John is Keck Observatoryʻs primary scientific liaison and is responsible for maintaining the relationship between the Observatory and its scientific stakeholders, including the observing community and federal funding agencies. He helps set the science policy for the Observatory and is responsible for identifying new partnership and funding opportunities.

John has a deep interest in ensuring the health and success of the field. He is a member of multiple national astronomical oversight and advisory committees. Currently, he chairs the Astronomy and Astrophysics Advisory Committee, which reports to Congress on astronomy and astrophysics issues that are of mutual interest to the National Science Foundation, NASA, and the Department of Energy Office of Science. He also serves as the Cosmic Origins science team lead for the Large UV/Optical/IR Surveyor (LUVOIR) mission concept, a multi-wavelength space observatory concept for NASA.

John has been a Keck observer for over two decades. He is an experienced observational research astrophysicist, authoring more than 75 papers published in refereed journals about distant quasars, Big Bang nucleosynthesis, the intergalactic medium, galaxy formation and evolution, and more.