  Reducing the form factor while retaining the radiation hardness and
performance matrix is the goal of avionics. While a compromise between a
transistor s size and its radiation hardness has reached consensus in
micro-electronics, the size-performance balance for their optical counterparts
has not been quested but eventually will limit the spaceborne photonic
instruments capacity to weight ratio. Here we performed the first space
experiments of photonic integrated circuits (PICs), revealing the critical
roles of energetic charged particles. The year long cosmic radiation does not
change carrier mobility but reduces free carrier lifetime, resulting in
unchanged electro-optic modulation efficiency and well expanded optoelectronic
bandwidth. The diversity and statistics of the tested PIC modulator indicate
the minimal requirement of shielding for PIC transmitters with small footprint
modulators and complexed routing waveguides, towards lightweight space
terminals for terabits communications and inter-satellite ranging.
