Tag: rocket science

Recap of Starship SN8 Test Flight

Starship – the grand vessel that will take humans to Mars – performs its historic 12.5 km launch.

Starship SN8 Test Flight Recap

spacex starship hop 1
source: NASAspaceflight

On December 9th, 2020, people gathered on the beaches, parking lots and balconies in the surrounding areas of South Padre Island in Boca Chica, Texas. Space enthusiasts had flown in, YouTubers had their streaming cameras live and ready, and millions more tuned in remotely in anticipation of SpaceX Starship’s 12.5 km unmanned “hop”.

All day, people waited. Hours pass, with not much action. The first sign of advancement was the formation of a small condensation ring on the body of the spacecraft, just above the fins. This happens during fueling, caused by the overflow of liquid oxygen from the condenser as it fills the tanks. The rapid expansion of pressurized gas (in this case, liquified oxygen) is an endothermic process in which the gas loses heat energy, making the surroundings extremely cold.

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Liquid oxygen is an important component of the fuel, serving as the oxidizer. Starship uses liquid oxygen (aka LOX), and Methane (CH4) as rocket fuel.

Key Events from Starship Hop:

  • Successful ascent
  • Successful switchover to header tanks
  • Successful pivot
  • Flap control
  • Longest in-flight firing of a raptor engine
  • In control until the end
  • On target
  • Sufficient data gathered

Starship Launch

As the engines fire, there is no turning back. All or nothing, skyward.

spacex starship hop 2
source: nasaspaceflight.com

As the rocket takes off, as clouds instantly balloon to twenty times their size. As they grow larger, and seem to resemble exhaust smoke, the clouds are actually just steam, H2O water vapor. This is the main byproduct of the combustion reaction.

The other byproduct of the combustion reaction between methane and liquid oxygen is carbon dioxide, which is invisible.

spacex starship hop 3
source: Nasaspaceflight

Surprisingly, shortly after launch, one of the Raptor engines goes out, leaving the rocket with 2 engines to finish the remainder of the test flight.

From the multiple YouTube live-steams, including EverydayAstronaut, NasaSpaceflight.com, SpaceX, and more, there was some confusion among viewers.

spacex starship hop 4
source: SpaceX

It is unclear whether or not this was a planned outage or not, as Starship has three engines, and the other two can function completely fine on their own. Being down to two engines did not appear to interrupt the flight, and there is a chance this was done purposefully in order to control fuel loads.

As Starship progressed further towards the peak of its flight, another raptor engine apparently shut off, which is also believed to have been intentional. At this point, the rocket began to progress skyward on just a single engine. Moving at a slight angle it performing a couple of hover maneuvers, barely in view of the cameras.

At this point, the flight was over 4.5 minutes in total, 10:16:04 on nasaspaceflight video, and the rockets had been firing the entire time.

spacex starship hop 5
source: Nasaspaceflight

The Belly Flop

The next occurrence was the “belly flop”, a stunt where Starship will orient itself 90 degrees sideways, falling horizontal to the Earth’s surface at terminal velocity.

spacex starship hop 6
source: nasaspaceflight 10:16:23

The photos above and below were taken just 7 seconds apart, during which time the rocket appears to have repositioned itself by over 45 degrees. We can tell that Starship has quickly begun its free-fall because none of the engines are firing at this point.

spacex starship hop 7
source: Nasaspaceflight 10:16:30

As Starship continues to fall, it surprisingly further orients itself towards the Earth, nose down. Watching the video live, the nosedive appeared slightly nerve wracking, but it was in fact planned and supposed to happen, thankfully.

spacex starship hop 8
source: Nasaspaceflight 10:16:40

The wing-like flaps of the rocket, two on the front and two on the back, angle themselves skyward to apply air resistance drag to control the direction of its free-fall.

spacex starship hop 9
source: SpaceX

As Starship nears the Earth’s surface, the flaps are doing their job. Starship appears to float almost effortlessly towards Earth’s surface, during which time we getting the sense that terminal velocity doesn’t actually seem that fast when we’re watching such a massive vehicle.

spacex starship hop 10
source: SpaceX

When its time for the cigar-shaped rocket to begin preparing for the landing, two of its raptor engines re-engage, swiveling at an angle to control the degree to which it will turn. Within half a second, the ship has rotated ninety degrees, now facing vertically. Starship then re-orients itself vertically again for the landing.

The Rocket’s Downfall

spacex starship hop 11
source: SpaceX

In the moments leading up to landing something strange starts to happen as Starship gets closer to the landing pad.

The flame turns green, as if this is a prelude to some gnarly fireworks display. It is unclear what causes the color change.

Looking closely, the human eye can observe a slight angle between Starship and the landing pad, which is a sign that something is not quite right.

It was at this moment that we all knew destruction would be inevitable.

In the photo to the right, we know something is wrong for two reasons:

  1. Skewed angle of Starship
  2. There are no landing leg folding out

As soon as Starship hits the ground, it immediately explodes, disintegrating, leaving almost no remains. Apparently, the driving cause of this was “lack of header tank pressure”. This means there was not enough fuel to produce the required thrust to slow down the rocket before the landing pad.

In the inevitabilities of what seem to be failure, somehow, the company still managed to put on a show. SpaceX Starship SN8 hop test flight ended with a literal BANG.

spacex starship hop 12
source: SpaceX

It seems there is consensus among SpaceX that many test objectives were successfully achieved. The company was able to gather sufficient data, so… the mission was a success! (regardless of the fact that they didn’t quite “stick the landing”).

crash landing gif
source: the atlantic

All in all, the rocket was airborne for 6 minutes and 42 seconds, and was well in aerodynamic control the entire time up until the crash landing.

What did you expect? SpaceX has a long history of testing rockets, many of which have failed the first time. As with any innovative and new technology, there’s never any guarantee. But one thing is for sure – SpaceX Starship will fly again. There will be another test flight in the not too distant future. There were a few key wins and objectives complete, which we will stay updated about as we learn more.

Wins for Starship

  • “Successful ascent, switchover to header tanks & precise flap control to landing point!” – Elon
  • This was the longest in-flight firing of a raptor engine, ever.
  • The spaceship was in fine-tuned control almost the entire time.
  • Starship demonstrated a successful pivot
  • SpaceX gathered all the data they need.
  • The world has been inspired.

The victorious path towards Mars is well underway, its going to happen faster than we realize! Stay updated with the latest on Starship, missions to Mars, and more space technology by signing up for the newsletter.

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