John D. Strong; Detected Water Vapor on Venus

John D. Strong, 87, a researcher and educator who discovered water vapor on Venus. Strong developed telescopic mirrors and other optical devices, including a vacuum evaporation process for coating glass that made telescopes more durable and sensitive. He taught and did research at Caltech, Johns Hopkins University and the University of Massachusetts at Amherst. He first claimed to have detected water vapor on Venus in 1964 based on data collected with a balloon at 87,500 feet. That claim was disputed by other scientists at the time but he was later proved correct. Strong also wrote several textbooks, including “Procedures in Experimental Physics,” “Concepts of Classical Optics” and “Procedures in Applied Optics.” On Saturday in Amherst, Mass., of pancreatic cancer.