Frank Close

Career

In addition to his scientific research, he is known for his lectures and writings making science intelligible to a wider audience and promoting physics outreach.

From Oxford he went to Stanford University in California for two years as a Postdoctoral Fellow on the Stanford Linear Accelerator Center. In 1973 he went to the Daresbury Laboratory in Cheshire and then to CERN in Switzerland from 1973 to 1975. He joined the Rutherford Appleton Laboratory in Oxfordshire in 1975 as a research physicist and was latterly head of Theoretical Physics Division from 1991. He headed the communication and public education activities at CERN from 1997 to 2000. From 2001, he was professor of theoretical physics at Oxford. He was a visiting professor at the University of Birmingham from 1996 to 2002.

Close lists his recreations as writing, singing, travel, squash and Real tennis, and he is a member of Harwell Squash Club.

Honours and awards

• He became a Fellow of the Institute of Physics (FInstP) in 1991.
• The Institute of Physics awarded him its 1996 Kelvin Medal and Prize, which is given "for outstanding contributions to the public understanding of physics".
• From 1993 to 1999, he was vice-president of the British Association for the Advancement of Science.
• He was appointed an OBE in 2000.
• Since 2003, he has been Chairman of the British team (BPhO) in the International Physics Olympiad, based at the University of Leicester.
• 2013 Awarded the Royal Society Michael Faraday Prize.
• He became a Fellow of the Royal Society (FRS) in 2021.

Christmas lectures

His Royal Institution Christmas Lectures in 1993, entitled The Cosmic Onion, gave their name to one of his books. He was a member on the council of the Royal Institution from 1997 to 1999. From 2000 to 2003 he gave public lectures as professor of astronomy at Gresham College, London.

Contested claims about lunar helium‑3

In an August 2007 Physics World article, Close argued that proposals to mine lunar helium‑3 (³He) for “clean” fusion were misguided. He wrote that in tokamaks, deuterium–³He fusion proceeds far more slowly than deuterium–tritium (D–T), that mixed plasmas would inevitably generate tritium and neutrons via side D–D and D–T reactions, and that importing ³He from the Moon would ultimately result in the very type of fusion system it was meant to avoid. He also asserted that “we don’t even know for certain if there is any helium‑3 on the Moon,” and characterized the overall lunar‑³He concept as “moonshine.”

However, the existence of helium‑3 on the Moon was well established long before Close’s 2007 article. Apollo mission samples had confirmed the presence of solar-wind–implanted ³He in lunar regolith as early as the 1970s, with peer-reviewed publications reporting concentrations in the parts-per-billion range. For example, soil samples from Neil Armstrong's bulk sample 10084 from Apollo 11 was measured to contain approximately 11.8 ppb of ³He. By the early 2000s, remote sensing data from missions like Clementine and Lunar Prospector had been used to generate global models reaffirming the presence and distribution of helium‑3 in the lunar regolith, especially in mature, titanium-rich mare soils. Given the widespread availability of this data in the scientific literature, Close’s suggestion that “we don’t even know for certain if there is any helium‑3 on the Moon” was a significant misrepresentation. This assertion contradicts decades of well-documented lunar science.

In addition, tokamak experiments have in fact produced measurable D–³He fusion: JET reported non‑thermal D–³He fusion power of ~50–140 kW in the late 1980s–early 1990s and later pulses up to ~140 kW, using ³He as a minority species for ICRF heating.

Many of Close’s technical criticisms of helium‑3 fusion are supported by the scientific literature. It is widely accepted that deuterium–helium‑3 (D–³He) fusion is significantly more challenging to sustain than deuterium–tritium (D–T) fusion and that D–³He plasmas are not truly neutron-free. Side reactions, especially deuterium–deuterium fusion, inevitably produce tritium and neutrons, undermining claims of a “clean” process. In this respect, Close correctly challenged oversimplified narratives around lunar helium‑3 fusion.

However, Close overstated the extent of these challenges. Studies estimate that neutron production in optimized D–³He systems can be reduced to a small fraction of total fusion energy—far lower than in D–T fusion. His suggestion that using helium‑3 would effectively recreate a D–T machine overlooks this important distinction. Additionally, his claim that helium‑3 reactions produce deuterium was inaccurate; the standard helium‑3–helium‑3 fusion reaction produces two protons, not deuterium, consistent with well-established nuclear physics.