JOAN FEYNMAN: 1927 - 2020
Joan Feynman, who has died aged 93, was an astrophysicist who led the way in discovering what causes the aurora borealis and aurora australis, the cosmic light shows that illuminate the sky around the poles; encouraged by her brother, the Nobel laureate Richard Feynman, she overcame deep-seated prejudice against female scientists – not least in her own home.
"My mother warned me 'Women's brains can't do science', " she recalled. But Richard, older by nine years, was keen to encourage her, and when he built an electronics lab in his bedroom he "hired" Joan as his assistant for a few cents a week.
When she was 14 he gave her an astronomy textbook containing charts of data compiled by a female astrophysicist; then one night he got her out of bed in the early hours and took her to the local golf course, away from the city lights, to show her the aurora borealis. "No one knows how it happens," he told her.
Her path was set, and she would go on to investigate not only the Northern and Southern Lights and the solar wind, but also sunspot cycles and coronal mass ejections, or CMEs (essentially the sun "burping"), and the attendant effects on climate change, as well as the high-energy particles that bombard spacecraft.
She was born into a Jewish family on March 31, 1927 in Queens, New York to Melville, a businessman, and Lucille, née Phillips, who brought up the family. Inspired by her brother, who would become one of the foremost theoretical physicists of the 20th century, she first attended Oberlin College, then studied solid-state physics at Syracuse University.
After a year out in Guatemala studying the Maya people, she returned to Syracuse – where a professor told her she should do her doctoral dissertation on cobwebs, since that was what she would be dealing with as a housewife. Instead, her thesis was entitled Absorption of infrared radiation in crystals of diamond-type lattice structure.
She was awarded her doctorate in 1958, and although she initially spent a few years unable to find a job, she went on to a succession of posts, notably at NASA's Ames Research Center, the High Altitude Observatory, the National Center for Atmospheric Research and the Jet Propulsion Laboratory.
The bulk of her career was devoted to studying the interaction between the solar wind – the stream of charged particles that flows from the sun – and the Earth's magnetosphere. Although she wanted to share her work with Richard she feared that he might beat her to the key discoveries, so did a deal with him.
"I said, 'Look, I don't want us to compete, so let's divide up physics between us. I'll take auroras and you take the rest of the universe.' And he said, OK!"
It was when Joan Feynman was taken on by the Jet Propulsion Laboratory in Pasadena in 1985 that she used data collected by a NASA spacecraft, Explorer 33, to demonstrate that auroras occur when the solar wind penetrates the magnetosphere – the wild colours and formations are caused by colliding particles.
She also studied the effects of CMEs on spacecraft and astronauts: when solar material is hurled into space huge waves of protons are unleashed that can interfere with communications and other activities. Her work led to a rethink in spacecraft design.
Her later career was devoted to studying the effects of solar activity on climate change. She retired from the Jet Propulsion Lab in 2004 but continued to publish papers on the subject and go into her office until 2017. "How could I retire when the sun is doing such crazy things?" she said.
Joan Feynman married firstly Richard Hirshberg; they had a daughter and two sons but divorced. In 1987 she married a fellow astrophysicist, Alexander Ruzmaikin. He survives her along with her children.
The Telegraph, London