NASA prices nuclear Mars mission at $2.1 billion

NASA has submitted a preliminary cost estimate of approximately $2.1 billion to Congress for Space Reactor-1 Freedom, the agency's first nuclear-powered interplanetary spacecraft, according to documents outlining spending plans across fiscal years 2026 through 2029. The mission, championed by Administrator Jared Isaacman, is scheduled to launch in late 2028 and would mark the first time a fission reactor has been used for propulsion beyond Earth orbit.nasa+3

A Four-Year Spending Plan

Under the funding plan sent to lawmakers, NASA expects to allocate $640 million in fiscal year 2026, $890 million in 2027, $415 million in 2028, and $180 million in 2029, though the agency has cautioned the figures could shift during procurement. The spacecraft will pair a 20-kilowatt-class fission reactor fueled by high-assay low-enriched uranium with the Power and Propulsion Element originally developed for the now-paused Lunar Gateway station. Within 48 hours of launch, the reactor is expected to come online and begin powering electric ion thrusters for a roughly year-long transit to Mars.youtube+5

SkyFall's Unresolved Price Tag

The $2.1 billion estimate does not include SkyFall, the accompanying science payload that would deploy three next-generation helicopters — descendants of the Ingenuity Mars helicopter — to scout potential human landing sites and map subsurface water ice using ground-penetrating radar. As of late June, NASA had not disclosed SkyFall's cost. A NASA spokesperson told Scientific American that "cost assessments are currently being developed," and the agency's budget information hub contained no details about the mission. Mars researchers have warned that the project could divert funding from other science priorities, including the long-stalled Mars Sample Return program, at a time when the Trump administration's fiscal year 2027 budget request proposes cutting NASA's science budget from $7.25 billion to under $3.9 billion.meritalk+2

Fitting Into a Broader Nuclear Roadmap

SR-1 Freedom is the opening move in a broader push to integrate nuclear power into American space infrastructure. A White House directive issued in April ordered NASA, the Department of Energy, and the Department of Defense to develop space nuclear power systems, with a lunar fission surface reactor targeted for 2030. Former senior NASA officials have estimated that the lunar reactor alone could cost roughly $3 billion over five years. With Congress already resisting the administration's proposed budget cuts — lawmakers allocated $24.4 billion for NASA in fiscal year 2026, nearly $6 billion above the White House request — the $2.1 billion SR-1 price tag adds another pressure point to an already crowded ledger.spacepolicyonline+3