SpaceX’s Falcon 9 rocket will deliver 10 satellites to low-Earth
satellite communications. This is the fourth set of 10 satellites
in a series of 75 total satellites that SpaceX will launch for
Iridium’s next generation global satellite constellation,
SpaceX is targeting launch of Iridium-4 from Space Launch
Complex 4E (SLC-4E) at Vandenberg Air Force Base in
California. The instantaneous launch window is at 5:27 p.m.
PST on Friday, December 22, or 1:27 UTC on Saturday,
December 23. The satellites will begin deployment about an
hour after launch.
A backup launch opportunity is at 5:21 p.m. PST on Saturday,
December 23, or 1:21 UTC on Sunday, December 24.
Falcon 9’s first stage for the Iridium-4 mission previously supported the Iridium-2 mission from SLC-4E in
June 2017. SpaceX will not attempt to recover Falcon 9’s first stage after launch.
The payloads for this launch are the fourth set of 10 Iridium
NEXT satellites. Iridium NEXT will replace
largest "tech upgrades" in history. Iridium has partnered with Thales Alenia Space for the
manufacturing, assembly and testing of all 81 Iridium NEXT satellites, 75 of which will be launched by
SpaceX. The process of replacing the satellites one-by-one in a constellation of this size and scale has
never been completed before.
Iridium NEXT is enabling the development of new and innovative products and services including Iridium
, the Company’s next-generation communications platform. Iridium Certus will deliver faster
maritime, Internet of Things, terrestrial and government organizations. A service of this quality and
value is unprecedented in the industry, and is poised to disrupt the current market status quo. Among
the new technologies hosted by Iridium NEXT is the Aireon
aircraft tracking and surveillance system. In
operators that purchase the service with real-time, global visibility of ADS-B equipped aircraft.
Iridium's primary launch campaign consists of eight SpaceX Falcon 9 launches deploying 75 Iridium NEXT
satellites. These 75 Iridium NEXT satellites are scheduled to be deployed by mid-2018. Iridium is the only
mobile voice and data satellite communications network that spans the entire globe. Iridium enables
real-time connections between people, organizations and assets to and from anywhere.
Official SpaceX Iridium-4 Mission Patch
(all times approximate)
SpaceX Launch Director verifies go for propellant load
RP-1 (rocket grade kerosene) loading underway
LOX (liquid oxygen) loading underway
Falcon 9 begins engine chill prior to launch
Command flight computer to begin final prelaunch checks
Propellant tank pressurization to flight pressure begins
SpaceX Launch Director verifies go for launch
Engine controller commands engine ignition sequence to start
Falcon 9 liftoff
Max Q (moment of peak mechanical stress on the rocket)
1st stage main engine cutoff (MECO)
1st and 2nd stages separate
2nd stage engine starts
2nd stage engine cutoff (SECO-1)
2nd stage engine restarts
2nd stage engine cutoff (SECO-2)
Iridium NEXT satellites begin deployment
Iridium NEXT satellites end deployment
SpaceX’s Space Launch Complex 4E at Vandenberg Air Force Base has a long history dating back to the
early 1960s. Originally an Atlas launch pad activated in 1962, SLC-4E was in active use until its last Titan
IV launch in 2005. SpaceX’s groundbreaking was in July 2011, and the pad was completed just 17 months
later in November 2012. SpaceX took advantage of some existing pad infrastructure, but implemented
extensive modifications and reconstruction of the launch complex. Part of the renovation included
tearing down a 30+ story mobile service tower and a 20+ story umbilical tower. 97 percent of these units
SLC-4E consists of a concrete launch pad/apron and a flame exhaust duct. Surrounding the pad are RP-1
and liquid oxygen storage tanks and an integration hangar. Before launch, Falcon 9’s stages, fairing and
the mission payload are housed inside the hangar. A crane/lift system moves Falcon 9 into a transporter
erector system and the fairing and its payload are mated to the rocket. The vehicle is rolled from the
hangar to the launch pad shortly before launch to minimize exposure to the elements.
SpaceX Contact | John Taylor, Director of Communications, 310-363-6703,
Photos | High-resolution photos will be posted at
Webcast | Launch webcast will go live about 15 minutes before liftoff at