Pettit's research is primarily focused on glacial dynamics and exploring the interactions within the ice-ocean-earth system. Pettit is a National Geographic Emerging Explorer who innovated applying acoustic research with hydrophones to calving and melting glaciers reaching the ocean, to examine ice shelf disintegration and the ice-ocean boundary. Her work has been recognized by numerous high-profile sources, including EARTH magazine, and National Geographic, and she was invited to present a TEDWomen talk, on her investigations focused on "listening" to glaciers. Pettit's research on glacier sounds extends to how the underwater noise affects marine animals. She also created and runs the Girls on Ice program, a wilderness science program that teaches high school girls about glaciology, ecology, and mountaineering Girls on Ice started in Washington in 1999, with Pettit taking five girls to the South Cascade Glacier. During the program, adolescent girls learn mountaineering skills, how to use GPS for glacier measurement and how to calculate the velocity of streams.

As a Lead Principal Investigator on the TARSAN project, Pettit and her team will measure ocean circulation and thinning beneath the floating part of the glacier using state of the art technology such as automated underwater vehicles (AUVs) and automated land-ice stations, investigating how the ocean and atmosphere are affecting Thwaites Glacier.