Congratulations to SpaceX on the successful fourth flight test of the Starship spacecraft, which will soon take astronauts to the Moon as part of NASA's Artemis mission. This test sought to demonstrate Starship's orbital capability and obtain flight data.
Traveling to space, putting a base on the Moon, going to Mars — all these topics have become common in the daily news, making the accomplishments of SpaceX's flight test, carried out on June 6, 2024, explain why we are all so excited and prepared to make those trips.
Before the launch, I, and many others who could not fly to Texan and see the launch in person, were glued to the computer waiting for the T-0 moment, or the moment when the rocket Takes Off. For me, it started two minutes and twenty seconds (2:20 min) before the launch, and they announced that the booster had just been filled with 10 million lbs of fuel and was ready for takeoff.
At that time, the SpaceX broadcast showed Elon Musk in the Starbase control room with his son sitting on his lap. His son, X Æ a-12, seems excited and happy to be with his dad. Although he most likely doesn't understand what is happening, it must be incredible for Elon to share this moment with his son.
The rocket was finally launched at 7:50 AM CDT, from Starbase in Boca Chica, Texas. The takeoff seemed to go in slow motion, with the powerful Raptor engines lifting this enormous rocket from the surface but just little by little. Instinctively, I looked at the telemetry diagram of the SuperHeavy booster engines, and to my surprise, only 32 of the 33 Raptor engines were on - after reviewing the video, I saw that they all started up at first, but one went out shortly after takeoff.
Luckily Starship wasn't loaded, so I didn't worry too much (well, not that much). I started to feel less worried when Starship was at about 8km of altitude, and the SpaceX team announced that Starship had reached maximum aerodynamic pressure.
The next critical moment occurred at 2:54 into the flight, when Starship entered the Hot Separation Stage. At this stage, the SuperHeavy booster first shut down all but the 3 center central engines and, simultaneously, Starship ignited its engines, followed by the ejection of the SuperHeavy booster. Immediately afterward, the SuperHeavy executed a turning maneuver, re-igniting 13 Raptor engines - the 3 central engines + the 10 in the middle. These remained on for a little over 1 minute before turning off, after which the booster started coasting towards its landing point in the Gulf of Mexico, where it would attempt a soft landing on the water.
Meanwhile, at approximately 4:10 minutes into the flight, we saw the Super Heavy booster eject the Hot Separation stage. Getting rid of this section is a temporary solution to reduce the weight of the SuperHeavy booster. Later, SpaceX plans to make this booster lighter so that it does not need to be scrapped.
After about 7 min, the SuperHeavy was about 8 km from reaching the water and beginning to prepare for its landing. Less than 1 km from the water, the SuperHeavy re-ignited the 13 central Raptor engines; together with the fins, these began to move to position the booster in a vertical attitude. Shortly after, with only the 3 central Raptors engines on, the SuperHeavy booster completed its soft landing on the water. The first successful landing of this booster for SpaceX.
Meanwhile, the Starship continued to ascend with the help of its 6 Raptor engines. Shortly after, at 8:10 minutes into the flight, Starship shut down 3 engines. The other 3 engines turned off at 8:37 minutes into the flight, when its speed was slightly below 26,500 km/h, and it was at about 150 km altitude. Starship continued its ascent until reaching its final orbit at about 214 km altitude.
Starship continued coasting for about 40 minutes to where it would begin its descent and ultimately land in the Indian Ocean, where it would also attempt a soft landing.
Transmission or communication with the Starship was reestablished approximately 37 minutes into the flight, traveling at 27,000 km/h and approximately 162 km high. This transmission was provided by StarLink terminals installed at the top of the rocket. Thanks to Starlink's high transmitting frequencies and the continuous communication capability provided by the Starlink satellite constellation, SpaceX was able to obtain telemetry and video throughout the Starship's descent. The data captured is critical to enabling the rapid development of future Starships. It's a way for SpaceX to quickly learn what worked and what didn't.
The camera was focused on one of the vehicle's four fins — Starship has 2 fins on top and 2 on the bottom — which are used to help keep it in a stable attitude throughout the descent. Maintaining Starship's orientation ensures that its 18,000 thermal tiles protect it from the hot plasma generated during atmospheric reentry.
The first glow of the hot plasma began to appear at approximately 44:30 minutes when it was at about 104 km altitude. This phase lasted approximately 6 minutes and is when SpaceX would test the heat shield —the shield that SpaceX is designing is intended to protect the spacecraft for multiple flights and allow for rapid reuse, where the Starship can be immediately re-launched on another space mission.
Thanks to the Starlink shots, the view of the descent was spectacular. The information that SpaceX was getting was equally amazing -- at one point, we even heard when the SpaceX team indicated that the spacecraft reached its hottest point. During the entire descent, none of the engines were on, using only the friction with the atmosphere to slow down the spacecraft. As the descent continued, we could see bright particles appearing and passing at high speed around the vehicle. This was because Starship was now in a denser atmosphere; this is equivalent to saying that more particles are in the same volume of air, and hence these are also larger. This also implies that the vehicle is pushing denser air on its descent and getting exposed to higher pressure.
The combination of all these factors put the Starship's fins to the test, and at approximately 57 minutes into the flight, it began to put on an unforgettable show.
The fin captured by the video began to turn brighter at its base. This glow grew to the point where the frame of the fin could be seen, and pieces began to fly away. The smaller pieces began to cover the camera until it was finally blinded.
Jessie Anderson, Production and Engineering Manager, and Katie Tice, Executive Manager of Engineering Systems Quality, were the SpaceX commentators who kept us informed about every step of the test. When the camera was blinded, they thought this was the end of the flight. However, the telemetry was still transmitting and indicating the Starship continued descending. The SpaceX team also informed us that Starship was in the expected orientation.
Shortly after, the camera's glass broke, but even then, we could see the light produced by particles of the atmosphere heated by friction and flying at high speed on the periphery of the fins.
Although almost nothing could be seen through the camera, the telemetry provided by SpaceX still appeared at the bottom of the screen. This continued to show changes in the Starship's attitude, altitude, and speed. While following this information, when the Starship was flying at approximately Mac2 and approximately 27 km, it began to change its attitude and turn almost head first. Fortunately, it seemed to recover at approximately 19 km altitude while flying at 800 km/h.
Near the end of the flight, when Starship was approximately 10 km above the ocean, the camera began to clear, and we began to see the movement of the fin. When Starship was at approximately 1 km altitude, the 3 central engines turned on, and we could see that the fin had lost a large chunk. Despite its state, it continued to move, and just like for the booster, these acted together with the Raptor engines to turn the Starship to the vertical position, ending up with a soft landing in the Indian Ocean northwest of Australia.
Of course, at that moment, the SpaceX team celebrated the irrefutable success of its fourth flight test.
SpaceX did not attempt to recover any of the vehicles. On this flight, the focus was on generating the necessary data to help finish designing Starship and ensure it is safe and reusable. The images showing where the fin began to heat up and come apart, will help SpaceX collect data to improve the spacecraft and ensure that all its parts survive the descent and can make a complete landing.