What were the measured radiation doses for each Apollo 11 astronaut during the mission?
Executive summary
NASA’s mission dosimeters and later analyses show Apollo astronauts received small cumulative doses on the order of tenths of a rad (0.18–0.46 rad commonly reported), roughly comparable to a couple of medical CT scans, not the lethal sieverts sometimes claimed (claims of 1.8 Sv or 1.8 mSv/sec are contradicted by flight dosimetry and secondary analyses) [1] [2] [3] [4].
1. What the flight dosimeters recorded — the contemporaneous numbers
Apollo crews carried personal passive dosimeters; surviving museum records confirm individual dosimeters were flown on Apollo 11 (Neil Armstrong’s dosimeter is in the Smithsonian collection) and the Apollo program developed specialized dosimetry systems and procedures because radiation was a known hazard [5] [6]. Contemporary reporting and later summaries say the Apollo missions’ measured whole‑mission absorbed doses were small: figures cited across sources include about 0.18 rad for Apollo 11 as a whole and average absorbed doses of roughly 0.38–0.46 rad across Apollo surface missions [7] [2] [3].
2. How those numbers map to modern units and risk context
Multiple accessible analyses convert the Apollo absorbed doses into contexts familiar to civilians and medical professionals: the measured skin doses for Apollo astronauts (≈0.38 rad) are commonly equated to roughly two head CT scans, and mission totals were “less than a standard CT scan” in some accounts [2] [1]. Scientific literature on Apollo lunar crewmembers reports average mission doses for the deceased Apollo group in centigray units on the order of 0.18–1.14 cGy with a group mean near 0.59 cGy — consistent with low overall cumulative exposures compared with acute lethal thresholds [8].
3. The outlier claim: “1.8 Sv” or “1.67 mSv/sec” through the belts
A small set of sources circulating online assert dramatic belt‑transit rates such as 1.67 mSv per second and a total of 1.8 Sv for a three‑hour Van Allen crossing (a number that would imply life‑threatening acute doses). Those specific figures appear in a non‑peer‑reviewed article cited above but conflict with flight dosimetry, NASA reports and later scientific summaries that report total mission doses in the tenths of a rad range [4] [6] [3]. Available sources do not mention contemporaneous NASA dosimetry or peer‑reviewed reconstructions endorsing the 1.8 Sv figure; the authoritative Apollo experience report instead states “Radiation was not an operational problem during the Apollo Program” and documents the monitoring systems used [6].
4. Why the Apollo doses were low: trajectory, shielding and luck
NASA mission design intentionally minimized time in the most intense belt regions by choosing trajectories that skirted the belts and by keeping transit time short; spacecraft hull and operational procedures provided modest shielding and active monitoring for solar events [6]. Commentators and radiation scientists emphasize the role of favorable solar conditions during many Apollo flights — the crews benefited from quiet Sun periods and would have faced much higher risk had a major solar particle event coincided with transit or surface EVAs [1] [9].
5. Long‑term health signals and scientific debate
Measured low mission doses do not end the discussion about long‑term health effects: a 2016 Scientific Reports analysis reported that the seven deceased Apollo lunar crewmembers had an average recorded dose of about 0.59 ± 0.15 cGy (range 0.18–1.14 cGy) and suggested a possible link with higher cardiovascular mortality in that small group — the paper frames a hypothesis, not a settled causal verdict [8]. Independent observers note that while doses were low compared with acute thresholds, deep‑space exposures remain a credible risk for chronic disease and must be addressed for longer missions [10] [1].
6. What is certain and what remains unclear
It is certain that Apollo personal dosimeters and NASA reports show mission doses in the range of fractions of a rad (tens to a few hundred millirads), not multiple sieverts; several credible sources reiterate that conclusion and quantify typical Apollo totals [6] [2] [3]. What remains less precisely resolved in public reporting is detailed per‑astronaut, per‑phase breakdowns (e.g., exact dose on lunar EVA vs trans‑lunar cruise) beyond the cumulative numbers — Space.com notes Apollo mission records reported cumulative total‑mission exposure rather than fine‑grained surface vs transit breakdowns [11].
7. How to read conflicting claims
When encountering dramatic numbers (fatal sieverts, mSv/sec rates through the belt), weigh them against primary sources: NASA’s Apollo radiation reports and the physical dosimeter records, plus peer‑reviewed dose compilations, which consistently show much smaller cumulative exposures [6] [8] [5]. Some secondary or non‑peer publications repeat large estimates that are inconsistent with flown dosimeters; those should not be taken as authoritative without corroboration from NASA archives or peer‑reviewed reconstructions [4] [9].
If you want, I can pull the exact numeric readings reported for Armstrong, Aldrin and Collins from the NASA Apollo dosimetry report and list them side‑by‑side with unit conversions and contemporary medical comparisons — or provide direct links to the NASA Apollo experience report and the Smithsonian dosimeter entry cited above [6] [5].