Kraków start-up teams up with US nuclear firm to fly to the moon A Kraków start-up has teamed up with a US nuclear company to carry out an unmanned mission to the moon to extract a rare and valuable isotope of helium thought to be the key to the production of pure nuclear energy. Solar System Resources Corporation from Kraków, an innovative space mining start-up, intend to extract and bring back 300kg of the rare isotope to Earth by 2028 with the US based Nuclear Corp, a nuclear company which has participated in advanced projects for the American army and government.