Von Braun costs out a Mars expedition
Ten ships, seventy crew, and 950 launches to assemble the fleet in Earth orbit: the first Mars expedition worked out in real numbers, and never flown.
Wernher von Braun spent the late 1940s at Fort Bliss, Texas, with the surrendered German rocket team and very little to do, and wrote a novel about an expedition to Mars. He finished the German manuscript in mid-1949. No publisher wanted the fiction. What they took was the appendix — the part where he worked out whether the trip in the story would actually close. It appeared in the German spaceflight journal Weltraumfahrt and then as a short book, Das Marsprojekt, in 1952, and in English as The Mars Project in 1953.
The architecture is enormous and completely explicit. Ten ships, seven carrying people and three carrying cargo, assembled in Earth orbit from 950 launches of a three-stage reusable booster that would have massed more than twice a Saturn V and produced roughly three times its thrust. Seventy crew. A 260-day Hohmann transfer out, a stay at Mars of about 443 days while the planets came back into alignment, and 260 days home. Nothing in it is hand-waved: propellant loads, staging masses and transfer geometry are all tabulated, which is why the book is still cited and the novel is not.
The landing is where the era shows through. Von Braun's crews would descend in winged gliders with a 153-metre span. The first would land on skis on a polar ice cap — the only surface he could be sure was flat — and its crew would then abandon it and drive 6,500 kilometres overland to the equator to lay a strip for the other two. All of that requires an atmosphere thick enough to fly in. His re-entry calculations assumed 84 millibars at the surface, the accepted figure at the time; Mariner 4 measured 4 to 7 in 1965. In the real atmosphere his glider would not have dropped below the speed of sound until roughly 47 kilometres below ground level. The most careful engineering in the book was built on somebody else's bad number.
It was never funded, never approved and never scheduled. It was also the hinge. Before Das Marsprojekt, going to Mars was a story; after it, it was a mass budget you could argue with. Von Braun took the same material into Collier's between 1952 and 1954, illustrated by Chesley Bonestell, and onto American television with Disney, and in the process turned interplanetary flight from a pulp subject into a policy one. He himself cut the fleet from ten ships to two, and the crew from seventy to twelve, in The Exploration of Mars in 1956 — the first of many times those numbers have come down.
His notional departure year was 1965. That is the year Mars was actually reached — by a 261-kilogram robot with a camera.