As the Director of the Center for SETI (Search for Extraterrestrial Intelligence) Research, Dr. Tarter has devoted her career to the search for extraterrestrial life. It’s a search that has already yielded invaluable results about the nature of the universe, and is expanding exponentially thanks to the development of ever-more-powerful telescope arrays—and if some beacon from a far-off world ever calls us, Dr. Tarter will be the one picking up the phone.
Here, she sits down with Lightspeed to discuss her work past and present, the importance of international cooperation, and how being a scientist makes it tough to go to the movies.
For lit nerds, let’s start with the fact that you are the inspiration for Ellie Arroway, the heroine in Carl Sagan’s Contact, who suffers several rounds of professional slings and arrows in an attempt to be taken seriously, both as a woman in her field and as someone dedicated to the idea that in a vast universe, humanity is not alone. Can you speak a little about your experiences with SETI within the scientific community? How has scientific (or public) perception changed?
When I first started—people’s reaction was “what’s a nice girl like you doing in a field like this?” We’ve worked hard to demonstrate the scientific credibility of what we do. SETI has been recommended in multiple decadal reviews by the astronomy and astrophysics community—that’s the seal of approval from the National Research Council as well as our peers. However, that didn’t stop Senator Bryan from Nevada from terminating the funds for NASA’s SETI program in 1993, and we’ve had to rely on raising funds privately since then. Now that Kepler has announced 1235 exoplanet candidates (with many more to come), I think SETI is beginning to seem more reasonable and relevant to people. However, I’m afraid that most folks would still see this as an avocation rather than a full-time vocation. It isn’t! There’s an enormous amount of innovative and challenging work to be done. We partnered with UC Berkeley Radio Astronomy Lab to build the first radio telescope array from a large number of small dishes and we’re demonstrating just how capable that concept is for surveying the sky. We’re about to launch a citizen science project that will allow the crowd to work along side us, in real time, to help find signals that might otherwise be missed. Who knows what will come next.
In the 1990s, you co-created the HabCat Catalog of Nearby Habitable Systems with Margaret Turnbull. What was the process like? Were there any surprises? (Are there any of which you’re particularly fond?)
I’m fondest of those stars that Kepler and radial velocity studies tell us are orbited by exoplanets. Maggie Turnbull built this catalog as part of her PhD thesis and it’s been refined (and pruned down considerably) to serve as the start of a finding list for future space missions to attempt to image terrestrial planets around nearby stars. Maggie did the work on this—I think she did a great job. As we learn more about stars—particularly when the Gaia spacecraft begins to return results a few years from now—we can increase the number of stars in the catalog and improve our characterization of some of the stars that are already in there. In particular, we’re sure that we’ve mistaken some distant giants for nearby main sequence stars because we didn’t have a good measurement of their distances.
Based largely on your work, the list has expanded vastly from its original incarnation—you’re up to more than 17,000. What are the criteria involved in choosing candidates?
Actually, if you include the stars from the Tycho-2 catalog, our target list for SETI observations has slightly over a quarter of a million stars. We chose stars that didn’t seem to have any companions at an awkward distance that might disrupt planetary orbits. We wanted the stars to be over three billion years old, so that technologies might have had a chance to evolve; for that reason, you won’t find any early-type, massive stars in the list; they use up their hydrogen too fast. We excluded stars that were not variable and seemed to be in the stable phase of their main sequence lifetime. We wanted stars to have sufficient metallicity to be able to form rocky planets. In general, the more like the Sun, the more likely the star was to be included in HabCat.
In November of 2010, SETI launched The Dorothy Project, a massive observational campaign covering eighty-five Kepler planets. Can you speak a little more about the project, and any side-goals that might be achieved besides the obvious jackpot discovery?
It was Shin-ya Narusawa of the Nishi-Harima Astronomical Observatory in Japan that launched project Dorothy. He’s managed to get optical and radio observatories where SETI observations have never been done before to participate. It makes the point that SETI is an intrinsically international endeavor. As an unintended side benefit, Dorothy has created a network that allows us to check up on our colleagues in Japan following the devastation there from Friday’s earthquake.
What about your work surprises you?
I’m always surprised when people confuse what I do with the pseudo-science of alien abductions and UFOs. How and why can humans continue to be so lacking in critical thinking skills? Those are incredible claims—where’s the incredible evidence? I haven’t been shown any evidence that has stood up to scrutiny.
What are the greatest challenges in your work?
Our greatest challenge continues to be funding. Technology is allowing us to improve our searches exponentially, but buying that technology or getting it donated and paying scientists and staff to conduct the searches requires funding—continuously. This endeavor may take many generations, and we haven’t solved the problem of how to continue to pay for it.
What about your work do you most enjoy?
Two things. Going to the Allen Telescope Array observatory whenever I can—computers do the searching, so I’m not needed anymore. I still love the solitude and beauty of Hat Creek and the opportunity to think and dream about how to make the search even better. The other thing I like is talking to young people. I encourage them to have a more cosmic perspective, to think of themselves as humans, as Earthlings, as all the same when compared to other intelligent creatures that might share our universe. The only way to preserve our species is to embrace our commonalities and stop fighting over our perceived differences. Molecular biology has shown us exactly how identical we all are, but we haven’t internalized that into our world views.
Are there any alien-contact science fiction movies that drive you up the wall?
Almost all of them!
If SETI ever does detect a suspiciously awesome signal from the reaches of space, what are the verification processes involved in naming it a civilization-made signal? What is the chain of notification once the signal is confirmed?
Independent verification with hardware we didn’t build and software we didn’t write—we worry a lot about deliberate hoaxes. A number of observational tests that show the signal is really coming from a long distance away—probably interstellar, but perhaps a probe might be interplanetary. This will take time, so if the signal doesn’t persist, then we are going to be left with an unexplainable transient. There’s a different kind of fly’s eye telescope that would be good for detecting transients, but we don’t have the compute power to search the whole sky that way yet—in the future we will.
As far as announcing our discovery, we intend to tell the world, after we’ve quietly told our major donors as a way of saying thank you. We’ll use the IAU telegram system to alert all observatories, we’ll send off a discovery paper (but probably will not be able to keep the news under wraps long enough for the review process to complete), and we’ll hold a press conference. And of course, since it will be an incredible claim, we’ll make all our data available for scrutiny.
What are your hopes for SETI in the next ten years?
I’d like to find ways to search a million stars for engineered signals at radio, optical, and infrared wavelengths during the next decade—beyond that, it will depend on what scientific discoveries and technology developments have taken place. We reserve the right to continue to make our searches better.
What are some notable night skies you’ve seen?
It’s very dark at the Arecibo observatory in Puerto Rico—I always felt incredibly inspired at night when I’d walk from the visitors’ quarters to the control room to start my shift at midnight—Orion was right overhead, like an old friend. Undoubtedly the best skies I’ve ever seen were at another observatory—Parkes in the outback of New South Wales. The site is dark and the view from the south is much better than from the north, and it’s flat in all directions so the sky comes down to the horizon and appears even bigger. On one visit to Parkes I had the privilege to see comet McNaught arching across the whole sky—wow!
When you’re off-duty, do you find yourself still looking at the stars?
I always look at the stars—they inspire and humble me.
SETI’s mission addresses one of the fundamental questions of humanity (are we alone?), and as Dr. Tarter mentions, SETI is a privately-funded affair. If the idea of first contact sparks your imagination (and it should), or if you find yourself routinely gazing at the night sky and getting dreamy, consider getting involved: go to www.seti.org for more information on how the Kepler search is progressing, and how you can help spread the word about an institute devoted to the idea that, if we listen hard enough, we might someday hear someone calling for us.
Spread the word!