Samantha Scibelli: Chemical Detective

The clouds of gas and debris that Samantha Scibelli studies are “colder than the poles of Mars” and smell like green apples—and they hold some of the secrets behind the chemistry needed for life to form on planets. Scibelli, who just earned her PhD, uses radio telescopes to study very cold, dense clumps of gas and dust that will eventually give birth to stars like our sun. She has detected complex molecules in these “cores” that also show up in living systems: precursors to molecules for DNA, RNA, and amino acids. One of these molecules is acetaldehyde, which smells like fruit, can build up in human livers, and is responsible for hangovers. Another—found in a very young starless core—is vinyl cyanide, which astrobiologists believe could be important for building cell membranes on planets where oceans are made of liquid methane instead of water, like those found on Saturn’s moon Titan. Many of these molecules are showing up in very young cores—“more than a million years earlier in the star formation life cycle than previously thought.” She is currently leading up the GLUCOSE team, which has been awarded 600 observational hours at the Green Bank Observatory to better understand the origins of complex molecules in dense starless cores. As astronomers at Steward and elsewhere continue to look for biosignatures for earth-like planets, research like Scibelli’s helps us differentiate between markers that might represent life and similar markers that actually appear much earlier in the story of solar system formation. Ultimately, Scibelli hopes to uncover where these complex molecules originate from, and how early they begin appearing in starless cores. “If we want to understand the emergence of life on Earth and how we got here,” Scibelli says, “it's important to study solar analog systems . . . Our place in the universe starts in these stages of low mass star formation.”

In her time at UA, Samantha has used telescopes at every one of the University’s mountaintop observatories, but it’s a special full circle for her to have finished her dissertation using the same radio dish—the UArizona 12-meter Telescope—that she used when she first arrived on scholarship for Astronomy Camp as a junior in high school. Scibelli still returns to Astronomy Camp every summer—now as a mentor—to help inspire students curious about the cosmos. Having earned a Science Communications Certificate alongside her PhD, Scibelli is passionate about sharing her knowledge in ways that unlock excitement and understanding.

Scibelli has a small collection of hardware from telescopes she has worked on: a white and blue fuse from the Submillimeter Telescope (SMT) that can fit in her palm; a knobby laptop-sized correlator card from the instrument that recorded data for her first paper. The latter she looks at with an appreciative smile, turning the card over to show the latticework of ridges and circuits—technology that can now fit on a fingernail-sized chip. Scibelli says it’s nice to have a rooted, tangible connection to the equipment that goes into processing her data from faraway prestellar cores. It’s not so different from the way that Scibelli’s own work links the history of star formation in the universe with the chemicals in our own bodies—drawing lines of connection between what is distant and abstract and what is physical and familiar.

To hear more chemical detective stories before Scibelli leaves for her post-doc at University of Virginia this fall—or to pick her brain for favorite handcrafted pasta-making tricks—find out more about Sam’s research email her at sscibelli@arizona.edu.