Paul Allen, billionaire earthling and co-founder of Microsoft, has long been obsessed with space, and his pet project Stratolaunch Systems is beginning to bear fruit. The Washington Post reports that Stratolaunch, shaping up to be the world's largest airplane, is now 76 percent assembled—no small accomplishment given the sheer size of the beast, a twin-fuselage behemoth expected to weigh (payload included) 1.3 million pounds, be powered by six 747 engines, boast landing gear with 28 wheels, and house 60 miles of wiring, among other feats.

But to what end? Well, to shuttle rockets up to 35,000 feet and launch them into low Earth orbit. Oh, and to do this by the end of this decade.

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That's right: Someday it may actually be routine to transport people and objects in the couple-hundred-miles-above-Earth section of space, and Allen is willing to bet big on it.

"When such access to space is routine, innovation will accelerate in ways beyond what we can currently imagine," he says in a statement. GeekWire says walking into the hangar at the Mojave Air and Space Port "feels as if you're stepping into the Starship Enterprise's construction zone." No wonder, given the plane's 385-foot wing, which would put the aircraft on par with the fictional spaceship.

Allen isn't saying how many millions he's put into it so far, but his head of operations says this isn't just a big plane, but a big idea—and not a billionaire's "vanity project." The Los Angeles Times, meanwhile, rounds up some of the other big, or just simply bizarre, aircraft built in Southern California over the years, including Howard Hughes' Spruce Goose seaplane.

(See why Allen has been putting money into coral reef, too.)

This article originally appeared on Newser: Paul Allen's Massive Space Project Is 76% Done