Iridium Communications – in the midst of launching their next generation communications constellation – has formally signed an agreement with SpaceX to utilize flight-proven Falcon 9 boosters on their upcoming Iridium NEXT-4 and -5 missions. Iridium NEXT-4, scheduled to launch NET 22 December 2017 from SLC-4E, will be the first flight-proven Falcon 9 mission from Vandenberg. The change in boosters now negates the possibility of a Return To Launch Site landing of the Falcon 9 for the mission.

Iridium switches to flight-proven boosters:

Iridium Communications has formally announced plans to fly the company’s next 20 satellites (10 per mission) on flight-proven Falcon 9 boosters.

“Iridium has reached agreement with SpaceX to utilize flight-proven first stages for the next two Iridium launches,” noted the company in a media release Thursday morning. “Iridium conducted extensive due diligence work and is fully confident in the SpaceX booster refurbishment program.”

The agreement signed with SpaceX only addresses the Iridium NEXT-4 and -5 missions, which will loft the Iridium NEXT 31-40 and 41-50 satellites, respectively, and follows comments from Iridium CEO Matt Desch that Iridium was not opposed to flying on flight-proven Falcon 9 cores as long as the risk and insurance elements of that decision were properly understood by Iridium.

“I believe that reusability is the future for satellite launches, and I think SpaceX has intelligently built their Falcon 9 program around this strategy,” said Mr. Desch in today’s announcement.

“With three successful flight-proven Falcon 9 launches already this year, we’re excited to show leadership towards the sustainable access to space while also making sure we maintain our cadence to complete the five remaining Iridium NEXT launches by the middle of next year.”

Importantly for Iridium, and for the launch market as a whole, Iridium revealed in its announcement that the cost of insuring the Iridium NEXT-4 and -5 missions did not change with the switch to flight-proven boosters.

“Iridium confirmed with its insurers that there is no increase in premium for the launch program as a result of the use of flight-proven Falcon 9 rockets, further supporting Iridium’s conclusion that the risk profile is unchanged,” noted the release.

Overall, this is an excellent sign that the all-important insurance market element of spaceflight continues to see no increased risk with launching atop flight-proven boosters.

In fact, Iridium’s statement that their insurance price did not change actually shows an improvement from earlier this year.

In March, SES revealed that the insurance premium for SES-10, the first satellite to ride to orbit on a flight-proven booster, “did not materially change” and was only hundredths of a percent different than it would have been had SES-10 flown on a brand new Falcon 9.

Thus, Iridium NEXT-4 will move from a brand new Block 4 Falcon 9 booster to a Block 3 booster.

While the exact booster is not yet known, there is significant potential that Iridium NEXT-4 will use the Iridium NEXT-2 booster, which would make Iridium the first company to reuse the same booster for two of its missions.

Iridium NEXT-2 launched on 25 June 2017. Its first stage, core B1036, then successfully executed a landing on the ASDS (Autonomous Spaceport Drone Ship) Just Read The Instructions.

If core B1036 does indeed launch the Iridium NEXT-4 mission, it will be the second Iridium-launching core to be reused this year.

The Iridium NEXT-1 core was reflown on the BulgariaSat mission in June – just two days before the Iridium NEXT-2 mission launched.

The Iridium NEXT-1 booster – with BulgariaSat’s launch – became the first orbital class booster to launch from both coasts of the United States.

Overall, Iridium NEXT-4 is – coincidentally – the fourth Falcon 9 mission of the year to switch from a brand new core to a flight-proven booster: with SES-10, BulgariaSat, and SES-11/Echostar-105 preceding it.

Given the flight’s targeted NET (No Earlier Than) 22 December 2017 launch date, Iridium NEXT-4 might actually be the fifth, not fourth, flight-proven Falcon 9 mission in total.

Whether Iridium NEXT-4 is the fourth or fifth flight-proven mission will depend on the final NASA management decision – expected no later than early-November – on CRS-13’s potential use of a flight-proven core.

If NASA approves such use for CRS missions in time for CRS-13’s flow, it has been confirmed by sources that the CRS-11 booster (B1035) will again be used to launch Dragon to the ISS.

With Iridium NEXT-4 now confirmed on a flight-proven booster (and if CRS-13 joins the flight-proven club), previously flown cores will likely end up representing a full 25% of Falcon 9’s 20 targeted missions this year – an incredible accomplishment and continued force for change within the launch industry considering that flight-proven missions only began on 30 March.

Moreover, Iridium NEXT-4 will now be the first flight-proven Falcon 9 mission from Vandenberg Air Force Base.

Unfortunately, the switch – while excitingly showing the continued migration of payload customers to flight-proven hardware – now negates the ability of Iridium NEXT-4 to debut Return To Launch Site (RTLS) landings at Vandenberg.

While it was also confirmed a Block 4 could have RTLS-ed, the switch to a flight-proven Block 3 will now delay the first Vandenberg RTLS into 2018.

Exactly which mission that will be is unknown at this time.

Iridium NEXT-4 is targeted to launch NET 22 December 2017 at 17:26 PST (01:26 GMT on 23 December) – exactly 30 minutes after local sunset at Vandenberg.

(Images: Iridium Communications, SpaceX, and L2 Iridium-3 Collection, Jay DeShelter and Philip Sloss for NASASpaceflight.com)