Starship maiden orbital launch attempt

21. 4. 2023 0 By Space Seeker

On Apr. 20, SpaceX conducted the maiden launch of Starship, the most powerful rocket in history. The vehicle lost several Raptors during the first stage ascent before starting to rotate out of its trajectory before it was destroyed by the Flight Termination System (FTS). SuperHeavy Booster 7 along with Ship 24, both produced between late 2021 and early 2022 were used on this historic test flight. SpaceX considers this launch successful because much data were gathered for improving future missions.

Flight background

Before any Starship was built, the Starhopper was the only vehicle from Starbase (known as Boca Chica) in Texas. It conducted a 150-meter flight in August 2019. The first Starship prototype capable of high-altitude flight, SN8, underwent much testing including static fires before launching on a suborbital trajectory on Dec. 8, 2020. Followed SN9, SN10, and SN11 until we finally saw SpaceX successfully launch and land the Starship SN15 for the first time on May 5, 2021. These suborbital flights aimed to test the world’s most advanced rocket engines during flight and the landing maneuver also called the belly flop maneuver. The following progress included work on the first-ever SuperHeavy Boosters and construction of the Launch Pad (stage 0) Infrastructure. After the SuperHeavy Booster completed a 31-engine static fire and with the Wet Dress Rehearsal done, Starship and SuperHeavy were ready for the first full-stack launch attempt.

SN15 successfully landing

Countdown and First Flight

Once SpaceX employees completed the final work, the sheriffs began clearing Boca Chica Beach and the surrounding area to ensure no unauthorized personnel was present in the area during the launch attempt. Propellant loading began at T-1:39:00, with liquid oxygen and liquid methane flowing into Booster 7. Ship 24 loading began at T-1:22:00 with liquid methane flowing into the ship’s fuel tank followed by liquid oxygen loading a short time later at T-1:17:00. The first launch attempt ended up in a scrub as a stuck valve was observed. The second attempt looked more promising with a chill down of the Raptor engines on Booster 7 at T-16 minutes and 40 seconds, all the engines were cooled down to operating temperatures. At T-8 seconds, all 33 Raptor 2 engines began starting before ramping up to flight thrust levels (90% of maximum thrust for this mission). Raptors produced 67,000 kN of thrust while the 20 hold-down clamps secured Booster 7 to the OLM before releasing at T0. Right after liftoff, the Ship QD arm disconnected and begin to swing away from the vehicle to avoid being impacted by the rocket. After clearing the launch tower, the vehicle begins its gravity turn and starts pitching downrange toward the Gulf of Mexico. Starship passed the speed of sound and max-Q (period of maximum aerodynamic stress). With many Raptor engines not functioning, the full stack spun out of control and had to be destroyed by the Flight Termination System (FTS). Starship climbed to an apogee of approximately 39 km. No one was injured and all the debris from the rocket landed in the water.

What went wrong

Right after Liftoff, the live stream graphics indicates that 3 engines were not working. As the current OLM doesn’t feature a flame trench, it is likely that debris hit and damaged some of the engines. Photographers managed to capture the view of underneath the launch mount showing a huge crater and all of the concrete surface gone. Nevertheless, Starship continued ascending in a nominal fashion. At T+29 seconds, a small explosion was visible at the bottom of the Booster. Although not confirmed, it could have been the HPU (Hydraulic Power Unit) that runs the hydraulic actuators for engine gimbaling or it could have just been a Raptor malfunction – we don’t know yet. Later into the flight, the Booster lost more engines bringing a total to 5 or 6 Raptors which significantly reduced its thrust-to-weight ratio and also reduced the maneuvering capabilities. The onboard avionics did a great job keeping the rocket on course with multiple engines out until the vehicle became aerodynamically unstable and flipped multiple times still at supersonic velocities. After it started descending, the Flight Termination System (FTS) was triggered and explosives on both the Ship and the Booster destroyed the stack. An image from an unknown source shows from an onboard view that some sort of stage separation occurred right before FTS activation. Although probably not being commanded, it might have resulted due to the aerodynamical forces or the explosion. Before the breakup, The Liquid Oxygen tank was nearly empty with the CH4 tank having more propellant according to telemetry. This might have happened as a result of an incorrect Raptor burn mixture ratio, but this is only speculation and not confirmed by sources.

Damage to the Orbital Launch Mount

What’s next?

Before any future Starship or Superheavy launches or even get tested, SpaceX must first fix the damaged launch site and bring upgrades to Stage 0. The visible damage after launch includes the tank farm, Orbital Launch Mount, launch equipment, and possibly more but it appears that the launch tower is in good shape. One of many upgrades SpaceX will have to introduce is a flame diverter under the OLM. Although some may argue that Starship will have to launch from the surface of Mars at some point and the engines should survive debris hitting the engines, from the amount of damage caused by the plume of Starship, it certainly will be necessary. Every super-heavy launch vehicle or even small rockets have a flame diverter that deflects the rocket exhaust away from the launch site and the rocket itself. However, we will have to wait some time before we see this upgrade brought to Starbase. Also, the shielding for the tank farm and other sensitive equipment should be upgraded so expect a lot of work and changes to Stage 0 in Starabase. As for the Starship SuperHeavy, the next Boosters will be equipped with electric TVC and newer Raptor engines. For the next Launch attempt, so far we expect to see Booster 9 and Booster 10 along with Ships 26 and 27 which are not equipped with flaps or heat shield tiles, so they would not be able to survive a reentry or land afterward. All things considered, even in the best-case scenario, it will likely take several months before the second Starship test flight would be ready.