While at Oxford, she contributed to the analysis of remote sensing data to help evaluate safe landing sites for the Mars Exploration Rover in a 2005 study.

(by research) Geography thesis was entitled "Developing quantitative techniques for evaluating rock breakdown morphology: a case study of basalt boulders in the Channelled Scablands, Washington, USA.

[10] The discovery could be a clue of past life on Mars, as serpentine arises from a mineral called olivine in a hydrothermal process that could serve as an energy source for methane-producing microbes.

[12] Following her doctorate, Ehlmann became a European Union Marie Curie Fellow at the Institut d’Astrophysique Spatiale at University of Paris-Sud.

[16] By contrast, her group demonstrated the important role of sequestration of large volumes of water in Mars' crust as hydrated minerals.

[18] She was part of the team that proposed the Jezero crater, where rivers once fed into a lake, as the landing site for the Mars 2020 mission, citing that the crater was also an excellent landing site to look for signs of life underground, collecting river and lake sediments that might retain signs of past life.

She and collaborators found the bright spots were due to a variety of highly reflective salts that have accumulated on Ceres, likely as a result of some water-related process.

In June 2019, Lunar Trailblazer was selected as a finalist for NASA's Small Innovative Missions for Planetary Science call.

[24] In 2020, she began service on the National Academies Planetary Science and Astrobiology Decadal Survey 2023-2032 as a member of the Steering Committee and vice-chair of the Mars Panel.