The Impact of Radiation Protection on the Design of Space Habitats
- Paper number
IAC-07-A1.5.-A1.7.08
- Author
Mr. Mark Hempsell, University of Bristol, United Kingdom
- Coauthor
Dr. Roger T. Moses, University of Bristol, United Kingdom
- Year
2007
- Abstract
Cosmic radiation is one of the key problems for long duration human space flight, especially outside the Earth’s Van Allen belt. The two main sources, intermittent solar flare and continuous galactic background impose different and conflicting requirements on the design for crew protection. Solar flares have comparatively low energy but a particle density so high that only a complete shield exceeding 100 kg/m2 will prevent lethal doses during a solar storm. By contrast the dose from unshielded galactic background integrated over several years, while not lethal, is considerably above that normally permitted and may lead to long-term health problems. Galactic radiation requires considerably more than 1000 kg/m2 shielding to reduce the equivalent dose, however, shielding below this density can actually increase this dose due to the generation of secondary radiation. Thus effective solar flare radiation shielding can actually increase the dose from galactic sources. The paper examines strategies in the layout of space habitats that both provides adequate flare shielding and reduces the overall dose from galactic radiation. Considering both material selection and architectural arrangement, it was found that the construction of a habitat from modules around 4 m diameter makes meeting this goal virtually unachievable. All sensible arrangements give considerable “visibility” of shielding between 100 kg/m2 and 2000 kg/m2 and therefore exposure to secondaries leading to an increased overall equivalent dose. However, when larger diameter modules were considered it was found that stores and habitat equipment could be arranged to reduce the dose from galactic sources, but that effective protection from solar flares still required some special shielding. It was found that the mass of such habitats is in the order of 100 tonnes, exceeding the capacity of all current launch vehicles, and with achievable flight rates assembly in pieces would require several years. It was concluded that such habitats require either a heavy lift system that can accommodate the required diameter and mass with one launch, or a high flight rate reusable launch vehicle. If a reusable vehicle were employed, the payload diameter would be restricted to around 4 m and secondary generation becomes a critical issue. It follows that to achieve the required radiation protection the habitat will either have to be an inflatable structure, (which is then internally fitted out on orbit), or a habitat that involves more extensive in orbit construction than simply docking modules together.
- Abstract document
- Manuscript document
IAC-07-A1.5.-A1.7.08.pdf (🔒 authorized access only).
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