GPU meaning in Space Science ?

Shore power or shore supply is the provision of shoreside electrical power to a ship at berth while its main and auxiliary engines are shut down. While the term denotes shore as opposed to off-shore, it is sometimes applied to aircraft or land-based vehicles (such as campers, heavy trucks with sleeping compartments and tour buses), which may plug into grid power when parked for idle reduction.

The source for land-based power may be grid power from an electric utility company, but also possibly an external remote generator. These generators may be powered by diesel or renewable energy sources such as wind or solar.

Shore power saves consumption of fuel that would otherwise be used to power vessels while in port, and eliminates the air pollution associated with consumption of that fuel. A port city may have anti-idling laws that require ships to use shore power. Use of shore power may facilitate maintenance of the ship's engines and generators, and reduces noise.