In this series of posts, we sit down with a few of the keynote speakers of the 243rd AAS meeting to learn more about them and their research. You can see a full schedule of their talks here, and read our other interviews here!
In the most remote locations both on Earth and in the solar system, Dr. Karen Meech hopes to understand how a key ingredient to life originated on our planet: water.
Despite covering over 70% of the globe, the question of where Earth got its water from is still under debate. Our understanding of the formation of the Solar System unfortunately doesn’t favor the simplest explanation – that Earth’s oceans formed with the planet. When the Solar System was nothing more than a hot disk of gas and dust swirling around the Sun, the Earth was forming in a region where temperatures were too high for water to condense and accrete onto our fledgling planet. But farther out, beyond the “frost line”, conditions were cold enough to condense water into ice, which could be trapped in rocky bodies such as comets and asteroids. These ice- and volatile-rich masses could have acted as a “cosmic H2O delivery service”, crashing into early Earth and depositing the water that is so crucial to sustaining life. These icy messengers are how Dr. Meech, an astronomer at the Institute for Astronomy at the University of Hawaiʻi, started her career and what she has been studying ever since.
“I really am keenly focused on understanding where Earth got its water and, in that extent, you know, you’ve got to look at the chemistry in the comets. You’ve got to compare it to the water on Earth, the chemistry of water,” Dr. Meech says. Studying comet chemistry is not easy, in part because comets are always on the move, leaving astronomers with small windows of opportunity to get close enough to point their telescopes at them. Dr. Meech has used telescopes on the mountains of Chile and Hawaiʻi to look at these distant visitors, currently focusing on observing comets that “almost have no activity, but come from the distant reaches of the Solar System from the Oort cloud, because they may provide clues on what the material was like that made Earth.” You might have heard of one of these distant visitors – the object 1I/2017 U1 also known as ‘Oumuamua, the first observed interstellar visitor to grace our neighborhood. Dr. Meech led the team that analyzed data from this traveling asteroid, including understanding its shape, size, trajectory, and composition. She has also been instrumental in NASA missions such as Deep Impact and Stardust/NExT that have sent spacecraft to comets and is involved in planning a mission to explore the water content of asteroids in the asteroid belt. While planning for new missions, Dr. Meech hasn’t also forgotten about the wealth of data we already have: one of her other current projects is trying to compile an online interface of 30-40 years of comet observations. While still a couple of years away from being complete due to the large amount of data cleaning needed, Dr. Meech is hopeful that the end result will be accessible to everyone and can be archived into NASA.
Dr. Meech’s work crosses interdisciplinary boundaries – besides looking into space, she is also currently trying to get funding for geological expeditions to Baffin Island to get samples of material buried deep into the Earth. What does a remote island in Canada have to do with comets? One way astronomers can understand the origin of water is by looking at chemical fingerprints such as the deuterium-to-hydrogen (D/H) ratio. If a small body like a comet has a similar D/H ratio as Earth’s water, this could be a supporting piece of evidence for the water delivery scenario and could help differentiate different planet-formation models. The challenge is the passage of time: the D/H ratio in surface water like our oceans has been altered over billions of years by atmospheric and geological processes. But “certain regions on earth have primordial signatures of helium, which means that this material has not mixed much with Earth’s mantle at all,” meaning that samples of water from these regions would be excellent indicators of Earth’s initial D/H ratio. One of those places is the picturesque Baffin Island, where Dr. Meech hopes to go to measure the primordial D/H ratio. Even though she’s not a geologist by trade, her desire to go on an expedition like this is unparalleled: “If I happen to get the funding, I’m going, even if my role is camp cook.”
Dr. Meech’s early love of space was ignited more by science fiction than her initial science classes: “I decided space was for me, I think, in second grade, that’s when Star Trek came out, and a lot of scientists will admit the same thing. I remember my parents saying, you better wait and see if you like physics. I was stubborn, and I said, ‘I’ll like it.’ I didn’t at first.” Nonetheless, she stuck through the seemingly endless onslaught of frictionless planes and balls rolling down inclined ramps and was accepted early decision to Rice University to do a BS in Space Physics. Working on her first research project there taught Dr. Meech an important lesson: “Don’t be afraid to ask questions….I think the ability to just speak up and not be afraid to show that you don’t know everything, and to just ask questions [is good advice]”. After taking a year off to work for the American Association of Variable Star Observers (AAVSO) she headed off to grad school at MIT, ultimately landing her position at the Institute of Astronomy straight out of grad school, where she’s been ever since.
Besides an impressive research track record of research accomplishments, Dr. Meech has also been heavily involved in outreach during her time at Hawaiʻi, founding an outreach program called Towards Planetary Systems (TOPS) that aimed to give high school teachers and students in the Pacific Islands an intensive experience with (exo)planetary science, which also included workshops on subjects like cultural astronomy and mirror grinding. While the program is no longer running, it lasted 8 years and spurred the creation of other impactful outreach programs around the islands.
If you want to learn more about how the Earth got its water, tune into Dr. Karen Meech’s 2023 Dannie Heineman Prize Lecture, currently scheduled for Thursday, January 11, 2024 at 3:40 PM CT at #AAS243!
Astrobite edited by: Huei Sears
Featured Image Credit: AAS
