Comet HLLV

The Comet HLLV was a proposed super heavy-lift launch vehicle designed for NASA's First Lunar Outpost program, which was in the design phase from 1992 to 1993 under the Space Exploration Initiative. It was a Saturn V-derived launch vehicle with modernized engines, stretched fuel tanks, and strap-on boosters. Its main goal was to support the First Lunar Outpost program and future human mission to Mars. It was designed to be inexpensive and simple while relying on existing technology to lower development costs.

Comet HLLV

Artist's impression of a Comet HLLV being rolled out of the VAB
Function	Crew / Cargo Launch Vehicle
Country of origin	United States
Size
Height	410 ft (120 m)
Diameter	11.5 m (38 ft)
Stages	3
Capacity
Payload to LEO
Mass	254,400 kg (560,900 lb)
Payload to TLI
Mass	60,600–97,600 kg (133,600–215,200 lb)
Launch history
Status	Proposed and cancelled
Launch sites	Kennedy Space Center
Boosters
Height	155 ft (47 m)
Diameter	260 in (6,600 mm)
Empty mass	75,678 kg (166,841 lb)
Propellant mass	985,368 kg (2,172,365 lb)
Powered by	2 Rocketdyne F-1A
Maximum thrust	16,013 kN (3,600,000 lbf)each on sea level
Propellant	RP-1/LOX
First stage
Height	160.4 ft (48.9 m)
Diameter	33.0 ft (10.1 m)
Empty mass	209,030 kg (460,830 lb)
Propellant mass	2,729,770 kg (6,018,110 lb)
Powered by	5 Rocketdyne F-1A
Maximum thrust	40,050 kN (9,000,000 lbf) sea level
Propellant	RP-1/LOX
Second stage
Height	103 ft (31 m)
Diameter	33.0 ft (10.1 m)
Empty mass	60,767 kg (133,968 lb)
Propellant mass	634,439 kg (1,398,699 lb)
Powered by	6 Rocketdyne J-2S
Maximum thrust	7,750 kN (1,740,000 lbf) vacuum
Propellant	LH2/LOX
Translunar Injection stage
Height	55.6 ft (16.9 m)
Diameter	33.0 ft (10.1 m)
Empty mass	21,336 kg (47,038 lb)
Propellant mass	135,392 kg (298,488 lb)
Powered by	1 Rocketdyne J-2S
Maximum thrust	1,180 kN (270,000 lbf) vacuum
Propellant	LH2/LOX

Design

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. Each of the two side boosters had two F-1A engines. Development costs were expected to be modest due to reliance on Apollo-era technology.

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

Main article: National Launch System

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.