The Search for Extraterrestrial Life in the Photo Archives

The Perseverance rover. Image via NASA, public domain.

Last month, humanity got a small break from the humdrum reality of lockdown life on Earth to celebrate otherworldly scientific achievement:

The Perseverance rover successfully landed on the Jezero Crater of Mars on February 18, 2021. Events like these always boggle my mind with their sheer human scientific ingenuity - cool enough on its own - but I also enjoyed this chance to contemplate the existence of astrobiology, a.k.a. one of my favorite science fiction tropes ever: aliens! The Perseverance’s mission is to “seek signs of ancient life and collect samples of rock and regolith (broken rock and soil) for possible return to Earth.” Besides the aliens (!), equally sci-fi worthy goals of the mission include technological demonstration of the rover’s equipment for future missions to Mars, as well as geological exploration of the planet. As the Perseverance explores the terrain, the mission’s team will assign names to the geological features it encounters in Navajo, in cooperation with the Navajo Nation. 

The Perseverance’s hunt for traces of long-extinct Martian microorganisms inspired me to think about the history of our search for extraterrestrial life (SETI) and the history of our attempts to contact this life. Although we do not anticipate reciprocal communication on this mission, I would consider the search for evidence of life to be a kind of contact in itself. On a somewhat silly note, March seems an auspicious month to think about Mars and SETI, as the month of March in French is “mars,'' and World Contact Day is celebrated on March 15th. On a more serious note, I wondered what threads of the scientifically grounded story of our search for life and contact might be lurking in our photo collections. Let’s take a look. 

Philip Morrison emulating a telescope. Image information: Morrison Philip B3, AIP Emilio Segrè Visual Archives, Physics Today Collection

Philip Morrison, along with colleague Giuseppe Cocconi, proved that it is possible for extra-terrestrial species to use radio waves to broadcast their presence, and that astronomers could search for these signals. They are also responsible for the realization that human radio technology is capable of sending information to points lightyears away. These findings were published in 1959 in what became a pioneering paper in the history of SETI, “Searching for Interstellar Communications,” found in volume 184 of Nature. 

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Otto Struve viewing a slide rule. Image information: Struve Otto B2, AIP Emilio Segrè Visual Archives

Otto Struve was the first director of the National Radio Astronomy Observatory and an early advocate for SETI. The Drake equation was first discussed at the Green Bank Conference of November 1961, which Struve organized in conjunction with Frank Drake.

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Left to right: Harold Craft, Frank Drake, and Rolf Dyce stand outdoors. Image information: Craft Harold C1, Copyright Cornell University. Contact http://rmc.library.cornell.edu/ about this photograph.

Sara Seager. Image from MIT

Frank Drake, center, is responsible for the Drake equation, written for that 1961 Green Bank Conference conference. It is an equation that aims to estimate the number of active extraterrestrial civilizations in the Milky Way. You can try the equation out at this PBS website. The equation has seen some criticism for being uncertain and conjectural, but as MIT astrophysicist Sara Seager states in this National Geographic article, "It's a way to frame the problem. In science, you always need an equation—but this isn't one you're going to solve. It just helps you dissect everything.” Seager has written her own Drake equation.

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Carl Sagan in Death Valley with the Mars space probe, 1979. Image information: Sagan Carl F2, Copyright Bill Ray. Please contact Bill Ray at [email protected] for prints and permission, www.billray.com.

If there is a household name in the history of SETI, it is astrophysicist and wildly popular science communicator Carl Sagan. He used both his talents as a scientist and as a communicator in support of METI: Messaging Extraterrestrial Intelligence. Amongst many lectures, television programs, and novels, METI-related efforts, he is especially well-known for his collaboration with Frank Drake of the Drake equation to send messages into space: the Pioneer plaque and the Voyager Golden Record, universal messages that have the potential to be understood by alien intelligence that might find them. Frank Drake and Carl Sagan, along with a team, also designed the Arecibo Message: the 1974 interstellar radio broadcast. 

L-R: The Pioneer Plaque (public domain), The Voyager Golden Record (public domain), and a visual representation of the Arecibo Message. Arecibo Message image by Arne Nordmann (norro), CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=365130 

Here is a clip of Carl Sagan explaining how aliens might decode a message from humans and why it is important to send messages:

 

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Very Large Array. Image information: Telescopes F27, E-Systems, Inc., courtesy AIP Emilio Segrè Visual Archives, Physics Today Collection

What appear to be alien mushrooms sprouting on the plains of San Augustine, 52 miles west of Socorro, NM, are actually the telescopes of the Very Large Array, an observatory built in the 1970s. I would argue that although this telescope has not historically been the site of SETI research, it is nonetheless important to the recent history of SETI because it featured heavily in the 1997 sci-fi film Contact, based on the book by Carl Sagan. 

In recent developments: in 2020, the SETI Institute and the National Radio Astronomy Observatory (NRAO) announced a collaboration that will allow for SETI research to take place at the Very Large Array. From the press release announcing the collaboration: “‘Having access to the most sensitive radio telescope in the northern hemisphere for SETI observations is perhaps the most transformative opportunity yet in the history of SETI programs,’ said Bill Diamond, President and CEO of the SETI Institute.  ‘We are delighted to have this opportunity to partner with NRAO, especially as we now understand the candidate pool of relevant planets numbers in the billions.’”

Speaking of Contact...

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Portrait of Jill Tarter with a Radio Telescope Model in the back. Image information: Tarter Jill A1, Astronomical Society of the Pacific, courtesy AIP Emilio Segrè Visual Archives, Physics Today Collection

Jill Tarter was the Project Scientist for NASA’s SETI program, and when funding for the program ended, she was responsible for finding funding to continue SETI research. In addition to her research and leadership positions, she is also heavily involved with science education outreach and communication, both for the general public and for K-12 audiences. Jodie Foster’s character in Contact is based on Jill Tarter.

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National Astronomy and Ionospheric Center, Arecibo Observatory - Puerto Rico. Image information: NAIC - Arecibo Observatory, a Facility of the National Science Foundation (NSF). Copyright Cornell University. Contact http://rmc.library.cornell.edu/ about this photograph.

Although it has sadly collapsed and been decommissioned as my colleague Audrey Lengel discussed in the December 2020 Photos of the Month, Arecibo Observatory has been the site of prominent SETI observatory research. From “Goodbye, Arecibo” by Seth Shostak, Senior Astronomer at the SETI Institute:

“Arecibo’s efforts to locate alien societies have largely been its listening experiments: SETI.  While there were some early SETI observations made on an ad hoc basis, in 1992 the NASA SETI Program began a study of 1,000 star systems at Arecibo.  Some of these stars were several hundred light-years away, so Arecibo’s unrivaled sensitivity was a major selling point.

After the cancellation of the NASA program scarcely a year later, private- and university-funded projects kept Arecibo in the SETI game.  The Berkeley SETI group ran a piggyback observing program that took advantage of a second receiver on the antenna to observe random parts of the sky while the main receiver was in use by other astronomers.  The SETI Institute used Arecibo for three years beginning in 1998 as part of its Project Phoenix, a scrutiny of about 800 nearby star systems.”

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Finally, a few words from the Carl Sagan clip on the importance of pursuing the search for extraterrestrial life:

“If we made a serious... search and succeeded, the results would be inestimable. We would have ended the isolation of mankind from the rest of the universe forever. If we made a serious search and failed, we would have determined something of the uniqueness, fragility, preciousness of human beings. It seems to me either way, we win.”

References and Resources

Records of the NRAO, “Conference on Extraterrestrial Intelligent Life, Green Bank, 1-2 November 1961,” NRAO Archives, accessed April 12, 2021, https://www.nrao.edu/archives/items/show/15837.

Kellermann K.I., Bouton E.N., Brandt S.S. (2020) Is Anyone Out There?. In: Open Skies. Historical & Cultural Astronomy. Springer, Cham. https://doi.org/10.1007/978-3-030-32345-5_5

Philip Morrison obituary

Otto Struve Wikipedia 

A New Era in the Search for Life in the Universe by Lemarchand, G

SETI Institute and National Radio Astronomy Observatory Team Up for SETI Science at the Very Large Array

Dr. Jill Tarter SETI Institute