Why is NASA testing bomb-grade materials for its Mars mission?

A new space race is afoot. President Donald Trump and CEOs Elon Musk (Tesla) and Jeff Bezos (Amazon) are all advocating manned missions to Mars, a tantalizing objective. However, in humankind's drive to explore strange new worlds, we must be careful not to endanger life here on Earth.

Regrettably, to power its Mars mission, NASA's Goddard Space Center is trying to develop a nuclear reactor fueled by weapons-grade, highly enriched uranium — the stuff of the Hiroshima bomb — threatening to undermine decades of progress in phasing out such dangerous material from reactors worldwide to reduce risks of nuclear terrorism and proliferation.


Instead of violating U.S.-led nonproliferation norms, NASA should embrace an ongoing alternative reactor design that uses fuel made with low-enriched uranium, unsuitable for nuclear weapons.

If terrorists got hold of a sufficient quantity of highly enriched uranium, they could set off an actual nuclear explosion simply by slamming two pieces of the material together. This was the principle behind the Hiroshima bomb that killed tens of thousands in 1945. The resulting devastation from blast effects, fire and high radiation would dwarf that from an improvised "dirty bomb," which disperses relatively tiny amounts of radioactive material.

The world changed forever--and World War II effectively ended--when a U.S. B-29 bomber called the Enola Gay dropped the first atomic bomb on an inhabited area: Hiroshima, Japan. An estimated 140,000 people were killed.

In the 1960s, the United States foolishly exported large quantities of weapons-grade uranium for civilian applications, opening huge security risks. Belatedly recognizing this error, Washington launched a global effort in the 1970s to phase out use of such bomb-grade fuel, eventually eliminating hundreds of pounds annually from research reactors and medical isotope production. More recently, Congress has even started funding the U.S. Navy to explore converting its own nuclear reactors in aircraft carriers and submarines to safer low-enriched uranium fuel.

But NASA inexplicably is headed in the opposite direction, proposing to renew use of bomb-grade uranium in U.S. space reactors for the first time since 1965. Each of NASA's proposed "Kilopower" reactors would use at least 65 pounds of highly enriched uranium, more than sufficient for a nuclear weapon. Indeed, the U.S. government requires maximum security for even a fraction of that amount — a mere 11 pounds.

NASA plans to start testing its bomb-grade uranium space reactor next month at a former nuclear weapons testing site in Nevada. Other countries and private interests could well respond by pursuing their own highly enriched uranium space reactors, increasing both proliferation and terrorism risks.

The U.S. government needs to practice what it preaches. No competitor would forego bomb-grade uranium if NASA charges ahead with use of this dangerous material. Now is the moment to make clear that the global norm against highly enriched uranium in reactors applies to space missions too.

Fortunately, bomb-grade uranium is not necessary for a nuclear Mars mission — either to get to the planet or to provide energy once there.

A space reactor could instead use low-enriched uranium fuel, unsuitable for bombs, just like state-of-the-art nuclear research reactors on Earth. In the past, to minimize space payloads, highly enriched fuel was thought to be essential. But according to research co-sponsored by a U.S. national laboratory, innovative nuclear reactor designs could utilize bomb-proof uranium even more efficiently than Hiroshima-grade uranium. In addition, by eschewing highly enriched uranium, commercial ventures would enjoy lower barriers to entry and avoid prohibitive security costs.

Admittedly, it would take some time to perfect a new space reactor using low-enriched uranium. Fortunately, there is no great rush. Just last month, NASA's chief of human spaceflight, William Gerstenmaier, acknowledged that the space agency's budget lacks funding for a manned mission to Mars, estimated to cost $100 billion to $1 trillion over a quarter-century. Even the wealthiest private companies are unlikely to pony up such resources in the near future.

Absent funding for a manned mission to Mars, why is NASA rushing toward a September test of a bomb-grade uranium reactor that could undermine global efforts to minimize use of such dangerous fuel? Good question. Taxpayer dollars and private capital would be better spent developing space reactors that use safe low enriched uranium, so these systems can be ready when the U.S. government eventually marshals the funds for a mission to the red planet, or beyond.


Alan J. Kuperman ( is associate professor and coordinator of the Nuclear Proliferation Prevention Project ( at the Lyndon B. Johnson School of Public Affairs at the University of Texas at Austin; he is editor of Nuclear Terrorism and Global Security: The Challenge of Phasing Out Highly Enriched Uranium. Dr. Edwin Lyman ( is senior scientist in the Global Security Program at the Union of Concerned Scientists and co-author of "Fukushima: The Story of a Nuclear Disaster."