John E. Brandenburg is an American plasma physicist whose published work runs from fusion and spacecraft-propulsion research to an unorthodox body of writing about Mars. In UFO and ancient-mysteries media he is best known for arguing that the isotopic makeup of the Martian atmosphere preserves traces of enormous nuclear explosions in the planet's past, which he has linked to the idea of a lost Martian civilization.

His technical publications trace a career spent largely in research firms and aerospace industry. In 1988 he co-wrote work on plasmoid simulations as a researcher at Mission Research Corporation, and in 1990 he published a theory of the relaxation of tokamak discharges in the Journal of Plasma Physics. Later conference papers list him at Research Support Instruments and the Aerospace Corporation, where he worked on microwave electrothermal thrusters that use water as propellant, and then at Orbital Technologies Corporation, Morningstar Applied Physics and Kepler Aerospace. A 2026 paper for an IEEE plasma-science conference lists him with American Fusion in Fort Worth, Texas. Alongside that work he has developed what he calls the GEM theory, an attempt to unify gravity and electromagnetism, presented largely at AIAA propulsion and aerospace conferences.

Brandenburg's interest in Mars predates his nuclear thesis. In 1987 he proposed a primordial Martian ocean he called the Paleo-Ocean, and the paleo-shorelines he suggested are part of the documented history of the Mars ocean hypothesis. In 1996 he argued in Geophysical Research Letters that the CI carbonaceous chondrite meteorites came from Mars, a proposal that drew a published comment and his reply. With writer Monica Rix Paxson he published Dead Mars, Dying Earth in 1999, followed by Life and Death on Mars in 2011 and Death on Mars in 2015, both from Adventures Unlimited Press.

The nuclear argument appears in a 2016 AIAA SPACE paper, co-written with Paul Murad, that presented what the authors called evidence of past massive nuclear explosions on Mars and linked it to Fermi's paradox and to what they called the Cydonian Hypothesis, named for the Cydonia region of Mars. He returned to the theme in a 2023 AIAA paper and a journal article the same year describing climate-altering explosions. His case centers on the excess of xenon-129 in the Martian atmosphere. The standard scientific reading is different: because xenon-129 is produced by radioactive decay, its relative abundance on Mars is commonly interpreted as a sign that the planet lost most of its primordial atmosphere early in its history.

Brandenburg remained active on the subject in 2026. In July the American Alchemy account circulated a clip of him discussing Martian xenon-129 as possible evidence of a nuclear catastrophe, and he was the featured guest on Mars Disclosure Live, a panel program hosted by Dave's Multiverse. He holds an unusual position in the Mars-anomaly field as a working physicist with an early, recognized contribution to the Martian ocean debate who has spent more than a decade advancing the nuclear-Mars hypothesis in books, conference papers and interviews.