Observing Everything, Everywhere, All At Once with Chenoa Tremblay
The Very Large Array Radio Observatory. Credit: Jeff Hellerman, NRAO/AUI/NSF
The search for extraterrestrial life is accelerating. SETI scientists observe more stars more often with the Very Large Array (VLA) radio telescope’s newly installed mega-computer network, the Commensal Open Source Multimode Interferomic Cluster (COSMIC).
Collecting data alongside the VLA’s standard radio astronomy operations, COSMIC surveys hundreds of thousands of stars over a wide range of frequencies as compared to previous SETI surveys that searched a few thousand stars at confined radio frequencies.
Star Goddesses spoke to Chenoa Tremblay, COSMIC’s project scientist, about her circuitous career, from accountant to chemist to SETI scientist.
Discover the latest advancements in radio astronomy with Chenoa Tremblay who weighs in on the evolution of galaxies, stars, and intelligent life.
Q: What advice can you share with future Star Goddesses?
Tremblay: Students often think they are locked into a career pathway. They wonder if they can pivot from their degrees. My journey allowed me to explore different realms of science. I’ve been flexible about developing and applying my skill set, and that flexibility has taken me along some interesting career paths that I probably would never have sought out myself.
Q: What are some of those unintended career pathways?
Tremblay with her first telescope.
Tremblay: Well, I grew up in a very small town of about 600 people. Growing up in the 80s, I was expected to pursue goals that would make me intelligent and interesting enough to get a decent husband! I lacked confidence in grade school. I had a lisp, so I had to do speech therapy. I was in special education classes because I struggled with reading and wrote my numbers backward. Instead of taking math classes, they had me answering phones in the school office.
But when I got to high school, I realized I really liked math. It wasn’t until college, where I had people who supported me, that I gained the confidence and courage to be something different. Initially, I pursued a bachelor’s degree in business accounting. However, I discovered I was spending more time helping my roommate with her biology and chemistry classes than studying for my own classes. I decided to change degrees, but since I was funding my own education, I couldn’t afford to start all over. Fortunately, my professors understood my predicament, and they helped me shift my class credits toward graduating with a degree in chemistry.
After college, I began working in the pharmaceutical industry in Massachusetts. But when my husband started a PhD in New Mexico I moved to working in corporate research and development in an analytical chemistry lab. We then took a trek to Perth, Western Australia, when my husband took a postdoctoral position at Curtin University; I shifted again, applying my skillset as a chemist to work in the mining industry. When the price of gold crashed around 2014, the mining industry took a blow. The company cut jobs and cut my hours. So, I had some free time and shifted again. That’s when I got into astrochemistry and started to pursue my Ph.D. in Physics at Curtin University.
Q: So why study chemistry in space?
Tremblay: Well, one reason is that we don't fully understand star evolution. Astrochemistry allows us to study the dynamics of the space environment around stars. We can probe temperatures, turbulence, and the flow of gas. Stars evolve over millions of years, so we can’t study one star continuously through its lifetime. We need to survey large populations of stars to understand the whole life cycle of a star.
Q: Was star evolution the focus of your Ph.D.?
Tremblay talks to local Aboriginal comunity about the Murchison Widefield Array. Credit: Robert Hollow, CSIRO
Tremblay: With my background in chemistry, I focused on observing molecules around stars using these new kinds of telescopes at the time. In 2013, three low-frequency telescopes came online. One of these telescopes was the Murchison Widefield Array (MWA) in Western Australia. These telescopes are not big dishes but rather small antennas only a few feet high. They operate at lower frequencies. They don't require the complexity of high-frequency telescopes, like having to cool down their electronics, and they have a wide field of view. For example, the Very Large Array in New Mexico offers an amazing amount of detail for sky surveys, but its field of view is about 1/12 the size of our moon. The MWA can fit about 1,600 moons into its field of view.
So for my Ph.D., I worked on developing an approach for studying molecules around stars using these brand new low-frequency telescopes that offer a wide field of view. In retrospect, I should have titled my thesis — Really Big Lonely Stars, Small Molecules, Huge Atoms, and Aliens. One of the things we can study with these low-frequency radio telescopes is the transitional chemistry of high-mass stars. These are stars that are ten times the size of our sun that form in dense clouds of dust particles. So, with these really big stars, it’s a challenge to understand their formation. Do they form in a cluster of smaller stars, or can they form all by themselves? It's a huge question and an important one to answer because it impacts the amount of chemicals that are available for star formation inside an entire galaxy. So we went looking for different mechanisms to try to find a situation where a super large star might be forming all by itself. And we think we found one — only one out of hundreds and hundreds of stars! But that one is still important because if you look at 400 billion stars inside of a galaxy, then there's probably more than one, right?
Q: You discovered just the one very big, lonely star among billions. Did you find any small molecules in space?
Tremblay: At lower radio frequencies, we can look for the building blocks of life or biosignatures. So far, we’ve discovered over 200 molecules in space. With the MWA data, we found the potential for the existence of a nitric oxide molecule. If you google nitric oxide, you’ll see a ton of advertisements for bodybuilding supplements. It's also critical for fetal development.
This nitric oxide molecule should be prominent in our galaxy, but we don't find it as often as we should. My theory was maybe we're just looking at the wrong frequency. Maybe there’s a frequency where its emission might be more frequent and detectable. We believe there is evidence of this molecule in our data, but it’s inconclusive. What we did conclude is the telescope needs an upgrade to probe more deeply. That upgrade is going on right now at the Murchison Widefield Array. We are working to increase its spectral regime capabilities, which means improving how the telescope can break up frequencies into really fine detail, like fine-tuning a knob on your radio.
Q: Stay tuned for that upgrade, pun intended! And did you find any huge atoms or aliens?
Tremblay: At lower frequencies, we can study the cold neutral medium, which is a phase of gas that's prominent within the galaxy. And you do that by studying atoms that undergo a process called recombination. Essentially, you have an atom that's missing an electron, and then it finds a free electron, and it gains it. That process forms across the radio spectrum, including at low-frequencies. If you like the planetary orbital model of an atom, where you have a nucleus in the middle and the electrons orbiting the nucleus, electrons that are orbiting so far away from the nucleus in the cold neutral medium. It makes those atoms in the cold neutral medium a hundred times bigger than any atom here on Earth. These huge atoms are extremely diffuse. We think we detected some of these huge atoms, but again, we need to upgrade the telescope to confirm our findings.
As far as the SETI aspect, another researcher piggybacked on the low-frequency data I was collecting from the MWA. We surveyed two patches of sky, one toward the galactic center and another at the galactic anti-center, or where you see the Orion Nebula. We surveyed the stars in those regions with known exoplanets for any indication of an artificial signal. But we didn’t find any, so yeah, we didn’t find any aliens.
Q: So how did you shift from working at Australia’s Murchison Widefield Array to New Mexico’s Very Large Array radio observatory?
Tremblay wrestles with COSMIC’s innards.
Tremblay: I started my postdoctoral research at Australia’s National Science Agency (CSIRO) in 2019. I was still working in the mining industry, and I had a young child. There were a few years when everything was just a blur for me, but eventually, the whole family moved back to New Mexico because I got the position working on COSMIC with The SETI Institute in 2022.
When I arrived at COSMIC, we had one computer system, kind of sitting on the floor with pieces of electronics plugged in randomly and cords everywhere! Fortunately, I had project management experience, functioning as a go-between for business and technology, working with software developers, and speaking the lingo. I’ve had to learn a lot about engineering systems as far as testing and operations. But almost everything I've done at COSMIC is something I didn't know how to do before I got here. It's been a steep learning curve, a huge challenge, but really fun.
Q: So what the heck is COSMIC?
Tremblay: COSMIC stands for the Commensal Open Source Multi-mode Interferometric Cluster. It’s a big computer that’s hooked into the Very Large Array’s 27 dishes. Commensal means we are piggybacking on observations that are already taking place by scientists who are using the telescope to study, for example, black holes and galaxy formation. COSMIC scans the skies and collects data in real-time. Previous SETI projects like Phoenix surveyed a few thousand stars over five years. With COSMIC, we are scanning a few thousand stars in just a few days. In the next few years, we will have scanned hundreds of thousands of stars over a wide range of frequencies. That’s more stars surveyed over the entire scope of SETI’s history.
Q: As compared to the Murchison Widefield Array, what frequency is COSMIC tuned into via the Very Large Array telescope?
Tremblay: The Murchison Widefield Array is a low-frequency telescope, right? It’s observing between 100 and 300 megahertz, or wavelengths that stretch from about 3 meters to 1 meter respectively. The Very Large Array operates at around 50 gigahertz to 700 megahertz. So that’s wavelengths as small as about 6 millimeters up to as wide as about 0.4 meters. (Note to reader — if you ever get confused about frequencies, like the writer of this Q+A often does, I highly recommend this website that Chenoa shared with me: https://www.everythingrf.com/rf-calculators/frequency-to-wavelength. )
Q: So why do we care about frequencies since humans have no clue what frequency extraterrestrials might use for interstellar contact?
Tremblay: Yeah, there’s always a concern in the back of everybody's mind that we're thinking a bit too human. What we think is the most obvious way to communicate might not be the most obvious for another civilization that might have different elements and technologies. That’s why SETI searches have broadened to optical SETI and infrared SETI, not just radio SETI.
As far as radio, originally, the watering hole frequency was considered the likeliest place to search. That frequency is based on hydrogen since it's the most abundant element in the universe. Hydrogen emits a photon with a wavelength of approximately 21 centimeters, which corresponds to a frequency of around 1420 MHz. Philosophically, the watering hole is where animals come together, and they tend to be more amenable, right? Natural predators leave their prey alone. But now, with our current software capabilities and computer infrastructures, we don’t have to make these kinds of assumptions. The watering hole was based on our limitations, so we had to narrow down our searches. Today we can search more frequencies, more efficiently, over a wider swath of sky.
Tremblay at Breakthrough Discuss in 2022.
Q: As a SETI scientist, do you ever confront skepticism or hostilities? Do you ever get bad or weird vibes?
Tremblay: With the public, you get those people who assume that SETI means UFOs. Every time I'm on a live YouTube talk or something like that, there’s always those odd online comments like — Hey, I’m an alien who's been on Earth for ten years. Do you wanna meet up for dinner? Yeah, no thanks.
And then you've got people in the astronomy community who still struggle with SETI because it’s often privately funded. They think you’re taking money away from their favorite science. They think SETI is a risky, long-shot endeavor. And that’s true, but honestly, I think that understanding the evolution of life is just as important as understanding the evolution of stars, galaxies, and our universe. There are so many unknowns. That's why the SETI community can pair up with something like the dark matter community. We're both looking for something that we have some indication of what we think we're looking for, but we don't know exactly what we're looking for.
I also get the people who are afraid, right? The people who read The Three Body Problem, and are expecting the aliens to come and take over our planet. Or maybe they'll take over our government, and the world will be better? Personally, I’m not too concerned about that concept. The thing that concerns me is running out of time! I'm just so curious. I love the different pursuits of science. There’s too much that I find interesting. I've had times when I've completely worn myself out and needed to take time off. It’s a challenge for me to say I need to put that aside for now. More than anything else, I think time is my biggest problem!
Q: Yes, not being able to do it all is a frustrating reality check. What else have you learned about yourself for sharing with other Star Goddesses?
Real women searching for signs of real extraterrestrials.
Tremblay: Women in STEM are still a rarity. I’ve learned it’s important to surround yourself with people, not necessarily within the STEM field but in general, who will give you the confidence and the courage to be the only woman in the room. In all of my upper-level chemistry classes, I was the only girl. When I worked in the mining industry, the first time I met customers in person, they were shocked that I was a woman. In some ways, it’s been helpful to have a weird name that’s not assigned a particular gender. I walk into boardrooms or meetings, and I'm the only woman present. On the COSMIC team, there are two women out of about twelve of us. But nowadays, I don't notice it anymore. I read once that guys don’t apologize for being late. They don’t bother as much with pleasantries in the workplace. They tend to portray lots of confidence. So yeah, be confident. It’s okay to have that niggling feeling of not belonging, but just be yourself in that room.
Q: So, when are we going to find an extraterrestrial signal? And what would it mean for you, or for humanity?
Tremblay: As far as the first question, I think with these commensal systems like COSMIC, we're getting closer to either ruling out that it's not a radio signal or finding something — whether it's another unknown or signs of technological or intelligent life. We can say for sure, over the next three years, that we're going to cover 100 million stars. That's 1/10th of the stars within our galaxy. So, I think with these commensal systems and how much sky we can cover now, we have greater potential than at any other time in history.
However, if you factor in all the other challenges and approaches to SETI, then defining timeframes or narrowing down possibilities is just too tricky to make any predictions. As far as what it would mean, I think a discovery of this level and having it confirmed would just be life-changing, right? Wouldn’t it be nice to know that another intelligent life is out there?
Q: Yeah, it’d be nice to have a friend. Is there anything we didn’t cover, that you think is critical or important about your work?
Tremblay: Only that SETI is a worthy pursuit. It’s challenging, particularly getting through to colleagues, that the pursuit of understanding the prevalence of intelligent life in the galaxy is just as important as understanding the prevalence of stars, their formation, and their life cycles. SETI doesn't have to be done at the exclusion of the other fields in astronomy. In its pursuit, there’s the potential to discover a lot more unknowns, as well.
Q: And that's pretty much what COSMIC is doing, right?
Tremblay: Exactly!