Derek Lawden

Derek Frank Lawden (1919 to 2008) was a British-New Zealand mathematician who worked on rocket trajectories and space flight. After reading mathematics at Cambridge he served in the Royal Artillery, then lectured at the Royal Military College of Science and the College of Advanced Technology Birmingham, where he studied rocket trajectories. In 1956 he became a professor at the University of Canterbury in New Zealand, and in the 1960s he received a DSc from Cambridge, was appointed a Fellow of the Royal Society of New Zealand and won the Hector Medal. He returned to the United Kingdom in 1967 to the University of Aston. After the Second World War he was the first to register in the literature considerations about the use of gravity assist for space exploration, and in his pioneering work on optimal space trajectories in the 1960s he coined the term primer vector for the adjoint variables associated with the velocity vector, pointing out their fundamental connection to optimal thrust.