The National Aeronautics and Space Administration (NASA) will launch a nuclear-powered spacecraft to Mars for the first time. The goal is to verify whether nuclear propulsion can be used for deep-space exploration. The nuclear-powered craft plans to send three helicopters down to Mars.
NASA announced at its Washington, D.C., headquarters on the 24th (local time), "We will launch the nuclear-powered spacecraft 'Space Reactor-1 Freedom' to Mars before the end of 2028." A nuclear-powered spacecraft has never been launched.
◇ Generating electricity for propulsion with fission energy
A nuclear-powered spacecraft operates in the same way as a nuclear power plant. Nuclear power generation uses the immense heat from the chain reaction of uranium fission to boil water into high-temperature, high-pressure steam. This steam turns a turbine and drives a generator to produce electricity.
A nuclear-powered spacecraft uses electricity produced in the same way to create electrically charged ions. When an opposite electric charge is applied at the end of the nozzle, the ions move toward it, generating thrust. This is the so-called nuclear electric propulsion (NEP) method.
NASA said the Space Reactor-1 Freedom mission will demonstrate that nuclear propulsion can power a spacecraft and will invigorate an industrial base for future fission power systems. This could include exploration missions to planets or celestial bodies in the outer solar system.
Conventional spacecraft cannot explore such distant bodies. That is because they cannot carry massive amounts of liquid fuel. Only small spacecraft that can run on batteries or solar power, like Voyager or Juno, have been able to reach the outer regions of the solar system.
Voyager, the unmanned probe launched by NASA in 1977, is powered by a nuclear battery called a radioisotope thermoelectric generator (RTG). The heat generated as radioactive isotopes undergo nuclear decay is converted into electricity through thermoelectric modules. A thermoelectric module is a device that generates current when temperature changes.
Thanks to its nuclear battery, Voyager is still operating at the edge of the solar system, where solar panels are useless. The Jupiter orbiter Galileo, the Saturn orbiter Cassini, and the Mars rover Curiosity also carried the same type of battery. The nuclear-powered spacecraft announced this time is different in principle from a nuclear battery in that it uses the same mechanism as commercial nuclear power plants.
◇ Gathering crewed exploration site data with six helicopters
The nuclear-powered spacecraft will arrive at Mars and send down a payload called "Skyfall" consisting of six helicopters. In 2021, NASA landed the four-wheeled rover Perseverance and the ultralight unmanned helicopter Ingenuity on Mars. Mars exploration robots existed before, but a helicopter flying in the Martian sky was a first. The rover is still operating, but the helicopter crashed in Jan. 2024, ending its mission.
NASA said the helicopters to be sent by the nuclear craft will be modeled on Ingenuity. Ingenuity carried out 72 flights from Apr. 2021 to Jan. 2024. While Ingenuity was for technology demonstration, the Skyfall helicopter squadron is expected to conduct specific scientific exploration missions.
Earlier, the U.S. space company AeroVironment said in a statement on July 24 last year, "We designed Skyfall to deploy six reconnaissance helicopters on Mars," adding, "The helicopters will survey multiple sites selected as top-priority landing candidates for America's first Mars astronauts."
AeroVironment said, "While exploring Mars, each helicopter will operate independently," adding, "By transmitting high-resolution surface imagery and subsurface radar data to Earth for analysis, they will help ensure that crewed landers can safely touch down in areas richest in water, ice and other resources."
◇ Three-phase plan to build a crewed lunar base also announced
NASA Administrator Jared Isaacman said the plan for the next 10 years aims to restore Americans' confidence in space exploration missions. NASA has resumed crewed lunar exploration, halted since Apollo 17 in 1972, with the Artemis program.
Artemis II, set to launch on the 1st of next month, will conduct the first crewed test flight in lunar orbit with four astronauts aboard. Earlier, in 2022, the Artemis I mission proceeded as an uncrewed test flight in which the Orion spacecraft, carrying mannequins, orbited the Moon.
Astronauts' lunar landing has been revised to 2028. Artemis III, which was initially scheduled to put astronauts on the Moon, will test docking with the lunar lander in Earth orbit in 2027, and the following year Artemis IV will land astronauts on the Moon. NASA said, "Starting with Artemis V, we plan to land a crewed lander on the Moon every six months."
NASA also said it will move in earnest to build a crewed lunar base. Administrator Isaacman told space corporations and officials from national space agencies and lawmakers, "There will be an evolutionary process to build humanity's first permanent surface outpost beyond Earth."
NASA announced it will pursue a phased approach to secure a sustained human foothold on the Moon. As part of this strategy, it said it will temporarily pause the Gateway lunar space station project it had been pursuing and shift the focus to building infrastructure that supports continuous lunar surface exploration.
In phase one, privately led corporations will send landers, rovers and instruments to the Moon. This includes nuclear batteries. Phase two will establish semi-habitable infrastructure and a regular logistics supply chain to support astronauts' surface exploration on the Moon.
At this stage, lunar exploration vehicles will change from open to sealed types. The pressurized rover from the Japan Aerospace Exploration Agency (JAXA) is also included in phase two. Apollo astronauts once rode rovers with only wheels, but the Artemis pressurized rover being developed by Toyota, a Japanese automaker, has a roof, allowing boarding without spacesuits.
Phase three is the process of establishing a full-fledged foundation for long-term stays. The lander will transport astronauts and cargo together to secure a sustained foothold on the Moon. This phase includes a multipurpose habitation module under development by the Italian Space Agency (ASI) and a multipurpose lunar rover from the Canadian Space Agency (CSA).
NASA (2026), https://www.nasa.gov/news-release/nasa-unveils-initiatives-to-achieve-americas-national-space-policy/
AeroVironment (2025), https://www.avinc.com/resources/press-releases/view/av-reveals-skyfall-future-concept-next-gen-mars-helicopters-for-exploration-and-human-landing-preparation