How SpaceX Lands Rockets with Astonishing Accuracy
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How SpaceX Lands Rockets with Astonishing Accuracy

February 12, 2020


For the past decade, the entire world has
had their eyes on SpaceX as they have revolutionized rocket engineering and space travel.
From launching a sports car into orbit, to the promise of establishing a futuristic colony
on mars, their spectacles have generated levels of public excitement and media coverage that
haven’t been seen since NASA’s Apollo program which ended more than 40 years ago.
At the core of their ambitious plans is one of the greatest technological developments
in the history of rocket engineering: reusable rockets.
First announced to the public in 2011, the SpaceX reusable launch system development
program set out to create a new generation of launch vehicles that would drastically
reduce the cost of reaching orbit. To accomplish this, SpaceX proposed the seemingly
impossible task of recovering rocket boosters using powered-descent.
Their goal was to develop a rocket that could be launched vertically to deliver a payload
into orbit, and then return back to earth with a controlled descent and vertical landing
at a pre-determined landing site. Either on land, or on an autonomous floating
drone ship. In just 7 years, SpaceX was not only able
to achieve their goal of creating such a rocket, but they have proven that their system is
both reliable and economical with more than 60 successful launches and 30 successful landings
of their Falcon 9 boosters, along with a 100% success rate since the completion of their
experimental testing program. Or at least that was the case until December
2018, but at least they had a pretty good run.
17 of their boosters were also re-used on successive missions, and their unit cost for
launching a kg of payload into orbit has been reduced to just a fraction of the nearest
competitor. But how exactly did SpaceX accomplish this,
and how do they manage to land 70 m tall rockets weighing in excess of ½ a million kilograms
precisely on a 50 m wide landing pad after they are launched more than 70 km into the
atmosphere at speeds exceeding 8,000 km/h? It all comes down to just 2 key things: experience,
and ridiculously well-engineered rockets. Let’s start with experience by taking a
brief look at the history of the reusable launch system development program.
The program itself was first announced in 2011, but it wasn’t until late 2015 that
SpaceX was able to land a Falcon 9 booster on land successfully, and it took several
years beyond this to achieve a respectable landing success rate.
Before this, SpaceX spent 5 years conducting experimental landings where they tested their
new technologies and learned how to build better rockets through trial and error.
They began with a prototype vertical takeoff and vertical landing vehicle called Grasshopper,
which completed 8 successful flights from 2012 to 2013.
Following the initial success of Grasshopper, SpaceX then equipped their first Falcon 9
boosters for powered-descent and conducted several soft landings on the ocean surface
from 2013 to early 2015. Unfortunately, these first tests with the
Falcon 9 were only able to achieve a landing accuracy of about 10 km, but this was greatly
improved in future tests. When the first landings on an autonomous floating
drone ship were attempted later in 2015, SpaceX endured a series of public failures as 4 consecutive
barge landings failed quite dramatically. Despite these failures, they obtained valuable
data from every single flight, and they used the failures as opportunities to learn from
their mistakes in order to develop a more robust landing system.
SpaceX continued to perform Falcon 9 landing tests through 2015 and 2016, both on drone
ships and on land, and successful landings became routine by early 2017, with SpaceX
deciding to stop referring to their landing attempts as experimental.
From the beginning of 2017 to nearly the end of 2018, SpaceX maintained a 100% landing
success rate with a minimum landing accuracy of just 10 m.
This impressive accuracy represents a 1000-fold improvement compared to the initial soft-landing
tests which were only able to land within a 10 km radius from the intended target.
But how did SpaceX manage to increase the landing accuracy of their rocket boosters
by 10,000% in just 4 years? Obviously, this wasn’t achieved through
experience alone, and so this brings us to point number 2: ridiculously well-engineered
rockets. When SpaceX performs a rocket launch with
the Falcon 9, the rocket separates into two stages in Earth’s upper atmosphere.
The second stage of the rocket carries the payload into space, while the first stage
booster returns to Earth and lands at a landing site for re-use.
The booster is programmed to follow a precise flight path back to Earth, and it must autonomously
perform a series of controlled maneuvers in order to maintain that path and land vertically
on the landing pad. The exact flight path depends on whether the
rocket is landing on a floating drone ship in the ocean, or on land, and for landings
at sea there is the added complexity of ensuring that the drone ship is in the correct position
when the rocket touches down. However, the greatest engineering challenge
by far is building a rocket capable of performing the maneuvers that are necessary for controlled
descent and landing. After stage separation occurs, the rocket
booster re-orients itself and performs a boost back burn to achieve the proper trajectory
towards Earth. During the descent, it performs a re-entry
burn which is used to reduce its velocity. As the booster approaches the landing site,
it re-orients itself again so that it is in line with the landing pad, it deploys its
landing legs, and it performs a landing burn to bring its velocity to zero as it touches
down on the pad. During the entire flight, from stage separation
to landing, the rocket continuously measures its orientation and velocity, and it adjusts
its trajectory accordingly so that it maintains the correct flight path.
To accomplish all of this, SpaceX has implemented several rocket technologies that were developed
and refined through their experimental testing program, and it’s these technologies that
have been pivotal to the development of their reusable high-accuracy rockets.
The six key technologies incorporated into the Falcon 9 rocket booster are as follows:
1) Thrust vector control. The merlin rocket engines of the first stage
booster are gimbaled using hydraulic actuators so that the direction of thrust can be adjusted.
This is a method of thrust vectoring that can be used to control the orientation of
the rocket both within Earth’s atmosphere and outside of Earth’s atmosphere where
aerodynamic control surfaces such as fins are ineffective.
Thrust vectoring is actually a common technology that is used for rockets, as well as military
aircraft and missiles, however it is absolutely necessary for the maneuverability of the Falcon
9. 2) Cold gas thrusters.
The Falcon 9 is equipped with a total of 8 nitrogen cold gas thrusters that are mounted
towards the top of the first stage. There is 1 pod on each side of the rocket,
each containing 4 thrusters. Like the gimbaled main engines, the cold gas
thrusters are used to control the orientation of the rocket.
They are particularly useful for the flip maneuver after stage separation because of
the large lever arm between the thrusters and the rocket’s center of mass.
They are also used to control the rocket at times during flight when the gimbaled main
engines are shut off. 3) Re-ignitable engines.
Since the first stage must perform three separate burns after stage separation, it is necessary
for the main rocket engines to be re-ignitable. The engines of the first stage booster have
therefore been designed so that they can re-ignite in the upper atmosphere at supersonic speeds
as well as in the lower atmosphere at transonic speeds.
4) Inertial navigation and global positioning systems.
The Falcon 9 is equipped with an inertial navigation system, or INS, that uses several
types of sensors to measure the position, orientation, and velocity of the vehicle.
A global positioning system, or GPS, is also used to measure geolocation.
The onboard computer receives data from the INS and GPS in real-time and checks this information
against the pre-programmed flight path. If the computer detects any deviations from
the flight path, then it instructs the rocket to adjust its orientation and velocity as
necessary. 5) Deployable landing gear.
In order to perform vertical landings, the Falcon 9 is equipped with 4 lightweight landing
legs that are deployed using high-pressure helium just before touchdown.
Each leg is constructed from carbon fiber and aluminum, and contains an impact attenuator
for particularly hard landings. The total span of the deployed landing gear
is approximately 18 m, and the entire landing system weighs less than 2,100 kgs.
6) Deployable grid fins. Four titanium grid fins are mounted at the
top of the first stage booster, and are deployed during the rocket’s descent back into Earth’s
lower atmosphere. The fins are aerodynamic control surfaces
that are used for precise control of the rocket’s position and orientation prior to landing.
The four grid fines alone are primarily responsible for the incredible 10 m landing accuracy of
the Falcon 9 first stage booster. Grid fins were first used on the fifth soft-landing
attempt of the reusable launch system development program in 2015, and iterations on their design
were continued through 2017 in order to achieve the accuracy that we see from SpaceX today.
So in the end, SpaceX was able to employ experience and good engineering to develop a reusable
and highly accurate launch vehicle, the Falcon 9.
The Falcon 9 is an astonishing feat of modern engineering, and I hope that it sets a precedent
for the future of space travel. Without a doubt, the development of a reusable
launch system has been one of the greatest technological developments in the history
of rocket engineering, and I can’t wait to see what the future has in store for SpaceX.
Or perhaps I should rather say, what SpaceX has in store for the future. I really hope that you enjoyed this video, and I hope that I was able to provide some insight into the landing technology used by SpaceX.
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  1. Which SpaceX milestone are you most excited for in 2019?

    Video corrections:
    1) At 2:50, I provide the measurements of the entire Falcon 9 rocket at liftoff, which is misleading. Only the first stage of the rocket returns for landing, which is approximately 43 meters tall and weighs around 22,000 kg empty.
    2) At 5:00, I state that the improvement in landing accuracy from 10 km to 10 m is 10,000%. This is incorrect. The increase in landing accuracy is actually a 99.9% improvement.

  2. The landing accuracy has been very reliable. I wonder whether they could do away with the deployable landing legs altogether by landing in a cradle or capture system of some sort. That would save weight, simplify the design (of the rocket), reduce drag and reduce the risk of deployment failure leading to damage.

  3. Private industry accomplished this in less than 10 years. If NASA had started working on this at the same time … we'd be watching the test firing of an engine right about now.

  4. UNLESS U HAVE SEEN THIS TYPE OF ROCKER 🚀 LAND OR TAKE OFF 🚀!!!! . WITH YOUR ( OWN EYES ) ITS , ( JUST ANOTHER ( SCAM ) .!!!!!! . JUST LIKE ( THE SPORT CAR IN SPACE ) . STOP , BELIEVING IN ( SCIENCE FICTION ) .!!!!!!!!
    ALL IT , DOES , IS TO ( DUM U DOWN ) .!!!!!!! . 😂🤣😂😜……THATS WHAT THEY PERFER .!!!!!!!!! .

  5. Next time make your videos to imperial units. I dont see why even space x launches rockets in USA and still decides to use KPH. You' re in the USA use imperial and not metric. Shittt

  6. Which SpaceX milestone are you most excited for in 2019?

    I think the Eric Swalwell deep Space Pulsed Rocket Engine is the one I'm keeping an eye on.

  7. Landing and reusing rockets is great and all
    But we are far from capable from having a colony on mars we just don’t have the technology and resources to do that yet the things we need to have a city on mars are ideas and still need refining and testing which is far from what we are doing now…we have the reusable rockets yes but that’s 1 part to a giant plan

  8. 4:19
    This is how we get things done and do things right
    We don’t quit when something fails or goes wrong this is why technology in the past 50 years should’ve been worked on instead of giving up because of a failure…failure is a tool to make better versions of itself and everyone even the folks who fund/invest in these things have to learn that failure is part of the creation of great things…sadly these things cost money and investors turn tail at the first sign of failure which halts progress and that’s the reason we don’t see technology that can change our way of life

  9. As soon as I clicked this I said to myself: This had BETTER fucking tell me exactly how this thing does its GNC. Otherwise, I'm going to be very pissed off.

  10. If I did a channel like this, I could and would have over a million subs. Because I actually designed and wrote software for aircraft and spacecraft that went INTO space, including several of the ISS nodes (1 and 3, specifically). Yeah I could do it. But honestly, it wouldn't be worth my time. And honestly, 99.9998% of the folks out there wouldn't understand one single sentence. So what's the point? If you want to learn about rockets and space, stay in school, study hard, read everything, and get a job. Then work hard again and about 10 or so years later you might begin to have a clue or opinion that would or could make a difference. Full stop.

  11. Nice video. Minor correction: your graphic & narration are mismatched. 5:56 When landing on a droneship, there's no need for a boost-back burn. It follows its natural ballistic trajectory and performs only the re-entry & landing burns. The boost-back burn is only performed when returning to land, hence the term "boost-back".

  12. Curious fact: The accuracy of the Falcon 9 landing is the same as the accuracy of the delivery of a warhead by modern ICBMs.

  13. Neil DeGrasse Tyson is very annoying. I would take a video of Carl Sagan reading from a dictionary over anything Tyson has ever done. Half the crap he says doesn't even make sense. "Know enough about a subject to think you're right, but not enough to know you're wrong." That is gibberish that doesn't even make sense. Can we trade him for a CGI version of Sagan?

  14. I was wondering if Buraq – the Supernatural Nonsense
    Flying Donkey-Horsey Thingy Story Character Pet –
    poops when he travels through maximum dynamic
    pressure on his way to visit Allah when Allah dictates
    the Holy Buraq Chronicles (Hadith) to Mohammed ?

  15. I'm 67 years old, so I'm a child of space flight, and it's totally amazing what SpaceX has done in less than 10 years. Simply amazing.

  16. Sheeple will believe it if it comes from their authority; the media. Then the paid to cheer Craig's List extras cheering all completely the same body language ie. both arms up and the practiced cheer. Then the guys behind the screens are distracted or mildly clapping. Then when does the "rocket" turn from going forward burner in the back to burner forward on descent "rocket" trailing. hahahahahahahaaaa omg! then the superimposed blurred out video around 1:24 after the Burner didn't burn a hole in the floating dock hahahahaha… space golf. omg I just hope that no one considers this real. And then that tall lampshade of a "rocket" sitting on a floating dock with swell making white caps; with no support bare what a lampshade would have. After all this is light weight material. GO Elon shake up those sheep.

  17. the one where they have a hydraulics failure is pretty great to watch, the grid fins get frozen yet the booster compensates out of a spin that looked fatal and crashed into the water at such slow speed

  18. Huh? Who are you trying to fool? To the question, "How [does] SpaceX Land[] Rockets with Astonishing Accuracy[?]" your answer is "Ridiculously well engineered rockets." Huh?!!!?!!!?!!!? 1) Thrust vectoring has been around since WWII. 2) Cold gas thrusters have been around since the 1960s. 3) Every Apollo mission had re-ignitable engines. 4) Intertial guidance was invented for Apollo. 5) Deployable landing gear — ok, that's the secret. 6) Grid fins are a Russian invention going back to the sixties. Nothing you've offered here about HOW they do it is a secret after someone watches just one launch. You've provided no insight at all.

  19. Dude is this some sort of high school report? What a dumb video. You didnt actually explain shit. You basically said "they did it cuz they gud at it thats how".

  20. Come on please its cgi cant shoot rocket up and land it back down like that no way common sence tells you not possible powered decent? Ok but no way is it possible for vertical rocket with tiny wingd on bottom to land like that cgi with people cheering in bsck ground yea they do launch rockets but do not land then like they say and if you research enough no rpcketz go to space they brought elon musk in to bring life back into failing fake nasa thier is no iss it's fake all rockets go up and level off the start goin down then poof switch cameras or poof cgi in space but what really happens they go out of sight inin big arch and land out in sea do research and always scroll way down to find videos of what people are starting to figure out thier is massive deception goin on and I feel bad so many people belove this crap

  21. Bricht außer Tesla auch Gold in Zukunft voll ein ?

    Viel mehr Gold als existent machbar aus Quecksilber teils durch Neutronen Absorption bei 0,15% Hg-196 viel mehr durch Ausschlag von Neutronen mit Fusionsneutronen bei anderen Hg Isotopen etwa mit Uran in D2O Lösung von Uran damit gehen Spaltpartikel in D2O fusionieren und Gold sinkt in Quecksilber dabei ab siehe CANDU Reaktor wobei auch Hg Nukleon in D2O rein geschoßen aus Ringbeschleuniger wie LHC fusioniert so Kombi mit Schiffsantrieb wen Hg in Röhre mit D2O linear gebremst bis nahe c in All wobei Hg auch bei Schlag auf D2O Neutronen abgibt
    usw.

    [email protected]

  22. The crashes on the drone ship are astonishingly big. I would have thought that the rocket is nearly out of fuel so I don’t know why it is such a huge explosion.

  23. Remind me of the scene in the JAMES Bond movie You Only Lived Twice in which a rocket was seen descending vertically
    and landed inside a hollowed out volcano It take 50 years to achieve this manoeuvre !

    Terrylau

  24. I’m am so tired of coming across these fake videos they need to stop with this bullshit and people need to wake the hell up.SMDH….

  25. No matter how many times I see it, watching those boosters land vertically like something out of a 1950's sci-fi movie somehow looks fake or CG. I'm not saying it is fake, I'm just saying it looks so incredible that my brain can scarcely believe what it's seeing.

  26. How does inertial navigation system works? Is there a Fibre-optic gyroscope
    s? How acceleration is measured in SpaceX rockets?

    https://en.wikipedia.org/wiki/Fibre-optic_gyroscope

  27. Great summary explanation for laypersons to understand. Well done video. it's too bad we are running out of well educated and disciplined people.

  28. Very good question..How on earth spaceX ca do that. Most scenes show a remotely view of a thing that looks like rocket landing successfully. Why not a zoomed video? I suddenly recalled Capricorn One movie.

  29. @ 6:00 they do not perform a boostback burn when landing on the droneship. They only use it when landing on lz-1 or lz-2 at the cape…

  30. https://www.forbes.com/sites/startswithabang/2020/01/30/dangers-to-astronomy-intensify-with-spacexs-latest-starlink-launch/#3e539ff56a57

  31. rather than using thrust produced by fuel for vertical landing to land on earth they should connect automated drone fins which can slide out as soon as the rocket enters back on earth"s atmosphere and allow drone-fins to control the rocket landing. then it would be safer and save more fuel as well.

  32. building the antichrist 666 global monitoring system. let spaceboy nazi get the first ice pick brain interface with wifi link to D-wave satan technology.

  33. It looks like something built in someone's garage. The "launch" pad is an absolute joke – once you begin to examine it closer. You are correct !

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