The fourth batch of Iridium Next satellites is scheduled to ride a recycled rocket into orbit Friday from Vandenberg Air Force Base.

A Falcon 9 rocket is poised for blastoff at 5:27 p.m. from Space Launch Complex-4 on South Base. An instantaneous window allows proper placement in space for the satellites.

The team has Saturday reserved as a back-up date for departure, if it's needed due to unfavorable weather or technical troubles.

Ten Iridium Next satellites will ride in the Space Exploration Technologies rocket which previously carried the second set of Iridium satellites to orbit in June from the base..

This is the first of two Iridium Next missions that will use “flight proven” — previously flown— Falcon 9 rockets.

It’s believed to be the first time a company has used the same rocket booster to carry its satellites.

“We’re approaching our halfway point on this journey, and with each launch, we gain more momentum,” said Iridium CEO Matt Desch. “This launch will bring us to 40 Iridium Next satellites in space, which is more than half the number required for a full Iridium Next operational constellation.

“It has been remarkable to witness the increased speed, capacity and throughput of our network as we continue to replace our original satellites with new Iridium Next satellites.”

The 10 Iridium Next satellites, each the size of Mini Cooper car, arrived at Vandenberg by late November to undergo final preparations for liftoff including mating to the dispenser, fueling and encapsulation within the rocket nosecone.

Manufactured in Arizona, the satellites were shipped two by two, in specially-designed motion and temperature-controlled containers designed to keep them healthy and safe for the road trip.

Since the beginning, SpaceX’s founder, Elon Musk, has touted its rocket’s ability for reuse — believed to be a key to trimming launch costs.

Once its job is done, the Falcon rocket’s first stage can return to Earth, landing on a ocean-faring droneship or touching down on land, letting SpaceX reuse the component. Recycled rockets have previously launched from Florida.

Iridium is replacing its existing constellation by sending 75 Iridium Next satellites into space on a SpaceX Falcon 9 rocket over eight different launches.

The majority of the first-generation Iridium satellites also launched from Vandenberg starting in the late 1990s.

The operational Iridium constellation boasts 66 satellites divided into six polar orbiting planes with 11 satellites apiece.

The constellation also will have nine on-orbit spare satellites ready to move into position if needed.

Iridium provides voice and data communication virtually anywhere across the globe.

"Team Vandenberg is excited to begin and end 2017 with Falcon 9 launches," said Col. Michael S. Hough, 30th Space Wing commander who also gives the final decision for the launch to occur.

"We take our mission of providing assured access to space seriously and we've diligently worked with our SpaceX mission partners to ensure a safe and successful launch,” Hough said.

— Noozhawk North County editor Janene Scully can be reached at .(JavaScript must be enabled to view this email address) . Follow Noozhawk on Twitter: @noozhawk, @NoozhawkNews and @NoozhawkBiz. Connect with Noozhawk on Facebook.