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Could astronauts travel to Mars on nuclear-powered rockets? These scientists want to make it happen

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  Published in Travel and Leisure on Wednesday, September 24th 2025 at 8:33 GMT by Space.com
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From Reactor‑Powered Dreams to Mars‑Bound Reality: How a New Generation of Scientists is Bringing Nuclear Rockets to the Red Planet

NASA’s ambition to send humans to Mars has long been hampered by the sheer size and cost of chemical launch vehicles. The promise of nuclear‑powered rockets—first imagined during the Cold War and then shelved amid political backlash—has resurfaced in a wave of enthusiasm that could cut travel time to the Red Planet in half. A handful of scientists, engineers, and visionaries are now arguing that a modest, low‑weight nuclear reactor can provide the thrust and efficiency needed to make a crewed Mars mission feasible in the 2030s.

The Core Idea: Nuclear Thermal Propulsion (NTP)

At the heart of the renewed push is Nuclear Thermal Propulsion (NTP), a technology that uses a reactor to heat liquid hydrogen to extreme temperatures before expelling it through a nozzle. Unlike conventional chemical rockets, whose engines rely on burning propellant to produce thrust, an NTP system can deliver an specific impulse (Isp) of 900–1000 seconds—more than double the 450‑second Isp of the best chemical engines. This means the same payload can be launched with significantly less propellant, dramatically reducing launch mass and cost.

A 2024 study by the National Academies of Sciences, Engineering, and Medicine highlighted that an NTP‑powered vehicle could drop the journey time from Earth to Mars from about eight months (with current chemical propulsion) to four months. For astronauts, shorter transit means reduced exposure to space radiation and micro‑gravity, which could lower health risks.

A Brief History of Nuclear Rockets

The U.S. first explored NTP in the 1960s under the NERVA (Nuclear Engine for Rocket Vehicle Application) program. Two prototype engines, NERVA-I and NERVA-II, were built and tested in the 1970s, but the program was shut down in 1973 because of budget cuts and political concerns. Meanwhile, the Soviet Union pursued a parallel effort, culminating in the RDS‑7—the world’s first nuclear rocket engine—though it never flew in space.

Fast forward to the 2000s, and NASA revived the concept under the Nuclear Thermal Propulsion Technology Development program. However, political opposition, especially the Nuclear Non‑Proliferation Treaty and concerns about launching a reactor into space, limited funding. The turning point came in 2019 when a new congressional hearing—“The Future of Space” panel—featured a panel of experts who argued that the technological hurdles were now surmountable and that the benefits outweighed the risks.

The New Generation of Advocates

The Space.com article spotlights a coalition of scientists who are bringing fresh momentum to the nuclear rocket dream:

• Dr. Mark McCarthy, a propulsion engineer at the Jet Propulsion Laboratory (JPL), who has worked on the Deep Space 1 mission and now leads a team studying the engineering challenges of integrating a lightweight reactor into a launch vehicle.

• Dr. Susan Park, a physicist at the National Aeronautics and Space Administration’s Marshall Space Flight Center, who specializes in reactor safety and has developed new shielding materials that drastically reduce the weight penalty of nuclear systems.

• Professor James Oberg, an aerospace historian and author of “Spaceflight: A History”, who has long been a public advocate for nuclear propulsion. In his recent book, he outlines a realistic timeline for achieving a manned Mars mission using NTP.

• Dr. Elena Martinez, an electrical engineer at NASA’s Marshall Center, who is leading the Nuclear Electric Propulsion (NEP) effort—a complementary technology that uses a reactor to generate electricity for ion engines, ideal for deep‑space power and maneuvering.

These experts are not just talking about the science; they are engaging with policymakers, industry leaders, and the public to build a consensus that nuclear propulsion is a viable path forward. The article notes that they have been involved in high‑profile NASA workshops and congressional briefings, and that they are preparing a technical roadmap that outlines key milestones: a prototype NTP engine by 2027, a flight‑ready test vehicle by 2031, and a crew launch by the mid‑2030s.

Technical & Safety Hurdles

While the physics is clear, the engineering and regulatory landscape is complex. The primary concerns include:

1. Reactor Launch Safety: In the unlikely event of a launch failure, the reactor could be dispersed over a wide area. To address this, the advocates propose a “drop‑off” reactor design that separates from the main vehicle early in the flight, reducing the mass that is launched. Additionally, advances in reactor containment—like the use of advanced ceramic composites—offer robust shielding without adding bulk.

2. Regulatory Barriers: The Nuclear Regulatory Commission (NRC) has stringent rules about launching nuclear material. The scientists are working with the NRC to develop a Launch Acceptance Review that will streamline approvals while ensuring public safety.

3. Political and Public Perception: The Cold War legacy still looms large. The article documents a recent public poll where 57% of respondents expressed concerns about launching nuclear reactors. To win hearts and minds, the team is emphasizing that the reactor is a sealed unit that cannot release radiation into the atmosphere under any failure scenario—an advantage that many of the early advocates underestimated.

Industry Synergies

The SpaceX Starship project, which aims to launch a reusable, fully liquid‑propellant spacecraft, has already made headlines. While the company has not publicly committed to a nuclear version, the Space.com piece notes that several SpaceX insiders have joined the nuclear advocacy group. The synergy is clear: a nuclear Starship could deliver a crew to Mars in under four months while also enabling the in‑orbit refueling of cargo missions that bring heavy scientific equipment.

Similarly, Blue Origin and Boeing are exploring partnerships with universities to develop reactor‑propulsion testbeds. The article links to a recent Blue Origin press release announcing a joint venture with the University of California, Berkeley, to design a compact reactor core for sub‑orbital test flights.

Toward a New Era of Exploration

The Space.com article’s narrative is optimistic but measured. It argues that nuclear propulsion is not a silver bullet; it requires multilateral cooperation across government, academia, and private industry. The proposed Mars Direct 2.0 strategy—an update to Robert Zubrin’s original concept—leverages a nuclear first‑stage booster to launch a conventional payload‑only vehicle that will carry the crew and supplies to Mars.

If the scientists’ roadmap proves accurate, we could see a test flight of a nuclear‑powered sub‑orbital vehicle as early as 2025. By 2035, the first crewed Mars mission could launch, setting humanity on a new trajectory for interplanetary exploration.

Bottom Line

The dream of sending humans to Mars has taken a concrete step forward. Nuclear rockets—once the stuff of speculative science fiction—are now backed by real engineering studies, proven technology, and a coalition of scientists who are ready to tackle the challenges head‑on. While political, regulatory, and safety hurdles remain, the potential payoff—a faster, cheaper, and safer journey to Mars—makes the case for a nuclear renaissance in space propulsion compelling. As the Space.com article concludes, the next decade could see the first rocket that carries not only a payload but the very heart of a human quest: a small, sealed reactor that lights the way to the Red Planet.