Solar sailing might not sound like an obvious candidate for PhD funding, but investment during the1980s is paying dividends today
I first stumbled across the idea of solar sailing by accident, not long after I matriculated as an undergraduate student at Glasgow University in 1984. While browsing through some popular science books in Hillhead library, I came upon a wonderful colour painting of a large solar sail. Reading on, I remember being struck by the aesthetic beauty and romance of the idea of sailing through space propelled only by the pressure of sunlight.
Several years later I began postgraduate research funded by the Royal Society of Edinburgh. The scholarship was not tied to any particular topic, although it was awarded for work in the general area of astronomy. Luckily, my supervisor took a fairly liberal interpretation of the definition of astronomy and, knowing of my undergraduate interest in orbital dynamics, suggested I explore the orbital dynamics of solar sails. I quickly found that although it had been studied for many years, and indeed a mission was almost flown by American space agency Nasa in the mid-1970s, not much had been published.
One of the first problems I tackled was the orbital dynamics of the three-body system, comprising Sun, Earth and solar sail. The effect of light pressure on a related three-body problem had been studied in detail in the astronomy group at Glasgow for application to mass transfer in binary star systems, so I had some work to build on. I found that the solar-sail problem had rich families of solutions that rapidly filled up my PhD dissertation. By October 1991, my thesis was bound and submitted and I had started in a lecturing position. Thoughts of solar sailing drifted away as I explored new problems in spacecraft dynamics, most of which were more near-term and so held out hope of attracting some funding.
Several years later, in August 1996, I was put in touch with Patricia Mulligan at the National Oceanic and Atmospheric Administration in the United States and John West at Nasa. Mulligan and West were beginning to investigate deploying a relatively small solar sail on a trajectory inside the orbit of the Earth. Such an orbit would provide early warning of the solar storms that disrupt communication satellites and terrestrial power lines. The orbit for the mission, later named Geostorm , was one of the family of solar-sail trajectories I had explored during my PhD studies eight years earlier and so I began a long and fruitful association with Nasa's re-awakened interest in solar sailing. This has led to a position on the new Nasa solar-sail technology working group and funding from the European Space Agency to map out future solar-sail missions for the agency. The first solar-sail mission - built by Russia - is scheduled to fly within the year, so things are looking up for this promising and elegant technology.
What lesson can be taken from this tale? It is vital that bright young researchers be given the freedom to follow their curiosity, explore their ideas and follow obscure avenues of investigation. More PhD scholarships are driven by industry and research council priorities and are tied to specific, and in some cases mundane, projects. Who could have predicted that obscure research in mass transfer in binary star systems would wind up providing solar storm warnings? Not me, and not the Royal Society of Edinburgh, which funded my initial work by throwing some money at a PhD student with crazy ideas of sailing through space.
Colin McInnes is professor of space systems engineering at Glasgow University and author of Solar Sailing: Technology, Dynamics and Mission Applications , published by Springer-Verlag, £45.00.