Jim knew that Langley had made immense contributions to the U.S.’s prowess in aeronautics and astronautics. It had gotten involved with the development of military aircraft during the Second World War and then in the programs which led to the first supersonic airplane, the Bell X-1. Langley staff had formed the task force which had been responsible for the Mercury program, and later it became involved with studies for the optimal shapes for the Gemini and Apollo ships…

Gregory never talked about his past. Dana knew he’d suffered during the war. Maybe, he thought, Langley was kind of a refuge, after all that. It buffered him from the pressures of the competitive aircraft industry, and on the other hand from NASA politics. It was as if the men of Langley — and they were men, almost exclusively — had made a kind of unconscious decision that their site and budgets and scope should remain small, even as the space program Langley had spawned had grown like Topsy.

Gregory was still only forty-one. But Dana could see, having grown a little more, that Gregory had found a place that suited him; and there he was going to stay, getting older and slower, charming everyone with the lingering traces of his French accent, working at his own pace inside that peaceful, isolated cocoon. Staying at Langley meant, though, that Gregory and Sylvia were more or less stuck, here in downtown Hampton, on Gregory’s plateaued-out salary; and here they’d probably have to stay, despite the inexorable decay of the neighborhood…

Gregory had drawn a half ellipse, which touched Earth’s orbit at one extreme, and reached out to kiss Mars’s orbit at the other. “Here we have a minimum-energy transfer orbit. It is called a Hohmann ellipse. Any other trajectory requires a greater expenditure of energy than this… To return to Earth, we must follow a similar half ellipse.” He moved Mars around perhaps two-thirds of its orbital path, and drew another kissing ellipse, this one out of Mars and inward toward the Earth. “The flight home takes just as long as the flight out, around 260 days. And in addition, we must wait all this time at Mars, until Earth and Mars have moved into the right configuration for us to return: for no fewer than 480 days. And so our mission time is a remarkable 977 days: more than two and a half years. Our longest spaceflight to date has been around two weeks; we surely can’t contemplate a mission of such magnitude.”

“And yet, Rockwell is studying just such a mission profile, for NASA,” Dana said. “Chemical technology only. And at Marshall they are looking at nuclear options.” Nuclear rockets, more powerful, could put ships into shallower, more direct ellipses. “The Marshall study is showing journey times of no more than 450 days, total…”

“More big rockets! Huh!”