This study proposes an alternative and complementary method to bibliometric analysis to measure disciplinary diversity in research teams. Shannon's entropy index, which is used in ecology to measure biodiversity in habitats, is adapted to measure disciplinary diversity of a research team (habitats become teams, and biodiversity becomes disciplinary diversity). Data come from the National Aeronautics and Space Administration Astrobiology Institute, which funded 14 interdisciplinary virtual research teams in 2012. Authors examined not only team rosters but also the project rosters (167 projects for 2012) of each team to calculate disciplinary diversity. Results suggest that the intended diversity is being achieved for some teams. However, for more than half of the teams, disciplinary diversity scores are lower on the project level compared to the overall team level, which suggests that for these teams, the intended diversity is not being achieved.