Contact, SETI and the science of the search for extraterrestrial life

More than a quarter century ago, famed astrophysicist and science broadcaster Carl Sagan and his wife Ann Druyan, creative director of NASA’s Voyager interstellar message project, wrote a story about the search for intelligent life. This story, which started as a cinematic treatment, turned into a novel, and then finally a movie directed by Robert Zemeckis and starring Jodie Foster, was released 25 years ago this week.

In Contact, Foster’s character Ellie Arroway discovers an alien signal from another star and embarks on a species-altering journey to meet them face to face. At least that is his experience of events. The film leaves its ending open to interpretation.

To have Sagan and Druyan, the minds behind Cosmos, at the helm of a sci-fi story means it comes a little closer to the truth than some of its big-screen peers and is an interesting opportunity to examine our continuous search for life elsewhere in the universe.


In 1960, as interest in space grew, a group of scientists thought about all the radio noise we were pushing into space and wondered if we could detect similar signals not from Earth, but of an extraterrestrial civilization. . They thought, at the very least, it was worth looking into, so they pointed a radio telescope in Green Bank, West Virginia, at the stars and started listening. They observed two stars, Epsilon Eridani and Tau Ceti, both located about 11 light years away. This search turned up no extraterrestrial signals, but it launched the larger SETI project, one of humanity’s most promising endeavours. He also inspired the events of Contact.

At the start of the film, Foster’s Ellie Arroway works for SETI at the Arecibo Observatory in Puerto Rico. Arecibo is a real telescope – or at least it was – and was the largest single aperture telescope in the world for more than half a century until it was dethroned by the FAST telescope in 2016. 2020, the telescope, which was built in a natural sinkhole, partially collapsed and is no longer in use.

Prior to his tragic death, however, he was part of the SETI program in addition to searching for near-Earth objects for NASA. That said, it wasn’t used quite the way we see it depicted in the film. As is the case when adapting anything to film, even if what you are adapting is the real thing, some concessions have been made in favor of drama or visual appeal.

Shortly after the opening scenes of the film, Arroway and his colleagues lose their funding and turn to a private donor to continue their work at the Very Large Array, a collection of 28 radio telescopes located in New Mexico. Like Arecibo, the VLA is also an actual location that is indeed used, at least in part, in the search for extraterrestrial intelligence. Private funding is also true to life, much of SETI’s activities have been funded in part or entirely by private donations.

In the movie, we see Arroway using the VLA to scan the skies for any alien signals she apparently finds. In SETI’s own review of the film, they noted that the VLA is actually not the ideal tool for this type of work. They further stated that if you wanted to search for alien radio signals, Arroway and company had the right idea the first time around. Arecibo was four times larger and more sensitive than the VLA telescopes. That said, they also admitted that the image of radio telescopes reaching into the distance provided a more visually interesting setting for the film. Sometimes in Hollywood, that’s what matters.

The search method depicted on the screen also reflects real-life SETI activity under the aegis of Phoenix Project. Between 1995 and 2015, SETI used several telescopes around the world, including the Parkes Telescope in New South Wales, the National Radio Astronomy Observatory in Green Bank, and notably the Arecibo Observatory. It should be mentioned that the Very Large Array was not part of the project.

Rather than scanning the entire sky for spurious signals, Phoenix strategically aimed for about 800 Sun-like stars at a distance of about 200 light-years. As far as we know, they never received construction drawings for a complex interstellar spacecraft.


Despite decades of extensive research, we have so far found no confirmed evidence of extraterrestrial intelligence. Depending on your perspective, the absence of clear signs of life is either totally expected or shockingly unlikely. One way to quantify which end of this spectrum you belong to is to consider the values ​​you would plug into the Drake equation.

Appropriately, Drake’s equation was the first proposed at the SETI inaugural meeting in Green Bank, West Virginia in 1961. That first meeting was a veritable who’s who of scientists interested in the search for extraterrestrial life. Frank Drake was there, of course. So did Melvin Calvin, a biochemist who received a phone call warning him that he had won the Nobel Prize at the meeting. Carl Sagan was also present, along with several others. Their goal was to determine whether or not the search for extraterrestrial intelligence was a worthwhile endeavor and Drake offered his equation as a possible way to focus on an answer.

The equation looks at seven factors, all of which solve for N, the number of technologically intelligent civilizations in our galaxy. These factors are: the rate of formation of stars suitable for the development of intelligent life, the fraction of these stars with planets, the number of planets per system with an appropriate environment, the fraction of those on which life appears, the fraction of those on which the intelligence evolves, the fraction of those who develop the technology that we could detect, and finally the average length of time such a civilization persists and creates these signals.

We have a pretty good idea of ​​the appropriate star rating there, at least as defined by the kind of life we ​​might recognize. In recent years, with the increased discovery of exoplanets, we have developed a better idea of ​​the second criterion and to some extent the third. The remaining four criteria are almost entirely a matter of speculation, and depending on which numbers you plug in, either suggest the galaxy is teeming with intelligent life or is tragically empty.

The fact that we haven’t found a whisper yet might suggest that this last conclusion is probably true. Alternatively, it could be that we have only been searching for a short time on a cosmic scale and the universe, even the galaxy, is a very large place.

In any case, if there’s even a chance there’s someone else out there waiting to be found, the answer to the meeting’s original question of whether it was a worthwhile undertaking is a resounding yes. No calculation required.

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