Hal Clement (1922 - 2003) Hal Clement is the nom de plume under which Harry Clement Stubbs wrote science fiction. Born in Massachusetts in 1922, he graduated from Harvard with a BSc. in astronomy, and later added degrees in chemistry and education. A former B-24 pilot who saw active service during the Second World War, he worked for most of his life as a high-school science teacher. He made his reputation as an SF writer with the work that appeared in Astounding, where his best-known novel, Mission of Gravity, first appeared in serialised form in 1953.