For decades, the high cost of space launch has been the greatest limiting factor on the number and size of space missions. Recently commercial rockets have reduced launch cost to about one-twentieth of the space shuttle cost. This provides opportunities for a matching reduction in the cost of space systems and more and more massive missions. High launch costs greatly increase the cost of developing space systems, since the need to reduce mass forces the use of light materials, high packaging densities, and fragile structures that are difficult to manufacture and test. Lower launch costs allow the use of more robust and well tested off-the-shelf systems. Increased mass can be used to increase single string reliability and also to provide spares and redundancy. A crewed mission can benefit from lower launch costs by using mass to provide more accepted fully hydrated food, additional hygiene water, laundry, radiation shielding, and even artificial gravity. The crew can be made healthier, safer, more comfortable, and more productive. Lower launch cost makes every space activity easier, whether it is science, human exploration, commercial including communications, weather, surveillance, and geo-positioning services, or the defense of similar military services. Most of the solar system is empty space, with the energy of the sun’s radiation passing through to the cold of deep space. The missing mass needed to support human activities is now much easier to provide.