WASHINGTON — SpaceX carried out the third of eight missions for Iridium Communications early Oct. 9, launching ten more Iridium Next satellites on a Falcon 9 from California.

The SpaceX Falcon 9, on the 14th mission of the year for the company, launched at 8:37 a.m. Eastern from Vandenberg Air Force Base in California. SpaceX landed the rocket’s first stage on the drone ship “Just Read the Instructions” in the Pacific Ocean about seven and a half minutes after liftoff, marking the 17th successful landing.

The payload of 10 Iridium Next satellites, each capable of L-band voice and data communications using a 48-beam phased array antenna, separated from the Falcon 9’s second stage during the final 15 minutes of the 72-minute mission.

As the satellites drift to their designated orbital slots after separation, Iridium will conduct a “slot swap,” where the legacy satellite and the Iridium Next satellite are briefly collocated before full acceptance of the upgraded spacecraft. The new satellite then takes over, cross-linked into the full constellation, while the first-generation satellite is either deorbited or kept as a spare in a lower orbit.

European manufacturer Thales Alenia Space is building the Iridium Next constellation of 81 satellites and integrating them at partner Orbital ATK’s satellite facility in Gilbert, Arizona. Along with Iridium’s telecommunications payload, the satellites carry hosted payloads for Aireon’s upcoming flight tracking service and Harris and exactEarth’s maritime ship tracking business.

Iridium is launching 75 of the 81 satellites, nine of which will be on-orbit spares, while reserving six as ground spares. The operational constellation will have 66 satellites, the same as the original system.  

Iridium expects to have all 75 satellites in orbit by mid-2018. Those missions all involve newly produced Falcon 9 rockets, though the operator has expressed a willingness to launch on pre-flown rockets should they prove able to accelerate the pace of launches.  

SpaceX will now focus on its next launch on Oct. 11 from Kennedy Space Center in Florida. That launch, of SES-11/EchoStar-105, will be SpaceX’s third to use a previously-flown first stage booster.

Caleb Henry is a former SpaceNews staff writer covering satellites, telecom and launch. He previously worked for Via Satellite and NewSpace Global.He earned a bachelor’s degree in political science along with a minor in astronomy from...