The Synergistic Air-Breathing Rocket Engine is uniquely designed to scoop up atmospheric air during the early part of its flight to orbit. This slashes the need for the vehicle to carry bulky onboard oxygen for this part of the ascent, before switching to rocket mode drawing on internal propellants for its final climb to space. To allow SABRE to use the superfast onrushing airstream as oxidiser, the air must be cooled from 1000°C to –150°C within just a hundredth of second, at the same time avoiding the formation of dangerous ice.