epidemics from space
Fred Hoyle and Chandra Wickramasinghe made the highly controversial claim that viruses carried by comets, and released from their tails, are the cause of mass outbreaks of influenza and other viral diseases on Earth.1 Although the great majority of scientists are dismissive of this idea, it was lent some credence by the detection, in 1987, of a polymeric form of the organic molecule formaldehyde in the dust from Halley's Comet by the Giotto probe. Christopher Chyba and Carl Sagan of Cornell University commented at the time that the observations "strongly suggest the presence of complex organic grains or organic-coated grains". There remains, however, an immense gulf between the growing recognition that some types of basic organic chemical synthesis do take place in space and acceptance of the idea that the evolution of primitive life-forms takes place on cosmic dust grains as proposed by Hoyle and Wickramasinghe.
1. Hoyle, Fred, and Wickramasinghe, Chandra. Viruses From Space. Cardiff: University College Cardiff Press (1986).