After humanity establishes a new economy in orbit above Earth, builds a self sustaining moon base and off world Martian colony it will need to reach out even further into deep space.
Where will we go?
There's now a national ambition to put boots on Martian soil and begin colonization of the red planet as soon as possible, but humanity's expansion into space doesn't have to stop there.
To get to Mars, NASA plans on testing important technology on the surface of the moon including mining robots capable of extracting natural resources and robots assigned to build habitats from 3D printed material.
It's called in-situ resource utilization and it will allow astronauts to live off the land on Mars, according to NASA administrator William Gerstenmaier.
"Robotic missions to the moon could inform our Journey to Mars and how we might use available materials to generate water, oxygen and fuel in space."
"New technologies, some of which have nothing to do with space, like self-driving cars and waste-recycling toilets, are going to be incredibly useful in space, and are driving down the cost of a moon base to the point where it might be easy to do."
Venus offers one option for human explorers and NASA has already designed habitats capable of floating in the planet's acidic clouds. The world is closer than Mars meaning it's easier to get to, has Earthlike gravity, and a heavier atmosphere that could offer better protection to interplanetary setters than the red planet.
There's also the massive asteroid belt that sits between Mars and Jupiter. The dwarf planet Ceres is the largest object in the asteroid belt and could serve as a base of operations for miners looking to extract valuable resources from nearby space rocks.
Scientists think Ceres has more water, in the form of ice, below the surface than all the fresh water on Earth combined and its relatively higher gravity, compared with other asteroids, make it a good location for a mining base. Ceres doesn't have an atmosphere and no one could live unprotected on its surface, but water found underneath its surface could be sold as rocket fuel to passing spaceships.
Then of course there is space itself. Using metals, water, and carbon mined from asteroids it would be possible to build habitats situated nowhere, but in space itself.
By attaching engines to the newly built habitats you would have humanity's first space cargo haulers capable of shipping goods between planets, as Mathematician Robert Walker writes in Science 2.0.
"We tend to think that the place to look for resources for colonization must be the surfaces of planets. But there are abundant resources in space too."
Far out in space past the asteroid belt there lie the giant planets of Saturn and Jupiter, both of which have moons that might just be suitable for human colonization given the proper tools.
Saturn's moon Titan might be the least hostile place for human life in the outer solar system. Brave explorers living on Titan wouldn't even need a spacesuit, just a breathing mask and protection from the cold; the heavy atmosphere, 1.5 that of Earth, would make visitors feel like they were standing on the bottom of a swimming pool.
Titan is also home to methane lakes, which could contain alien life and water trapped in ice rocks that could be mined for trade, as NASA astrobiologist Chris McKay told Space.com.
"If you were in the outer solar system and you had to make an emergency landing, go to Titan."
The best place to establish a human outpost would be close to the tiger stripes, cracks in the moon's surface near the south pole, where giant fissures spew frozen particles. Strangely, the area emits more heat than Yellowstone National Park on Earth, an energy level recorded at 15.8 gigawatts of power, Cassini project scientist Linda Spilker told Space.com.
"If you build your base fairly close to the tiger stripes, you might have a source of heat you could tap into."
No discussion about colonizing the solar system would be complete without talking about Europa, famously referred to in the movie 2001: A Space Odyssey.
Long considered the best place to look for alien life, any human outpost on Europa would need to be specially located on the side of the moon that leads its orbit around the planet to avoid being showered with deadly radiation from Jupiter.
Europa residents would also need to worry about icequakes and giant plumes of water that violently shoot out from the icy surface.
It would probably be impossible to live on Neptune, because it's a gas giant, but human explorers could possibly establish an outpost of the surface of its moon, Triton, if they managed to avoid the geysers of nitrogen gas that occasionally erupt.
With Elon Musk busy at work on his Interplanetary Transport System it's only a matter of time before humans push out into deep space and colonize the solar system. Who knows what we'll find when we get there.
[Featured Image by draco-zlat/iStock]