NASA plans to repurpose Gateway’s Power and Propulsion Element (PPE) for Space Reactor-1 (SR-1) Freedom, a nuclear-electric propulsion demonstration targeted for launch before the end of 2028 and aligned with the December 2028 Mars launch window. The PPE is being built by Lanteris Space Systems in Palo Alto and would carry three 12-kilowatt electric engines, four 6-kilowatt thrusters, solar arrays, and an approximately 20-kilowatt uranium-fueled fission reactor. NASA has spent approximately $4.5 billion on Gateway since its official start in 2019.
For lunar habitation, this is a strategic cancellation of an orbital staging node in favor of surface capability. Nuclear power and high-efficiency electric propulsion could enable sustained operations, high-mass cargo movement, and resilient energy systems, but SR-1 will not itself provide a lunar habitat, radiation shelter, closed-loop life support, or an assured supply chain. NASA’s replacement plan targets a lunar base through three phases: site selection from 2029 to 2032, and long-duration surface habitats from 2032 to 2036. Over 28 landings, the agency proposes delivering 150 metric tons, including fission power, rovers, manufacturing equipment, and systems capable of returning hundreds of kilograms to Earth.
The Ark team should track SR-1 reactor safety, autonomous fault management, propulsion lifetime, launch-readiness risks, and the conversion of PPE hardware from a lunar-orbit asset to a Mars demonstrator. Research should prioritize modular fission power, radiation-hard control systems, high-efficiency electric propulsion, lunar surface logistics, in-situ manufacturing, and preservation facilities that can operate without continuous Earth resupply. The 2029–2036 lunar-base schedule and the scaled-up Commercial Lunar Payload Services program should be treated as critical external dependencies for Ark site selection, cargo integration, and technology demonstrations.