Applications are invited for the NASA Postdoctoral Fellowship Program which is available to early-career and more senior scientists. U.S. and international scientists are eligible to apply for this fellowship program. NASA Postdoctoral Fellows work on 1 to 3-year assignments with NASA scientists and engineers at NASA centers and institutes to advance NASA’s missions in earth science, heliophysics, planetary science, astrophysics, space bioscience, aeronautics, engineering,human exploration and space operations, astrobiology, and science management. In order to apply applicants must have completed the requirements for a PhD or an equivalent doctorate degree before beginning the fellowship.