On a Scenario for Sustained Human Space Exploration

The next steps in human space exploration could be three missions: (I) return to the Moon with sustained habitation; (II) first human travel to Mars; (III) possibly a New International Space Station (NISS) with both habitation and spacecraft assembly facilities. The three missions I to III are considered from the points of view of technological challenge, safety of the crew, rescue in case of incident and resources required for implementation. It is argued that the safest sequence, compatible with likely available resources and mature technology, is: (a) first the Mission I of return to the Moon with sustained habitation, which is the focus of ongoing international activities led by the U.S. and China; (b) next an NISS that could support a major large scale expansion of lunar habitation, allowing assembly of a family of spacecraft, including an emergency moon recue service; (c) the experience gained with sustained lunar habitation combined with the spacecraft assembly capabilities of the NISS, would provide the best background to the more challenging human exploration of Mars, in a sustained and safe manner. An important safety aspect of the Mars mission, due to its long duration, is protection against solar flares and outbursts, for which passive shields may not be sufficient, due to excessive weight and volume; a novel ‘active’ protection system against high-energy radiation and high-speed particles from solar outbursts is proposed, consisting of a magnetic capsule between the spacecraft and the sun, creating an ‘artificial ionosphere’ protecting the spacecraft and crew, during the periods of high solar activity.