SpaceX Launched Starhopper Two Years Ago, Let’s Look Back At Starship’s Amazing Development!

by Evelyn Arevalo August 27, 2021

SpaceX Launched Starhopper Two Years Ago, Let’s Look Back At Starship’s Amazing Development!

SpaceX is taking on the challenge to develop the Starship launch system that will enable humanity to return to the Moon and build a city on Mars. The aerospace company has been working tirelessly to have a space-ready Starship before the year 2023. Two years ago today (August 27) SpaceX launched 'Starhopper', the first Starship prototype to ever take flight at its Starbase facility in Boca Chica Beach, Texas. The company is now preparing to launch the first Starship launch vehicle to orbit this year. Let’s look back at Starship’s amazing development progress and the challenges SpaceX encountered since January 2019 to today. This article is a summary all that has happened, from explosive tests to successful Starship flights!


It all started with ‘Starhopper,’ the first prototype of the Starship spacecraft. The company started to build the stainless-steel vehicle in the middle of a almost empty grassy field with a single tent. Starhopper featured three landing legs that made the spacecraft look like a spaceship from retro comic books. SpaceX called the vehicle Starhopper because it would only conduct a series of short “hop” tests, involving the craft flying at very low altitudes above Boca Chica. Starhopper was stacked for the first time on January 9, 2019, it looked surreal to see it along the Highway 4 road, video below.


SpaceX engineers unassembled Starhopper to allow additional assembly work to continue. They still had a lot of more work to do involving, inner construction like installing sensors, avionics, tanks, plumbing, attitude thrusters, etc. A couple of weeks later, high winds caused the top portion of Starhopper to tip over. SpaceX had no high bays to protect the vehicles from high winds at the sandy village at that time. The months that followed, SpaceX was simultaneously working on the Raptor engine production/testing, as well building the next Starship prototype ‘MK1,’ and launch pad's supporting structures.

The month of June arrived and SpaceX had the first flight-ready Raptor engine. Teams installed it to Starhopper and performed the first static-fire test of the one-of-a-kind, methane-fueled Raptor. Fast-forward to August, SpaceX decided to launch Starhopper without a nose cone to save on costs and time. On July 26, 2020, SpaceX launched Starhopper 20-meters off the ground. Then it launched the vehicle much higher on August 27, 2019; Starhopper lifted off 150-meters off the ground powered by a single Raptor engine. The incredible flight test demonstrated the company’s capability to perform a controlled flight and landing. 



In September 2019 SpaceX unveiled a new Starship spacecraft design when it completed the construction of the Starship MK1 prototype, simultaneously other teams were building Starship MK2 in Florida. The new design features: 4 fins, retractable landing legs hidden behind steel mount covers, 3 Raptor engines for aerodynamic flight, 3 vacuum-optimized Raptors for propulsion in space (vacuum engines weren't installed at that moment). Starship MK1 looked beautiful and you can really see all of the hard work SpaceX teams put into the craft's manufacturing. SpaceX founder Elon Musk hosted a ‘Starship Update’ presentation on September 28, 2019, during which he discussed technical aspects of the new design and the importance of making life multi-planetary. "It appears that consciousness is a very rare and precious thing and we should take whatever steps we can to preserve the light of consciousness. Only now, after 4.5 billion years has that window been open. That’s a long time to wait and it might not stay open for long," Musk said in 2019, "I’m pretty optimistic by nature, but there’s some chance that window will not be open for long, and I think we should become a multi-planet civilization while that window is open.” You can watch the presentation video below.

Starship 2019 Presentation


Engineers planned to launch Starship MK1 into an altitude of 20-kilometers above Boca Chica Beach, but MK1 ruptured during a cryogenic proof test during which they pressurized the craft to the max in order to check for any leaks – that's when the top dome structure of Starship Mk1 ruptured. Soon after that ordeal, Musk decided to move on to the next phase of Starship development. The next phase left all the Starship MK edition prototypes behind and Florida Starship plans were scrapped to focus on Boca Chica production. Not all was lost though, the MK prototypes engineers learn how to manufacture the vehicle. The company began building the flight design version of Starship, the ‘SN’ series (SN: Serial Number) which Musk said that they could manufacture and test at least 20 prototypes.




SpaceX picked up its innovation and iteration pace in 2020. By February/March, teams completed the construction of the Starship SN1 prototype. This vehicle did not resemble the spaceship design, it looked more like a stainless-steel cylindrical tank. Engineers planned to launch SN1 ~20 kilometers high, but when engineers conducted a cryogenic pressure test Starship SN1 it was ruptured by too much pressure. “It's fine, we’ll just buff it out. […] Where's Flextape when you need it!?” Musk joked after SN1 ruptured on March 2nd. A TESMANIAN reporter (@JaneidyEve) asked via Twitter: “So, what did y'all learn from this event?” To which Musk replied: “There’s a puck at the base that takes the engine thrust load. Don’t shuck the puck!” he joked. The ‘thrust puck’ is the structure where Starship's Raptor engines are mounted. So, what he meant is that the thrust puck design and welding needed to be strengthened.





SpaceX then opted to build a smaller scale prototype, SN2, which was just a dome tank meant to undergo cryogenic proof testing to assess the thrust puck-to-dome weld under pressure. SN2 was first tested with water, then at cryogenic temperatures with liquid nitrogen in March 2020. SN2 passed all proof tests and SpaceX moved on to test Starship SN3, which was also a cylinder prototype that did not look like a spaceship.


Starship SN3 passed an ambient proof test but ended up collapsing during a cryogenic pressure test on April 2, 2020. According to Musk, the mishap “may have been a test configuration mistake,” he shared via Twitter, “Some valves leaked at cryo[genic] temp[erature]. Fixing & will retest soon.” Musk says that a stainless-steel Starship structure and welds need to withstand a pressure strength between ~6 and 8.5 bar, an 8.5 bar is necessary for safe crewed flights, 6 bar is needed for uncrewed orbital flight tests.



The next prototype in line, Starship SN4, did pass all proof testing. Musk told TESMANIAN reporter (Evelyn J. Arevalo) that it reached a strength of 4.9 bar. “Kind of a softball tbh [to be honest], but that’s enough to fly!” he said on April 27, 2020. This vehicle was expected to conduct a flight test of 20-kilometers. However, even though engineers did improve the stainless-steel vehicles tank strength, the vehicle exploded when they test-ignited its Raptor engines on May 29, 2020. Musk did not elaborate on what caused the issue. The Raptor engine is fueled by cryogenic propellants, liquid methane and liquid oxygen (methalox). In the rocket-manufacturing industry explosions are quite common when developing a new craft. Every test provides engineering teams with valuable insight towards the spacecraft and rocket development.







By July 2020, SpaceX engineers used all they learned from the destructive tests to prepare the Starship SN5 prototype. SN5 also did not look like a spaceship, but it helped the company accomplish many development milestones. SN5 passed cryogenic proof tests and static-firing of its Raptor engine nominally. On August 4th, 2020, SpaceX conducted Starship SN5’s debut test flight. The stainless-steel vehicle conducted a low-altitude "hop" test, it soared 150-meters into Boca Chica Beach’s sunny sky and landed flawlessly, powered by a single Raptor engine. The successful flight enabled engineers to push Starship’s development further. By September 3, just a month from launching SN5, SpaceX completed another low-altitude test flight of a twin Starship prototype in South Texas. The Starship SN6 test vehicle performed a similar flight, lifting off 150-meters and deployed a set of six legs to perform a controlled landing on a nearby pad. With two successful landings, SpaceX engineers gained confidence to push Starship’s development further and conducted the first high-altitude test flight in December 2020.

SpaceX’s Starship SN5 and SN6 ‘Hop’ Test Launches Side-by-Side



Before launching the first high-altitude flight, SpaceX intentionally popped SN7, which was a Starship test tank to assess how much pressure the propellant tank could take. On December 9, 2020, SpaceX accomplished performing the first high-altitude test flight with the Starship SN8 prototype. Teams launched Starship SN8 approximately 12-kilometers) into Boca Chica’s sky powered by a trio of Raptor engines. It is the first vehicle that lifts off to such heights with three engines. During the epic flight test SpaceX tested the vehicles aerodynamic flaps with an impressive ‘belly flop’ dive maneuver. The maneuver is important towards Starship’s development, it is how the spacecraft will move to enter a planet’s rough atmosphere before landing. The test flight lasted around seven minutes in which Starship used its aerodynamic flaps to glide itself down the sky. SN8 was capable of reorienting itself to a vertical descend position to prepare to land but the vehicle exploded upon landing.

Musk said that the explosion was caused because the “Fuel header tank pressure was low during landing burn, causing touchdown velocity to be high & RUD, but we got all the data we needed! Congrats SpaceX team hell yeah!!” he said soon after the flight test. “Thank you, South Texas for your support! This is the gateway to Mars.” Musk declared that day.

Despite the epic fireball landing finale, SpaceX learned many things from the flight test – “from how the vehicle’s three Raptor engines perform to the overall aerodynamic entry capabilities of the vehicle (including its body flaps) to how the vehicle manages propellant transition [...],” the company stated, “With a test such as this, success is not measured by completion of specific objectives but rather how much we can learn, which will inform and improve the probability of success in the future as SpaceX rapidly advances development of Starship.”



By January 2021, SpaceX significantly picked up its manufacturing rate. The next prototype in the series, Starship SN9 and Starship SN10, stood side-by-side at the Starbase launch pad, it looked like a scene from a Sci-fi movie. On February, 2, 2021, Starship SN9 completed all flight objectives but also exploded. SpaceX shared the failed landing attempt was due to “one of the Raptor engines [that] did not relight and caused SN9 to land at high speed and experience a RUD [Rapid Unscheduled Disassembly].” “It was foolish of us not to start 3 engines & immediately shut down 1, as 2 are needed to land,” Musk said after Starship SN9's flight test. Another lesson learned; each Starship test in South Texas takes the company one step closer towards achieving its ambition to launch the first astronauts to Mars.



By March 7, 2021, SpaceX conducted the next high-altitude flight test. Starship SN10 had a similar fate as its predecessors with some improvements – SN10 completed all flight objectives, even aced the landing but it burst into flames a few minutes after touching down. Musk said that the explosion was caused because it landed at a high speed due to low thrust of its Raptor engine trio. He said the low thrust was probably due “to partial helium ingestion from fuel header tank. Impact of 10m/s crushed legs & part of skirt,” he said.



Starship SN11’s history is still hazy. This year, on March 30, the vehicle soared into Boca Chica’s cloudy sky through thick fog and clouds causing the six-minute launch to be invisible in person. The company’s broadcast was also very foggy. According to SpaceX, the vehicle soared into a max altitude of around 10-kilometers, its onboard cameras cut out as the launch commentator John Insprucker said, “Looks like we've had another exciting test of Starship Number 11. […] Starship 11 is not coming back, do not wait for the landing,” he said, suggesting SN11 exploded above the landing pad. “Looks like engine 2 had issues on ascent & didn’t reach operating chamber pressure during landing burn, but, in theory, it wasn’t needed. Something significant happened shortly after landing burn start,” Musk said at that time.


On May 5, 2021, SpaceX performed its first successful flight test. Starship SN15 finally aced the landing with no RUD! The 50-meter-tall Starship SN15 vehicle blasted off 10-kilometers into the cloudy sky; It was nearly invisible to spectators on the ground due to foggy weather conditions in the South Texas region. The company’s broadcast showcased SpaceX’s engineering talent as the vehicle performed all flight objectives flawlessly, video below. “SN15 has vehicle improvements across structures, avionics and software, and the engines that will allow more speed and efficiency throughout production and flight: specifically, a new enhanced avionics suite, updated propellant architecture in the aft skirt, and a new Raptor engine design and configuration,” SpaceX representatives stated. "These test flights of Starship are all about improving our understanding and development of a fully reusable transportation system [...]."



Starship SN15 is currently on display at the Starbase facility next to Starship SN16, a vehicle that has not flown yet. It is unclear if these twin test vehicles will be retired soon, Musk previously said that they may attempt to perform a “hypersonic” flight test with Starship SN16.



The company decided to skip all other prototypes to manufacture the first orbital launch system comprised of Starship SN20 and Super Heavy Booster 4. It will be the first fully-stacked launch vehicle to conduct an orbital flight attempt. Musk’s full focus is on achieving a successful orbital flight. SpaceX stacked the gigantic launch vehicle for the first time at the launch tower earlier this month on August 6, pictured below. The 394-foot-tall vehicle is the world’s largest rocket, taller than the Statue of Liberty. Musk shared stunning photographs of the enormous rocket via Twitter and said that it is a “Dream come true” to see the vehicle he designed finally stacked. “An honor to work with such a great team,” Musk wrote. The Super Heavy booster is equipped with 29 methane-burning Raptor engines that will turn it into the most powerful rocket in the world once the vehicle becomes operational. The gigantic spacecraft has been unstacked to undergo pre-flight preparations. If pre-flight ground tests go smoothly and SpaceX obtains approval from regulatory agencies this year, Super Heavy (Booster 4) will propel Starship (SN20) to orbit from Texas and land it in the ocean off the northwest coast of Kauai, Hawaii. The future is exciting! Good luck to SpaceX!


Author's Note: Thanks for supporting ♡ Find me on Twitter: @JaneidyEve



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