Elon Musk, the billionaire founder of SpaceX, boldly proclaims that his company will begin sending colonists to Mars in a decade. Jeffrey P. Bezos, the founder of Amazon, is using part of his fortune to finance his rocket company Blue Origin, and predicts millions of people will be living and working in space.

As these companies go where no businesses have gone before, they raise questions only fuzzily addressed by the Outer Space Treaty: What are private companies allowed to do in space? Can a company mine the moon or an asteroid and then sell what it has pulled out? How are countries to regulate these businesses?

Internationally, countries have been discussing how to answer these questions. In the United States, Congress has begun tackling regulatory issues. Some warn that if the United States does not set up business-friendly policies and policies, then the start-ups could move elsewhere — including such seemingly unlikely places as Luxembourg.