NASA has been working for more than a decade on its next generation rocket setup designed to send robotic and ultimately human missions further into the solar system than ever before. 

But the quick advances in revolutionary, recyclable rockets made by Elon Musk and SpaceX in just the past few years could quickly make NASA's plans obsolete, perhaps before it is even able to carry out its first mission.

NASA hasn't regularly used an in-house launch system since the Space Transportation System, better known as the Space Shuttle, which flew for the last time in 2011. Since then, NASA has had to rely on Russian spacecraft to get astronauts to the space station and a variety of private launch providers, including SpaceX, for its other missions. 

When the end of the shuttle program was announced in 2004, the focus turned to again building gigantic, Saturn-like rockets that could fling bots and astronauts into deep space. After one false start called the Constellation program, the Space Launch System (SLS), came about in 2009 with the promise of being the most powerful rocket ever built.

But the SLS is continuing to slip while SpaceX and its ambitions are soaring.

Target dates for the debut of SLS have been perpetually pushed back for years now, and the latest reports indicate that SLS may not be ready for its first scheduled launch, expected to happen by June 2020. 

Meanwhile, SpaceX has dialed in a rocket system that is both significantly cheaper and reusable while NASA has spent a decade and billions on SLS without even testing it once.

Of course, all of SpaceX's commercial missions thus far have flown on the much smaller Falcon 9 rocket. But in February the company had a remarkably successful test launch of its Falcon Heavy rocket, the most powerful launch system to blast off from U.S. soil since the Saturn V that took astronauts to the moon.

By some measures Falcon Heavy is about 90 percent as capable as SLS will be, and was developed at a tiny fraction of the cost.

But SpaceX is already at work building its next big thing, the BFR (for "Big Falcon Rocket" or "Big F***ing Rocket"), which it hopes will one day take human passengers around the world, to the moon and Mars. It's also likely to be nearly as powerful and far more practical and economical than SLS.

Adding insult to injury, Elon Musk says we could begin to see limited test flights of BFR as soon as 2019, before SLS gets off the launch pad.

Of course, both SpaceX and NASA are notoriously bad at meeting their own timelines. Musk once hoped to make it to Mars by 2010 and Falcon Heavy's debut was a few years late. But SpaceX has still up-ended the space launch industry in just a few short years by introducing reusability and developing Heavy for less than a billion dollars.

We may not see either BFR or SLS get off this planet by 2020, but if I had to bet which we'll see fly first, I certainly wouldn't place my money on NASA's Space Launch System. In fact, I'm not sure it will ever fly at all if SpaceX's BFR gets off this planet first, proving itself to be the better and cheaper option for the future of space exploration.