SpaceX continues forward progress with Starship on Starhopper anniversary

by Lee Kanayama & Adrian Beil

SN10 lifted off on its second attempt and landed softly and upright on the landing pad; however, the vehicle was damaged during the touchdown, and the residual propellants ignited 8 minutes later, destroying the ship.

The hard landing was likely caused by a Raptor engine ingesting helium in the header tanks, as stated by Elon Musk.

SN11 and BN1

SN11 was the fourth and last of the first generation full-scale Starship to be flown. Just like SN9, SN11 was finished in the high bay with its Raptors already installed. The nose cone section was stacked to the tank section on February 7 and rolled out of the high bay a month later on March 8, 2021. 

It was moved from the build site to Pad B, where it would begin pre-launch operations. 

Starship SN11 immediately started testing on March 11 with a cryoproof test. Four days later, SN11 attempted its first static fire at approximately 12:26 pm CDT, but this was aborted right at ignition.

While checks and inspections of SN11 were completed, BN1, the first-ever prototype of the Super Heavy first stage, began build operations. It was used as a manufacturing pathfinder and was scrapped one month later.

SN11 second static fire occurred on March 22. While the static fire was nominal, it was later found that one of the Raptors (Raptor 46) was suspect and needed repair ahead of another static fire and flight attempt. 

Just after 8 am CDT on March 26, SpaceX static fire Raptor SN46 in a nominal full burn. The first launch attempt was later scrubbed due to technical issues. 

A second attempt on March 29 was later scrubbed due to the FAA inspector not being in Boca Chica in time for launch. 

SpaceX readied SN11 for an early morning launch on March 30, when the ship successfully ascended to 10 km with nominal engine shutdowns and a descent down to the landing pad.

At T+5:49, SN11 ignited a single Raptor followed a second later by another. All telemetry was then lost as the vehicle exploded. Elon Musk later tweeted Engine 2 (Raptor 52) had issues during ascent and never reached operating chamber pressure during its landing burn.

At T+25 seconds, a leak was seen on Raptor 52 causing a small fire. This fire likely caused a “hard start” in the methane turbopump of Raptor 52 during the landing burn. The hard start caused a RUD with the Raptor and led to the loss of the entire vehicle.  


The first Starship to fly with a new generation of Raptors was SN15. The new design fixed some of the flaws previous vehicles encountered.

Suborbital Pad A received the vehicle on April 9 where it would start the usual test campaign of an ambient pressure test on the same day, a cryogenic proof test on April 12, and a header tank proof test on April 13. 

The Raptors were then installed.

Two static fire attempts, one from the main tanks and one from the header tanks, followed on April 26 and April 27. Starship SN15 was ready to launch to 10 kilometers, which happened on May 5.

SN15 performed a flawless countdown, liftoff, flight to 10km, and descent. An engine shut down early and did not relight during the flip; however, the Raptor was not needed as the two engines that did relight completed the flip, and the vehicle safely touched down on the pad. After a small fire at the base of the vehicle was extinguished, SN15 was the first vehicle to perform a safe landing after a high-altitude flight test.

After the flight, it was found that the methane header tank had lower than expected pressure during landing. SN15 counteracted the potential lower thrust (as seen on SN8) by using a two-engine landing, instead of the planned single-engine landing. Despite this, SN15 was considered a huge success; the flight tests of SN16 and SN17 were scrapped.


Besides the vehicle test campaigns, another important aspect of launching a Super Heavy lift rocket is infrastructure. This part of the launch sequence, called stage 0 by Elon Musk, has made rapid progress in the past 12 months — which is crucial to support an orbital launch later this year.

At the build site, the last year saw the rise of the high bay, at 80 meters high. It is used for the final stacking of the Ship upper stage and general stacking of the Super Heavy booster stages. It was finished on August 29, 2020.

At the launch site, the last year saw the construction of the Orbital Launch Pad (OLP) and the launch tower next to it. The launch tower will soon host mechazilla to catch Boosters and potentially Ships. The final section of the tower was lifted on July 27.

The OLP saw its latest milestone in late July when SpaceX lifted the enormous launch table onto the pillars of the pad. According to permits, there is a second pad and a second tower planned to help the launch cadence that is needed to bring humans to the Moon, Mars, and beyond. 

SpaceX is also manufacturing its ground service equipment tanks (GSE tanks) which are needed to contain all the fuels and liquids for launch operations. As of now, many of these are already hosted at the launch site, and the final ones are in work at the build site. SpaceX is using the same 9-meter diameter Starship rings to build these GSE tanks. Around these tanks, a 12-meter diameter shell will insulate tanks and keep the liquids at their desired temperatures.

Booster 3, 4, and Ship 20

After successful testing using the BN2.1 test tank. SpaceX moved forward with the first Super Heavy booster that would be used for ground testing. Booster 3 was first spotted in March 2021. By June 29, it was fully stacked in the high bay and was rolled out to Pad A on July 1. 

Booster 3 was originally to be the first Super Heavy to complete an orbital attempt, but due to new updates after BN2.1, Booster 3 was only used for ground testing. 

On July 12, it completed the first-ever Super Heavy cryoproof test. Booster 3 would sport a total of three Raptors for its ground testing. Raptors 57, 59, and 62 were the Raptors installed on Booster 3, with 57 installed before the cryoproof and the other two installed after the test. 

A week later, SpaceX geared Booster 3 for a static fire. Following a similar countdown to those used on Ship, Booster 3 successfully static fired and was later detanked and the Raptors uninstalled. Elon Musk suggested a nine-engine static fire on Booster 3, however, due to the accelerated manufacturing of Booster 4, that plan was scrubbed.  

On August 14, SpaceX cut Booster 3 in half. Currently, its remains sit on and near Pad A. It will soon be scrapped; however, the success of Booster 3 allowed SpaceX to move ahead with the first orbital hardware for the Starship program. 

Ship 20 was first spotted in March 2021 and is currently the Ship set for the first orbital flight test. Booster 4 was spotted in early July 2021 when it was in the high bay. Both Ship 20 and Booster 4 were fully stacked in the first week of August. The accelerated stacking of the two was made due to a new urgency by Elon Musk to finish the two and stack them by August 5.

Booster 4 was completed on August 2 with a full complement of 29 engines mounted to the vehicle. The grid fins were installed the same day. On August 3, Booster 4 was rolled out to the launch site and was later lifted on the OLP, making it the first booster to be placed on the pad.

Ship 20 was then moved to the high bay for stacking with its nosecone. Ship 20 is the first to sport the full heatshield and the new smaller body flaps. Ship 20 also sported all six Raptors, the same three used on Booster 3 and as well as RVac 2, 3, and 5. 

Ship 20 was moved to the launch site on August 5 and stacked on August 6 at 7:56 am CDT.

While only stacked on Booster 4 for roughly an hour, this marked a large milestone in the Starship program. But additional work started immediately. 

Ship 20 was taken off Booster 4 once the fit checks were complete and returned to the high bay. Once there, its six Raptors were removed from Ship 20 and work started on its heat shield tiles. The Raptors were removed to allow Ship 20 to be tested on Pad B.

On August 10, Booster 4 was taken off the launch mount and moved back to the build site the next day where its raptors were removed.

On August 23, the Raptors were once again installed on Booster, and aerodynamic covers were added to each COPV (Composite Overwrap Pressure Vessel) on the exterior.

(A lunar variant of Starship has been selected by NASA to return humans to the surface of the Moon this decade. Credit: SpaceX/NASA)

Ship 20 was moved from the build site to the launch site on August 13 for a standard cryoproof test ahead of a static fire. When the static fire is conducted it will be the first time a Starship will have its entire set of Raptors fired. 

Ship 20 and Booster 4 are set to launch on an orbital flight attempt. Under current plans, the Booster is set to land in the Gulf of Mexico after launching Ship 20 toward space. Ship 20 will continue for a near-full orbit to complete an atmospheric orbital velocity reentry and attempt to land 100 km off the coast of the Hawaiian island of Kauai. 

Another set of orbital test vehicles, Booster 5 and Ship 21 have both started construction ahead of a similar flight to Booster 4 and Ship 20. 

Lead image: Ship 20 leaving the launch site with Starhopper in the foreground. Credit: Mary (BocaChicaGal)

Related Articles