Launching Science Science Opportunities Provided by NASA's Constellation System (2009) / Chapter Skim
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3 Technology Requirements for Future Space Missions
3 Technology Requirements for Future Space Missions
Pages 67-82
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From page 67... ...
Because the committee was asked to evaluate alternative implementation approaches, because advanced technology development is so important to the majority of these missions, and because many of the technologies affect several mission concepts, the committee sought more information on the status of NASA's overall technology development program for space science missions, particularly in the area of advanced in-space propulsion technologies and deep space communications. Of the mission concepts that the committee considered, the Interstellar Probe, Neptune Orbiter with Probes, Solar Polar Imager, and Titan Explorer could all directly benefit from some form of in-space propulsion technology even if the Ares V is available.
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From page 68... ...
. The overall technology requirements for the mission concepts studied in this report are summarized in Table 3.1.
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From page 69... ...
Aerocapture, solar sails, and solar/nuclear-electric propulsion all fall into the category of in-space propulsion technologies. aSignificant mission enhancement.
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From page 70... ...
Current development efforts include electric propulsion, solar sails, aerocapture, and advanced chemical propulsion. A brief overview of electric propulsion, solar sails, and aerocapture and their development status is provided below. Electric Propulsion Electric propulsion technologies generate thrust by using electrical energy to accelerate an onboard propellant, such as xenon gas, to very high ejection velocities.
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From page 71... ...
As does NSTAR, the NEXT system uses a gridded ion thruster, which uses two oppositely charged grids to accelerate and eject high-speed ions. The NEXT project incorporates advances in the gridded ion thruster, PPU, and propellant management system designs for increased system performance and life.
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From page 72... ...
In contrast to the gridded ion thrusters, where two oppositely charged grids are used to accelerate and eject ions to generate thrust, Hall thrusters use a radial magnetic field to accelerate low-density plasma to high velocities. The Isp of Hall thrusters is generally in the range of 1,000 to 3,000 seconds (s)
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From page 73... ...
Nuclear electric propulsion has the greatest potential to meet the propulsion needs of these missions. In addition to the high power levels, nuclear power plants provide a constant source of electrical energy throughout the mission, which is in direct contrast to SEP systems, for which the available solar energy declines dramatically as a spacecraft travels to the outer planets.
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From page 74... ...
150 >300 2,000 5,100 Life capability (thousand hr) 30 >15 93 243 NOTE: NSTAR, NASA SEP Technology Application Readiness; NEXT, NASA's Evolutionary Xenon Thruster; NEXIS, Nuclear Electric Xenon Ion System; HiPEP, high-power electric propulsion.
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From page 75... ...
Solar Sails The Interstellar Probe and Solar Polar Imager mission design options included the use of solar sails. These devices use photons from the Sun, which apply pressure on thin, lightweight, highly reflective sheets or sails to propel the spacecraft, much like wind pushes a sailboat across a body of water (see Figure 3.5)
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From page 76... ...
Even as a secondary payload on a Soyuz mission, the launch capability of the booster enables a simpler design of the Cosmos 2 spacecraft compared with the design of Cosmos 1, therefore improving the probability of successful deployment of the solar sail upon reaching orbit. Aerocapture Aerocapture ranges from being a strongly enhancing to an enabling technology for the Neptune Orbiter with Probes and Titan Explorer missions and has been identified as an enhancing technology for robotic exploration of Mars and enabling for human missions to Mars. It is an orbit insertion maneuver that takes advantage of a planet's atmosphere to decelerate a spacecraft sufficiently to allow it to be placed into its intended orbit.
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From page 77... ...
Both types of deployable designs have the benefit of a drag area that can be significantly greater than the cross-sectional area of the spacecraft. As a result, they are effective at higher NASA, Aerocapture Technology -- In-Space Propulsion Technology Project, NASAfacts FS-2007-09-12-GRC Pub ACap001, NASA Glenn Research Center, Cleveland, Ohio.
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From page 78... ...
78 LAUNCHING SCIENCE FIGURE 3.7 Mars Science Laboratory aeroshell, which has a blunt-body shape similar to that required for aerocapture missions at Mars and Titan. SOURCE: Courtesy of NASA.Figure 3.7.eps Bitmap image FIGURE 3.8 A potential slender-body aeroshield with atmospheric probes on top.
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From page 79... ...
A summary of the readiness of these aerocapture technologies is provided in Figure 3.11 for several space exploration missions. With the exception of Neptune missions, the technology is relatively mature, TiborKremic, NASA, "NASA Investments in In-Space Propulsion Technologies," presentation to the Committee on Science Opportunities Enabled by NASA's Constellation System, June 9-11, 2008.
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From page 80... ...
NOTE: GRAM, Global Reference Atmospheric Model; VIRA, Venus International Reference Atmosphere; GN&C, guidance, navigation, and control; DOF, degrees of freedom; APC, Analytic Predictor Corrector; TPS, thermal protection system; SOA, state of the art; ST9, Space Technology 9; LMA, Lockheed Martin Astronautics; ISPT, In-Space Propulsion Technology. SOURCE: Courtesy of NASA.
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From page 81... ...
PROPULSION SYSTEM TECHNOLOGY SUMMARY In the recent past, NASA undertook a number of impressive in-space propulsion technology development projects that reached moderate to high technology readiness levels and demonstrated significant promise for future missions. However, for various reasons the agency has eliminated much of this research.
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From page 82... ...
The DSN consists of three deep space communications facilities strategically placed approxi mately 120 degrees from one another. The Goldstone Deep Space Communications Complex is located in California's Mojave Desert; the Madrid Deep Space Communications Complex is in Spain, 37 miles to the west of Madrid at Robledo de Chavela; and the Canberra Deep Space Communications Complex is in the Australian Capital Territory, 25 miles southwest of Canberra near the Tidbinbilla Nature Reserve.
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