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Human Exploration of Space A Review of NASA's 90-Day Study and Alternatives (1990) / Chapter Skim
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II. Space Transportation: Launch Systems, Propulsion, and Power
Pages 11-16

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From page 11...
... Because operations of the space shuttle will continue to be labor-intensive and expensive, because the system is not robust, and because the system probably will reach the end of its useful life sometime between 2000 and 2010, the committee believes that a successor to the shuttle eventually will be necessary for human transport to orbit. For at least the next 10 years, however, the nation will necessarily rely upon the shuttle for this role, and it is essential that the existing shuttle fleet be maintained in a fully operable state.
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From page 12...
... At present, the most likely configuration of the required system is a two-stage rocket powered vehicle, with a try-back first stage, an orbiter with substantial cross range capability, and a thermal protection system or hot structure that allows reuse without major refurbishment. It may be that some of the technologies being developed in the National Aerospace Plane Program (NASP)
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From page 13...
... This is likely to become an increasingly serious issue as launch rates rise in the buildup of the HEI. Finally, the committee believes liquid bipropellant systems have the potential for significantly lower recurring costs compared to solids.
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From page 14...
... Several possibilities have been mentioned within this general class of systems, all of which offer higher specific impulse than chemical rockets and employ hydrogen as the propellant. The alternative nuclear propulsion technologies differ in the temperature to which the hydrogen is heated by the fissioning nuclear fuel; the pressure level in the thrust chamber (which along with the temperature determines the extent of dissociation of the hydrogen to atomic form)
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From page 15...
... Unless a new idea has appeared, which is always a possibility, the committee believes the gaseouscore nuclear rocket technology is too speculative at this time and should be dismissed as a possibility. If careful systems studies, using thrust-to-weight ratios and specific impulse known to be feasible, show a significant advantage for nuclear rockets in trip time or in weight to orbit, an in-space demonstration of this technology should be done as soon as possible taking into account requirements for crew, ground personnel, and public safety covering all phases of launch and flight, including mission abort.
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From page 16...
... If safety concerns can be successfully addressed, and feasibility demonstrated, the committee believes that use of nuclear power and propulsion can meet many needs in the human exploration of space.
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Key Terms

  • space shuttle
  • nuclear rocket
  • rocket technology
  • heavy lift
  • nuclear thermal

  • power density
  • human transportation
  • chemical propulsion
  • nuclear electric
  • nuclear rockets

  • power source
  • reference approaches
  • human transport
  • thermal propulsion
  • launch platform

  • power densities
  • liquid bipropellant
  • class technology
  • nerva class
  • nuclear propulsion

  • criteria outlined
  • structural weight
  • believes liquid
  • hot structure
  • major refurbishment

  • total impulse
  • enable transfer
  • cross range
  • trip time
  • attractiveness depends


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