A Falcon 9 rocket launch. SpaceX/Flickr (public domain) Rockets are as awe-inspiring as they are wasteful.

These marvels of engineering typically become trash soon after launch, either by sinking into an ocean or crashing into a desert. It's a big reason why sending anything to space requires unfathomable sums of money.

But SpaceX, founded and run by tech mogul Elon Musk, is working hard to end this wasteful tradition. Parts of its Falcon 9 rockets — and bigger, soon-to-launch Falcon Heavy system — can lift off, land, and be reused, ostensibly within 24 hours.

"This is going to be a huge revolution for spaceflight. It's been 15 years to get to this point," Musk said on March 30, minutes after a previously-flown Falcon 9 rocket booster helped launch a satellite into orbit for the first time. SpaceX hopes to fly its next used rocket on June 25, as part of a "weekend doubleheader" of two separate launches within 48 hours.

Musk's goal is to drastically lower the cost of access to space with reusable, orbital-class rockets, thereby making it as cheap as possible to launch people to Mars. So far, developing this capability has cost SpaceX about $1 billion.

This raises a major question: How quickly could the company pay off its super-size investment?

To estimate an answer, Business Insider has explored a few scenarios, which are detailed below.

Andy Kiersz contributed analysis to this post.