In Space, Ignorance is Not Bliss

The title of the Hogan Lovells event last week was "Beyond the Moon: Nuclear Power and NASA’s Ignition Program." The uninformed or uninitiated might have thought that NASA's Ignition Program would represent the introduction of nuclear technology to space, but the reality is something quite different.

Nuclear energy has been used to power spacecraft and landers since the 1960's. The most common device used to derive nuclear energy in space flight is the radioisotope thermoelectric generator (RTG), but radioisotope heater units (RHU) have also been widely employed as have fission reactors. According to Wikipedia, RTGs and RHUs produce heat by spontaneous decay of plutonium 238, converting the heat to electricity using a thermoelectric generator. Miniaturized fission reactors produce heat via controlled fission of highly enriched uranium 235 and convert it to electricity using a thermionic converter.

Wikipedia tells us that the U.S. has launched 32 RTG-equipped missions, 1 RHU-equipped, and one with a fission reactor. The former Soviet Union has notched 38 missions with fission reactors, 4 with RTGs, and 3 with RHUs. China has had 4 RHU-equipped launches and India has had one such launch.

NASA's Ignition Program consists of a wide range of elements including Moon and Mars missions, low-earth orbit stations and observatories, and streamlined processes for developing and launching missions with their related supply chains and international collaborations. Nuclear energy figures prominently both for powering permanent moon bases and ultimately for propulsion. 

Elements of the Ignition Program include:

• Standardizing the Space Launch System (SLS)

• Looking beyond Artemis V with an emphasis on commercially procured and reusable hardware to enable more frequent crewed missions

• A phased approach to building a lunar base in cooperation with multiple international partners

• The preparation for a next generation international space station in low-earth orbit

• Launch of the Nancy Grace Roman Space Telescope (Fall 2026)

• Dragonfly mission to launch a nuclear powered octocopter in 2028, arriving at Saturn's moon Titan in 2034

• Launching ESA's Rosalind Franklin Rover to Mars also in 2028 including NASA's Mars Organic Molecule Analyzer (MOMA) instrument

• Accelerated Commercial Lunar Payload Services (CLPS) targeting up to 30 robotic lunar landings starting in 2027 including rovers, hoppers, and drones, and the VIPER rover and LuSEE-Night mission

• A future mission to deliver the Mars Telecom Network

• The launch of the Space Reactor-1 Freedom, the first nuclear powered interplanetary spacecraft, to Mars before the end of 2028

• When it reaches Mars, SR-1 Freedom will deploy the Skyfall payload of Ingenuity-class helicopters

It is SR-1 Freedom that will, in NASA's words, "establish flight heritage nuclear hardware, set regulatory and launch precedent, and activate the industrial base for future fission power systems across propulsion, surface, and long‑duration missions."

The general public's ignorance of the details of the wide range of space missions unfolding around the world is to be expected especially given the secrecy surrounding defense- or security-centric missions. This lack of understanding can become a problem, as in the case of the Cassini-Huygens launch nearly 30 years ago.

A lawsuit was filed by the Green Party and experts (notably Michio Kaku) were recruited to speak out in opposition to the launch of the probe which carried 73 pounds of plutonium 238. Opponents were concerned over the potential for a failure of the rocket at launch or a collision with the Earth during its gravitational slingshot maneuver two years later. Though unsuccessful, the opposition was worrisome in the context of narrow launch windows that could have catastrophically altered the Cassini-Huygens mission.

Calculations regarding potential human exposure to radiation form a failure at launch or during the slingshot maneuver showed an extremely low risk and NASA engineers and executives took pains to point out that the on-board nuclear device was essentially a nuclear battery to power the craft during its sojourn in a portion of the solar system where the use of solar panels for power would be impractical.

The rest of the tale of Cassini-Huygens is one of monumental scientific discoveries and observations culminating in the spacecraft being crashed into Saturn - a mission conclusion that was also met with resistance and protest. It is worth noting that the Cassini-Huygens probe was launched on a Titan IV rocket. The successful launch was followed, months later, by three consecutive Titan IV failures including one rocket that was remotely destroyed at 17,000 feet. Overall, the Titan IV ended its service with a near 90% success rate.

Google tells us that launch protocols for spacecraft equipped with nuclear technology require:

• Inactive at Launch: Space reactors are strictly launched in a non-operational, "cold" state to prevent any accidental radiation release or chain reactions before the spacecraft reaches a stable, high Earth orbit.

• Robust Containment: The nuclear materials are sealed in highly reinforced, impact-resistant, and heat-resistant modules (e.g., carbon-composite and iridium clads) designed to survive a potential launch explosion or atmospheric re-entry intact.

• Multi-Agency Approval: Every nuclear space mission requires rigorous environmental impact statements and specific presidential/White House launch approval.

Meanwhile, back at the Hogan Lovells event, Zeno Power talked about its radioisotope stirling generators using radioactive isotopes such as strontium-90 and americium-241 as fuel. The company says these materials naturally decay, they emit heat that can be used directly or converted into electricity using thermoelectric generators or a Stirling engine. Zeno's Senior Vice President A.C. Charania further noted their RSGs are capable of generating 1-100s of watts of power, recycle nuclear waster into fuel, and run continuously for up to 5 years in any environment.

In essence, the space industry is not entering the nuclear age, it is merely expanding its exploitation of nuclear technology which began more than 60 years ago. What's new is the potential to use nuclear energy for propulsion which will no doubt be approached with appropriate degrees of caution.

ABOUT THE AUTHOR

Roger Lanctot is president of the Mobile Satellite Users Association and CEO and Founder of StrategiaNow Consulting. Roger draws on 30+ years’ experience in the technology industry as an analyst, journalist and consultant. Roger is a graduate of Dartmouth College. His 190,000 followers on LinkedIn reflects the influence of his insights and perspectives on automotive and transportation technology, policy, and strategy.