A 1966 North American Aviation preliminary design for a biconic aeroshell-protected spacecraft for Mars exploration. Instead of using rockets (and consequently a whole lot of rocket fuel) for deceleration into Mars orbit, this design would use aerodynamic braking in the Martian atmosphere. In effect, it would drop out of interplanetary space into the upper Martian atmosphere and skip off; in the process of doing so it would have lost enough velocity to be captured into Mars orbit with minimal expenditure of propellant.
This design had an overall length of 31.0 meters and a base diameter of 17.7 meters, and a gross weight of 353,360 kilograms. The baseline mission duration was 500 days. In order to keep the astronauts bones from turning into paper and their muscles into mush, artificial gravity was designed in. The vehicle would split apart along the separation plane, with the two sections connected by a set of cables. The entire assembly would tumble end over end, creating a sufficiency of artificial gravity for crew health. Prior to Mars interface the two sections would be winched back together.
A higher-rez version of this drawing is HERE.