Space is a great place, a wealth of resources and adventure to take. So, if you are the imaginative type, Earth provides almost limitless possibilities for humanity's expansion.
Of all the people who weigh in on how we get to space, what are we going to do there, and on what timeline is calling the voice of two billionaires – Elon Musk and Jeff Bezos – highest and most often.
Musk, the techmagule behind Tesla and the founder of SpaceX (a now-$ 33 billion rocket company), wants to establish a permanent, self-supporting city on Mars.
However, Bezos, founder and CEO of Amazon, has its own space carrier, Blue Origin. Her work so far focuses on building a "road to space" with new rockets that could ultimately pave the way for floating colonies.
These two grandiose dreams are markedly different, and their owners occasionally save on the details. But it is not unthinkable that one day the two companies will work together in the room.
Here's what Musk and Bezos have said about their ambitious visions, and how they are different, yet surprisingly similar.