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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 

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 to the Red Planet. SkyFall will deploy three Mars helicopters, evolved from NASA’s heritage Ingenuity Mars Helicopters design, to collect scientific data, demonstrate exploration zones, and identify potential water sources.

NASA's Moon Base
NASA’s Ingenuity helicopter unlocked its blades
NASA’s Ingenuity helicopter unlocked its rotor blades, allowing them to spin freely, on April 7, 2021, the 47th Martian day, or sol, of the mission.
NASA/JPL-Caltech/ASU

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. 

Infographic showing the planned flight path of NASA’s Space Reactor-1 Freedom from Earth to Mars. A blue line traces the spacecraft’s orbit around the Sun, with green and orange dashed lines representing Earth’s and Mars’ orbits. On the right side of the infographic, there are seven mission milestones identified. An illustration of the spacecraft with large blue solar panels appears in the lower-left corner, and the NASA logo is displayed in the upper-right corner.
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 exploration zones, 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

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