SpaceX Conducts 33 Engine Static Fire

SpaceX Conducts Historic Engine Test of Starship Booster

After many years of anticipation, SpaceX has completed the 33 engine static fire of the Super Heavy Booster #7. This test is the last of the necessary structural tests needed for Starship #24 and Booster #7, and both vehicles are now officially fit for flight.

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Ashe S.

Ashe S.

Thu Feb 09 2023Written by Ashe S.

After many years of anticipation, SpaceX has completed the 33 engine static fire of the Super Heavy Booster #7. This test is the last of the necessary structural tests needed for Starship #24 and Booster #7, and both vehicles are now officially fit for flight. Watch a replayy of the test here.

Static Fire

Booster 7 Conducting 33 Engine Static Fire

Today, SpaceX made history as they achieved a major milestone in their Starship testing program. Through a day of troublesome affairs and ideals, including recycling their entire test process, SpaceX successfully fired 31 out of the targeted 33 Raptor 2 engines. Elon Musk, founder and CEO of SpaceX, confirmed that of the 33 Raptor 2 engines, one was disabled manually during the engine start-up sequence, and a second was turned off by the onboard computer preceding the test. Both shut-offs were based on vehicle safety, as the launch teams did not want to risk extensive damage to the vehicle or pad infrastructure.


Notably, Elon followed up this tweet by mentioning that the booster is still considered flight ready and operational as the super heavy booster does not require a full 33 engines to reach a successful launch. This ability is called “Engine-Out Ability”, and is the metric that determines how many engines are needed to achieve a successful mission, and helps reduce risk during launch. One notable example of engine out ability is the SpaceX CRS-1 mission, in which a Merlin engine failed mid flight, yet the Falcon 9 vehicle was still able to deliver the cargo resupply capsule to the International Space Station.

Underside of Booster 7, Showing all 33 Raptor Engines

SpaceX went live for their outstanding test, which offered amazing views of the test as it happened, including live shots from the air. A static fire test, is when the vehicle fires a pre-specified amount of engines in a predetermined configuration, and the vehicle remains on the pad (does not lift off). 

On the Orbital Launch Mount, SpaceX use twenty clamps around the inside ring, which help rest the booster on the mount. These clamps have many uses, not only do they keep the booster stable and resting during day-to-day usage, but they also provide spin up gasses for some of the engines used, and was previously used to redirect the engine chill to a trench. However, SpaceX installed 2 hold down clips on each mount a couple of months ago, which allow the booster to be strapped down for a firing.

This massive test sets the boundaries for SpaceX’s future, as the Starship testing program is seemingly complete. Elon Musk noted in his tweet shortly after the test, that even though they didn’t fire 2 engines, this configuration of 31 engines can still reach orbit. Assuming this, it means that there is technically no need for another 33 engine static fire to be completed, but nothing should be taken for granted in such a rapidly moving test program.

With this massive accomplishment out of the way, all that remains for launch is for Ship 24 (currently located at the Rocket Garden) to be moved back to the Orbital Launch Complex and to be stacked upon Booster 7. Another Wet Dress Rehearsal is possible, or even a 33 engine static fire with a full stack integration, but we are definitely getting incredibly close to the first orbital launch of Starship.

What is Starship?

First announced in 2016, the “Interplanetary Transportation System”, an early nickname for the Starship project, was announced at the International Aerospace Conference. In 2018, the ITS idea was morphed into a smaller scaled project, the BFR. The modern Starship design took shape in 2019, with early test demonstrators being constructed originally in Florida, and later Boca Chica, Texas. All three concepts had the same core concept, to enable fully reusable, cheap, and accessible access to not just space, but Mars.

From the first sight of a small test demonstrator in the southern tip of Texas, the Starship program began to take shape. Slowly but steadily growing into one of the largest research and development complexes in the world, “Starbase” has become the hub of SpaceX’s future. 

Starship upper stage being stacked on the Super Heavy Booster

In its modern form, the Starship design consists of two major elements. Firstly; The Super Heavy booster is the backbone of the program. 

Developed out of stainless steel, Super Heavy is one of the most powerful rocket stages ever developed, with 33 raptor engines mounted on the booster. The booster is able to be fully recovered, being able to fly back to the launch site after stage separation and be caught and placed back onto the launch pad only minutes after liftoff.

The Starship upper stage is one of the most unique rocket stages to be flying, and is the first fully reusable second stage of a rocket ever developed. Made of stainless steel and six raptor engines, the starship upper stage is tuned to operation in the vacuum of space. After deploying a payload, the upper stage is able to then reenter into space by using its array of heat shield tiles. These tiles are able to absorb the heat and forces of reentry.

The Starship Super Heavy rocket is both taller and more powerful than NASA’s Saturn V and SLS vehicles, and will allow a new access to space that has never been seen before. Combined, both vehicles have undergone a rigorous testing campaign over the past year, and are closely approaching their first launch attempt.