He joined the HRC instrument team upon completion of his doctoral thesis and worked closely with Dr. Stephen Murray and the engineering team that designed and built the flight instrument. Since Chandra's launch in 1999, Ralph has divided his time between HRC operations to ensure the health and safety of the flight instrument, ongoing analysis of in-flight calibration data, and development of his own science program.
Ralph has broad scientific interests including the study of clusters of galaxies, black holes, jets, astrophysical hydrodynamics, the formation of structure in the Universe, and development of instrumentation for future mission concepts in both astrophysics and planetary science. Ralph is currently a member of the executive committee of NASA's Physics of the Cosmos Program Analysis Group (PhysPAG), and a co-chair of the X-ray Science Interest Group (XRSIG).