KOUROU, French Guiana — The first six satellites in a constellation that could one day number close to 2,000 were successfully launched Feb. 27 aboard a Soyuz rocket.

The Russian rocket, adapted for European launch provider Arianespace to operate in the tropical weather that defines the company’s spaceport in French Guiana, deployed the first two satellites 63 minutes after a 4:37 p.m. Eastern liftoff. Arianespace confirmed separation of the last four 97 minutes after liftoff, about 15 minutes after the scheduled separation time due to a lack of ground stations in range of the rocket as it passed overhead.

The launch marked the end of the beginning for OneWeb, a British company founded by American entrepreneur Greg Wyler in 2012 that seeks to make low-cost internet a global phenomenon via a constellation of mini-fridge-sized satellites each weighing roughly 150 kilograms.

The six satellites launched to a 1,000-kilometer orbit, where they will begin a 60- to 90-day test regime that includes orbit raising for another 200 kilometers. OneWeb originally planned to launch the satellites directly into their 1,200-kilometer operational orbits, but tweaked those plans sometime before the launch for reasons that were not immediately clear.

In the weeks preceding the launch, OneWeb also changed the number of satellites from 10 to six, opting to hold some back in the event of an anomaly. Four mass simulators from APCO Technologies of Switzerland substituted for the withdrawn spacecraft.

Soyuz is the most launched space rocket in the world with around 1,900 launches, but has struggled with quality control issues endemic to Russian launchers in recent years. Soyuz rockets have experienced four anomalies in 19 months, including one just five days ago that exhibited what Arianespace CEO Stéphane Israël described as “non-nominal third-stage behavior.”

A review of that mission, which successfully orbited the Egypsat-A observation satellite for Egypt, delayed OneWeb’s launch by one day. None of the four anomalies happened during Arianespace-operated missions.

OneWeb CEO Adrian Steckel, in remarks made this morning, described the company’s first launch as of near-vital importance.

“We’ve achieved a lot, which means we got here, and if today doesn’t go right, it will almost be for nought because it is going to be very complicated to get us back on the right path,” he said.

A major function of these six satellites is to “bring into use” OneWeb’s spectrum, meeting a deadline from the International Telecommunication Union to employ the spectrum or else lose rights to it. Wyler said the deadline is Nov. 29.

Steckel said today was about “getting our spectrum and making what was a project into a company.”

OneWeb has already exhausted more than $2 billion on preparing its low-Earth-orbit constellation, Steckel said, having secured launches, built ground stations and established the infrastructure to build two satellites a day through a joint venture with Airbus Defence and Space.

Today’s launch and the completion of in-orbit testing paves the way for the next 20 Soyuz launches, each carrying up to 36 spacecraft, Steckel said.

Israël said the subsequent OneWeb launches will start in the second half of the year from Russia’s Baikonur Cosmodrome in Kazakhstan. The majority of the remaining Soyuz missions are expected to occur from Baikonur, though Europe’s Guiana Space Center in Kourou, French Guiana, and Russia’s new Vostochny Cosmodrome in the country’s Far East are also possibilities, Israël said.

Virgin Orbit is also expected to start launching OneWeb satellites this year using its dedicated smallsat vehicle LauncherOne. Wyler, responding to a SpaceNews inquiry, tweeted that the four satellites OneWeb withdrew from the Feb. 27 Soyuz mission could launch this year with Virgin Orbit, which has a contract for 39 missions using the LauncherOne air-launched rocket.

Virgin Orbit is a spinoff of Richard Branson’s crewed spaceflight company Virgin Galactic. Branson said Feb. 27 that Virgin Orbit’s first launch is scheduled to occur “hopefully in just a handful of months time.”

Steckel said LauncherOne can carry one to two OneWeb satellites at a time, but will mainly be used for fleet replenishment rather than constellation deployment.

Arianespace and OneWeb announced after the launch that OneWeb will also fly satellites on the inaugural flight of Ariane 6. The mission, scheduled for 2020, will use the Ariane 62, a version with two strap-on boosters. Israël tweeted that the OneWeb-Ariane 6 launch agreement includes options for two more Ariane 6 missions, and will be finalized next month.

OneWeb anticipates having around 150 satellites in orbit by year’s end, starting regional service in 2020 with around 300 satellites, and reaching global coverage in 2021 with 600 satellites. Wyler said that with six satellites, OneWeb can provide service for 18 minutes at a time, with that number scaling as launches progress.

Save for this first mission, OneWeb’s other satellites will separate from their launchers roughly 500 kilometers above the Earth and use onboard electric propulsion to reach their final 1,200-kilometer orbit — a journey Wyler estimated will take about four months.

Steckel said the company is targeting 648 satellites initially, with 48 serving as in-orbit spares. Beyond that, OneWeb is deciding if it will scale its first-generation constellation to 900 satellites or shift into a second generation that would likely increase the total constellation to 1,980 satellites.

Each first-generation OneWeb satellite costs $1 million to produce. OneWeb Satellites, the joint venture of OneWeb and Airbus, built the first 10 satellites in Toulouse, France, but plan to build the remainder of the first-generation constellation at a new $85 million factory in Exploration Park, Florida.

OneWeb announced its first customers Feb. 27: satellite teleport and network operator Talia and Italian telecommunications company Intermatica.

OneWeb is targeting several markets for connectivity, including inflight Wi-Fi, maritime and government users, but also has a mission to bring internet access to every school in the world. Steckel said the company will start pursuing that goal by sponsoring connectivity for six schools — one each in Alaska, Rwanda, Nepal, Kyrgyzstan, Ecuador and Honduras — for 10 years. The Soyuz rocket carrying OneWeb’s first satellites also bore the logo of FIRST (For Inspiration and Recognition of Science and Technology), a nonprofit focused on instilling youth with a fascination for science and technology.