NASA astrophysicist Jason Kalirai observes stars and searches for habitable planets in the hopes of finding life.
Profile: Jason Kalirai
Published June 6, 2018
Onscreen: Which exoplanets could harbor life?
Jason Kalirai: Planets are really at the mercy of what happens to the stars that they’re orbiting around.
Suriya: Dad, can you walk slower, maybe?
Narrator: Jason Kalirai is a stellar astrophysicist.
Kalirai: So what are you guys excited about seeing tonight?
Suriya: I’m excited about seeing Saturn.
Narrator: An expert in the behavior of stars, he knows the profound influence they have on orbiting planets.
Kalirai: So by studying those stars, we can figure out what kind of planets might be most suitable for finding life.
Here’s our main mirror. Do you guys remember what this is called?
Daughters: First mirror?
Kalirai: Primary mirror.
Daughters: Primary mirror.
Narrator: Jason’s curiosity about the cosmos started early.
Kalirai: As a young kid, one of the things that I found most exciting was trying to figure out how the universe works. On countless times, I would be in our backyard looking up at the night sky, wondering what part of the universe I’m seeing.
Narrator: Jason had clear views of the sky in british columbia, where he grew up.
His parents moved there from Punjab, India in the 1970s.
Kalirai: If they had stayed in India, I would not be an astronomer. That’s just the way the system is. But in Canada, I could take a liking to whatever I liked, and as a very young kid, I liked astronomy. And when I wanted to become an astronomer and see that through, there was nothing stopping me.
Narrator: Today, he shares his love of astronomy with his twin daughters, Suriya and Mira.
Suriya: Is that Saturn? Whoa…
Kalirai: That’s Saturn. Can you see the rings?
...because you see so much more out there that’s otherwise invisible to us. That it instills that curiosity in a child to want to go and find out answers. And with astronomy, they’ll never be satisfied, because it’ll always just throw more questions at you.
Narrator: Today, Jason pursues his questions about the cosmos at the Space Telescope Science Institute in Maryland.
And when it comes to the search for alien worlds, he focuses on the kinds of stars that might be friendliest for life. Because not all stars are created equal.
Kalirai: When we look up at the night sky, we’re seeing just the brightest beacons of light. It’s not representative of the true distribution of stars, which contains many more lower-mass stars, stars much smaller than the sun.
Narrator: These low-mass stars, sometimes called red dwarfs, are smaller and cooler than our sun. And while our own sun will burn out in about 5 billion years, red dwarves could burn for trillions of years. Across the milky way galaxy, red dwarves probably host billions of planets, many of them small and rocky...like earth. So how likely is it these planets host life? One group of planets just 40 light years away has enticed scientists like Jason: the TRAPPIST-1 System.
Kalirai: One of the biggest discoveries in exoplanet research in the last few years was the discovery of the Trappist-1 System. This is an incredible star.
Narrator: TRAPPIST-1’s seven planets are all close to Earth-size—and circle it in tight orbits, like a condensed version of our own solar system.
Kalirai: These planets take a few days to go around their star, and they’re only located a few million miles from it.
Narrator: TRAPPIST-1’s innermost planet orbits its host star every one and a half days.
Kalirai: It’s 90 times closer to the TRAPPIST-1 star than our Earth is to the sun, and so, it’s going to be very hot on that planet.
Narrator: Though not a lava world, it’s too hot for liquid water—or for life as we know it.
Kalirai: The other end of the extreme, we’ve got this planet here, Planet H, which is going to take about 20 days going around the TRAPPIST-1 System—which is a huge amount of time, given how faint the TRAPPIST-1 star is, and so it’s going to be very cold, actually.
Narrator: Any water here is likely frozen solid. But a few TRAPPIST-1 planets seem to orbit in the goldilocks zone—just right—with temperatures that could be similar to those on Earth.
Kalirai: We think these planets in the middle are in the habitable zone of TRAPPIST-1. Conditions are going to be just right where liquid water could exist.
Narrator: When the discovery was first announced, hopes were high that some of these planets could harbor life. But Jason is more skeptical, not because of the planets, but because of the star. Red dwarfs may be small and cool—but they are also more violent and volatile than our Sun.
Kalirai: These are generally pretty active stars—they exhibit a number of solar flares where there’s material that can impact the planets.
Narrator: This material carries enormous amounts of radiation—many billions of hydrogen bombs' worth—enough to destroy the cells of any living thing on a nearby planet. Jason fears these radioactive solar flares could wipe out any life that might arise in the TRAPPIST-1 system.
Kalirai: It’s actually unclear whether or not the conditions necessary to sustain life and the time that life needs to develop are going to be stable on these planets.
Narrator: Jason isn’t giving up on planets that orbit red dwarfs, but he does worry that life there might be so different from our own we might never recognize it.
Kalirai: I have no doubt that planets that are very different from Earth and stars that are very different from the sun will still lead to different types of life. But we don’t know what we’re looking for. So the simplest experiment is to try and find life that resembles the life that we understand well on Earth.
- Digital Producer
- Michael Rivera
- WONDERS ARE WE ALONE?
- Produced and Directed by
- Jane Teeling and Phil Bertelsen
- © WGBH Educational Foundation 2018