Starship SN-4 | Static Fire Test

What Does it All Mean?

Starship, SpaceX’s answer to the “How do we get to Mars?” question will take to the skies for the first time … EVER!  Or, originally, that was the plan. The SN-4 prototype will get that glory in May 2020. During a test flight, at their south Texas facility, SN-4 will fly 150 meters into the air and then land. If successful, it will pave the way for subsequent Starships to perform even more complex tests. The story of how SpaceX got to this point is explained in the article below.

Lift Off Time

(Subject to change)

First static fire test May 5,  2020. Last test May 29, 2020.
Mission Name and what it is
Starship Serial Number 4 (SN-4) 150 meter hop
Launch Provider

(What rocket company is launching it?)

 SpaceX
Customer

(Who’s paying for this?)

SpaceX
Rocket
Starship
Launch Location
Boca Chica, Texas
Payload mass
No payload
Where are the satellites going?
 There are no satellites. The rocket is going to an altitude of 150 meters
Will they be attempting to recover the first stage?
Yes
Where will the first stage land?
The only stage (Starship) will land in Boca Chica near the launch pad
Will they be attempting to recover the fairings?
SN-4 doesn’t have fairings
Are these fairings new?
No fairings on this vehicle
This will be the:
First test flight of Starship
Where to watch
Official Livestream from SpaceX

Maybe even more fun you can watch with Tim Dodd, the Everyday Astronaut, starting at T- minus 30! Ask questions and join the conversation live!

What is Starship?

Starship is SpaceX’s next-generation reusable Mars rocket. To not be confusing, SpaceX calls the entire system Starship. But that is also the name used for the upper stage too! They call the booster stage Super Heavy. Therefore, we can loosely say “Starship,” meaning Starship and Super Heavy. However, we could also mean just the upper stage.

This thing will be crazy powerful! Initially, the reusable Starship system will have a 100-metric-ton payload capacity to low-Earth orbit. With in-orbit refuelling, it also can send that payload to the Moon or Mars. In other words, it will launch heavier payloads to the Moon or Mars than the Apollo-era Saturn V rocket.

Full and rapid reusability is key to Starship’s revolutionary capabilities. Therefore the Super Heavy booster and the Starship upper stage are reusable with expected jetliner-like turnaround. The booster and spacecraft should revolutionize space travel because it will reduce costs while also lifting the heaviest payloads to deep space.

Meanwhile, there are Earthbound services it can perform as well. For instance, Starship’s expected cheap cost and flexibility means it also can be used as a point to point transport on Earth.  Imagine, in under an hour, passengers flying anywhere in the world. Gone are the days of boring old airplanes. It’s rocket time.

When it’s complete, Starship will be the tallest, most powerful rocket ever built. Eventually, it will take people to the Moon, Mars, maybe even to Jupiter’s moons. But first, they have to build the thing. Thankfully, that’s well underway. SpaceX’s team in Boca Chica, Texas is working at an unprecedented pace. Soon, they hope to turn out rockets as quickly as jetliners.

Where and How is This Thing Built?

When SpaceX broke ground on its Starship facility in 2014, they thought it would be operational soon after. However, it took three years of soil preparation to stabilize the site before they could start facility construction. They originally intended it as a launch site for the Falcon 9 and Falcon Heavy rockets. But, over the years, it became apparent that they would use it for Starship.

Starhopper

Meanwhile, Boca Chica became operational in 2018 when SpaceX began building its Starhopper test vehicle. They built Starhopper as a test bed for SpaceX’s Raptor engine. Subsequently, it flew twice in the summer of 2019 to an altitude of 20 meters and later 150 meters. Water towers really can fly, after all.

Starhopper in flight, or a water tower is flying in the air for some reason.
Starhopper during its 150-meter hop.

Starship MK-1

When you think “rocket factory,” you think of large buildings with clean rooms and expensive and precise machinery. That’s not how SpaceX is doing this. During most of 2019, they built their first Starship prototype, MK-1, outside in the Texas coastal plains with steel plates and hammers.

Rings

After MK-1, which used multiple steel plates for each ring, they switched to using only a single piece of steel for each ring. As a result, it looks smoother, and it’s also much stronger. Also, it allows them to build the rocket much faster.

Starship Mk-1 and SN-1 compared, basically two silver grain silos.
Left: MK-1. Right: SN-1. Credit: LabPadre and NASASpaceFlight

Meanwhile, SpaceX bought machinery from the Italian company IMCAR to bend the metal sheets into rings. Incidentally, their machines are often used for water towers and tanks, but never before for rockets. So, with these machines, SpaceX’s Boca Chica facility is shaping up to be a veritable rocket factory. With three massive football-field-sized tents and two tall windbreakers, they’ve shown that their plan to make multiple Starships a week is more than a pipe dream.

 

Lime green machine used to roll metal with reddish brown rollers laying horizontally in a warehouse.
An IMCAR steel rolling machine similar to what SpaceX used during this year’s construction.  Credit: IMCAR

 

If It’s Tight It’s Right, If It’s Long It’s Wrong

It’s true that Elon Musk isn’t much of a sentimentalist. As an example, Starship’s first prototype, MK-1, was intentionally tested to destruction on November 19, 2019. Fortunately, it failed at a higher pressure than the tank would experience during a normal flight. Since then, their building techniques have changed drastically.

Starship Mk-1 blows its top with lots of steam against a blue background.
Starship MK-1 during a deliberate over-pressurization test. Credit: LabPadre

Pressure Tank Testing Early 2020

After that, they got back on their feet quickly. Moreover, SpaceX rang in the new year with pressure test upon pressure test. These tanks used distinct single-piece rings and redesigned bulkheads. Their first pressure test failed at 7.1 bar, below the 8.5 bar required for safe human flight. However, their second test successfully reached that threshold.

 

Starship test tanks
“Starbopper” propellent tank test article during pressure checks. Credit: BocaChicaGal via NasaSpaceFlight

By February, they were confident enough in their new rings and bulkheads to begin construction on their first actual Starship, SN-1. In just over a month, they finished the SN-1 tank section, and they rolled it out to the launch pad. However, SN-1 also suffered an untimely demise. At exactly ten o’clock at night, local time on February 28, 2020, a cloud of super-chilled nitrogen engulfed the rocket. When the fog cleared, the rocket was no longer standing on the pad. Similar to its older cousin, the pressure was too much for it and it imploded.

Starship SN-1 blows up in the dark.
Starship SN-1 implodes during pressurization test, February 28, 2020. Credit LabPadre

Starship SN-2 Tank Test

Subsequently, SpaceX quickly found the root of the problem. In short, the thrust puck, the attachment point for the Raptor engines, was found to be the culprit. Therefore, it failed at an unknown pressure and sent rocket pieces flying. In a matter of days, SpaceX cleaned up the debris and moved another test tank onto the pad. This time, it used a redesigned thrust puck.

 

For the first time, in a long time, it did not blow up on the pad. On Sunday, March 8, 2020, it stood on its stand for hours, venting and covered in ice. The thrust puck held up, and they deemed the test a success. SpaceX moved SN-2 to the scrapyard. Meanwhile, its fate remains uncertain.

 

Starship SN-2, a silver tank on a multi-legged iron red looking test stand
Starship SN-2 test tank, during pressurization check outs. Credit: BocaChicaGal via NasaSpaceFlight

 

Starship SN-3

Immediately after SN-2’s success, SpaceX went full-swing into Starship SN-3’s construction. With the knowledge gained from constructing the previous vehicles, they built Starship SN-3 in record time. During the following month, it went from two rings on the ground to a full-blown Starship (sans nosecone and fins). Though this time around, it had legs. In addition, it’s also bigger, about two meters taller, and better than ever before.

 

Starship SN-3 looking up towards the metalic grey thrust structure with a yellow metal structure attached to it to simulate rocket thrust
Looking up Starship  SN-3’s engine skirt during a fit test. Credit: Elon Musk on Twitter

Starship SN-3 Tests

In the beginning, Starship SN-3 was to do a cryogenic pressure test before a static fire. Unfortunately, SN-3 crumpled during cryogenic testing and the test was unsuccessful. Fortunately, the failure wasn’t the fault of the vehicle. Improper testing procedures doomed the vehicle. Workers didn’t pressurize the lower tank as much as the upper tank. Therefore, the vehicle collapsed under its own weight.

Starship SN-3 at night siloetted by lights, looking like a can being crushed
Starship SN-3 in the process of being crushed during a pressurization test. Credit: BocaChicaGal via NasaSpaceFlight

Starship SN-4

Meanwhile, SN-4 was already being built before SN-3’s implosion. After that, final stacking occurred on April 17, 2020. Then, they rolled it out to the pad on April 23.

Starship viewed from a drone, from a high angle looking down on its silvery silo.
An aerial drone captures Starship SN-4 during transfer to the launch pad. Credit: Elon Musk

Static Fire Test: It Survived!

First, SN-4 underwent an ambient nitrogen leak test on April 25. And then they performed a successful cryogenic test the next day, reaching 4.9 bar.  Later, Starship’s first successful wet dress rehearsal, and apparent pre-burner test, happened on May 4. SpaceX engineers carried out a static fire on May 5. A second static fire occurred the next night. This time, fuel was fed through the smaller header tanks rather than the main tanks. Again, it was a success.

Starship SN-4 on the launch pad as fire comes out is bottom.
Finally, a Starship survived a static fire test on May 5, 2020. Credit: BocaChicaGirl via NASASpaceFlight

Raptor SN-18, which conducted the first two static fires, was removed on May 6 and transported back to the shipyard. The hydraulic rams used to simulate thrust on the thrust puck were reinstalled. A second cryogenic pressure test took place on May 10, that time to a pressure of 7.5 bar, which is enough for orbital flight. The next day, Raptor SN-20 was transported to the launch pad and installed.

Rapter engine in the dark, with the silver Starship silo in the background
Raptor SN-20 being transported to Starship SN-4. Credit: @SpacePadreIsle on Twitter

Several days later, a spin prime test occurred followed by a static fire on May 19. That was the longest static fire test so far. However, it caused a fire to break out on the stand, and SN-4 got scorched. The next day, the test stand was still not safed, as apparent damage to ground support equipment left propellants in the Starship’s tanks.

Starship SN-4 with Raptor SN-20 static firing at point of ignition
Starship SN-4 firing Raptor SN-20 for the first time.

The vehicle was eventually made safe and technicians made their way out to the pad. After a few days of minor repairs, SN-4 fired up for a fourth time. A few days later, SN-4 fired up one final time. Seconds after static fire, a large amount of abnormal venting started coming from the skirt section. Shortly after that, a failure occurred and the vehicle blew up.

Starship SN-4 Static Fire Tests Live

On launch day, we will stream this hop live, starting at T-30 minutes.  Why not join us on YouTube  to watch and ask questions? Or, you can just join in the conversation live! Do you want to know when a launch is happening? Then we suggest monitoring Prelaunch Previews and downloading the Next Spaceflight mobile app to stay in the know. Finally,  the SpaceX Fleet website tracks the ships that don’t go into space.

18 comments
  1. Getting your hands on the shrapnel of one of the prototypes may be a profitable investment! If this wing-legged two-stage abomination does fly as well as Elon says it will.

      1. Super Heavy is currently in the development stage, they’re now working on Starship first. I think that’s because if Starship won’t work, there’s no purpose for Super Heavy.

  2. I believe, it would be best to build a solid landing pad on the moon first, before attempting to land on the moon.

    The rocket engines will dig a hole under the rocket filled with bigger uneven ragged edged rocks, that the rocket blast from the landing don’t blow away.

    Smaller lighter Dragon Crew type vehicles (Dragon Lunar Lander) must land with either concrete bags or a glue like substance and build it.

    Or six sided metal plates laid out in a hexagonal pattern by 4 to 6 Lunar Landers. Anyway it must be flat, level and blast prof.

    I also suggest, that the first space operational Starship should be named “Flash Gordon”.

    1. Have you seen the new concept for the Artemis lander? NASA awarded a study concept to SpaceX for Starship, and in their concept image, it looks almost like there are smaller engines on the side so that the massive engines on the bottom don’t blow regolith everywhere. They may end up doing something similar for later ambitions of there own, especially for travel to the surface of the moon until they have the pad you speak of.

      1. I was thinking some kind of machine to melt lunar dust into hard rock-like material using solar power would be awesome, however I have know idea if that would be possible, and even if it was possible if it would be economical. If it worked at least it could lower the amounts of launches needed to make a landing pad.

  3. I have a quick question. Can the dragon use the super dracos as a backup if the main chutes fail?

    1. It could in theory, but there is no real way to test that (well, I guess they could test it; but why would SpaceX at this point?), and you really wouldn’t find out that your chutes don’t work until it’s too late. That’s one of the reasons that the Dragon has 4 parachutes: it works with 3, and the astronauts inside would probably live with two (don’t quote me on that, however). It would be very interesting if they had no other choice if SpaceX would end up doing that (although I think – and hope – it would never ever come to something like that. Besides, there probably isn’t the right software installed for a challenge like that).

      Great question!

    2. I thought about that too. I guess if i were an astronaut and could choose from certain death and almost certain death I would choose “almost certain death”. I mean technically it was designed to be able to do that kinda thing (as the super dracos are liquid fueled, can be restarted and can throttle a lot), so it would make sense to me having that as a last option if for some reason all chutes were to fail.

  4. Could Starpship be used in similar manner as Space shuttle? for example to service Hubble telescope? it would be awesome if we could extend HST’s lifespan and maybe even do upgrades …

    1. If Starship meets its design objectives, there’s no physical reason why Starship couldn’t perform a Hubble service mission. In the cargo version, it could potentially retrieve Hubble and bring it back to Earth to be displayed at the Smithsonian museum. But that’s a political decision, not one based on capability.

      1. I didn’t even consider dragging HST back, that’s cool idea … ofc it would be political for that, but I was more on the lines of upgrading Hubbles capabilities specially since JWST is way past scheduled launch date

  5. I am so excited for the future of Starship Superheavy and the potential to colonize other worlds. Some day I really hope to be on Mars. Question, I know Tim Dod did a veidio on this but I was wandering sence the payload part of starship could possibly exchangeable could they put engines on that and in a emergency escape that way using the raptors or some sort of engine?

    1. The different payload sections are probably not interchangeable, as the nose cone (where all the payload is) is wielded to the fuel tanks. However, your proposal seems like a very good idea for a crewed version, except for a few problems (these problems are not deal breakers, just things to think about). There would most likely have to be heat shielding in the gap between said ‘capsule’ and the second stage, but would have to come away easily for an abort. With the bottom of the capsule, there would probably have to be a heat shield for in-orbit aborts, which would add weight. Those secondary abort contingent engines on the capsule would also add a bit of weight, along with the fuel and oxidizer to run them. If these engines are on the side, there would have to be heat shielding in one way or another for ‘norminal’ reentry into the atmosphere, and if they are on the bottom they need to be able to not affect the abort heat shield. It would also be a very large capsule to attempt to land with parachutes, easily the biggest ever made.

      Keep in mind that most of this is about 2 minutes of thought, and I may have misinterpreted your question in one way or another. Great question, though!

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