Now, states like California and Nevada have some of the most densely populated cities in the world, as well as the most advanced. Although exploring these places had their risks, as space does, these voyages and adventures changed the world for the better. Space exploration today is no different than exploration was just a couple hundred years ago, and spreading out to other planets may be the greatest choice in human history. Another reason that humans should migrate to other planets is because there is the possibility of rapid scientific discovery that is not possible on Earth. NASA chief scientist James Green said that humans "can move faster than robots and make quicker decisions" (Rao). This means that when humans replace the rovers exploring the Moon and Mars, the speed at which the work is done will increase, leading to increased scientific activity. Discovery of new materials and properties has the potential to greatly improve daily life, and the more planets we move to, the more chances we have to improve the human species