SpaceX's "Grasshopper" rocket SpaceX What would you do if you were a billionaire and wanted to go to space?

The obvious answer: use that money to start a company to help you do just that.

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In recent years, some of the most famous names in tech, like Microsoft's Bill Gates and Paul Allen, Google's Larry Page and Eric Schmidt, and Amazon's Jeff Bezos have been founding and investing in companies that are looking to the stars.

Whether for personal dreams of adventure or for profit, these companies are doing the engineering and basic science needed to get humans into space.

They're also looking at other opportunities that space provides, like access to resources that are hard to get on Earth and the ability to collect information about our planet from a different perspective.