In the heady days of the early space program, the Moon seemed
like only a meager first step in the human exploration of space.
Years before Neil Armstrong and Buzz Aldrin first walked on the
Moon, in fact, NASA was already planning for missions to Mars.
And one of the keys to those plans was nuclear-powered rocket
engines. In fact, a test of an early prototype took place 50
years ago tomorrow. The engine almost blew itself apart, but
analysis of the problems led to better designs. The rockets
pumped liquid hydrogen through the nuclear reactor. The uranium
fuel was heated to thousands of degrees, so as the hydrogen
passed through, it quickly heated and expanded, then blasted out
of a rocket nozzle. The nuclear rocket could deliver twice as
much “kick” as a conventional one. Also in 1962, NASA
commissioned a series of studies to take advantage of those
engines to send astronauts to Mars. Two of the studies produced
missions in which astronauts would simply fly past Mars, while a
third envisioned them entering o