The Comet would have been capable of putting 254.4 tons into
low Earth orbit and 97.6 tons to
trans-lunar injection, roughly twice that of the Saturn V, making it one of the largest rockets ever designed in terms of payload. The vehicle resembled a Saturn V, but with stretched first and second stages, an increased-diameter third stage, and new side boosters. Additionally, the engines were updated to the
F-1A and
J-2S, and a sixth engine was added to the second stage. A nuclear-powered variant of the third stage, with two 222.5-kN engines, was also considered. It would have reduced the rocket's size, but at a predicted development cost of $2 billion over a chemical-only design. The nuclear option was planned to be developed later to support crewed Mars missions. To this end, NASA's
Lewis Research Center established a Nuclear Systems Office to develop and test a fully functional nuclear engine by 2005.
NLS derived launch vehicle An alternate version of the launcher based on the then-in-development
National Launch System was proposed. NASA's
Marshall Spaceflight Center looked into the Comet rocket or a possible configuration with four
F-1A boosters added to the basic 2-stage NLS vehicle. The main expected advantage was that the vehicle could rely on technology currently flying rather than having to resurrect 20 year old technology and manufacturing equipment. ==References==