PROSPECTS FOR INTERSTELLAR TRAVEL
by John H. Mauldin (PhD, Sci Ed, U Texas)
Volume 80 , Science and Technology Series
American Astronautical Society Publication
John H. Mauldin has a bachelor's degree in engineering physics (Cornell University, master's in physics (Purdue University), and Ph.D. in science education (University of Texas). He has four books published in science and technology covering mathematical graphics in Perspective Design (1985; second edition now being prepared), physics in Particles in Nature (1986), solar energy in Sunspaces (1987), and optics in Light, Lasers, and Optics (1988). He has taught physics and engineering at several colleges and universities, done education research and development at MIT and University of Texas, and worked at NASA in electronic power engineering on an early phase of the Voyager missions. Astronomy, space travel, and science fiction were his earliest interests. For lack of funds to build a space colony, he and his wife have designed and built the lowest-cost superinsulated circular solar house on Earth, for which they purchase or burn no fuel for heat and which received a state conservation award.
Cosmic particles are dangerous, come from all sides, and require at least 2 meters of solid shielding all around living organisms.
Solar (or star) flares of protons, an occasional and severe hazard on the way out of and into planetary systems, can give doses of hundreds to thousands of REM over a few hours at the distance of Earth [b-Lorr]. Such does are fatal and millions of times greater than the permitted dose. Death is likely after 500 REMs in any short time
Page 8.5 RADIATION DAMAGE, EROSION AND SHIELDING
Radiation as discussed here is not to be confused with electro-magnetic waves. Radiation as a hazard commonly refers to high-speed particles, charged and un-charged, and energetic photos from sources: material encountered b a high-speed starship, interstellar particles and protons, particles released from any particle or nuclear drive, and solor flares.
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traversed to leave or reach the planet. Near Earth the dose is about 1 rem per day [b-Lorr]. Some stellar objects, unlikely to be visited soon, emit intense energetic radiation. Solar (or star) flares of protons, an occasional and severe hazard on the way out of and into planetary systems, can give doses of hundreds to thousands of REM over a few hours at the distance of Earth [b-Lorr]. Such does are fatal and millions of times greater than the permitted dose. Death is likely after 500 REMs in any short time, whereas 500 rems spread over a lifetime is not likely to cause problems although not clearly safe. NASA has suggested astronauts might tolerate about 200 rems if received over several years.
While cosmic particle radiation provides less total dose, the higher energy can cause many kinds of secondary particles, flying through the starship after the primary particle is stopped by thick shielding. Cosmic particles are dangerous, come from all sides, and require at least 2 meters of solid shielding all around living organisms. Earth's atmosphere provides the equivalent of about 10 meters of shielding. The shielding requirement is determined by protection from cosmic radiation. A layer of cosmic particle shielding will absorb all forward protons and capture dust grains too. Another effect of cosmic particles is permanent damage to retina and neural cells which do not replace themselves. At the rate astronauts saw flashes in their eyes in unshielded spacecraft, they could lose most vision and brain function in a few years.
Dr. John Mauldin, partner Susan, and their superinsulated solar house on Earth that needs no other heat