Elon Musk, SpaceX employees, and space enthusiasts everywhere are cheering today as the commercial launch company’s Falcon 9 rocket successfully returned to flight and landed Saturday, launching the first 10 of at least 70 satellites for the Iridium NEXT communications constellation.
Four months ago, SpaceX experienced its second catastrophic rocket explosion in less than two years. The first occurred just two and a half minutes after liftoff during the CRS-7 supply mission to the International Space Station in June 2015. Nearly ten months separated that explosion and the company’s next launch to the ISS. SpaceX’s most recent mishap took place September 1 of last year, during the static test fire - sort of a rocket launch dress rehearsal - for Mark Zuckerberg’s $200 million, Israeli-built satellite. That time, the rocket didn’t even make it off the ground.
An extensive investigation of the explosion, which resulted in the total loss of SpaceX’s rocket and the Amos 6 communications satellite, as well as heavy damage to Cape Canaveral Air Force Station’s Launch Complex 40, found a failure in one of the Falcon 9’s second stage helium tanks.
Highly pressurized helium is used to push the Falcon 9’s super-chilled liquid oxygen and RP-1 kerosene fuel to the rocket’s engines. The helium is stored in aluminum canisters, and wrapped with an insulating carbon composite material. These canisters, known as composite overwrap pressure vessels (COPVs), are placed inside the rocket’s propellant tanks and submerged as frigid rocket fuel fills the tanks just 35 minutes prior to launch.
A large part of SpaceX’s success as a profitable launch company has been derived from its practice of super cooling its rocket propellant prior to launches. Chilling the rockets liquid oxygen to nearly 50 degrees colder than the element’s standard minus 298 degree Fahrenheit liquid state densifies the compound and allows more fuel to be stored and pumped through the engines.
The performance increase brought about by this practice has been SpaceX’s leg up in the industry, and has brought the cost of reaching orbit aboard a Falcon 9 rocket to just $62 million - just over half the price of launching aboard their competitor’s rocket, United Launch Alliance’s Atlas V. It also seems to be the root cause of the company’s biggest setbacks.
Investigators believe the extremely low temperatures may have caused some of the liquid oxygen to solidify during fueling, prior to engine ignition the morning of the static test fire.
Thankfully, last Thursday’s static test fire, in preparation for today’s launch, was incident-free. SpaceX wasn’t taking any chances, though. With the loss of the Amos 6 satellite in the forefront of everyone’s mind, the company opted to mate the Iridium NEXT payload to the rocket after the successful test fire.
The company received FAA approval for launch the following day, after providing a satisfactory explanation for the September 1 explosion. The Federal Aviation Administration’s license, which was approved last Friday, January 6, covers all seven upcoming Falcon 9 launch and landings planned for the Iridium NEXT satellite constellation.
Iridium’s NEXT program, which will cost a total of $3 billion, aims to replace the company’s existing satellites, all launched during the 1990s and early 2000s. Providing coverage for over 800,000 subscribers, the Iridium NEXT fleet will work to relay signals around the globe for multiple U.S. military, naval, aviation, agricultural and mining companies, as well as other commercial entities worldwide.
SpaceX seems eager to resume its launch schedule. With more than 70 launches piling up on the company’s manifest, including cargo supply missions to the ISS for NASA and the maiden voyage of the Falcon Heavy , SpaceX has over $10 billion in contracts on the line.
Today’s launch, which lifted off from SLC-4E at Vandenberg Air Force Base in California at 9:54:39am PST, hopefully marks a return to normalcy for the commercial rocket company. Falcon 9’s first stage rocketed back to Earth and successfully landed on the SpaceX Autonomous Drone Ship floating in the Pacific Ocean, playfully named Just Read the Instructions, just under 8 minutes after its successful liftoff, and will likely be reused for future launches.
The first 10 satellites for the Iridium NEXT constellation began deployment about an hour after launch, following two low-Earth-orbit burns of the Falcon 9 second stage. Now in a stable orbit, the group awaits an additional 60 satellites scheduled to join the constellation by early 2018.