NASA Space Technology Roadmaps and Priorities Restoring NASA's Technological Edge and Paving the Way for a New Era in Space (2012) / Chapter Skim
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Appendix E: TA02 In-Space Propulsion Technologies
Appendix E: TA02 In-Space Propulsion Technologies
Pages 117-130
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From page 117... ...
, robotic science and Earth observation missions, high-thrust Earth orbit departure for crewed vehicles, low-thrust cargo transfer for human exploration, and planetary descent, landing and ascent propulsion. This wide range of applications results in a very diverse set of technologies, including traditional space-storable chemical, cryogenic chemical, various forms of EP, various forms of nuclear propulsion, chemical and electric micropropulsion, solar sails, and space tethers.
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From page 118... ...
Engine Health Monitoring & Safety 2.4.2. Propellant Storage & Transfer 2.4.3.
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From page 119... ...
Additionally, cryogenic fluid transfer technology would enable other exploration architec tures, including propellant aggregation and the use of propellants produced using ISRU facilities. This technical challenge is enabling for the most plausible transportation architectures for human exploration beyond the Moon.
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From page 120... ...
The panel subsequently decided to override the QFD scoring results to designate micropropulsion systems as a high-priority technology to highlight the importance of developing propulsion systems that can support the rapidly developing micro-satellite market, as well as certain large astrophysics spacecraft. CHALLENGES VERSUS TECHNOLOGIES Figure E.3 shows how each of the TA02 level 3 technology supports the top technical challenges described above.
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From page 121... ...
no impact in addressing the challenge. FIGURE E.3 Level of support that the technologies provide to the top technical challenges for TA02 In-Space Propulsion Systems.
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From page 122... ...
As a result, EP systems are the most propellant efficient in-space propulsion technology available for the foresee able future, with applications to all NASA, DOD, and commercial space mission areas. While EP's large specific impulse enables a host of space missions that are not possible or affordable with conventional propulsion, its thrust is low, which results in long trip times for many missions.
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From page 123... ...
Multiple mission studies have shown that nuclear thermal rockets would enable rapid Mars crew transfer times with half the propellant and about 60 percent of the launch mass required by chemical rockets. Demonstrated NTRs use a solid-core nuclear reactor to heat hydrogen propellant, exhausting it through a standard nozzle to achieve a specific impulse of 800 s to 900 s.
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From page 124... ...
In parallel with the development of nuclear fuels, sub- and full-scale evaluations of ground testing NTRs using existing borehole testing would be needed to fully characterize effluent behavior. Initial studies for using existing boreholes at the Nevada Test Site have shown no major roadblocks to date, though considerable development and validation remains.
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From page 125... ...
The ability to increase the value of space missions at a relatively modest costs as enabled by micro-propulsion would be "game-changing." However, the broad field of micro-propulsion appears as a level 3 technology in the draft TA03 roadmap as part of the chemical propulsion technology subarea. Limiting research in the technology to chemical propulsion alternatives would exclude many other promising alternatives.
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From page 126... ...
focused his remarks on micropropulsion technology, which he said can be used both as a main propulsion system for small spacecraft and fine control of larger spacecraft. He believes that micropropulsion is a young technology that is poised to make a large impact on near term missions.
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From page 127... ...
made a presentation on behalf of the American Institute for Aeronautics and Astronautics (AIAA) Electric Propulsion Technical Committee.
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NTP efforts, which resulted in full scale engine ground testing in the 1960s and 1970s. He then noted the main advantage of NTP relative to conventional chemical propulsion systems is the much higher specific impulse that NTP can provide.
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Several speakers asserted that cryogenic fluid transfer will be required for almost any future human exploration beyond LEO. One participant questioned the value of high-power SEP in an era with low flight rates.
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From page 130... ...
He noted that both fusion and advanced fission propulsion technologies would enable astronauts to complete a round trip to Mars in just 3 or 4 months, instead of the multiyear missions envisioned with near-term technology. He went on to state that, except for these advanced concepts, NTP is the only technology that allows for reasonably quick human missions to Mars.
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