The cornerstones of NASA's lunar-orbiting space station "Gateway" are the Power and Propulsion Element (PPE) and the Habitation and Logistics Outpost (HALO). The PPE spacecraft, which has a 60-kilowatt solar electric propulsion class, will be able to propel the Gateway to various lunar orbits and supply power, high-speed communications, and attitude control. The cramped living area known as HALO is where astronauts who visit the Gateway—often en route to the Moon—will work under pressure. It will act as the outpost's docking center and provide command and control. In addition to providing power distribution, HALO will enable science investigations, enhance the life support systems on board NASA's Orion spacecraft—which is responsible for transporting the Artemis crew to the Gateway—and facilitate communications for visiting vehicles and lunar surface expeditions.