Why did SN8 starship fail?
“Failure is an option here.
If you are not failing, you are not innovating.”
These were the words by Elon Musk when had started his space company SpaceX.
The most recent example of it was the recent Starship SN8 launch by SpaceX, which according
to the medial articles and blogs was a failure.
But the it was a great success and almost did everything right.
Elon, SpaceX and many other scientists know that the days of going to mars are not very
distant.
After a long wait, SpaceX took a big leap when it conducted the first high-altitude
test flight with its prototype Starship vehicle!
On December 9th SN8, the latest incarnation of SpaceX’s Starship, a craft intended as
the second stage of a rocket that will be able to carry 100 tonnes of payload, people
included, into orbit, and hence to the Moon and Mars, took off perfectly from its pad
in Boca Chica, Texas.
The starship SN8 flew to the skies with three raptor engines, becoming the first full-scale
starship prototype to lift off with three raptor engines.
After reaching the maximum altitude of 12.5 kilometres, it flipped on its belly and had
a control descent using its flaps and performed some fancy manoeuvres before returning to
the launch pad.
Unfortunately, the landing was a bit hot and SN8 exploded as it touched the ground.
But still it was huge success.
Today in this video we will discuss Why did the Starship SN8 exploded and its significance
on future SpaceX missions.
So, make sure to watch the video to the end.
But before talking further, lets know why is Starship so Important?
Imagine a rocket that could launch and land 1,000 times a year.
Sounds unbelievable?
Well, that’s what SpaceX is working on- The Starship.
Its lifting capacity of 100,000 kilograms is more than any rocket currently in operation,
and the whole system is designed to be reusable for frequent trips to space.
It will launch atop a large booster called Super Heavy.
Super Heavy will be the backbone of getting Starship and its crew on a journey to another
world.
The ultimate goal of starship is to launch up to 100 people at a time per flight.
Starship will make it possible for us to go to mars.
The cost of launching payloads, going to orbit and mars is very expensive in today’s space
industry.
Because every time we launch, we lose a rocket.
With Falcon-9 we used to save the booster and reuse it thus saving a lot of money.
But with starship SpaceX plans to take this one step ahead.
With starship they plan to recover the stage 2 also after a launch, which will make the
launch cost way less.
Now let's take a look at the launch of Starship SN8 and know whether it was a success or not?
On December 9th, 2020 SpaceX launched its eight prototype of starship, SN8.
Despite failing to make it in one home, it was a huge success.
The Sn8 validated the Starship’s design for high-altitude flight, a major stepping
stone towards spaceflight.
But the important thing is the data gathered from this test which will be very helpful
for improving the next prototypes of starship to come.
So, this test was a very important milestone for the future of regular flights to the moon
and mars.
The launch window opened in the morning of 9th December at 07.00 a.m. CST and was set
to close at 05:00 p.m.
The launch was postponed for about an hour after an airplane had entered the restricted
airspace.
The launch began just an hour before the launch window was scheduled to close.
The three raptor engines ignited and the Starship slowly lifted off the launching pad.
SpaceX shared the entire event via a live stream and everything was recorded by an exterior
camera, a downward facing camera mounted to the exterior of starship and a third camera
which was mounted inside the engine compartment.
SN8 continued to soar and had a very stable ascent.
At around T plus 45 minutes after the launch, one of the raptor engines was shut down.
Anyone who was watching the livestream would have thought it was an engine failure but
it was done on purpose.
The starship kept up it ascend profile with two raptor engines and then after T plus 3
minutes and 13 seconds the second engine was shut down purposely and was part of the flight
profile what SpaceX did was intentional as they wanted the vertical velocity of starship
to be zero at the apogee.
The starship reached near its apogee of 12.5 kilometres with only one engine ignited and
was hovering for a small period of time.
Then the Starship started to descend.
The single engine that was still on, was used to flip the starship a few degrees on its
belly before it shut down and the starship was in a free fall and the flaps on the starship
took over for the control descent.
The aerodynamic flaps performed exceptionally well as the starship glided towards the launch
pad.
After a few minutes into the descent comes the most important moment of the flight profile
where the starship had to re-light the raptor engines and flip on its belly and perform
the much anticipated “belly-flop” maneuver, which tested the spacecraft’s manoeuvring
flaps and aerodynamic surfaces.
The starship then glided through the air for over a minute.
But then the ground crew reignited the three raptors for swinging the tail section swiftly.
We can easily see the thrusters also changing directions for the successful flip.
But at T plus 6 minutes and 40 seconds, as the starship slowed down for landing, we see
a green colour coming out of the exhaust and this tells us that something definitely is
wrong with what is burning.
What happened was one of the engines just melted burning with a bright green colour
and at the last moment the other went out which might have caused a loss of thrust which
resulted in high landing speed and the rocket went out in a ball of fire.
Though it may seem as a landing failure it was still a big leap towards achieving full
reusability.
So, what went wrong?
The starship had a successful ascent, it flipped on its belly and had a control descent successfully.
Starship successfully performed the belly flop too.
The only thing that went wrong was the engine failure during the landing.
Shortly after the flight, Elon tweeted about this, saying it was a “successful ascent,
switchover to header tanks and precise flap control to landing point.
As for the cause of failure he wrote that the pressure in the header tank was low during
the landing burn, causing the touchdown velocity to be high and a rapid unplanned disassembly.
The fuel in the header tank is kept at full pressure to use it for landing but the tank
did not had adequate pressure at the time of landing.
The starship uses two header tanks for its landing.
One header tank is for the liquid oxygen and the other is for the liquid methane.
The methane header tanker is located between the main oxygen tank and the methane tank
while the oxygen header tank is at the top of the starship in the nose cone section.
The responsibility of these tanks is to provide the fuel to ignite the raptor engines for
the landing burn.
But during the test flight of Starship SN8 the pressure inside the liquid methane tank
dropped and because of this very low amount of methane was being pumped inside the raptor
engine’s combustion chamber.
The engine therefore starved for the fuel for the oxygen cycle of the raptor engine.
This resulted the combustion to be oxygen rich.
So, when we have an oxygen rich cycle the temperature is very high and it can melt almost
all of the metals we know of.
This is also the reason SpaceX had to develop the internal super alloy for the raptor oxygen
rich cycle.
So as the combustion inside one of the engines went oxygen rich, it melted due to very high
temperatures.
This is the main reason behind the bright green light coming out of the exhaust as the
raptor was effectively using itself as propellant.
This resulted in loss of thrust and higher than expected landing velocity eventually
leading to the rapid unplanned disassembly.
We can easily see all this in the video released by SpaceX where you can see the belly flip,
the starship descending and relighting of the engines which were sued to flip the rocket
and then as the raptor went engine rich and then the RUD happened.
But the amazing part of this test flight was that it was a test.
During a test a lot of things can go wrong and complete success is the least expected
by engineers in the space industry.
What the starship did in the test flight was beyond everyone’s expectations.
Elon wrote about this on twitter, saying that SN8 did great and even reaching the apogee
would have been great so controlling all the way to putting the rocket in the exact landing
spot was epic.
Mr Musk said that the flight had provided “all the data we needed” before its RUD.
Given SpaceX’s highly iterative rapid-prototyping approach these failures can soon be converted
into success.
The other starships are also ready and next in line for the launch.
The flight of SN 8 has given SpaceX all the important data they needed and it will be
needed to make necessary changes in the hardware and software for the future prototypes of
starships.
This flight has proved that fully reusable rockets are not very far away and our dream
of becoming multiplanetary species will soon be a reality.
The starship looking on the target to achieve a big milestone of reaching the orbit next
year.
No matter how much the mainstream media has been saying that the launch of SN8 was a failure,
it was not.
It was a huge success for SpaceX.
The SN8 flight was just another milestone of many that are yet to come in the future
of industrial spaceflight.
Starship SN 9 also had a crash landing and we will discuss about it in another video.
So, stay with us to know what went wrong with the Starship SN9.
In the meantime, several more prototypes like starship SN 10 and starship Sn 15 are in various
stages of manufacturing.
And the assembly and construction of the first Super Heavy prototype BN1 is also underway.
The starship SN 15 is going to have massive improvement and changes.
We don’t know yet what they might be, but it could be something big.
All we have to do is wait and trust SpaceX and their amazing technology.
So, expect a plenty of exciting news from Boca Chica in the coming months and years.
And let us know what do you think about the Test flight of Starship SN8?
Do you think it was a success and why?
And how will it affect our future in spaceflight?
Do let us know your thoughts and ideas in the comment section below.
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