Halley began working at the now-defunct Kewanee Boiler Corp., which was located in Kewanee, Illinois, in the 1970s, and became involved with the ABMA. He was chairman of the ABMA's joint technical committee from 1981 to 1986 and was a member of several boiler industry advisory and working groups that were in collaboration with the U.S. Environmental Protection Agency and the Department of Energy, a statement from the ABMA said.

Among many other boiler industry-related projects, Halley was the editor of the ABMA packaged boiler engineering manual, an instructor at boiler technician training schools, and the author of several papers on boiler-related topics that were published in The National Board Bulletin, Boiler Systems Engineering, and Maintenance Management. Halley was the ABMA technical director from 2000-2019 and was recognized by the association in 2017 for his years of service.

Halley was born in 1937 in Southport, England, to John and Doris Halley. He grew up during World War II and graduated in the sciences from King George V Grammar School, where he also excelled in sports, according to an online obituary. He earned a full scholarship to the De Havilland Aircraft Corp.’s engineering apprenticeship program and studied mechanical engineering and electrical engineering. He worked on many projects, including England’s entry into the space race, a rocket program known as Blue Streak.

After graduating from engineering school, Halley married Sylvia Elbourn in 1959. He worked on the Blue Streak rocket flight test program in Australia and supported the program until it was canceled, then joined English Electric, for which he worked as a development engineer in the atomic power group.

Later, Halley was offered a position on the Apollo space program and moved his family to the U.S. At Bell Aerosystems, he worked as a combustion development engineer on the engine that eventually blasted U.S. astronauts off the moon. 

As the Apollo program wound down, Geoff was recruited by Kewanee Boiler, for which he started as a combustion development engineer. He eventually became the general manager of Kewanee, and spent 18 years at the company.

Halley was preceded in death by his wife, Sylvia, and by two grandsons, Derek Halley and Graham Halley. He is survived by two sons, Ian (Melanie) Halley and Stuart (Marilyn) Halley, a daughter, Jayne (Brian) Vickrey, a brother, Keith Halley, a sister, Margaret Searle, six grandchildren, and four great grandchildren.

Memorial donations can be made to the Missouri Botanical Garden, www.missouribotanicalgarden.org.