SpaceX starts 2019 manifest with successful Iridium 8 launch
LOMPOC, Calif. — After enduring several delays, SpaceX successfully launched ten Iridium NEXT satellites into a polar low-Earth orbit (LEO), marking the Falcon 9’s first flight of 2019, and the last of the original contract, signed in 2010, with Iridium.
Liftoff of the Iridium 8 mission occurred at 7:31 a.m. PST (10:31 EST / 15:31 GMT) at the opening of an instantaneous launch window. Today’s flight passed its final hurdle with the rocket’s Jan. 6 static test fire.
That eight-mission contract between SpaceX and Iridium marked the largest private launch deal ever engaged, tipping the scales for a total of $492 million, or $61.5 million per launch. To honor the occasion Iridium created a launch soundtrack on Spotify.
Today’s flight lifted off from Vandenberg Air Force Base’s (VAFB) historic Space Launch Complex 4E (SLC-4E), which originally hosted Atlas rockets starting in 1962. Between that time and 2005, the complex saw additional launches from Titan IIID, Titan 34D, and Titan IV rockets before being converted to process and fly Falcon 9 and, eventually, Falcon Heavy rockets.
The booster (B1049.2) for this flight had previously flown on the Telstar 18V mission, marking the second time that this Block 5 first stage has been flown.
The Falcon 9’s nine first stage Merlin 1D engines roared to life shortly before liftoff, building up to their combined 1.71 million pounds (7,607 kilonewtons) of sea level thrust. Clearing the strongback shortly thereafter, the rocket began its pitch, yaw, and roll maneuvers to assume a southerly heading.
Lifting off into the sky, the vehicle continued to build speed as it arced out over the Pacific Ocean, reaching the moment of maximum dynamic pressure—the time when the forces exerted on the rocket by the thrust of the engines, combined with the pressures of the thinning, but still substantial atmosphere, are greatest. This took place approximately seventy seconds after liftoff.
With everything progressing normally, the first stage continued to fire for another 75 seconds, with main engine cutoff occurring just shy of two-and-a-half minutes after launch.
After a short coast, the first and second stages separated, followed by ignition of the second stage’s lone Merlin 1D Vacuum engine shortly thereafter.
Although the primary mission was the delivery of the 10 Iridium NEXT satellites to orbit, many interested viewers were focused on what happened with the now-solo first stage.
The second stage – now above a great majority of the atmosphere and no longer needing thermal, acoustic, and aerodynamic protection for the Iridium satellites – shed its payload fairing at about 3 minutes, 15 seconds into the mission. Although the fairing is necessary for a significant portion of the flight, jettisoning the protective shell once in near-vacuum conditions lightens the overall mass of the second stage, and is necessary to allow for deploying the satellites housed within.
While the second stage, with its payload, continued accelerating to orbit, the first stage began preparations to land on SpaceX’s drone ship, Just Read the Instructions, waiting a few hundred miles off the California coast in the Pacific Ocean.
Flying free from the second stage, the first stage re-oriented itself so that it was flying engines-first, allowing it to perform a couple of trajectory modification burns on its way to a landing on the drone ship.
As the first stage neared the drone ship, it re-ignited the center Merlin 1D engine and brought the booster to a near-bullseye landing. Though the company still classifies these landing attempts as “experimental”, it’s clear SpaceX has the rocket’s landing system is very adept at making a difficult task look easy.
However, the recovery of the first stage didn’t mark the end of the mission. While the first stage was setting up to land on the drone ship, the second stage continued to climb to orbit, with the first cutoff of the second stage’s engine coming more than nine minutes after liftoff.
Next came a coast phase, lasting nearly 44 minutes, before the Merlin 1D Vacuum was re-ignited for a short three-second burn. Now positioned in the designated orbit, the second stage deployed the 10 Iridium NEXT satellites over the ensuing 15 minutes.
The newer Block 2 satellites will take up a position near its counterpart in the older Block 1 constellation. Once the new satellites are brought online, the Block 1 satellites will be placed in a disposal orbit. It is expected that the final group of Block 1 satellites will be deorbited in early 2019.
Video courtesy of SpaceX
Curt Godwin has been a fan of space exploration for as long as he can remember, keeping his eyes to the skies from an early age. Initially majoring in Nuclear Engineering, Curt later decided that computers would be a more interesting - and safer - career field. He's worked in education technology for more than 20 years, and has been published in industry and peer journals, and is a respected authority on wireless network engineering. Throughout this period of his life, he maintained his love for all things space and has written about his experiences at a variety of NASA events, both on his personal blog and as a freelance media representative.