding to SETI, three decades after Senator Bryan kiboshed the government-funded hunt for those little green fellows, would be a landmark moment.

That, of course, doesn’t mean the search will be any more successful.

“What if we simply don’t have what it takes to imagine the technology aliens have, no matter how hard we try?” asked Erik Zackrisson in a recent TEDx address at Uppsala University. ​“Would we really be able to identify or understand technology proposed by a civilisation thousands, tens of thousands or millions of years ahead of us?

“I’m not so sure we would.”