On-orbit performance of rad-hard SiC UV dosimeter flown in MicroSat-2C (EOS-08)

Ultraviolet Radiation emitted from the solar chromosphere and photosphere in the wavelength region 200–400 nm has most deleterious biological effects such as Erythema (250–298 nm), protein rupture (at 280 nm) and DNA/RNA mutation (at 265 nm) leading to carcinogenic lesion. Absorption of these radiations by O₂ and O₃ in the atmosphere attenuates the irradiance to by and large safer levels before they reach the Earth surface. However, a real time measurement of UV radiation is mandatory in manned space missions since even a very low biologically weighted UV dosage of 3.3 µW/cm² can cross the critical exposure limit of 3 mJ/cm² in about 15 min. 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. From the measured solar flux in three spectral bands (UV-A, B and C), the biologically weighted dose rate and critical exposure limit as applicable to outer space activities was estimated, which will assist the novel radiation mitigation design and techniques for manned space missions.