Tonight at 6:27 p.m. EDT, SpaceX will attempt to launch a satellite into orbit with a previously flown Falcon 9 rocket. It's the first time since the space shuttle program that a “flight-proven” launch system will have sent an object into orbit, and heralds the next era in spaceflight. The launch will happen from Kennedy Space Center in Florida, at launch complex 39A—a location that's no stranger to history, having previously been used for the Apollo moon missions and later the space shuttle. The rocket has 2.5-hour launch window, and will carry an SES-10 communications satellite for SES, a Luxembourg-based satellite company. You can watch it live beginning about 6 p.m.

HISTORY MADE

It was never a given that the 15-year-old SpaceX, founded by Elon Musk, would make it as far as it has. Starting an aerospace company to compete with Lockheed and Boeing was always a long shot, but the notion of landing rockets was the stuff of science fiction, let alone landing them vertically on an autonomous barge in the middle of the ocean, following an orbital launch at speeds greater than Mach 5.5. Then SpaceX started doing just that, repeatedly, and today SpaceX has seven previously flown rockets waiting for reuse.

To put this in context, every single orbital, cargo-bearing rocket used before the founding of SpaceX—except for those that blew up on the launch pad or otherwise went horribly wrong—was dropped into the ocean after launch. That's thousands of rockets confounding fish around the world.

For all the commercial and engineering triumphs of Elon Musk’s science fiction proving ground, however, one challenge has remained unattempted: to take one of those rockets used previously on a spaceflight, and to light that candle a second time. This has never been done before. The closest we’ve had was the space shuttle, which isn’t exactly a 1:1 comparison. The latter was one part of a much larger launch system, and at a billion dollars per launch, the shuttle wasn’t exactly a bargain.

Today it costs $62 million to launch a spacecraft with a Falcon 9 rocket. (They put it right there on their website.) Reuse could take launch costs down to as low as $40 million. This might not sound like much of a discount, but ULA charges approximately $109 million to launch something with an Atlas V rocket. For the same price, then, a company could buy two launches from SpaceX, or spend a lot more on research, development, and engineering of a spacecraft or constellation. The lower the barrier of entry to space, the more industries that can get involved.

“When SpaceX successfully launches a rocket with a reused booster, it will signal to mission operators and the financial markets that space industry margins are growing and that launch frequency will increase,” says Amir Blachman, the VP of Strategic Development for Axiom Space, a firm that specializes in building space stations and developing low-Earth orbit. “It is a signal that the upward inflection in space-generated revenue is happening now and not sometime in the far off future.”

Blachman tells mental_floss that this will also accelerate the number of human launches to the International Space Station and beyond. Elon Musk’s long term goal for SpaceX is to colonize Mars. Such a project will require scores of launches to move people and equipment from this planet to the next.

THE CARE AND FEEDING OF A ROCKET

Preparing a Falcon 9 rocket for a second launch involves its partial disassembly, inspection, refurbishment, and, again, inspection. The rocket was put through a static fire test earlier this week, which involves filling it with fuel bringing the rocket engines briefly to full blast, with the rocket still secured to the ground. That the same rocket engine will be used in this launch is yet another achievement. Previously, only the space shuttle main engines were reused. (Today they are being refurbished for use in NASA’s gargantuan Space Launch System rocket.) Otherwise, like the rockets that carry them, the engines generally end up at the bottom of the ocean.

With tonight’s launch, successful or otherwise, and the attendant lessons learned every step of the way, from initial assembly through launch, refurbishment, relaunch, and landing, the company can move rapidly toward total reusability. The long term goal at SpaceX is to engineer rockets that require almost no refurbishment at all before reuse.

As for the rocket’s payload, 32 minutes after launch, it will separate from the Falcon 9 and enter a geostationary transfer orbit. The rocket, meanwhile, will begin its descent and attempt its second landing ever, on “Of Course I Still Love You,” a drone ship in the Atlantic Ocean. (The barge is named for a starship in the sci-fi novel The Player of Games, by Iain M. Banks.) The rocket was previously flown in April 2016, for a resupply mission to the International Space Station.