WASHINGTON — The first launch of OneWeb’s low-Earth-orbit broadband constellation could still happen by year’s end, but may slip into early 2019, according to officials from OneWeb and launch provider Arianespace.

December’s planned Soyuz launch of the first 10 satellites, organized by European launch provider Arianespace, “may move back a month or so,” OneWeb founder Greg Wyler told SpaceNews.

“Arianespace had an urgent customer need, and being good partners we can move around a bit, but we are hoping to get up as early in our launch window as possible,” he said by email.

Arianespace CEO Stéphane Israël told SpaceNews that OneWeb’s targeted launch period is from Dec. 18 to Feb. 19.

“Arianespace will launch OneWeb ASAP in this slot taking into account its other contractual commitments,” he said by email.

Israël said there are no other customers on the Arianespace manifest pushing on OneWeb’s schedule.

Wyler dismissed reports in Russian media that setbacks with the satellites, each weighing 145 kilograms and carrying 10 gigabits per second of capacity, were reason for the delay.

“The satellites are ready,” he said. “OneWeb is ready.”

OneWeb’s first launch will carry production-grade satellites, not prototypes, according to the company. While the subsequent 20 Arianespace-Soyuz launches will carry 34 to 36 satellites to an altitude of 500 kilometers, the first launch will carry just 10 satellites straight to their 1,200-kilometer orbit, eliminating the need for orbit raising with each satellite’s onboard propulsion.

OneWeb is building 900 satellites through a joint venture with Airbus Defence and Space, but has signaled a desire to operate around 2,000 satellites. Additional launch providers include Virgin Orbit, which has a contract for 39 LauncherOne missions, and Blue Origin, which has a memorandum of understanding for five New Glenn launches.