WASHINGTON — SpaceX’s first launch to carry a large number of Starlink broadband satellites is scheduled for May 15, according to a company executive.

Gwynne Shotwell, SpaceX’s president and chief operating officer, said the launch will carry “dozens of satellites,” adding more prototypes to the two currently in low Earth orbit.

“This next batch of satellites will really be a demonstration set for us to see the deployment scheme and start putting our network together,” she said at the Satellite 2019 conference here. “We start launching satellites for actual service later this year.”

Shotwell said SpaceX anticipates launching two to six more times for its Starlink broadband constellation in addition to the May 15 launch. How many Starlink launches occur this year depend on the results of this first batch, she said.

SpaceX is planning a constellation that could number close to 12,000 satellites, according to filings with the U.S. Federal Communications Commission. The company said in 2017 that it would need 800 satellites in orbit for commercial service — a target estimated for the 2020 to 2021 timeframe.

Shotwell said the demonstration satellites launching May 15 will be scaled down “test satellites” that lack intersatellite links. The test satellites will have very capable onboard antennas and electric propulsion, she said.

Shotwell said the launch, anticipated in early May, was pushed back to May 15 as a consequence of delays with an earlier cargo mission to the International Space Station for NASA. SpaceX launched a Dragon supply capsule on a Falcon 9 rocket to the ISS on May 4 after a power problem on the station and a subsequent electrical issue with SpaceX’s rocket retrieval droneship delayed the mission from May 1.

SpaceX is targeting 18 to 21 launches for this year, not including the Starlink missions, Shotwell said. That rate is consistent with previous years — SpaceX launched 18 times in 2017 and 21 times last year — but lower than the 30 to 40 annual launches the company forecasted in 2017.

Shotwell said SpaceX expanded its manufacturing ability to 40 rockets a year in anticipation of a commercial boom that didn’t happen.

“We thought the commercial market might expand to that, I think we probably wished it had, but [now] we’ve got plenty of capacity to launch our Starlink system,” she said.

SpaceX has launched five times this year — four Falcon 9s and one Falcon Heavy.