NASA Budget Cuts Could End U.S. Exploration of the Outer Solar System
The U.S. planetary science community is sounding the alarm about plans to discard a nuclear technology that has powered dozens of NASA missions over the past 50 years
By Hannah Richter edited by Lee Billings
In the spring of 2022 the U.S. space community selected its top priority for the nation’s next decade of science and exploration: a mission to Uranus, the gassy, bluish planet only seen up close during a brief spacecraft flyby in 1986. More than 2.6 billion kilometers from Earth at its nearest approach, Uranus still beckons with what it could reveal about the solar system’s early history—and the overwhelming numbers of Uranus-sized worlds that astronomers have spied around other stars. Now President Donald Trump’s proposed cuts to NASA could push those discoveries further away than ever—not by directly canceling the mission but by abandoning the fuel needed to pull it off.
The technology in question, known as radioisotope power systems (RPS), is an often overlooked element of NASA’s budget that involves turning nuclear fuel into usable electricity. More like a battery than a full-scale reactor, RPS devices attach directly to spacecraft to power them into the deepest, darkest reaches of the solar system, where sunlight is too sparse to use. It’s a critical technology that has enabled two dozen NASA missions, from the iconic Voyagers 1 and 2 now traversing interstellar space to the Perseverance and Curiosity rovers presently operating on Mars.