NASA has identified a supplier for SR-1 Freedom, its planned nuclear-electric mission to Mars. An October 20, 2026 update names Sierra Lobo as the provider of the system that converts the reactor’s heat into electricity.
The closed Brayton-cycle equipment will be integrated with a fission reactor being developed by Idaho National Laboratory. The work falls under an existing NASA Glenn contract. The announcement describes development responsibilities, rather than a completed or flight-tested module.
Electric propulsion uses electrical energy to charge a gas propellant and accelerate it out of a thruster. Unlike the brief, forceful burn associated with a chemical rocket, an electric engine can deliver a small push over a much longer period. Sustained operation gradually changes the spacecraft’s speed.
NASA’s explanation of the technology distinguishes the energy source from the propulsion hardware: solar arrays or a nuclear reactor can supply the electricity. SR-1 is intended to demonstrate the reactor-powered version beyond Earth orbit, testing an approach to future journeys through deep space.
The mission overview lists a launch target of 2028 and arrival at Mars in 2029. Its planned encounter combines a Martian flyby with delivery of SkyFall, a payload of three helicopters descended from the Ingenuity design. Those dates remain targets for a future mission. Other objectives include demonstrating extended reactor performance and using existing technology and hardware where possible.
The helicopters are intended to carry imagers and ground-penetrating radar, alongside measurements of temperature and wind. Combining those observations could reveal terrain, subsurface structure and the distribution of potential water ice. If ice is detected, the measurements could help establish its depth and extent.
NASA’s latest update retains a late-2028 launch goal and says the reactor will remain inactive until the spacecraft has left Earth orbit. Interagency reviews and nuclear-safety work are part of the development process. The immediate milestone is building the power system that the wider mission depends on.
Artist’s concept of SR-1 Freedom near Mars. The spacecraft remains in development. Credit: NASA/Alberto Bertolin. Image source; usage guidelines.
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