Starship Flight 8 - What to expect

Starship Flight 8 is just a few days away, with a launch date NET (No Earlier Than) March 3rd, with a launch window that opens at 5:30pm CDT, or 23:30 UTC. Starship Flight 8 will be a repeat of Flight 7, which ended prematurely due to the RUD (Rapid Unscheduled Disassembly, a term signifying an explosion) of Ship 33. Now, we are going to explore several things, from the causes of the explosion of Ship 33 to new upgrades on this flight to an exciting prospect about the future of the Starship program.

Why did Ship 33 explode?

Ship 33’s debris raining over the Turks and Caicos Islands.

Overview 

In case you missed it, SpaceX launched their 7th flight test of Starship on January 16th at 22:37 UTC: the ascent was performed nominally, and the 2 stages separated at T+2m41s into the flight, with Ship 33 ascending powered by all its 6 Raptor engines, and Booster 14 performing its boostback burn with 12 out of 13 engines ignited to come back to the launch site. A “GO for Booster return” was issued after the boostback burn ended, and Booster 14 successfully descended and ignited all 13 engines for the landing burn before being caught by the chopsticks, marking the second Super Heavy Booster catch of Starship’s history! But while Booster 14 was the star of the show in that moment, concerning things were going on on Ship 33: at T+7m39s, the Raptor engine in the E1 position shut down, while a view of the flap camera at T+7m53s showed a violent fire from the hinge of the aft flap (coming from inside the Ship); just 10 seconds later, another sea-level Raptor and an RVac shut down… at T+8m18s and T+8m24s, the last sea-level and an RVac engine shut down, respectively, just before Ship 33 lost telemetry 2 seconds later; the Ship tumbled for approximately 3 minutes before the Flight Termination System activated, and the Ship broke up at 76 km over the Turks and Caicos Islands. 

Causes

Along with the confirmation of the launch date, SpaceX released an update on the causes of the failure of Ship 33: approximately 2 minutes into the Ship’s burn (so around T+4m40s), a flash was observed in the “attic,” near one of the Raptor Vacuum (RVac) engines; for future reference, the attic is an unpressurized section between the aft dome (the bottom) of the LOX tank and the Raptor engines, which includes the false ceiling (the layer that protects the tanks from the Raptor engines’ hardware); this flash was indicative of a leak, which was revealed as a rise in pressure by the sensors in the area; we don’t know if the leak was LOX or CH4… roughly 2 minutes later, around T+6m40s, another flash was observed, and this was followed by sustained fires in the attic area; this was indicative of a second leak, of the propellant opposite to the first (for example, if LOX leaked first, then CH4 leaked second); the mixing of the 2 propellants caused these sustained fires, which spread from one side to the other of the Ship’s attic; as the fires continued, they damaged the engines and caused them to shut down one by one, until just 1 RVac remained running and the Ship lost telemetry due to damages to the flight computers… Ship 33 tumbled and rotated for about 3 minutes as it reached an apogee and started descending, reentering the atmosphere until the Autonomous Flight Termination System (AFTS) activated when it went outside the safety zone. 

SpaceX also added that the cause of the leaks was harmonic oscillations higher than found during ground testing; these oscillations damaged the propulsion hardware and caused the leaks, which likely came from the RVac engine feedlines; the leaks caused a pressure rise that exceeded the vent capability.

Mitigation actions and solutions: to prevent damage from harmonic oscillations (the root cause of the failure), SpaceX conducted a 56-second-long static fire of Ship 34, the longest-ever static fire of the Starship program, to test multiple thrust levels and 3 different configurations in the RVac fuel feedlines to recreate and address the harmonic oscillations seen on Ship 33; thanks to the data received, SpaceX implemented new hardware on the feedlines, also implementing adjustments to temperatures and a new thrust target.

Additionally, a gaseous nitrogen purge system will be used in the attic to address flammability risk, and more vents have been added to manage higher pressure levels.

Booster 14 note: during the boostback burn, Booster 14 was supposed to ignite its 3 central Raptor engines and its inner ring of 10 Raptor engines, for a total of 13; however, 12 ignited since one engine in the inner ring did not correctly ignite. SpaceX revealed that the reason for the shutdown at ignition was a low-power condition in the igniter system, which ignites the fuel and oxidizer when they are mixed together in the preburners; SpaceX has implemented hardware in the ignitors to prevent this issue in the future.

Flight 8 vehicles

Starship is composed of 2 stages, the Super Heavy Booster and the Starship upper stage: Super Heavy is the first stage, 71 m tall and 9 m wide, powered by 33 Raptor engines; the first stage is designed to return to the launch site after hot staging, getting caught by 2 mechanical arms on the same tower it launched from (like it did during Flight 5 and Flight 7). Starship is the upper stage, 52.1 m tall and 9 m wide, designed to carry the heaviest payloads ever to space, making life multiplanetary; Starship is designed to be caught by tower arms as well in the future (we’ll talk more about this later). 

Booster 15

Booster 15 on the OLM ahead of launch. Credit: Starship Gazer

Booster 15 is the Booster that will be used on Flight 8 of Starship. It features several changes compared to previous Boosters: other than having an ignitor upgrade to all its ignitors (as explained above), it features upgraded avionics, including a more powerful flight computer, a better power and distribution network, and integrated smart batteries; all these improvements between flights make the vehicle more reliable and more powerful! Small upgrades to the reinforcements have been conducted; however, nothing else of major importance was changed (as far as we know).

June 4-8th, 2024: stacking of Booster 15 began in Megabay 1.

September 22nd, 2024: stacking of Booster 15 was completed, with the mating of the 2 tanks.

December 21st, 2024: Booster 15 was rolled out to the Massey’s test site to undergo its cryogenic campaign.

December 27th, 2024: Cryo test 1 of Booster 15’s CH4 tank.

December 28th, 2024: Cryo test 2 of both Booster 15’s tanks.

December 29th, 2024: Booster 15 was rolled back to MB1.

February 8th, 2025: Booster 15 is rolled to the Launch Site for its engine test campaign.

February 9th, 2025: Static fire 1 of all Booster 15’s 33 Raptor engines, lasting 8.5 seconds.

February 10th, 2025: Booster 15 is rolled back to the Production Site.

February 25th, 2025: Booster 15 is rolled to the Launch Site ahead of Starship Flight 8, with its HSR rolling separately after it entered and went out of Megabay 1 twice in the week. 

Ship 34

Ship 34 ahead of rollout for flight. Credit: Starship Gazer

Ship 34 will become the second Block 2 Ship flown during Starship Flight 8. It features many changes compared to Block 1 and many compared to Ship 33; we’re going to analyze them (the following Block 2 description can also be found on our previous Flight 7 article). If you have a lot of time and curiosity, we recommend reading Ringwatcher’s deep dive into Block 2 Ship.

Dimensions: Block 2 has changed in height, gaining 1.8 meters thanks to the addition of a stainless steel ring, making the new-generation ship equipped with 21 rings plus the nose cone.

Forward flaps: the most notable change is that the forward flaps have been completely redesigned, and they feature a lot of changes: they’re smaller, and they’re spaced 140° apart instead of 180°; they’re located lower on the Ship and closer to its “belly,” the leeward side, so that they should be completely shielded from the heat of reentry, eliminating the hinge burns that occurred for the past 3 flights. Their new design is also better for the aerodynamic descent, as the aft flaps don’t have to compensate for the tendency of raising the nose cone anymore.

Extended tanks and new header tanks: a thing you’ll certainly notice during propellant loading, the Ship’s tanks have been optimized and lengthened, giving enough volume for 300 tons, or 25%, more fuel, for a total of 1500 t. This will allow Starship to carry heavier payloads, up to 100t (per SpaceX); the header tanks (which are secondary tanks used for every burn after SECO) have been redesigned to avoid propellant sloshing and fluid problems, especially for future long-duration missions. The internal plumbing, including the fuel transfer tubes, has also been redesigned.

New heatshield: the heatshield is now composed of approximately 18.500 tiles, which have been optimized in some areas, but the key feature is the ablative layer underneath to protect the Ship’s body in case one of the tiles breaks or falls off. This launch will also feature many interesting experiments, featured in the explanation below.

Payload bay: the volume that has gone to the tanks has been taken off from the payload bay, which has gone from a 5-ring to a 3-ring section; however, thanks to optimizations of the hardware inside of the nosecone, more space is now available for the payload.

Propulsion: Ship 34 still features Raptor 2s, as many of the upcoming Ships will for quite some time, until Raptor 3 becomes operational; however, SpaceX has optimized the propulsion of the Ship, vacuum-jacketed the feedlines, designed a new, more efficient downcomer for the RVacs, and improved valves and sensors.

Avionics: there has been a complete redesign of the avionics, which include upgrades to the flight computer, more antennas including Starlink, GNSS, and RF communication systems as backups, new sensors for navigation and tracking, new smart batteries and power units that distribute over 2.7 MW of power across 24 high-voltage actuators, and more than 30 cameras to give beautiful and important views on the ground.“Additionally, SpaceX has confirmed the ability to stream 120 Mbps of data throughout the flight.

These are the Block 2 vs Block 1 changes for Ship; however, Ship 34 also features all the aforementioned changes, including a gaseous nitrogen purge and more vents in the attic area, redesigned RVac fuel feedlines, and several other upgrades. Also, heatshield tiles have been removed from several areas to stress-test the vehicle, and a tile line has received a smoothed and tapered edge to address hot spots on the vehicle; non-structural catch fittings have been bolted on the vehicle’s side to test their thermal performance! Several heatshield experiments will be performed, including several metallic tiles and one featuring active cooling. During Max-Q at reentry, the vehicle will be stressed to its maximum to reach the structural limits of the rear flaps.

There are a lot of changes and many new things that will be seen during Starship’s flight!

September 19th, 2024: stacking of Ship 34 begins in Megabay 2, with the mating of the nosecone and the payload section.

November 18th, 2024: stacking was completed in 60 days.

January 15th, 2025: Ship 34 was rolled from the Production Site to Massey’s for cryogenic proof testing.

January 17th, 2025: Cryo test 1 and 2; the first one was a cryo of the CH4 tank, and the second one was a cryo of both tanks.

January 18th, 2025: Cryo test 3 of both tanks.

January 18th, 2025: Ship 34 was rolled back to the Production Site.

January 28th, 2025: engine installation begins on Ship 34.

January 30th, 2025: 1st aft flap is installed on Ship 34.

February 2nd, 2025: 2nd aft flap is installed on Ship 34.

February 10th, 2025: Ship 34 is rolled to Massey’s for engine testing.

February 12th, 2025: Ship 34 conducts a 56-second-long static fire, the longest of the Starship program. 

February 13th, 2025: Ship 34 is rolled back to the Production Site.

Flight profile of Flight 8

After Flight 7’s demise (on the Ship front), Flight 8 may be the best Starship launch yet! As you may have guessed, most of what will happen on Flight 8 is what should’ve happened on Flight 7… and that’s why it’s interesting!

Pre-launch countdown

Before launch, several operations need to happen. Usually SpaceX decides at T-12h whether to attempt a launch or not that day; then, the road will be closed at T-7h, denying access to anyone who’s not cleared to go; at T-4h, the tank farm will start spooling up in preparation for propellant loading, but don’t worry if you still see workers at the Launch Site, as they may be troubleshooting an issue or just checking things; subsequently, the propellant lines that bring the propellant from the ground tanks to the Booster and Ship will start chilling down, and you will see 2 big vents: one coming from the OLM (Orbital Launch Mount) for the Booster lines, and one coming from the tower for the Ship lines; this occurs around T-2h/T-1h30m. At T-1h15m, SpaceX’s Flight Director will conduct the GO/NO-GO poll for propellant loading; if a GO is given, LOX will be loaded on the Ship starting at T-45m59s, 5 seconds earlier (where earlier means it starts further from T0 in the countdown) than Flight 7, followed by CH4 loading at T-42m59s, 1 second later than Flight 7; Booster propellant loading will follow, starting with CH4 at T-41m22s (2 seconds later) followed by LOX at T-35m35s (7 seconds ealier); halfway through propellant loading of both stages, at T-19m40s, a small amount of cryogenic propellant will be run through all 39 (33 on Booster + 6 on Ship) Raptor engines’ turbomachinery to allow slow cooling and avoid thermal shock at ignition. At T-3m20s and T-2m50s, the Ship and Booster will wrap up propellant loading, respectively, as the countdown clock ticks closer and closer to launch! At T-30s, SpaceX’s Flight Director verifies GO for launch; at T-15s, the DSS (Detonation Suppression System, a nitrogen purge under the OLM that manifests as a grey cloud to prevent fires) will activate, followed by WDS (Water Deluge System) activation at T-10s for sound suppression and damage reduction; finally, at T-3s Raptors will begin igniting!

Interesting fact: during engine ignition, Super Heavy’s 33 Raptor engines ignite in a 13-15-5 pattern: the 3 central Raptor engines and the inner ring of 10 ignite first at T-2s, followed by 15 out of 20 engines on the outer ring at T-1s, and the last 5 engines at T0; that’s what T0 represents: the moment where all the engines are ignited.

Flight timeline

After ignition of Super Heavy’s Raptor engines, Starship will lift off at T+2s, and it will begin to pitch downrange, ascending towards space! At T+1m2s during ascent, Starship will experience Max-Q, the moment of peak mechanical stress on the rocket due to the atmospheric pressure lowering while Starship accelerates; this will leave the characteristic cloud of plume, through which the Booster seems to pass during descent; at T+2m32s, Super Heavy will shut down 30 out of its 33 Raptor engines, leaving just the central 3 ignited, while Starship will turn on its 6 Raptor engines at T+2m40s while still attached to the Booster! This maneuver was introduced in Flight 2, and it’s called hot staging; it involves keeping some engines lit on the first stage while the second stage ignites its engines while still attached to the first stage; according to Elon Musk, this can increase payload capacity by 10% compared to traditional stage separation. 5 seconds after separation, Booster 15 will ignite 13 Raptor engines to begin the boostback burn, lasting 45 seconds; at its end, the SpaceX Flight Director will need to send a manual command based on the data from the Booster and the tower to initiate the catch maneuver; otherwise, the Booster will automatically aim for a soft splashdown in the Gulf of Mexico, roughly 30 km offshore. At T+3m32s, Booster 15 will jettison its HSR (Hot Staging Ring), which is not needed anymore and would cause a balance problem during descent and catch; while the Ship will ascend towards space, Booster 15 will descend towards (hopefully) the launch tower! At T+6m37s, Booster 15 will ignite its 13 central Raptor engines to begin the landing burn, transitioning to 3 for final maneuvering a few seconds later… if all goes well, at T+6m57s Booster 15 will be caught, marking the third Booster catch in the Starship program!

In the meantime, at T+8m44s, Starship will cut off its engines, reaching its intended trajectory… assuming all goes well, Starship will coast through the nightside of the Earth, but something special will be coming up: at T+17m24s, Starship will attempt to deploy its first-ever payload! The payload will be composed of 4 Starlink-V3 simulators, with a mass of approximately 2 tons each, which is less than Flight 7, which carried 10; these payloads will be integrated onto the PEZ dispenser in Starship’s payload bay, and whilst in space, the payload bay door will open and deploy these satellites 2 by 2, meaning there will be 2 deployment events! This is going to mark an incredible milestone in the Starship program… these satellites will be on a suborbital trajectory and will burn up upon reentry in the atmosphere less than 40 minutes later… but this is not going to be the only test on Starship’s coast phase, because at T+37m28s Starship will perform an engine relight lasting a few seconds! This will validate, for the first time, the reliability and functionality of Block 2’s redesigned header tanks and related propulsion hardware; just 10 minutes later, at T+47m22s, Starship will begin its reentry phase: as it reenters in the atmosphere, its heathshield will experience more than 1000°C of heat, likely even more; the majority of the experiments will be performed during this phase, including how the redesigned heatshied works, which material works better, how do the catch fittings endure the heat, and how the flaps perform during max heating and Max-Q; if Ship 34 gets through reentry, then we will be in for a treat because it’s going to perform another daytime descent and landing! At T+1h3m5s, Starship will be transonic as it descends through the thickest parts of the atmosphere, putting the fwd flaps to the test, and it will be subsonic at T+1h4m20s; then, the most awaited part: at T+1h6m4s, Starship will perform the flip maneuver followed 2 seconds later by the 3-engine landing burn, culminating 20 seconds later in an exciting landing!

Note: this will be the most daring Starship flight yet: thousands of things will work in an integrated way, especially on Ship, for the first time. There is a real chance that some things won’t work out the way they’re intended, or won’t work out at all… however, this can’t stop our faith! So let’s hope for the best, and let’s go see Starship!

Why is this launch important? 

This launch could prove to be the most daring, interesting, and important Starship launch so far for several reasons: well, first of all, it’s Starship, the highest, most powerful rocket ever developed, and even one of the most advanced! But aside from that… let’s explore the reasons for why this flight is so important:

Catch: the Super Heavy Booster catch is one of the most beautiful things of the Starship launches! This one in particular will be important from a cadence side: thanks to a label spotted with “B18.1” written on it, it’s safe to assume that Booster 17 is the last Block 1 Booster, after which Block 2 will start to be implemented; however, that’s still half a year away at least, because Pad B needs to be ready and no Block 2 Booster hardware has been seen… that said, SpaceX might have to rely on Block 1 Booster reuse in the coming flights, and catching Booster 15 would be very important since it would provide 1 more booster to reuse! 

Payload deploy: approximately 17 minutes into the flight, Ship 34 will attempt to perform the program’s first payload deployment, consisting of 4 Starlink V3 mockups, with a mass of 2 tons each; this will mark an important milestone because it might validate the payload bay door, the PEZ dispenser, and other important hardware… Starship is designed to carry up to 54 Starlink V3 satellites in the future, which will greatly increase the constellation’s capability and performance.

Engine relight: while an engine was already relighted in space on Ship 31, that was a Block 1 Ship; Ship 34 is a Block 2 Ship, and it has a very different design of the header tanks (the 2 small propellant tanks in the nosecone that are used for every burn after SECO) and the feed system. This capability will be needed to validate deorbit burn capabilities.

Reentry: during reentry, Starship will mark several firsts: as we’ve said, several heatshield experiments have been placed to validate the best materials, locations, and cooling methods for atmospheric reentry. Additionally, the thermal performance of the catch pins will be determined, along with verifying whether the redesigned fwd flaps have solved the plasma burn-through problem.

Descent: during Starship’s descent in the thickest parts of the atmosphere, under 30 km, both the fwd and aft flaps will be stress-tested to their structural limits to validate their design or to address problems. 

Landing: this phase will test the header tanks, engine reliability, and aerodynamic performance, plus landing accuracy. If this maneuver is successfully completed, then it will mark the first landing of a Block 2 Ship and it might validate it for ship catch… wait, ship catch? What are we talking about? Well, there is some news!

What does the future hold?

If this launch goes well, then Flight 9 has the potential to become the greatest Starship flight ever seen: according to speculation, Flight 9 might feature the first Booster reuse (likely Booster 14) and the first Ship catch attempt! But how do we know this? Let’s see:

If the current queue of Booster/Ship pairings, then Booster 16 should fly on Flight 9; however, it just conducted cryogenic proof testing and therefore might not be ready to fly until early/mid-May, which is a long time from now. Additionally, Booster 14 has been in Megabay 1 since it was caught, instead of being displayed in the Rocket Garden like Booster 12 was, which might mean that it’s undergoing preparations for a reflight! If true, then Flight 9 might really feature a flight with Booster 14-2!

As for the Ship catch, Elon Musk mentioned a potential Ship catch on Flight 8 if Flight 7 went nominally, but since it didn’t, it’s plausible to think that the first Ship catch attempt has shifted to Flight 9 if Flight 8 goes nominally.

The new FAA license features an “orbital” paragraph (they do not have clearance yet, but they’re ready to), suggesting that Flight 9 might be orbital! Additionally, for the first time, Starbase is among the possible landing locations for the Ship! All lines up for a Ship catch attempt on Flight 9… but the interesting thing is where: if you were thinking Pad A, you’re wrong, because it looks like SpaceX is planning to catch the Ship with the shorter chopsticks at Pad B, since they would only need the chopsticks and the SQD (Ship Quick Disconnect), making it a reality within reach.