  Recently, silicon photomultipliers (SiPMs) have been used in several
space-borne missions, owing to their solid state, compact size, low operating
voltage, and insensitivity to magnetic fields. However, operating SiPMs in
space results in radiation damage and degraded performance. In-orbit
quantitative studies on these effects are limited. In this study, we present
in-orbit SiPM characterization results obtained by the second detector of the
Gamma-Ray Integrated Detectors (GRID-02), which was launched on 6 November
2020. An increase in dark current of $\sim$100 $\mu$A/year per SiPM chip (model
MicroFJ-60035-TSV) at 28.5 V and 5 $^{\circ}$C was observed. Consequently, the
overall noise level (sigma) of the GRID-02 detector increased by $\sim$7.5
keV/year. The estimate of this increase is $\sim$40 $\mu$A/year per SiPM chip
at -20 $^{\circ}$C, highlighting the positive effect of using a cooling system.
