New focus, new possibilities

“The studies show clearly what is possible and how well it all fits inside ESA’s long-term strategy 2040,” explains Valère Girardin, ESA’s programme manager for the study, “We now better understand what technologies are missing and what to target in research and development.”

All studies conclude the use of nuclear-powered propulsion opens new paths for exploration: there are destinations or missions that are simply unattainable with traditional spacecraft propulsion.

Safety is no problem, all designs rely on unirradiated uranium that is not activated until in orbit, meaning no high radiation, even in case of launcher explosion, splashdown to the ocean or other launch failure. The uranium’s chain reaction is only activated –once in space and safely in orbit, until then the uranium is inert.

The tipping point for spacecraft designs is around the 100 kW power level, below that power production a solar-electric propulsion system relying on solar panels is ideal, above that a nuclear-electric design rules. All consortia foresee two launches, one with the payload, and one with the spacecraft that would dock in Earth orbit continue their voyage in space together.

“These studies are kick-starting progress and putting nuclear-powered European spaceflight on the roadmap,” concludes Valère, “the technologies we need fit well with ESA Member States industrial capacities and the political will is gaining traction, we now have a clearer target to work towards.”

The next step is to increase knowledge and experience of each system separately, the nuclear reactor, the radiation shield, the energy conversion system, the thermal heating and cooling system and the electric thrusters. ESA has formed a nuclear propulsion working group that will oversee the design and building of sub-scale hardware and tests in laboratories.