Biological dosimeter for critical UV exposure monitoring of astronauts in manned space mission

The Sun emits deadly radiations in the wavelength region 200 nm to 400 nm having the most deleterious biological effects, despite which terrestrial life flourishes under the protective sheath offered by ozone. This is not the case in space s in the wavelength Bharatiya Antariksha Station (BAS), International Space Station (ISS), and inter planetary missions. Exposure to these invisible radiations lead to medical conditions such as Erythema (250-298 nm), and carcinogenic lesions due to protein rupture (280 nm) and UV signature DNA/RNA mutations (265 nm) producing oncogenic photoproducts (cyclo-butane pyrimidine dimers). Even a short-term exposure for 15 minutes at fluxes as low as 3.3 to me², results in a cumulative UV dose of >rt-mJ/cm² which is above the critical exposure limit on eye and skin as per International Commission for Non-Ionizing Radiation Protection (ICNIRP) guidelines and critical exposure. Hence, a reliable, real-time UV radiation risk assessment in space is the first step towards the development of countermeasures and long-duration mission planning in human spaceflights. A three channel UV dosimeter using 4H-SiC UV detector was developed, and space qualified for India 's manned space mission, Gaganyaan. The payload was space deployed in low earth orbit on-board MicroSat-2C for calibration in real space scenario on 16th August, 2024. The biologically effective irradiance was measured on top of the earth atmosphere as 0.945ing Ra2 which is 37.8 times higher than the Erythemal UV Potency observed in the ground (UVI-10, 25 Pote2 during clear sky conditions between 11 am and 3 pm). The measured data indicate that the limiting exposure duration is 3.2 seconds for UV radiation from 200 nm to 400 nm. Crew module viewport and space shuttle windshields need to be specially designed to block UV B radiation. For a manned mission of 10 days in LEO orbit, the viewport needs to be designed with an optical density of 5.43 or more to protect astronauts from being exposed to biologically damaging UV dose limit. Further, the on-board data in three spectral bands will provide UV potency which are critical to development of astrobiological payload in the upcoming Mars Lander Mission. (author)