It&#x27;s interesting that ULA has such a different approach to reducing the cost of space exploration, by using fuel from the Moon. For them that makes a lot of sense. The upper stage of a rocket already get&#x27;s pretty much into orbit but currently leaving the spent stage in orbit has no value. If you could cheaply refuel it from the moon though, suddenly it&#x27;s a useful vehicle again.<p>That calculation doesn&#x27;t apply for Spacex though because they&#x27;re planning on making their main booster stages reusable. That would dramatically reduce the cost of putting fuel in orbit directly from earth. No detours to the Moon required. Space technology and the future of space exploration has never been more exciting.