Karen Collins: Exoplanet Hunter
Astronomer Karen Collins of the Smithsonian Astrophysical Observatory didn’t actually become an astronomer until she was in her 50s, but despite her late start, she has already helped discover an exoplanet (a planet outside our solar system) that might be able to sustain life.
Karen Collins has worked at SAO for six years, “about a year longer than the TESS spacecraft has been searching for planets,” she told Eye on Science. Launched in 2018 by NASA, TESS (Transiting Exoplanet Survey Satellite) has been looking at distant stars and searching for signs of orbiting planets. So far, it’s detected nearly 300 confirmed exoplanets, and has found evidence of thousands of other candidate planets that astronomers still need to confirm are real.
Karen is one of many astronomers analyzing TESS’ data to confirm these candidate planets orbiting stars other than our Sun. Her work today is a culmination of a lifetime seeking a career that would allow her to follow her passion for space.
A childhood fascination with space
When Karen was a child, NASA wasn’t as interested in finding exoplanets as much it was focused on racing to send humans to a much closer celestial object: the Moon. Like thousands of other kids, the Apollo missions inspired Karen to go into science. “I was completely captivated by the Apollo missions to the Moon. Growing up during this unique time in history, I was always fascinated with anything to do with space travel and anything beyond the skies of Earth.”
But as she was growing up in a small town in Georgia, becoming an astronomer didn’t seem very practical to her at the time. Karen was the first in her family to earn a college degree—she went to the Georgia Institute of Technology to study electrical engineering. For the first part of her career, she worked in the telecommunications industry, building technology and eventually leading engineering teams that developed technology for transmitting telephone and cable television signals. Eventually, she and five colleagues started their own company, developing cable modems much like the ones many people have in their homes today.
“After the company was acquired, I decided it was my chance to finally pursue my childhood fascination with space and astronomy.” So, at age 53, Karen went back to school and earned her Ph.D. in physics and astronomy from the University of Louisville. “That’s where I discovered the burgeoning and fascinating field of exoplanets.”
Karen Collins (center) with her PhD advisor John Kielkopf and fellow student Jeff Hay at the University of Louisville. (Photo courtesy Karen Collins)
Now, Karen spends her days observing these distant worlds. Recently, she worked with colleagues to identify the orbital period (or the length of a year) of a distant exoplanet named LP 791-18d by watching the planet cross in front of its host star. By measuring how often the light from the star dimmed (from being blocked by the planet), they could infer the length of its year. Also, with another planet orbiting the same star and tugging on LP 791-18d, they knew the planet’s year varied. By measuring this variation, the researchers were able to determine that this planet is slightly more massive than Earth.
Exoplanet LP 791-18d
But then, things started getting really interesting. Researchers determined that the planet is probably covered in volcanoes. They also concluded that one side of this planet is always facing its star, and the other side is always in darkness. The light side is probably too hot for liquid water to form, they thought, but potential volcanic activity taking place all over the planet might sustain an atmosphere. These conditions may allow water to condense on the dark side of the planet. These conditions could potentially sustain life!
Karen Collins at the Apache Point Observatory in Sunspot, New Mexico. (Photo courtesy of Karen Collins)
Eye on Science asked Karen whether we’d ever be able to travel to this planet to see if we could search for life ourselves. “It’s possible for us to study the atmosphere from afar, but even at the speed of light, it would take more than a typical human lifetime travel to the planet.” she said. (The planet is 90 light-years away). “To make matters worse, our current spacecraft travel at only a small fraction of the speed of light, so we’ll need some new type of propulsion system, such as a Star Trek-like warp drive, wormhole technology, or some other approach not even dreamed about yet, to make it possible to vacation on LP 791-18d.”
So, if we can never travel to this planet, why do we care if it hosts life?
“LP 791-18d brings us a planet with a possible volcano-fueled atmosphere and mantle, which could contain the building blocks for life and in certain regions on the planet and could potentially support some forms of life that exist on Earth,” Karen said. “And to top it off, the planet is close enough and its host star is bright enough that we may be able to determine if the planet’s atmosphere exists, and if so, detect some markers of its chemical make-up.
“In my view, one of the primary reasons discovering planets like LP 791-18d is important is that it helps us continue to build humankind’s catalog of planets that are like the Earth in many ways. These discoveries are helping us better understand how differing conditions can affect the development and evolution of planets like the Earth.”
Collins making observations at the Gemini North Observatory in Hawaii. (Photo courtesy Karen Collins)
Will we find life on other planets?
Even if we don’t directly detect life on LP 791-18d, Karen believes there’s a reasonable chance that we will find life in our own Solar System. “Possibly in the ice-covered oceans of Saturn’s moon Enceladus, or in some other unexpected place on one of the 13 planet and dwarf planets and more than 200 moons in the Solar System,” she said.
“We’ve now discovered more than 5,000 planets orbiting other stars in our Milky Way galaxy, and this is just scratching the surface. In my opinion, we are extremely likely to find evidence of life in the chemical signatures embedded in the atmospheres of some of the TESS exoplanets, and I would not be surprised if those signs of life are discovered by the new James Webb Space Telescope. However, because these exoplanets are so far away, it’s difficult for us to directly confirm life, at least until we develop more advanced spacecraft propulsion systems that will make interstellar travel possible.”
So, if you saw Interstellar and thought, “huh, I wonder when we’ll be able to do that,” it’s going to be a while.
A theoretical “travel poster” to a lava-covered exoplanet. (Courtesy NASA)
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Posted: 8 November 2023
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Categories:
Astrophysical Observatory , Eye on Science , Feature Stories
