System Architecture

Goal: For a 1 MW orbital data center whose GPU chips run at a fixed 95 °C and whose pumped ammonia coolant loop runs at a fixed 20 kg/s, find the radiator temperature, the radiator's fin efficiency, its ideal, absorbed and net heat rejection per square metre of panel, the solar array area, the aluminium radiator area, the ammonia's temperature rise along the loop, and the mass per megawatt, in tonnes, of the solar array, of the radiator, of the ammonia and of all three together, and how those change with the chip-to-coolant temperature drop (nominal 30 K, from 10 K to 50 K), the radiator's exposure to sunlight and Earth-reflected light (nominal 5 %, from 0 % to 25 %), the polyimide substrate thickness of the solar array (nominal 30 µm, from 7.5 µm to 50 µm), the array's structure and cover mass per square metre (nominal 2 kg/m², from 0 kg/m² for a frameless film array to 2.5 kg/m²) and the aluminium sheet thickness of the radiator (nominal 0.5 mm, from 0.1 mm to 2 mm).

Description: A whiteboard block diagram of an orbital data center: two Solar array wings, one above and one below, are joined to a Power conditioning unit between them, which powers the Compute module; a Coolant loop leaves the compute module and carries the waste heat to two Radiator panel wings, one above and one below its far end. A sunlight arrow arrives at the solar array, an ammonia flow arrow runs along the coolant loop, and heat arrows leave both faces of each radiator panel. The diagram is symbolic and not to scale.