When NASA announcement On a new helicopter mission to Mars called Skyfall last week, the immediate response from most scientists had little to do with the ambitious plan to launch a tiny robotic plane to the Red Planet in December 2028. The biggest and most shocking news was that Skyfall would fly to Mars aboard a nuclear-powered spacecraft, the first of its kind.
“After decades of study and billions spent on concepts that never left Earth, America is finally going to pursue nuclear power in space,” NASA Administrator Jared Isaacman said at a press event at which Skyfall was announced.
This revelation stunned the American planetary science community, including NASA’s official list of recommended future missions had not mentioned a nuclear mission to Mars. Besides the “Who ordered this?” » In terms of reaction, there is also a question of timing: In terms of spaceflight, the end of 2028 is practically tomorrow, which sets a deadline too close for comfort, even without the added complexity of NASA’s nuclear aspirations. How could the space agency make this work?
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“A possible future”
No clarity emerged from Scientific Americanrepeated, unanswered phone calls and emails to NASA headquarters in Washington, D.C., and the agency’s Jet Propulsion Laboratory near Pasadena, Calif., where Skyfall’s predecessor helicopter, called Ingenuity, was born. Ingenuity, a robotic plane the size of a tissue box, made more than 70 flights on Mars between 2021 and 2024. Although the space agency remains relatively tight-lipped about the finer details of its plan, a former senior NASA official, speaking anonymously, believes there is reason to be optimistic.
“If someone came into my office and offered me a handful of Ingenuity helicopters to launch in 2028, and it would be [2026] At the moment, I would say: “Ah, it’s tight”,” says the former manager Scientific American. “But is it impossible? No. I would like to see what the plans are… The biggest indicator of the seriousness of this situation will be to look at the budget, because a vision in itself is a dream, a vision and a budget are a possible future.”
Even within NASA’s multibillion-dollar annual budget, nothing comes for free. Most of NASA’s money goes toward the space agency’s human spaceflight efforts: maintaining the International Space Station and continuing the Artemis program to return astronauts to the Moon and build a permanent lunar base there. If Skyfall’s funding comes from human spaceflight largesse, many scientists say, they won’t complain about new helicopters and a new nuclear-powered mission architecture. If, instead, funding comes from NASA’s much smaller planetary science coffers, barring a significant budget increase, something else has to die for Skyfall to fly.
Despite the risk that NASA’s nuclear ambitions could starve other areas of planetary science, Skyfall and the proposed nuclear-powered spacecraft should be considered good news, says Paul Byrne, a planetary scientist at Washington University in St. Louis. “This is the kind of thing NASA should have been doing in the late 1970s. Like, where the hell is our moon base? If this happens – and there’s a huge ‘if’ here – it will bring us to a NASA that many of us grew up hoping to see: people on the moon – with routine landings, nuclear propulsion that gets us quickly to distant targets, carrying big payloads.”
Propulsion ready for use
Skyfall is intended to reach Mars using a small, 20-kilowatt nuclear-powered spacecraft called Space Reactor-1 (SR-1) Freedom. Many elements of the spacecraft and reactor are either under development or already built, Isaacman said at the news conference, with NASA taking the lead on the project and acting as the spacecraft’s “prime integrator” in partnership with the Department of Energy, which manages the U.S. nuclear stockpile.
Despite this, the reactor itself has not been built and is separate from a reactor that NASA intends to land. on the lunar surface by 2030 and this is planned to power an outpost there. The SR-1 Freedom’s primary add-on module will be repurposed from NASA’s Power and Propulsion Element (PPE). Door space station, a controversial Artemis initiative that the space agency actually canceled last week. (This is familiar territory for the PPE concept. In a previous life, it was the core of NASA’s program during the Obama era. Asteroid redirection missionwhose cost is estimated at $2.6 billion and which was canceled in 2017.)
The legacy of nuclear propulsion is deep and starry. In 1961, when President John F. Kennedy announced to the world that the United States would, before the end of the decade, send humans to the Moon and return them safely to Earth, he also committed funds to accelerate the development of a nuclear rocket. “This provides hope that one day we will provide a means for even more exciting and ambitious space exploration, perhaps beyond the Moon, perhaps to the farthest reaches of the solar system itself,” he said.
Four years later, in 1965, the United States launched SNAP-10A, which to this day remains the country’s only nuclear reactor to reach orbit. Its predecessor, SNAP-9A, released about a kilogram of radioactive plutonium into the atmosphere after failing to reach orbit in 1964. And several Soviet space reactors also contaminated Earth with fissile material. Since then, anti-nuclear public sentiment, budget cuts and regulatory challenges have scuttled subsequent U.S. space reactor programs, fostering a widespread impression that bringing nuclear power back to the launch pad is more trouble than it is worth.
However, NASA has studied two types of reactor-based rockets: nuclear thermal propulsion and nuclear electric propulsion. The first is the fastest possible way to get astronauts to Mars, operating at a frightening peak temperature of 4,400 degrees Fahrenheit (2,425 degrees Celsius) – and venting radioactive exhaust – but only for short, intense bursts. Conversely, nuclear electric propulsion operates continuously but slowly and slowly; it is capable of reaching high speeds over many years. Combined with the PPE, the SR-1 Freedom will rely on the latter method; it will convert heat from its nuclear reactor into electricity to power xenon gas thrusters that produce no radioactive exhaust.
The reactor itself will be fueled by high-grade low-enriched uranium, borrowing an approach from an ill-fated earlier project, the Demonstration Rocket for Agile Cislunar Operations (DRACO), which NASA pursued in partnership with the Pentagon’s Defense Advanced Research Projects Agency. Conceived in 2023, the DRACO mission was a half-billion-dollar accident program aimed at launching a thermal nuclear-powered rocket by 2027 at the earliest. By using a larger amount of low-enriched uranium rather than a smaller amount of weapons-grade highly enriched uranium, DRACO was supposed to avoid regulatory red tape that could stifle the launch approval process. To simplify testing, DARPA designed it to turn on for the first time only after being in space.
In 2024, however, the DOE added a requirement for ground testing, which would take years and hundreds of millions of dollars. DARPA abandoned the project in 2025.
“In many ways, DRACO was a pilot program that was part technical, part regulatory,” says Scott Pace, director of the Space Policy Institute at George Washington University. “I regretted its cancellation because we lost an opportunity to drive the regulatory approval process for installing a nuclear reactor in space.” Today, he says, the situation may have improved thanks to four executive orders signed last year that streamlined some nuclear regulations.
“The political foundations are absolutely there,” Pace says. “I’ve seen more positive support from the Department of Energy for doing things in space than I’ve seen since, probably,” the George HW Bush administration.
Better late than never
Not everyone is so optimistic about NASA’s remaining chances for nuclear success. Andrew Higgins, an aerospace engineer at McGill University, worries that the LEGO way the SR-1 Freedom was planned — with many parts from different, unrelated projects just waiting to be assembled — significantly underestimates the challenge ahead.
Although nuclear spacecraft and Mars helicopters are packed together like peanut butter and jelly, there is no obvious reason to combine the two, he says. “If you’re orbiting several of Jupiter’s moons or going to Neptune’s moon Triton, then nuclear electric propulsion makes sense. You have years and years of thrust to contribute,” Higgins says. But Mars, he adds, is too close for the SR-1 Freedom to flex its muscles and achieve high speed. Additionally, solar power is much more efficient for most destinations in the inner solar system. “Maybe SR-1 [Freedom] It’s fine as a demonstration of how a nuclear reactor works in space,” Higgins says, “but it won’t help shorten a mission or bring more payload. »
The realistic view is that NASA wants to get a nuclear reactor flying as soon as possible, and the Mars launch window justifies the aggressive development schedule (and commensurate funding) to the appropriate ones. The December 2028 deadline also coincides with the final month of the Trump administration’s term, a time that could help maintain White House support for the program and defend against any attempts at Congressional override during its delicate and rushed development.
But why Skyfall? The answer is that this is the simplest Mars surface mission possible, because the helicopters are essentially printed to order and the mission will not require a separate lander. In other words, sure, SR-1 Freedom makes no sense for Skyfall, but that’s okay, because Skyfall wouldn’t exist without SR-1 Freedom. Each, by necessity, hoists the other by their straps out of an abject improbability . And as a bonus, it reminds everyone that sending astronauts to Mars is the over-the-horizon goal of NASA’s moon-centered Artemis plan.
It’s not yet clear whether the mission will launch in 2028, but with strong support from Isaacman, supporters say, Skyfall could make enough progress to ensure NASA sticks with it until 2030.
“Suppose everything works, but the launch is two years late,” explains the former NASA official. “You think that would be a horrible failure? We’d have nuclear electric propulsion! I’d be up and down.”
