Max Hunter and a team of engineers at Douglas proposed this nuclear single-stage-to-orbit launch vehicle in February 1961. The low weight loading on the heat shield meant that re-entry temperatures would not exceed 1100 deg C, which in turn meant that a reusable re-radiative structure could be used. A Thrust-Augmented Thor booster would launch the subscale the RITV test vehicle. This would be equipped with a 8000 kgf Centaur engine, and prove structural concepts, the heat shield design, and reusability for the much larger nuclear-powered production version.
The RITA-A (Nexus) launch vehicle would be equipped with a 91,000 kgf nuclear engine with a specific impulse of 850 seconds. It could take 7300 kg to low earth orbit. Use of a Saturn S-IB first stage would allow it to take 38,200 kg to low earth orbit or 13,600 kg to lunar orbit. First test flight would come as early as 1965.
The RITA-B follow-on vehicle would be equipped with 4 x 200 tonne thrust nuclear engines with a specific impulse of 950 seconds. The RITA-B would perform a manned Mars mission, with departure in late 1967. A single RITA-B would be refuelled in low earth orbit by multiple launches of other RITA-B's. It would then depart for a direct flight to the Martian surface and return. The vehicle could use body lift to produce an L/D ratio of 0.7 for aerobraking to the Martian surface and on return to earth. With a total delta-V capability of 20.7 km/sec, RITA-B was capable of making the flight to Mars in 225 days.
RITA-C would be a shuttle version of the design, for transporting one million pounds of payload to low earth orbit.
LEO Payload: 454,500 kg (1,002,000 lb) to a 325 km orbit.
Stage Data - RITA C
Status: Study 1963.
Gross mass: 4,399,000 kg (9,698,000 lb).
Payload: 454,500 kg (1,002,000 lb).
Height: 60.00 m (196.00 ft).
Diameter: 21.30 m (69.80 ft).
Thrust: 59,572.37 kN (13,392,402 lbf).
Apogee: 325 km (201 mi).