Compositional interpretation of PFS/MEx and TES/MGS thermal infrared spectra of Phobos

► We use thermal infrared spectra to investigate the composition of Phobos' surface. ► No class of chondritic meteorites is in agreement with the observed features. ► We detected phyllosilicates, particularly in the area northeast of Stickney. ► Our derived surface temperatures are consistent with previous results. ► Currently, the most likely scenario is the in-situ formation of Phobos.