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SpaceX’s next launch, scheduled for no earlier than May 15, will loft dozens of small test satellites into orbit from Cape Canaveral for the company’s planned Starlink broadband network, with fully operational Starlink spacecraft to follow on future missions, a senior SpaceX official said Tuesday.

Gwynne Shotwell, SpaceX’s president and chief operating officer, said Tuesday that the company’s second launch of Starlink test satellites is scheduled for May 15, a few days later than previously planned after delays in the company’s previous launch — a resupply mission to the International Space Station that took off early Saturday, May 4.

The 90-minute launch window on May 15 — next Wednesday — opens at 10:30 p.m. EDT (0230 GMT on May 16). The Starlink satellites will ride into space from Cape Canaveral’s Complex 40 launch pad aboard a Falcon 9 rocket with a previously-flown first stage booster, which will attempt a landing offshore on SpaceX’s drone ship in the Atlantic Ocean.

Shotwell confirmed the target launch date in response to questions about SpaceX’s Starlink program at the Satellite 2019 conference in Washington, D.C. Next week’s mission will be the first of numerous launches SpaceX says will be dedicated to the Starlink network.

But she demurred on the number of satellites on-board next week’s launch. Despite multiple inquiries from Spaceflight Now, SpaceX officials have not confirmed how many spacecraft are on the mission.

“I don’t know if we’ve ever released it (the number of satellites) publicly, so let’s call it dozens,” Shotwell said. “Dozens of satellites on that launch.”

“This next batch of satellites will really be a demonstration set for us to see the deployment scheme and start pulling our network together,” Shotwell said. “We start launching satellites for actual services later this year. I wouldn’t be surprised if we had two-to-six (additional) launches at the end of the year (for Starlink.) It largely depends on how we do on this first batch.”

The Starlink satellites are around the size of a mini-refrigerator, but SpaceX has not disclosed information about each spacecraft’s dimensions or mass.

The Starlink satellites are built and manufactured at a SpaceX facility in Redmond, Washington. SpaceX eventually plans to launch and operate up to 4,400 Ku-band and Ka-band satellites, and a follow-on network of 7,518 additional Starlink satellites transmitting in V-band frequencies.

SpaceX continues raising funding for network, which company officials have previously said could cost $10 billion to develop and deploy. The Starlink satellites are designed to beam broadband signals around the world from orbits hundreds of miles above Earth, creating a global umbrella of high-speed Internet connectivity.

The Federal Communications Commission last month approved a SpaceX proposal to deploy an initial network of 1,584 Starlink spacecraft in a lower orbit than originally planned. The first Starlink satellites, presumably including the spacecraft set for launch next week, will operate at an altitude of 341 miles, or 550 kilometers, instead of the 714-mile-high (1,150-kilometer) orbit SpaceX previously proposed to federal regulators.

The satellites launching next week are expected to separate from the Falcon 9 launcher’s upper stage in an orbit somewhat lower than their 341-mile-high operating altitude.

The first segment of Starlink satellites will fly in orbits inclined 53 degrees to the equator, allowing coverage of most of the world’s population. Later Starlinks will launch into polar orbit for global coverage.

Two pathfinder satellites for SpaceX’s Starlink network launched last year as piggyback payloads on a Falcon 9 mission from Vandenberg Air Force Base, California. The satellites launching next week are expected to be more capable, but Shotwell said they still lack at least one key system required to make the network function as designed.

“They’re capable, but there are no inter-satellite links on it,” Shotwell said. “I’ll call them test-class satellites, but the antennas are pretty hot on these things. They’re a very capable system.”

The operational Starlink fleet will use laser inter-satellite links to hand off Internet connections around the world without routing the signals through a ground station.

In its request to modify its Starlink license with the FCC last year, SpaceX officials said the lower operating altitude for the first batch of Starlink satellites would help assuage space debris concerns. If a Starlink relay station in the lower orbit fails, atmospheric drag will bring the satellite back to Earth within about five years, and most of the spacecraft will burn up during re-entry.

The Starlink satellites have an electric propulsion system for orbital maneuvers. The Starlink satellites launching next week will carry the electric thrusters, Shotwell said.

SpaceX launched 18 missions in 2017, and the company conducted 21 launches last year, all successful.

“This year, depending on customer readiness, we’ll launch between 18 and 21 times,” Shotwell said. “I think next year, roughly the same, I think (we have) 16 to 20 missions on the manifest.”

Those numbers do not factor in Starlink launches, she said.

Shotwell said SpaceX has signed 22 launch deals over the last 14 months, despite a downturn in the market for commercial geostationary communications satellites.

“I think we’re feeling a little pain right now on the commercial side,” Shotwell said.

Growth in SpaceX’s market share for U.S. government launches have helped offset the weak commercial market.

“We’re still seeing pretty strong uptake of our services, and then Starlink would be on top of that,” said Shotwell, who said SpaceX currently has the capability to launch up to 40 Falcon rocket missions per year.

“So we’ve got plenty of capacity to launch our Starlink system,” she said.

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Follow Stephen Clark on Twitter: @StephenClark1.