While SpaceX continues to investigate a payload fairing issue, the company’s only two confirmed December missions remain on track for their respective launches, including Iridium NEXT-4. The Iridium NEXT-4 mission is not affected by the payload fairing issue and is processing toward a planned No Earlier Than 22 December launch from Vandenberg Air Force Base, California – a launch that will make Iridium the first company to reuse the same Falcon 9 booster for two of its missions.

Iridium NEXT-4 progress:

While SpaceX is understood to still be investigating a payload fairing issue that delayed the mysterious Zuma mission from its intended mid-November launch, the Iridium NEXT-4 flight is not affected by that investigation and remains on track to meet its December launch target.

In a release this morning, Iridium Communications noted that all of the mission’s preparations – including payload encapsulation – are progressing on track to support the 22 December launch date, which will mark the halfway point in the Iridium NEXT launch campaign.

“We’re approaching our halfway point on this journey, and with each launch, we gain more momentum,” said Iridium CEO Matt Desch.

“[Iridium NEXT-4] 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 satellites which will launch on the Iridium NEXT-4 mission were shipped two at a time in specially-designed motion and temperature-controlled containers designed to maintain optimal environmental conditions as the satellites were trucked from Arizona to the launch site at Vandenberg.

With all 10 satellites – numbers 31 through 40 – now at the launch site, technicians at Vandenberg are in the process of mating the satellites to their launch adapter, after which they will all be fueled prior to encapsulation inside their payload fairing.

Once the satellites are encapsulated, they will await final transportation to the launch site for mating atop the Falcon 9 rocket after it completes its customary static fire at SLC-4E.

This mating of the Iridium satellite payload to the top of the Falcon 9 will mark a first for Vandenberg, as Iridium NEXT-4 will be the first mission of a flight-proven Falcon 9 from the West Coast launch facility.

To date, three flight-proven Falcon 9 missions have launched from the Kennedy Space Center in Florida – SES-10, BulgariaSat, and SES-11/EchoStar-105 – but none have taken place from Vandenberg.

Moreover, Iridium NEXT-4 will use the same booster that launched the Iridium NEXT-2 mission on 25 June 2017.

That booster, B1036, successfully performed a landing on the ASDS (Autonomous Spaceport Drone Ship) Just Read The Instructions in the Pacific Ocean and was then towed to the Port of Los Angeles prior to being refurbished by SpaceX and prepared for this mission.

With booster B1036’s previous use on Iridium NEXT-2, Iridium NEXT-4 will be the second flight of core B1036 and will mark the first time a public company will reuse the same booster for two of its missions.

According to Iridium Communications, “Noteworthy for the fourth launch, the same Falcon 9 rocket first stage that carried 10 Iridium NEXT satellites for the company’s second launch in June of 2017, will also carry this payload of 10 satellites.

“This will make Iridium the first company in history to reuse the same rocket.”

Coincidentally for SpaceX, December seems likely to represent a month of only flight-proven Falcon 9 flights dedicated to a company and a government agency reusing the same boosters that previously launched their missions.

In addition to Iridium NEXT-4, NASA’s contracted CRS-13/Dragon flight will reuse the same booster that launched the CRS-11/Dragon mission to the Space Station in June of this year.

While NASA has still not publicly confirmed the reuse, core B1035 (CRS-11’s booster) is expected to be the booster that will launch CRS-13 in December.

This creates a coincidental alignment of both the CRS-11 and Iridium NEXT-2 boosters – which both launched in June 2017 – now being used again for the CRS-13 and Iridium NEXT-4 missions in the same month.

Moreover, it is an immensely positive development and leap forward for SpaceX’s and Elon Musk’s desire to make the reuse of rocket stages – instead of discarding them to a destructive end in the ocean – the industry standard.

For Iridium, while NASA will likely beat them to the finish line of using the same booster to launch two missions for the agency, NASA is part of the U.S. federal government while Iridium Communications is a public company.

Thus, even with CRS-13 in consideration, Iridium will be the first company – accountable to its shareholders – to make use of the same Falcon 9 booster for two of its missions.

Iridium NEXT-4 is scheduled to launch from SLC-4E on Vandenberg Air Force Base No Earlier Than (NET) 22 December 2017 at an instantaneous launch time of 17:32 PST (01:32 UTC on 23 December).

A backup opportunity exists on 23 December (PST) should the 22 December opportunity encounter an issue that prevents the Falcon 9 from launching at its instantaneous window.

The launch will occur a precisely the right second to send all 10 satellites into Iridium orbital plane two – into which nine of the 10 satellites will be deployed and enter immediate service.

The 10th satellite, after deployment, will undertake a year-long drifting journey to Iridium orbital plane one, where it will serve as a spare.

(Images: Iridium, SpaceX, and Chris Gebhardt for NASASpaceflight.com)