This afternoon, six fridge-sized satellites will launch into space from South America on board a European rocket. The flight will spark the beginning of a planned mega-constellation that will total 650 satellites aimed at creating global internet coverage from space.

The satellites belong to Virginia-based company OneWeb, which has been developing this mega-constellation for the last five years. The company’s vision is to use these satellites to provide internet connectivity practically anywhere in the world, with very minimal delay in signal. It’s a dream that has yet to be realized. Current satellites that provide internet from space are situated over the equator, 22,000 miles high — a long distance that makes transmission and connectivity slow.

“from the point of view of our satellites, you’re essentially standing still.”

But from a vantage point of about 750 miles up, the planned OneWeb satellites will orbit from pole to pole in a synchronized dance over the Earth, transmitting signals to ground-based terminals. In theory, at least one satellite will be in sight of a terminal at all times, providing seamless coverage to most locations on the planet. The terminals, in turn, will transmit WiFi, LTE, and 3G signals to devices like cellphones and computers, even on the move.

“No matter if you’re in a car or you’re walking or you’re in a plane, from the point of view of our satellites, you’re essentially standing still,” Adrian Steckel, OneWeb’s CEO, tells The Verge. “And it’s handing off your signal from one satellite to another.” Steckel also envisions bringing coverage to schools and local governments in remote areas, where laying fiber is too expensive or just not viable.

It’s a grand project not unlike that of aerospace rival SpaceX, which also plans to provide global internet coverage through a giant satellite constellation. SpaceX’s project, known as Starlink, is even larger in scope, though. The company wants to put up two constellations, equaling 12,000 satellites in total. In February of 2018, SpaceX launched the first two test satellites for Starlink in order to lay claim to part of the radio wave spectrum — the range of frequencies SpaceX can use to communicate with its satellites. With today’s launch, OneWeb will do the same.

It hasn’t been an easy road for OneWeb, and there’s still quite a long way to go. In 2017, the Federal Communications Commission approved the company’s plans to launch this first mega-constellation, but the launch of its first test satellites was periodically delayed. Once the initial six satellites launch this evening, OneWeb hopes to start launching the bulk of the constellation this fall. The plan is to send the satellites up in batches of 36 on top of Soyuz rockets operated by Arianespace, the same rocket that’s flying the satellites today. A total of 21 Soyuz launches will be needed to complete the first constellation.

“Coordinating all this stuff, bringing it together, has been incredibly complicated,” Steckel says. “But we have a lot of great partners, and I’d love to say getting all these groups of people has been easy work, but it’s been years and a lot of effort.” The company is backed by SoftBank, Richard Branson’s Virgin Group, Qualcomm, and Airbus, to name a few. Steckel won’t say the exact cost of the constellation, but he notes the company has already spent more than $2 billion on the project.

“Coordinating all this stuff, bringing it together, has been incredibly complicated.”

Steckel says the initial 650 satellites will be more than enough for global coverage, but the company intends to launch even more spacecraft in the future. The capacity of the original constellation is going to be used up quickly by OneWeb’s signed customers, Steckel says, and they’ll need even more satellites to reach more people.

“As more and more people sign up, you need to add capacity,” Steckel says. “Think about our satellites as flying base stations. We will need to put out more of them, and the second generation will be more advanced than the first one.” Eventually, the plan is to put an additional 1,330 satellites into space at various altitudes, bringing the total number of OneWeb satellites to 1,980. The company is still waiting on approval from the FCC for this next class of spacecraft.

With companies like OneWeb and SpaceX developing these epic multi-billion-dollar constellations, experts are concerned about the effect these programs will have on the space environment. Right now, there are about 1,800 operational satellites in orbit. These new endeavors could quadruple that number, significantly raising the risk of spacecraft running into each other in orbit. And a recent study from NASA argued that 99 percent of these satellites will need to be taken out of orbit once they’ve completed their missions — a lifetime of around five years — or else the risk of in-space collisions will drastically increase.

experts are concerned about the effect these programs will have on the space environment

OneWeb’s plan is to lower the altitude of the spacecraft after about five years, bringing them closer to Earth where they’ll be dragged down to the planet and burn up in the atmosphere. “You will have to de-orbit them in a controlled way and we’re very focused on that,” says Steckel. He also notes that SpaceX recently adjusted the planned altitude of the bulk of its Starlink satellites, putting them on a different plane than the OneWeb satellites — a change that will help the spacecraft avoid each other.

For now, OneWeb will have just six satellites in orbit if today’s launch goes well. The batch is slated to fly on Arianespace’s Soyuz rocket out of French Guiana at 4:37PM ET. Once the probes make it to orbit, OneWeb will be testing them to see how they fare in space. The company has ground stations in Norway, Canada, and Italy, which will be used to communicate with the satellites. Data gathered from the tests may be used to improve the next round of satellites launching later this year.

Of course, everything hinges on this first launch, and Steckel says the company is eager to see the satellites fly. “We’ll feel a lot better on Thursday morning,” he says.