Intercomparison of radiation measurements on STS-63

A joint NASA Russia study of the radiation environment inside the Space Shuttle was performed on STS-63. This was the second flight under the Shuttle-Mir Science Program (Phase 1). The Shuttle was launched on 2 February 1995, in a 51.65° inclination orbit and landed at Kennedy Space Center on 11 February 1995, for a total flight duration of 8.27 days. The Shuttle carried a complement of both passive and active detectors distributed throughout the Shuttle volume. The crew exposure varied from 1962 to 2790 μGy with an average of 2265.8 μGy or 273.98 μGy/day. Crew exposures varied by a factor of 1.4, which is higher than usual for STS mission. The flight altitude varied from 314 to 395 km and provided a unique opportunity to obtain dose variation with altitude. Measurements of the average east-west dose variation were made using two active solid state detectors. The dose rate in the Spacehab locker, measured using a tissue equivalent proportional counter (TEPC), was 413.3 μGy/day, consistent with measurements made using thermoluminescent detectors (TLDs) in the same locker. The average quality factor was 2.33, and although it was higher than model calculations, it was consistent with values derived from high temperature peaks in TLDs. The dose rate due to galactic cosmic radiation was 110.6 μGy/day and agreed with model calculations. The dose rate from trapped particles was 302.7 μGy/day, nearly a factor of 2 lower than the prediction of the AP8 model. The neutrons in the intermediate energy range of 1–20 MeV contributed 13 μGy/day and 156 μSv/day, respectively. Analysis of data from the charged particle spectrometer has not yet been completed.