NASA's Three Stages:
1. Earth Stage - This is our current stage that we've been occupying throughout the entire era of manned space exploration. During this stage we are focused on conducting research aboard the International Space Station (ISS). New emerging technologies will continue to provide critical contributions, including 3d printing materials and being able to grow food in space
2. Proving Stage - The second stage involves NASA learning how to conduct sophisticated operations in a deep space environment while still allowing crews to return to Earth in just a few days. These operations would mostly take place in cislunar space, the region between Earth and the Moon. During this stage we will be testing critical new capabilities, including asteroid redirect attempts and a deep space habitation facility.
3. Earth Independence - During this stage we will begin human missions to Mars as well as other planets. At this point humanity's expansion will undergo a transition, and we will see people beginning to live and work within commuting distance of Mars. We will begin harvesting resources on the red planet in order to create key elements needed to survive, including oxygen, water, and some type of fuel.