Space Radiation Hazards and the Vision for Space Exploration Report of a Workshop (2006) / Chapter Skim
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A Reports of the Working Groups
A Reports of the Working Groups
Pages 59-77
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From page 59... ...
Appendixes
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From page 61... ...
It is known that magnetic-field maps show the equatorward drift of active regions, Hale's polarity law, differential solar rotation, and poleward meridional flow. "Magnetic persistence," or the duration of the Sun's memory of its own magnetic field, can be controlled by meridional circulation in the solar convection zone.
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. The ice core record shows that solar particle events can occur at any time during the 11 year solar activity cycle, but there is evidence that solar particle event peak intensities have been somewhat lower in recent times than they were in the late 19th century.
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589:665. WORKINg gROUP B SOLAR ACTIVE REgIONS, FLARES, AND CORONAL MASS EjECTIONS The focus of Working Group B was to understand the relationship between solar phenomena that lead to particle acceleration, solar flares, and coronal mass ejections (CMEs)
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From page 64... ...
Owing to the evolutionary behavior of the photospheric magnetic field on many timescales, the accurate prediction of the time of a flare/CME event is still not possible. Emerging technologies developed for heliosesimology have shown their ability to forecast active regions before these regions come around the solar limb.
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As part of theVision for Space Exploration, NASA seeks to establish a human presence on the Moon for short (days to weeks) and long-term (weeks to months)
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SEPs are a potentially serious risk to humans and their sensitive instruments when they journey beyond Earth's protective magnetosphere to reach the Moon and other locations called for in the Vision for Space Exploration. From a science standpoint, it is important to understand the variability and extreme values for properties of SEP events in order to develop a predictive capability that could eventually be incorporated into an operational space weather warning system.The science community recognizes that an accurate and reliable warning system requires a better understanding of the physical processes that produce SEP events.
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Table A.1 shows the energetic particles and their energies of most interest to astronaut safety and preventing hardware disruption or damage. TABLE A.1 Energetic Particles and Their Energies of Most Relevance to the Vision for Space Exploration Application Ion Species Particle Energies Astronaut safety H, He, heavy ions >10 MeV per nucleon Dosimetry e >1 MeV Hardware systems H, He, e, plus heavy ions Greater than a few MeV per nucleon
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can be obtained in coronal regions within a few solar radii of the Sun. Ground-based radio observations of Type-II radio bursts can reveal information about the magnetic fields and temperatures within CME shocks that produce energetic particles.
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To summarize, the heliophysics community recognizes its responsibility to contribute in a timely manner to the Vision for Space Exploration by engaging in the following activities: · Improving basic understanding of governing physical processes of the space radiation environment; · Developing models that can form the basis of greatly improved predictive models; · Validating these models with improved observations; · Developing the conceptual and hardware infrastructure for an operational space weather system; and · Carrying out exciting exploratory missions such as those recommended by the 2005 NASA Roadmaps and the NRC (2002) decadal survey, The Sun to the Earthand Beyond.
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From page 70... ...
The magnetosphere needs to be coupled through physics-based global models to the surrounding heliosphere. The radiation belts and ionosphere need to be more intimately coupled to influences of changes in the heliosphere, including during periods of solar activity and increased flux of energetic particles.
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, SEP events, and dosimetry at the Moon.There is surface neutron information from Lunar Prospector, plus surface neutron models (Space Ionizing Radiation Environments and ShieldingTools [SIREST] transport codes and others)
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Suggestions on how to proceed, raised during the working group's breakout session, included the following: · Validate radiation transport codes, for example, with measurements on stratospheric balloons at Earth and on the martian surface. There is a need for a science-based review to determine if the planned Mars Science Laboratory measurements are sufficient for the validation of transport codes.
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This list should be used as a starting point and could be the focus of a workshop. · Near-term activities: Updates and upgrades of radiation transport codes; Radiation-transport-codes validation on stratospheric balloons; Lunar data restorations and synthesis activity; Creation of data-mining infrastructures: Earth, Moon, and Mars; Collection and synthesis of Mars atmosphere data specific to VSE needs; Radiation environment and upper-atmosphere/ionosphere model developments based on data mining and ongoing observations.
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From page 74... ...
The greatest needs in the area of SEP events, as reported by personnel from the Space Radiation Analysis Group at the NASA Johnson Space Center, are the following: · Predictions of the temporal evolution profile of the next most likely SEP event at selected energies with associated probabilities, before particles begin to arrive; · Flux data from the actual event at the selected energies in real time; · The capability to refine the temporal profiles and associated probabilities as the data arrive in real time; and · Reliable forecasts of no solar activity of interestthat is, all-clear forecasts. Accomplishing the first item of the previous list involves developing methods for forecasting differential fluence rates (particles/cm2/time/energy)
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access to particle and dose data from missions conducted by other countries that enable addressing the needs mentioned previously. Monitoring at L1 is preferred because it is outside Earth's magnetosphere, is approximately at 1 AU, and allows for continuous coverage of the deep space radiation environment.
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From page 76... ...
Instruments and equipment will be exposed to a broad range of particle energies and composition from sources such as galactic cosmic rays, solar energetic particle events, and trapped radiation environments. There is also an expectation that commercial off-the-shelf parts and systems such as personal computers and videocameras will be heavily utilized and will need testing to ensure performance in the disparate environments.
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From page 77... ...
Without a doubt, new tools will be needed for forecasting space environmental conditions on Mars missions. Solar particle event occurrence and the expected time profile at the vehicle location are among the most serious environmental conditions to contend with, yet they are also among the most difficult to forecast.
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