McKay was the first author of a scientific paper postulating past life on Mars on the basis of evidence in Martian meteorite ALH 84001, which had been found in Antarctica.

[3] As a graduate student in geology at Rice University, McKay was present at John F. Kennedy's speech in 1962[4] announcing the goal of landing a man on the Moon within the decade.

On July 20, 1969, in Houston, McKay was the only geologist present in the Apollo Mission Control Room when Armstrong and Aldrin walked on the Moon, serving as a resource.

As a result of this effort, McKay contributed to major discoveries, including:[6] McKay published numerous papers and abstracts relating to planetary materials and space resource utilization: lunar regolith,[7] cosmic dust, meteorites, Martian soil analogs, and technologies for producing oxygen, water, and building materials from lunar soil.

Using one of the largest returned Apollo regolith samples released to scientists, the research team separated and studied the tiniest sized lunar dust particles.