On this day nine years ago, SpaceX’s first and only in-flight anomaly with the Falcon 9 occurred after the rocket carrying a cargo mission for NASA exploded in mid-air. The launch was carrying SpaceX’s Cargo Dragon spacecraft as part of NASA’s Commercial Resupply Services (CRS) program, and while the Dragon successfully ejected itself from the Falcon 9, the ship’s parachutes did not deploy due to software configuration. A NASA investigation later pinned the fault on stainless steel being used inside the ship, and since then, SpaceX’s Dragon spacecraft has completed dozens of crew and cargo missions to space.
SpaceX’s Only Mid-Flight Falcon 9 Launch Failure Took Place On June 28th, 2015
Back then, SpaceX was flying NASA’s seventh cargo mission contracted to the Falcon 9 rocket with the Dragon spacecraft. The vehicle was SpaceX’s first generation Dragon, and liftoff took place at 9:21 a.m. Eastern time. Things appeared to go smoothly for most of the rocket’s ascent portion of the flight. As the Falcon 9 soared to the skies, SpaceX’s ground controllers regularly called out nominal milestones.
However, two minutes and nineteen seconds into the flight, the rocket was engulfed in smoke and roughly twelve seconds later, debris could be seen flying into the air. The rest of the live stream was quiet, with a SpaceX presenter commenting in the end that “there was some type of anomaly during first stage flight. What we know is that the countdown was satisfactory; we did ignite the nine Merlin engines; we successfully lifted off of the SLC-40 launch pad at Cape Canaveral; we proceeded through the stressing events during flight, went through maximum dynamic pressure, and went supersonic. However it appears that something did occur during first stage operations.” He added that engineers would analyze the data, with the Falcon 9 compiling data from multiple streams to help engineers make informed decisions.
SpaceX’s initial investigation revealed that it took a mere 0.893 seconds between the time the first indication of a fault to the loss of all telemetry. Detailed investigations conducted by NASA and SpaceX’s first take outlined that the Falcon 9 first stage did not cause the explosion.
Instead, it was the second stage that was responsible for the accident. SpaceX shared that an “overpressure event” inside the liquid oxygen tank inside the second stage caused the explosion, with a failed strut damaging the helium pressurization system inside the tank. A rocket’s propellant tanks are pressurized internally throughout flight. This is because as the fuel is used, the tank needs to maintain pressure, or it will collapse internally due to lower pressure. The strut was certified to handle 10,000 pounds of force, but it failed at 2,000 pounds, according to SpaceX.
NASA’s thorough investigation added more details. It outlined that while SpaceX’s explanation of the strut could have broken due to a defect was possible, other explanations, such as manufacturing damage and mis-installation, were equally probable. NASA added that SpaceX chose to use an industrial-grade stainless steel part instead of an aerospace-grade one, without screening or testing the part, without following the manufacturer’s recommendation, and without modeling or load testing the part under “predicted flight conditions.”
Daisy Hips is a science communicator who brings the wonders of the natural world to readers. Her articles explore breakthroughs in various scientific disciplines, from space exploration to environmental conservation. Daisy is also an advocate for science education and enjoys stargazing in her spare time.
