Value chain · CLM-1161
In plain terms
The 1978 plan assumed space workers would be allowed about ten times the radiation dose an ordinary radiation worker may take, under 1970 astronaut rules that doubled a person's natural cancer odds over twenty years at the career limit; the authors said the design, and possibly the feasibility, turned on whether those rules would be tightened.
The claim as recorded
The 1978 LBL evaluation planned SPS crews to the 1970 National Academy of Sciences Space Science Board mission limits, "Bone marrow (5 cm) 0.2 25 35 75 400" rem daily, 30-day, 90-day, yearly and career, "Skin (O.l mm) 0.6 75 105 225 1200", "Eye lens (3 mm) 0.3 37 52 112 600", "Testes (3 cm) 0.1 13 18 38 200", set on a "primary reference risk" of "an added probability of radiation-induced leukemia and other neoplastic diseases over a period of about 20 years that is equal to the natural probability", taken as "400 rem at the mean (5 cm) depth of the bone marrow"; against the occupational limits of "Blood-forming organs 0.014 3 5 5(N-18)" and "Skin 0.082 7.5 30", it states that "If the much lower exposure limits listed in Table 7 for professional radiation workers were applied to personnel in space, the feasibility of the SPS mission would be challenged severely" because the 90-day LEO and GEO doses "exceed the exposure limits in Table 7", and concludes that "A critical question affecting the design and possibly the feasibility of the SPS is whether or not the radiation exposure limits in current use will be reduced", with "a major uncertainty ... because of the lack of information on the biological effects of the HZE particles" and high-altitude nuclear detonations as "a politically unpredictable source" that could force the mission to be aborted.
Evidence behind this: T3-the 1970 NAS Space Science Board limits and the occupational limits as tabulated by the synthesis paper, with the paper's own feasibility judgement; the limits are T1 in their instruments, not held.
Scope and limits
THE 1970 LIMITS ARE THE ONES THE PAPER PLANNED TO; whether they were later reduced is not answered here and the register holds no later space-worker standard. The 90-day GEO figures are surface doses behind the wall, not the 5 cm marrow doses Table 6 is written in, so whether a tour would exceed Table 6 is not stated by the paper and is not asserted. The page's "Table 4" for the GEO doses is a cross-reference slip for Table 5.
What it assumes
Quality factor 1 for the electron and bremsstrahlung dose when reading rad as rem in the recomputation; the paper itself compares only to Table 7 in words.
Where it comes from
PDF 244 / printed 242: "The Space Science Board of the National Academy of Sciences (1970) proposed these exposure limits to serve as radiation" protection guides (normalised). PDF 247 / printed 245, Table 6 (layer): "Bone marrow (5 cm) 0.2 25 35 75 400"; "Skin (O.l mm) 0.6 75 105 225 1200"; "Eye lens (3 mm) 0.3 37 52 112 600"; "Testes (3 cm) 0.1 13 18 38 200" (normalised; the page's "O.l" for 0.1); Table 7: "Blood-forming organs 0.014 3 5 5(N-18)"; "Skin 0.082 7.5 30" (normalised). PDF 246 / printed 244 (render read): "the radiation exposure limits for space workers are higher than the conventional standards for professional radiation workers" (normalised); "If the much lower exposure limits listed in Table 7 for professional radiation workers were applied to personnel in space, the feasibility of the SPS mission would be challenged severely" (normalised); "The 90-day mission doses in LEO (Table 3) and GEO (Table 4) exceed the exposure limits in Table 7" (normalised; the GEO table is Table 5). PDF 248 / printed 246: "The primary reference risk corresponds to an added probability of radiation-induced leukemia and other neoplastic diseases over a period of about 20 years that is equal to the natural probability for the specific population at risk" (normalised); "a dose-equivalent of 400 rem at the mean (5 cm) depth of the bone marrow irrespective of the exposure rate" (normalised). PDF 256 / printed 254 (render read): "A critical question affecting the design and possibly the feasibility of the SPS is whether or not the radiation exposure limits in current use will be reduced" (normalised); "There is a major uncertainty in the assessment of the radiation hazards because of the lack of information on the biological effects of the HZE particles" (normalised); "High-altitude nuclear detonations represent a politically unpredictable source of radiation" (normalised). PDF 231 / printed 229: "the trapped radiation environment could be enhanced to the extent that the SPS mission would have to be aborted" (normalised). Recomputed: 35 / 3 = 11.7, the 90-day marrow ratio between the two tables; 75 / 5 = 15 yearly; with quality factor 1 the GEO 29-56 rad tours are 10-19 times the 3 rem occupational 90-day limit and the LEO 18 rad is 6 times; 5(N-18) at N = 40 is 110 rem career against 400.
Basis: rem dose-equivalent per day, 30 days, 90 days, year and career at organ depth
Cite this
energyaperture.com/c/clm-1161
CLM-1161, Energy Aperture, as of 1978-09.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-546
- CLM-1158The 1978 plan put seven hundred people in orbit at a time, on ninety-day tours of sixty-hour weeks, adding up to about 270,000 tours over...CLM-1159A ninety-day shift in low orbit would give a worker about 20 rad, the trip up and back about 3, and ninety days at geostationary altitude...CLM-1160A big solar flare like August 1972 would push a spacesuited worker past the skin limit in three hours and the eye limit in two, so the...