By analyzing the isotopic compositions of stable and radiogenic nuclides in meteorites, Dauphas investigates the timing and processes that lead to the formation of Solar System bodies and the establishment of habitable conditions on Earth and Mars. He used iron isotopes to study how the iron biogeochemical cycle of the Earth changed through time. He established that Mars was formed rapidly, within the first 2~4 million years of the birth of the Solar System, which explains the much smaller size of Mars compared to Earth and Venus. He first identified the mineralogical carrier of the Cr isotopic anomalies in meteorites as Cr-rich nano-sized spinels from supernovae. He constrained the nature of Earths accreting materials through time, using a novel approach that relies on the different affinities of elements with Earths core, and showed that the materials formed Earth are from an isotopically homogeneous reservoir.
Dauphas was part of the preliminary examination team for JAXA's Hayabusa2 mission, which returned a fragment of Ryugu carbonaceous asteroid to Earth for scientific research. He was selected as a member of the Mars Sample Return Campaign Science Group in 2022.