Long-duration missions with limited solar exposure need a reliable power source to operate. This makes nuclear power sources (NPSs) an attractive alternative to solar energy for such missions. The implementation of the ESA Safety Policy on the Use of Nuclear Power Sources by the European Space Agency’s Independent Safety Office (ISO) provides a framework for ensuring the safe use of NPSs and sets a standard for future ESA missions. This article provides an overview of how the ISO is implementing the policy in the development and operation of the Argonaut mission, which serves as a valuable case study for understanding the practical application of the ESA safety policy and the importance of ensuring the safe use of NPSs in space.

A “resurgence of interest” in nuclear propulsion for space missions is described in a new article authored by science writer Jon Kelvey for the American Institute of Aeronautics and Astronautics’ (AIAA’s) Aerospace America website. The focus of Kelvey’s article is nuclear thermal propulsion (NTP), which, according to the Department of Energy, “could significantly reduce travel times and carry greater payloads than today’s top chemical rockets­—giving humans a great chance of exploring deep space.”

As a spacecraft on a research mission hurtles at up to 100,000 miles per hour toward the surface of a gas giant like Jupiter, the atmospheric gases surrounding the spacecraft turn to plasma, and spacecraft temperatures increase to more than 10,000 °F.