Elon Musk, founder of SpaceX, wants to put American astronauts back in space. He wants them to go there aboard American-built rockets powered by American-built rocket engines.

And if he succeeds, American taxpayers could save billions of dollars.

Last month, SpaceX, the "space exploration" firm that Elon Musk built, released a video documenting its progress toward building our first reusable spacecraft since NASA canceled the Space Shuttle program. The video shows SpaceX's Falcon 9 rocket descending to Earth after boosting a payload into orbit -- firing its reentry boosters, extending its landing gear, and then softly landing back on "Earth". Actually, as intended, the Falcon 9 rocket landed in water, so upon "landing," it promptly tipped over and sank...

It was a pretty impressive accomplishment, and you can watch it all happen right here:

Grasshopper evolves
Last month's soft landing represents the next step in the evolution of SpaceX's experimental Grasshopper program into a new Falcon 9R (for "reusable") rocket. Standing 10 stories tall, Grasshopper featured a first-stage Falcon 9 rocket powered by a single Merlin 1D engine, bound by a steel support structure, and standing perched atop four steel and aluminum landing legs with hydraulic dampers.

Falcon 9R will be bigger than Grasshopper, featuring a full-size first-stage rocket, powered by a full complement of nine Merlin rocket engines.

SpaceX Grasshopper at rest. Photo: SpaceX.

Operating off a launch pad in Texas, Grasshopper spent several months from 2012 to 2013, rocketing to higher and higher heights in successive test flights, and landing back on its launch pad each time. Grasshopper even made the job harder for itself at one point, shifting horizontally away from its pad after launch, then self-correcting and still landing back on home base.

Now, SpaceX's almost-successful landing of the mission-ready (and USAF certified) Falcon 9 shows that the project that Grasshopper began, is evolving into something nearly ready for prime time. So why is this important?

An end to disposable spacecraft
The successful, controlled reentry and landing of SpaceX's Falcon 9 shows us how the Grasshopper experiment is morphing into a true replacement for the now defunct Space Shuttle program. This is key for U.S. taxpayers.

Ever since the Space Shuttle stopped running, the U.S. government has been sending its satellites into space aboard "disposable" spacecraft. Tens of millions of dollars are spent building rockets from scratch. After launch, those rockets are jettisoned to burn up in the atmosphere.

Want to launch another satellite? First, you've got to build yourself another rocket.

Reintroducing the reusable spacecraft
A "reusable" Falcon 9 would put an end to this practice. It would permit a rocket, once built, to be launched, refurbished, refueled, and launched again. According to Musk, the rocket fuel needed to put a satellite in orbit accounts for only 0.3% of the cost of a space launch. Accordingly, adding extra fuel to permit a rocket booster to make a controlled reentry and landing should only add 0.3% to the cost of a space launch.

Though, 75% of the cost of any rocket launch can be attributed to building its first-stage rocket. By making this first-stage rocket reusable, instead of disposable, Musk thinks he can drop the cost of a space launch by 75%.

Total potential savings: 75% minus 0.3% equals 74.7%.

SpaceX wants to save you some money
Now, the math is actually a bit more complicated than that. Additional costs will be involved in:

  • building a bigger rocket, or adding rocket boosters, to carry the reentry fuel
  • buying even more fuel to lift the necessary reentry fuel into space
  • the costs of recovering and reconditioning rockets for reuse

But you get the point: Even with all the added costs attendant on running a reusable rocket operation, the savings here could still be significant.

How significant? In testimony before Congress back in March, Musk suggested that at the very least, his firm can save taxpayers about two-thirds of the cost that Boeing (BA 4.24%) and Lockheed Martin (LMT 5.63%) currently charge to launch government satellites into space. Over the next 15 years, that could add up to about $50 billion in savings.

With savings like these, the rocket that used to be called "Grasshopper" could one day save taxpayers some serious green.

One small hop for Grasshopper, one giant leap for taxpayers. Photo: SpaceX.

Editor's note: A previous version of this article was misleading about whether the SpaceX rocket's "wet landing" was intentional or accidental. The Motley Fool regrets the confusion.