The chemical mode had some advantages. The development program would be comparatively cheap, since the hardware would be based on incremental upgrades of Saturn technology, for example the use of an enhanced Saturn second stage to serve as an orbital injection booster.

But the nuclear camp from Marshall, led by Udet and Conlig, didn’t find it hard to pick holes in the case. Compared to the NERVA profile, twice as much mass would have to be hurled into Earth orbit, for a mission twice the length. Chemical technology couldn’t manage much better than that. Not without imagination, anyway, Dana thought; not if you stick to direct transfer…

Dana knew that most of the points raised in the discussion were a repeat of the sterile arguments which had plagued NASA for some months.

At the end of the question session Seger didn’t call for any applause.

Lunch turned out to be steak and chicken served buffet style. The debate continued during the meal, with delegates making points by jabbing bits of steak or fried potato at each other.

Dana spotted the sleek, handsome figure of Wernher von Braun himself. He was talking to an astronaut: Joe Muldoon, a moonwalker, tall, erect, his thinning, gray-blond hair clipped to military neatness.

Few people spoke to the obscure little man from Langley with his peculiar presentation. Venus swing-by modes? What the hell is that about? That suited Dana. He left the lunch early and returned to his seat in the hall; he didn’t much like steak anyway.

The conference looked at two more options, before Dana’s pitch. Both of those were more ambitious, technically, than either the main chemical or nuclear options reviewed earlier; Dana suspected they had been explored just to make sure nothing obvious was missed before the primary mode was selected.

A representative of McDonnell presented a so-called nuclear electric option, together with representatives of NASA and ARPA, the government’s Advanced Research Projects Agency. Plasma — a charged gas — would be accelerated electrodynamically out of a rocket nozzle. A plasma rocket’s thrust was tiny, but would last for months; plasma rockets would move spaceflight techniques away, at last, from the antique Jules Verne kick-and-coast model. The technology was unproven, but there had been some trials; an electric rocket had been operated at high altitude as long ago as 1964.

The McDonnell man flashed up a conceptual design for a manned nuclear-electric ship. It was a staggering arrangement, like a three-armed windmill. Two of the arms — each fifty yards long — contained reactors, and the third the habitable section. The rockets were mounted at the hub of the rotor, and the whole thing was designed to spin about the hub to provide artificial gravity. It would be, Dana thought, like a great metal snowflake, spinning toward Mars. It was a terrific concept, and utterly impractical.