Update 5-23-2019, 3:30 pm EDT: After delaying the Starlink launch twice, SpaceX will attempt to launch the satellites on Thursday night. The launch window opens at 10:30 pm EDT. A link to the livestream is provided below.

Internet access is so ubiquitous in the United States and Western Europe that it has spawned an entire cottage industry to help people disconnect. Yet for roughly half the world’s population, this level of connectivity is simply unfathomable. Nearly 4 billion people haven’t been online once in the past three months—the UN’s comically low threshold for counting someone as an internet user—which means they miss out on the many social, economic, and educational benefits that come with an internet connection.

Entrepreneurs in Silicon Valley quickly realized that connecting the world presented a huge business opportunity, one that could be wrapped in feel-good humanitarian language to boot. The underwhelming result? Internet balloons and internet drones. There was another idea, though, that was equally bold and perhaps more realistic: internet satellites. Thousands upon thousands of internet satellites.

On Wednesday evening, SpaceX is expected to launch 60 internet satellites into low Earth orbit. They will be the first members of its satellite megaconstellation, Starlink. The 500-pound “flat panel” satellites will be boosted to nearly 275 miles above the Earth by a Falcon 9 rocket, at which point they will use their onboard ion thrusters to reach a final orbital altitude of about 340 miles above the Earth.

These satellites are still considered “production design” by SpaceX. They won’t include many planned features, including the laser crosslinks that will allow the satellites to communicate with one another while in orbit. But they represent the first big step toward the company’s long-range plan. By 2027, SpaceX plans to have as many 12,000 Starlink satellites in orbit beaming high-speed internet to tens of millions of customers around the planet.

The history of satellite internet, however, is defined by failure, including one of the largest corporate bankruptcies in history. This was a reality Elon Musk candidly acknowledged to reporters ahead of the Starlink launch. “No one has ever succeeded in making a viable low Earth orbit communication constellation right off the bat,” Musk said. “I do believe we’ll be successful, but it is far from a sure thing.”

Failure can come in many forms. SpaceX will face stiff competition from other satellite operators and terrestrial broadband providers, huge regulatory hurdles, and at the end of it all may find that the demand for satellite internet just isn’t what it thought it would be. In short, entering the satellite broadband market is a big risk. Yet SpaceX might not have another choice. Musk has made it clear that SpaceX’s ultimate mission is to send humans to Mars, but the price tag on that will be astronomical. A 2014 NASA study put the cost of a human mission to Mars in the ballpark of $220 billion. SpaceX’s revenue from launch contracts alone, which Musk said shakes out to about $3 billion annually, is unlikely to get anyone to the Red Planet.