Space Reactor-1 Freedom

Space Reactor-1 Freedom 

Destined for Mars, Space Reactor-1 (SR-1) Freedom is humanity’s first fission-powered interplanetary spacecraft. It will demonstrate nuclear electric propulsion in deep space.

Future Mission

Golden age of space exploration

Ignition

space nuclear propulsion

Nuclear Electric Propulsion

skyfall Payload

Mars Helicopters

Space Reactor-1 Freedom is a pathfinder mission that will lay groundwork and develop technologies for future applications, including for surface power on the Moon and Mars and for outer solar system exploration. The spacecraft will also carry the SkyFall payload: three Mars helicopters evolved from NASA’s heritage Ingenuity Mars Helicopter design. 

target

Mars

Mission type

Martian flyby and science payload deployment 

Launch/Target Arrival

2028 / 2029

Partners

Department of Energy 

Mission Overview

Mission Objectives

Vehicle Information

A Trailblazing Voyage

NASA will launch Space Reactor-1 Freedom, the first spacecraft to use a nuclear fission reactor for propulsion beyond Earth orbit.

Targeting launch in late 2028, the mission will showcase American nuclear power operations in space, prove fission surface power technology for NASA’s Moon Base, and help enable future fuel-efficient spacecraft that will be capable of supporting ambitious science and human exploration missions to Mars and deep space.

The Space Reactor-1 Freedom spacecraft will demonstrate nuclear electric propulsion and deliver SkyFall, a science-driven demonstration payload, to the Red Planet. SkyFall will deploy three Mars helicopters, evolved from NASA’s heritage Ingenuity Mars Helicopter design, to collect scientific data, demonstrate the ability to scout potential human landing sites, and identify potential water sources.  

NASA’s Moon Base

In this artist’s concept, NASA’s Ingenuity Mars Helicopter stands on the Red Planet’s surface.
Credit: NASA

Paving The Way

Space Reactor-1 Freedom will pave the way for space nuclear hardware development, set regulatory and launch precedent, and activate the industrial base for future fission power and propulsion systems. 

Explore the mission’s objectives:

1. Demonstrate nuclear electric propulsion  
2. Launch in the Mars transfer window by December 2028  
3. Leverage existing hardware for cost and schedule efficiency  
4. Perform Mars-relevant science and transmit incredible footage back to Earth  
5. Maximize extensibility to future higher power and longer duration missions  

Learn More

NASA’s Space Reactor-1 Freedom, the first fission-powered interplanetary spacecraft, cruises past Mars in this artist’s concept, demonstrating nuclear electric propulsion in deep space.  
Credit: NASA

Powering SR-1 Freedom

Space Reactor-1 Freedom will demonstrate nuclear electric propulsion in deep space.

Explore features of the vehicle:

Weight: About 26,455 pounds (12,000 kilograms)  
Fuel: High-Assay Low-Enriched Uranium (HALEU)  
Power: 20 kilowatts electric closed Brayton cycle power conversion system 
Spacecraft Bus: Power and Propulsion Element generating 48 kilowatts of electrical power  
Thrusters: Advanced Electric Propulsion System, 12-kilowatt Hall thruster 
Communications: X-band communications with NASA’s Deep Space Network 

Learn More About Hall Thrusters

The Advanced Electric Propulsion System qualification thruster inside one of the vacuum chambers at NASA’s Glenn Research Center’s Electric Propulsion and Power Laboratory.
Credit: NASA/Jef Janis

SR-1 Freedom Flight Path

This mission is the first step in a deliberate sequence. It will inform and enable Lunar Reactor-1 (LR-1), a fission surface power system designed to keep NASA’s Moon Base operating through periods of darkness and in locations where solar power alone is not sufficient. By flying a reactor first — without the added complexity of a lunar landing — SR-1 reduces nuclear flight risk, stimulates and qualifies the supply chain, and builds the workforce necessary for future space nuclear missions.  

Together, SR-1 and LR-1 are the beginnings of a domestic nuclear-space industrial base that scales to power permanent lunar outposts and secures American leadership in space for decades to come. 

NASA’s Space Reactor-1 Freedom mission concept flight path illustrates the spacecraft’s journey to Mars, including launch, reactor startup, multiple Mars flybys, and deployment of the SkyFall payload during the mission.
Credit: NASA

NASA’s SkyFall Mission

NASA’s SkyFall mission will build on the success of the Ingenuity Mars Helicopter, which achieved the first powered, controlled flight on another planet. Using a mid-air deployment, SkyFall will deliver three Mars helicopters, evolved from the heritage Ingenuity design, to collect scientific data, demonstrate scouting and aerial mapping of the subsurface, and identify potential water ice sources.  

The three SkyFall helicopters will carry an advanced instrument package featuring ground-penetrating radar and imagers, and will be capable of measuring air temperature, wind speed, and direction. The radar will collect data about subsurface features that can be combined with data from the imagers, which could help map the terrain and characterize environments on Mars that are different from those we have explored before. If subsurface ice is detected, these measurements may help determine its extent and depth, which could help scientists understand potential formation mechanisms.  

In this animation, SkyFall delivers the Mars helicopters using mid-air deployment.
Credit: NASA/JPL-Caltech

Measurements of wind speed, direction, and temperature at different elevations could provide a meteorological dataset that is different from what other spacecraft at the surface have previously been able to collect. These meteorological data combined with imaging could also provide insight into regional dust transport. Overall, this exploration and mapping from aerial vehicles could demonstrate how future missions to potential landing sites could serve as precursors to human-scale exploration. 

The science payload will include an advanced instrument package that aims to: 

Use ground penetrating radar to find ice deposits  

Measure air temperature, wind speed, and direction 

Demonstrate usefulness and feasibility of potential exploration zone scouting methods using aerial mobility 

NASA is planning a landing site selection process to determine the best possible landing sites for SkyFall to maximize the scientific return of the helicopters and their payloads, keeping within the capabilities of the Entry, Descent, and Landing system. To best support safe landing for human exploration on Mars, NASA is also targeting flat, low-elevation areas that are free of many geological obstacles. The helicopters could last months, and potentially years.   

While the significantly lower gravity on Mars (one-third of Earth’s) makes flight on Mars slightly easier, this is offset by difficulties associated with flying in the Red Planet’s extremely thin atmosphere (only 1% of the density at the surface compared to Earth), which means there are relatively fewer air molecules with which the helicopters’ two 4-foot-wide (1.4 meter) rotor blades can interact to achieve flight.  

In this animation, the SkyFall Mars helicopters fly away during the mid-air deployment.
Credit: NASA/JPL-Caltech

Media Information

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Media Contacts

Jacqueline Minerd, Lead Communications Integrator, SR-1 Freedom: jacqueline.minerd@nasa.gov
Jan Wittry, Public Affairs Officer, Space Reactors Division: jan.m.wittry-1@nasa.gov
Alana Johnson, Mars Exploration Program Communications Lead, SkyFall: alana.r.johnson@nasa.gov
DC Agle, JPL Media Lead, SkyFall: david.c.agle@jpl.nasa.gov

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Resources

Ignition Fact Sheet: America Underway in Space on Nuclear Power 

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