1965: US nuclear reactor still orbiting Earth after 60 years

In 1965, the US placed a nuclear reactor in orbit. Sixty years later, it’s still circling Earth, and its radioactive debris will take 2,000 years to disappear. No plan exists to retrieve it.

A Snapshot reactor in zero gravity

On April 3, 1965, the US launched the SNAP-10A satellite from Vandenberg Base in California. On board: a 45 kg nuclear reactor designed to power long-duration space missions. The system, named Snapshot (Systems for Nuclear Auxiliary Power), was the first and only fission nuclear reactor ever activated in Earth orbit.

The reactor operated for 43 days, producing 500 watts of electricity, before an electrical failure shut it down prematurely. Despite this, the satellite remains in orbit at an altitude of about 1,300 km, where it still circles today.

2,000 years of radioactive debris

SNAP-10A carries 1 kg of uranium-235 enriched to 96%. If it disintegrates in the atmosphere, this material could release radioactive particles. According to NASA estimates, the satellite is not expected to re-enter the atmosphere for several centuries. Even if it does fall, the debris would take about 2,000 years to decay naturally.

No recovery mechanism was planned. The reactor, still intact, remains a concern for space debris experts. Its trajectory is stable but unpredictable in the very long term.

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A space legacy with no solution

SNAP-10A is not the only nuclear object in orbit. Other satellites, such as the Soviet RORSAT series reactors, have also left radioactive traces in space. But unlike these, which sometimes dispersed liquid sodium-potassium, SNAP-10A remains a solid block, less likely to contaminate the atmosphere.

No international treaty specifically governs the management of nuclear debris in orbit. The US and Russia monitor these objects, but no current technology can safely capture them.

SNAP-10A is a reminder that space, like Earth, has its own long-lasting waste. And unlike terrestrial wrecks, these have no expiration date.