Encyclopedia Astronautica
Saturn S-N V-25(S)U

American space tug. Study 1968. Upper stage / space tug - study 1969. Launched by Saturn V-25(S)U. Version of Nerva studied by Boeing for manned Mars expedition.

Early version of Nerva engine proposed for use in Saturn and RIFT configurations in 1961.

Gross mass: 245,760 kg (541,800 lb).
Unfuelled mass: 71,190 kg (156,940 lb).
Height: 48.17 m (158.03 ft).
Diameter: 10.06 m (33.00 ft).
Span: 10.06 m (33.00 ft).
Thrust: 889.33 kN (199,928 lbf).
Specific impulse: 825 s.

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Associated Countries
Associated Engines
  • Nerva DoE nuclear/lh2 rocket engine. 266 kN. Study 1968. Early version of Nerva engine proposed for use in Saturn and RIFT configurations in 1961. Isp=800s. More...

See also
Associated Propellants
  • Nuclear/LH2 Nuclear thermal engines use the heat of a nuclear reactor to heat a propellant. Although early Russian designs used ammonia or alcohol as propellant, the ideal working fluid for space applications is the liquid form of the lightest element, hydrogen. Nuclear engines would have twice the performance of conventional chemical rocket engines. Although successfully ground-tested in both Russia and America, they have never been flown due primarily to environmental and safety concerns. Liquid hydrogen was identified by all the leading rocket visionaries as the theoretically ideal rocket fuel. It had big drawbacks, however - it was highly cryogenic, and it had a very low density, making for large tanks. The United States mastered hydrogen technology for the highly classified Lockheed CL-400 Suntan reconnaissance aircraft in the mid-1950's. The technology was transferred to the Centaur rocket stage program, and by the mid-1960's the United States was flying the Centaur and Saturn upper stages using the fuel. It was adopted for the core of the space shuttle, and Centaur stages still fly today. More...

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