Power and Propulsion Element
The Power and Propulsion Element (PPE) is a critical spacecraft module designed for NASA's Lunar Gateway, a planned space station in lunar orbit that will serve as a staging point for Artemis missions to the Moon and beyond.[1] It provides up to 60 kilowatts of electrical power through large roll-out solar arrays and advanced solar electric propulsion using xenon gas, enabling efficient maneuvering, attitude control, and sustained operations in deep space while reducing propellant needs by up to 90% compared to traditional chemical systems.[1] Launched as the "backbone" of the Gateway, the PPE will integrate with the Habitation and Logistics Outpost (HALO) module to form the initial core of the station, supporting crewed expeditions to the lunar South Pole and future Mars missions.[2] Managed by NASA's Glenn Research Center in Cleveland, Ohio, the PPE is being built by Lanteris Space Systems (formerly Maxar Space Systems) based on their proven 1300 spacecraft platform, incorporating technologies from prior missions like NASA's Double Asteroid Redirection Test (DART).[1] Key components include two yoga-mat-like roll-out solar arrays spanning the size of a football field's end zone, high-efficiency electric thrusters operating at 12 kilowatts, and systems for communications and docking.[1] Development began under a 2020 NASA contract awarded to Maxar, with assembly progressing at facilities in Palo Alto, California; the module achieved a major milestone in November 2024 when its structural assembly was completed and equipped with xenon and liquid fuel tanks, marking the "topping off" phase. In 2025, the solar arrays passed testing, the electric thrusters were delivered in August, and the module achieved its first power-up in October.[2][3][4][5] The PPE is scheduled for launch aboard a SpaceX Falcon Heavy rocket alongside HALO from Kennedy Space Center no earlier than 2027, ahead of the Artemis IV mission in 2028; it will undertake a year-long transit through deep space before entering a near-rectilinear halo orbit around the Moon, demonstrating its propulsion system's capability for long-duration operations.[2] This orbit, chosen for its stability and Earth-Moon visibility, will allow the Gateway to host international partners, conduct scientific research, and facilitate sustainable lunar exploration.[1] As the most powerful solar-electric spacecraft ever flown, the PPE represents a technological leap in efficient deep-space propulsion, paving the way for commercial applications in cislunar space.[2]Design and Capabilities
Technical Specifications
The Power and Propulsion Element (PPE) is designed as a high-power solar electric propulsion spacecraft based on Maxar's 1300-series satellite bus, with an approximate launch mass of 5,000 kg, including about half in propellant for initial operations. The structure features a central cylindrical propellant tank configuration, comprising two 825-liter xenon tanks for the solar electric propulsion system, integrated with a dedicated propulsion bus module that houses thrusters, power processing units, and related subsystems.[6] This modular architecture supports the spacecraft's role in providing propulsion and power to the Lunar Gateway while maintaining structural integrity in cislunar space.[7] The PPE's power subsystem relies on two Roll-Out Solar Arrays (ROSAs) capable of generating 60 kW of electrical power, making it the most powerful solar electric spacecraft ever flown.[1] Each ROSA deploys to a length of approximately 20 meters, providing a compact stowed volume while achieving high power density through advanced flexible blanket technology tested on the International Space Station.[8] Efficiency is enhanced by the arrays' design, which supports up to 120 W/kg specific power, enabling reliable energy generation for Gateway operations despite varying solar flux in lunar orbit.[9] The spacecraft is engineered for a minimum operational lifespan of 15 years in near-rectilinear halo orbit around the Moon, with built-in redundancy to ensure mission reliability.[10] Key redundancies include dual xenon tanks equipped with latch valves to isolate potential leaks and prevent single-point failures in the propulsion system, alongside backup power distribution paths for the solar arrays and electric thrusters.[6] These features allow for extended operations, including potential refueling to extend life beyond the baseline.[11] To withstand the deep space environment, the PPE employs advanced materials and thermal management systems optimized for extreme temperature swings, radiation, and micrometeoroid impacts. Structural components utilize lightweight composites and aluminum alloys for the bus and tanks, while thermal control incorporates multi-layer insulation (MLI) blankets, embedded heat pipe radiators with optical solar reflectors (OSRs), and specialized coatings to manage heat dissipation from the 60 kW arrays and thrusters.[12] Sputter shields and thermal conditioning for propellant lines further protect against degradation during electric orbit raising and long-term exposure, maintaining operational temperatures within narrow limits for critical subsystems.[12]| Specification | Details |
|---|---|
| Launch Mass | ~5,000 kg (including ~2,500 kg propellant)[6] |
| Power Output | 60 kW from two ROSAs[1] |
| ROSA Dimensions (Deployed) | ~20 m length each[8] |
| Operational Lifespan | 15 years minimum in lunar orbit[10] |
| Key Structural Components | Central cylindrical xenon tanks (2 × 825 L), propulsion bus module[6] |
| Thermal Management | MLI blankets, heat pipes, OSRs, sputter shields[12] |