Almost every rocket that has ever flown has experienced some anomaly. With thousands of components that must all work in perfect harmony to ensure mission success, it is likely that a component will fail to function from time to time.
While witnessing an anomaly in spaceflight is not as unlikely as it seems, it is becoming increasingly unusual as the cadence of flights increases. It is almost expected that the first launch of a new rocket will end in a mid-flight failure. However, when a rocket that has been flying fast and trouble-free for more than seven years fails to deliver its payload, the space industry takes notice.
On Thursday, July 11 at 10:35 p.m. EST (Friday, July 12 at 2:35 UTC), Falcon 9 was grounded after an upper stage failure caused the loss of the Merlin Vacuum (MVac) engine. The anomaly also resulted in the loss of the Starlink satellites on board, which failed to reach a stable orbit.
Falcon 9 is an extremely reliable launcher, with only four failures to date. Most of those failures occurred while the Block 2 and Block 3 vehicles were still in the early stages of design. Falcon 9 Block 5 has completed 297 successful launches through Saturday’s 298th launch, making it one of the most reliable rockets ever launched.
The History of Falcon 9 Anomalies
The first in-flight failure of the Falcon 9 rocket occurred on June 28, 2015. After a nominal liftoff of Block 2 of the Falcon 9 rocket on the CRS-7 mission, the liquid oxygen (LOX) tank on the second stage overpressurized and ruptured 139 seconds into the flight. The tank rupture resulted in the destruction of the rocket 11 seconds later. This mission was scheduled to resupply the International Space Station using SpaceX’s uncrewed Dragon capsule, which separated from the rocket before it crashed into the ocean and was lost.
CRS-7 launch. (Credit: NASA/Charles Babir)
This failure of NASA’s vehicle and payload led to NASA’s involvement in the investigation. It was discovered that a strut inside the second stage LOX tank failed to handle the forces it was designed to withstand. SpaceX fixed this problem by replacing the faulty strut with a more robust version and requiring more audits of the vehicle’s quality before it could fly. After the failure, Falcon 9 had a 95 percent success rate, and it took nearly six months for the next mission to fly on December 21, 2015.
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After the CRS-7 failure, routine launches resumed and landings began to succeed for SpaceX. The first successful landing of an orbital rocket occurred on the next launch when booster B1019 touched down on SpaceX’s Landing Zone 1. Then, four launches after the failure, the first successful landing of a booster atop a drone ship Of course I still love you occurredSpaceX has racked up new launch and landing successes through September 1, 2016.
Nine months after CRS-7, Falcon 9 experienced another anomaly. AMOS-6 was to be SpaceX’s 29th Falcon 9 launch. While loading propellant for a pre-flight static firing test, a liner inside the Composite Overwrapped Pressure Vessel (COPV) buckled, causing propellant to pool under the liner, triggering a friction-induced spark. This created an explosion that destroyed the entire vehicle. The AMOS-6 anomaly caused Falcon 9’s reliability to drop to just under 90 percent. On January 14, 2017, SpaceX resumed flights just over four months after AMOS-6.
The AMOS-6 static firing anomaly. (Credit: SpaceX)
Recent anomalies in the space industry
Early in the development of a brand new rocket, and even new iterations of operational rockets, it’s almost expected that something will go wrong. Many promising startups and even government agencies have experienced failures during the first launches of a brand new system. SpaceX has even started to adopt the “fail fast but iterate faster” approach to rapidly accelerate design. No rocket has this idea behind it as much as SpaceX’s Spatialship.
Each of Starship’s test flights, from the Starhopper to the high-altitude suborbital Starship hops to today’s near-orbital flights, has been fast-paced. For example, it took the teams five attempts to learn how to land the Starship. However, as the flight tests continued, SpaceX learned from its mistakes and quickly improved the vehicle in ways that would never have been anticipated if it were just a project. Today, Starship is not a reliable vehicle, but each integrated flight test has helped meet more of SpaceX’s system requirements and goals. It may not be long before Starship is considered a reliable satellite launcher.
Starship’s maiden flight. (Credit: Max Evans for NSF)
There are many examples of space startups working on developing a rocket into a profitable aerospace company. Firefly Aerospace is currently embarking on this process with its Alpha rocket. Alpha has completed five flights and does not have the best track record. There was a failure on the first flight, a partial failure on the second and fourth flights, and two successes on the third and fifth flights. Buoyed by its recent success, Firefly is planning to follow up with another clean launch in October later this year. If all goes well, Firefly may have already passed the inflection point of success.
The European Space Agency (ESA) is the latest government agency to build and launch a brand new rocket with Ariane 6. The maiden flight of Ariane 6 went smoothly until an hour and 14 minutes into the flight. Ariane 6 successfully entered a circular orbit and deployed the majority of the 11 payloads on board. Then, an auxiliary propulsion unit (APU) malfunctioned, causing the third planned deorbit launch to fail. Even after many years and billions of dollars invested in development, it is common for a small anomaly to partially derail an entire mission.
Inaugural launch of Ariane 6 (Credit: ESA)
Another government Japan’s space agency, the Japan Aerospace Exploration Agency (JAXA), has had some problems with its new H3 rocket launched last year. After the first TF1 test flight failed in March 2023 due to a failed second-stage engine ignition, it took JAXA just under a year to prepare for the next H3 flight. On the second flight, H3 successfully reached its planned sun-synchronous orbit and deployed its satellites. Then, just over four months later, the first-ever designated flight was a complete success.
Rocket Lab is following a similar path to the other private companies mentioned above. On Rocket Lab’s first flight of Electron, the rocket successfully survived stage separation and fairing separation. However, due to a software failure that resulted in the loss of telemetry data, the flight termination system was activated, ending the mission. After that launch, Electron successfully flew to its 13th flight. That flight failed during the second stage burn due to a faulty wire that severed the electrical connection to the engine’s turbopumps.
Sparks visible at the anomaly point during Rocket Lab’s 41st launch. (Credit: Rocket Lab)
On Electron’s 20th mission, the second stage shut down prematurely due to an igniter fault. The igniter failure caused the thrust vector control system to malfunction, sending the rocket off course. Another 20 missions went smoothly until Electron’s 41st mission. Electron failed to reach orbit due to an electrical arc that caused a short circuit, causing the upper stage’s Rutherford engine to lose thrust. After the failure, it took Rocket Lab just under three months to get Electron back in the sky. Rocket Lab has now completed 50 launches and has a 92% success rate.
Blue Origin’s New Shepard suborbital rocket has successfully launched 24 times. However, during the NS-23 mission, a failure was caused by the BE-3 main engine, which activated the capsule’s launch escape system. Tail 3, who was carrying out his ninth mission, The capsule was structurally flawed due to the BE-3PM engine overheating that had not been accounted for on the booster. Fortunately, there were no crew members and only commercial payloads on board the capsule. The launch escape system worked as designed and returned the payloads safely to Earth. New Shepard achieved a 96% success rate on 25 missions with only one failure. It took New Shepard over 15 months to resume flights after NS-23 interrupted Blue Origin’s operations.
New Shepard anomaly on the NS-23 mission. (Credit: Blue Origin)
Falcon 9 resumes flight
Falcon 9 will return after its short hiatus with the Starlink Group 10-4 mission. The launch is scheduled from Cape Canaveral Space Force Station’s SLC-40 on Saturday, July 27 at 12:13 a.m. EDT (04:13 UTC). The FAA announced on July 25 that no public safety issues were involved in the anomaly. This doesn’t mean the investigation is over, but it does mean SpaceX can resume Falcon 9 launches.
SpaceX revealed that the problem was likely caused by a crack that developed in a “sense line” during the first burn of the second stage. The sense line is responsible for checking the pressure in the second stage’s LOX tank. When the second stage burn began, the MVac engine had too much cryogenic LOX flowing through it and had cooled so much that the engine was overpressurized. This likely led to an explosion, terminating the burn and causing the loss of attitude control. SpaceX mentioned that the sensor connected to the sense line is not used by the flight safety system and that other systems make the sensor redundant. Therefore, SpaceX’s plan going forward is to remove the sense line and the faulty sensor from the vehicle.
Thanks to the pace at which we have been able to launch our project, we are able to collect unprecedented levels of flight data and are ready to resume flights quickly as early as Saturday, July 27 → https://t.co/DvO0z1NbUm
— SpaceX (@SpaceX) July 25, 2024
It is in itself abnormal that SpaceX was able to return Falcon 9 to service in less than 14 days after a second stage failure. With 355 missions and only four failures in 14 years of operation, Falcon 9 is one of the most reliable rockets ever to fly, with a 99% success rate.
(Main image: Falcon 9 launch from SLC-40 at Cape Canaveral Space Force Station. Credit: Max Evans for NSF)
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