Managing Space Radiation Risk in the New Era of Space Exploration (2008) / Chapter Skim
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4 Shielding Approaches and Capabilities
4 Shielding Approaches and Capabilities
Pages 62-79
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From page 62... ...
During the Apollo era, human missions to the Moon used this method of minimizing exposure to the Van Allen radiation belts on the transits to and from the Moon. Transit times to Mars, however, may be driven by other considerations, such as available means of propulsion and spacecraft trajectory.
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From page 63... ...
Once the combined vehicle is in lunar orbit and systems checks have ensured a "Go" for landing, the Lunar Lander will separate from the Orion and initiate the lunar landing. The Orion Block-2 design requirements respond to two major mission scenarios: • Supporting crew and cargo transportation to the International Space Station (ISS)
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From page 64... ...
Table 4-1 displays the timeline presented at the 2nd Space Exploration Conference (Lavoie, 2006) , which was also presented at the committee's first meeting by Geoffrey Yoder, NASA.
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From page 65... ...
For the approximately isotropic incidence of space radiation, spherical shields provide the minimum mass for a given volume; however, a long cylinder is superior, presenting the minimum shielding at the ends, where it subtends the smallest solid angle; and that incoming radiation will have to traverse an increased amount of material, seen at an angle. These examples are for modules in free space, but the same will be true for habitat modules to be deployed to the Moon or to the surface of Mars.
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From page 66... ...
Therefore, this pressurized rover would need to carry its own radiation shielding to protect a crew throughout an SPE. A three-dimensional computer-aided design radiation shielding model could be developed for the pressurized rover, and parametric SPE radiation analyses be performed to ascertain the intrinsic shielding capability of the pressurized rover.
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From page 67... ...
This will be true of either sculpted regolith or of shielding that has been brought from Earth but left behind when the Lunar Lander departs. Geomorphology-Dependent Shielding Lava tubes, caves, tunnel borings, and other shielding solutions based on existing lunar formations offer the potential to reduce but probably not eliminate the need for heavy construction equipment.
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From page 68... ...
Space suits are not intended to provide significant protection. Since mass is tightly constrained during space suit design, any mass taken up solely by shielding could otherwise be used to store more oxygen, enable a thicker thermal shield, or make the suit less cumbersome.
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From page 69... ...
. The setting of requirements, and the efforts of the space suit designers to incorporate radiation shielding early in the process are both very positive signs.
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From page 70... ...
The portable radiation shield is envisioned to be a rapidly deployed and easily transported "blanket-design" made of a lightweight material that exhibits good radiationmitigating properties, such as high-density polyethylene. The "blanket" could be transported on a lunar rover or a multipurpose trailer.
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From page 71... ...
The Make-up Power Unit primarily includes a selfcontained proton exchange membrane regenerative fuel cell subsystem with gaseous H 2/O2 storage. The Prometheus Power and Propulsion program, originally tasked to investigate nuclear propulsion for longduration missions to the outer planets, was restructured to support the long-duration stays on lunar and martian surfaces called for by the Vision for Space Exploration.
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From page 72... ...
On Earth, where weight is a much lower concern, there has been limited attention to the development of very lightweight shielding. On a mission to the Moon, NASA will be limited to available lightweight shielding materials or materials from the lunar surface.
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From page 73... ...
hat is a safe distance from the fission surface power systems to ensure acceptable annual exposure, W including the variations of power and shielding from the base-design when added to the natural radiation exposure on the lunar surface?
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From page 74... ...
Therefore, this section provides only an overview of some of the pluses and minuses associated with the topic. Nuclear propulsion includes a broad range of propulsion methods that use nuclear reaction as a primary source of power.
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From page 75... ...
Because of its high performance potential, nuclear thermal propulsion could be used for human exploration missions and cargo transport to the Moon or Mars, for outer-planet robotic explorations, and for Earth-orbit t ransfers of satellites. The main benefit of nuclear propulsion is that it can provide a greater specific impulse, or the amount of thrust provided per unit mass of propellant.
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From page 76... ...
Creating a powerful electromagnetic field could loft dust over the outpost. The Apollo crews foundhalfdusta fixed image, the skin and respiratory system during their Each the is to be irritating to not changeable short 2- to 3-day stays on the lunar surface.
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From page 77... ...
in patients who are being treated for head and neck cancers. The drug has been available to NASA for several decades, predominantly because of its ability to inhibit the induction of mutations following radiation exposure, thus suggesting the possibility of reducing stochastic effects (cancer)
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From page 78... ...
Pp. 71-96 in Radiation Protection Studies of International Space Station Extravehicular Activity Space Suits, eds.
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From page 79... ...
Pp. 19-53 in Radiation Protection Studies of International Space Station Extravehicular Activity Space Suits, eds.
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