This is an ERS (European remote sensing satellite) transponder. It was part of the ERS satellites project. ERS satellites were launched in 1991 and 1995 (there were 2 of them) for scientific research purposes, not about the space but about the Earth.
This thing has antennas and with them it captures radio frequencies from the satellites. Then it processes and converts them to signals that computers and other machines in Earth can understand.
Beautiful, isn't it?