Comet HLLV

Design

The Comet rocket was designed to lift 254.4 tons to low Earth orbit or 97.6 tons on a path to the Moon, about double the Saturn V’s capacity, placing it among the largest rockets ever conceived in payload terms. Its appearance was similar to the Saturn V, but with longer first and second stages, a wider third stage, and new strap-on boosters. The propulsion system used upgraded F-1A and J-2S engines, and the second stage gained a sixth engine. Each of the two side boosters carried two F-1A engines.

Development costs were seen as manageable because the design relied heavily on Apollo-era hardware. A nuclear-powered third stage with two 222.5-kN engines was also studied. This version would have been smaller, but its development was projected to cost $2 billion more than the all-chemical design. The nuclear option was intended for later use on crewed Mars missions, and NASA’s Lewis Research Center created a Nuclear Systems Office to build and test a working nuclear engine by 2005.

Another alternative was based on the National Launch System then in development. NASA’s Marshall Spaceflight Center examined the Comet or a version with four F-1A boosters attached to the basic two-stage NLS vehicle. The main benefit of this approach was that it could use current flight-proven technology instead of reviving two-decade-old manufacturing methods and equipment.