Christiansen is a staff scientist at Caltech's IPAC astronomy center; chief scientist of the NASA Exoplanet Science Institute; and project scientist of the NASA Exoplanet Archive.
She specializes in exoplanet science, and analyzes data from the extension of NASA's Kepler mission, called K2, as well as NASA's TESS mission. She helps develop citizen-science projects involving exoplanets, and, in 2022, gave a popular TED Talk on exoplanets.
She is the most successful woman planet hunter in the world, and is helping plan NASA's next generation of flagship missions, including the Nancy Grace Roman Space Telescope, and the Habitable Worlds Observatory.