This mission was to launch JCSAT-14 to geosynchronous orbit which requires the falcon 9 to move the already heavy satellite into a geosynchronous transfer orbit. That meant the first stage had to do a lot more work and was left with a lot less fuel as a result. Therefore, the re-entry burn was less aggressive, the first stage came in with twice the speed, and SpaceX needed to do a far harder landing with three engines lit in the quicker and riskier suicide burn. Somehow, despite playing down expectations, they managed an even more precise landing than last time.
That said, I have no idea where he got that number, whether 40 m/s or 40 m/s^2; both are incorrect.
The best estimate available for the flight dynamics can be found at flightclub.io, specifically for JCSAT-14: https://flightclub.io/results/?id=eeaf889e-f3d8-4f9b-be98-b7...
This shows the landing burn starting at a velocity of 269 m/s and experiencing a peak deceleration of 12.3g = 121 m/s^2
I don't know how accurate these numbers are, but some fans put quite a bit of effort into getting the flightclub.io profiles as close to reality as possible, so they tend to be pretty good.
The approximation I had is almost certainly less reliable than flightclubs, not sure why it was so low, will have to look at the math I did and figure out what I screwed up.
The actual force would have been closer to 5.1G
Ugh sorry, there's a bug of some sort in Flight Club there. There's no way it was that large. A constant deceleration down from terminal velocity over 6 seconds is
a = (300 - 0)/6 = 50m/s2 = 5.1g
I'll need to look into that
So it looks like that peak is due to the sudden increase in drag during my landing legs deployment. I deploy them at 500m altitude which is a time when the stage is probably still moving a bit too fast. It's a really large increase in cross-sectional area, but I'm probably not treating it correctly. I'll revise before Thaicom-8
The overall structure actually goes through all sorts of stresses, not all of which are measured in G. The combination of push from the rocket and air resistance compresses the rocket from both ends, something that isn't reflected in G numbers.
I think this is only sort of true. Yes, the fueled rocket is much, much heavier. But not all parts of the rocket are load bearing as it sits on the pad waiting for launch. All parts of the rocket experience the 12g (or whatever it was) deceleration.
Also, rocket skins are really, really thin (relative to their size, the forces they endure, etc.) I've read that without the fuel inside to reinforce the rocket, it is quite fragile - think of trying to crush an empty soda can vs a full one. This is part of why rockets which deviate too far from prograde on launch are ripped apart mid-air.
The Falcon 9 has a sort of partial balloon tank. It's strong enough for ground handling without pressurization, but it requires pressurization to handle flight loads.
Note however that it's pressure, not fuel, that provides the extra strength. These tanks are still pressurized even when almost empty.
Tack-welding fixtures to a steel deck is apparently SOP in big shipping, so it's not as radical as it sounds.
Bonus points that the overwhelming majority of ships lack the giant oil rig thrusters that all of the ASDS armada contain to keep them as stable as feasible and prevent listing too much in normal ocean condiditons.
It could be that having the first stage untethered is deemed less risky to personnel than having a team of welders board the barge and tie it down.
While I suppose that the rocket could be heavy enough to lower the center of gravity of the entire vessel below the troughs of any waves enough to make it incredibly unlikely, it isn't just the prospect of tipping over that makes it important to secure cargo.
Engineering is conservative "just in case." So are a lot of practical activities that happen on the sea. In neither case, is this irrational or a waste of time.
It needs to be both stable and secured, because only one is inviting woe.
... which means there's nobody around to be injured or killed if the rocket falls post-landing. Maybe it's a precaution worth taking when they intend these stages for commercial re-use; for now, the whole thing is one big experiment.
how much money would a few ditched rockets cost, in comparison? hint: less than a shitload
would a recovery crew approach this platform in rough seas, even if a robotic lash were in place? hint: nope
then what exactly is the point of securing this 'cargo'? hint: there isn't one.
And yes, it will be secured. The previous recovered rocket was secured, this one will be too.
Apparently they do secure to the deck after landing.
Discussed here: http://space.stackexchange.com/q/6403/574
Maybe they still weld it this time, but that is done by having someone go to the barge and do it.
Instead, coming in very hot, the rocket had to use three engines (instead of one) to slow for landing. The last time this was attempted, the first stage put a nice hole in the deck of the drone ship.
Seeing the rocket dead-center on the barge was quite a sight!
This means that it must slow to a standstill, cut the engines and hit the platform at exactly the same time or it will either start going up again or be dropped onto the platform from a less than ideal height.
And the guy said emphatically "Rocket engineer, there is a big difference"
I'm sure this particular task probably was a little bit of both. After all, they had to run several real world experiments to prove their calculations.
The most interesting work is right in the intersection of the two disciplines, though. :)
I guess "purity" is just another word for "lack of immediately applied practicality"
Scientist: Studies and uncovers mysteries of the universe and natural world
Engineer: Applies what scientists discovers
Scientist: Unknown outcome (e.g. hypothesis -> experimentation)
Engineer: Known (or should be) outcome
Science is the knowing of things by their causes. Science is the putting into knowledge what is in reality.
Engineering [which he would call techne, from which we get the word 'technology'] is the art of putting ideas into reality. It is putting what is in our knowledge into the real world.
Thus they are perfectly complementary things, one bringing the world into ideas, the other ideas into the world.
It's possible to argue that the implicit hypothesis there is that there is some sort of difference, but that is a particularly weak hypothesis compared to the specificity of hypotheses that can be formed once we have this pile of data -- i.e maybe X, Y, Z differences are important in this disease.
Sciencing: Uncovering mysteries about the world.
Engineering: Applying such discoveries.
Scientist: Predominantly sciences.
Engineer: Predominantly engineers.
There's so much overlap it would make sense for C.V.s of either to include a % science/engineering to suss out their own feel for both history and preference of activity.
Landing at 38:18mins
Great info on the thrusters on the first stage at 19:37. https://youtu.be/L0bMeDj76ig#t=19m37s
Edit: Thank you and sorry about the time stamp link, I posted quickly from my phone. Hopefully it works on shortlinks.
First stage landing is just after 38 minutes - https://youtu.be/L0bMeDj76ig?t=38m
Doing it twice in such a small window of time is a logistical/programmatic leap.
The second recovered rocket, F9-023, will be relaunched. It has already been static fired with no announced problems. Elon said it'd be a few months before a customer was announced, but the general feeling is that it will be an SES satellite as SES has already publicly expressed interest.
In all seriousness though, I'm not sure how I feel about this monument. It's going to be really crammed next to the main building and I don't think it will have a very strong visual presence with a giant grey wall directly in the background. There isn't really a good vantage point for viewing either. I suppose it will look ok from the opposite corner of Crenshaw.
We're dealing with a corporation -- I'm not sure we can count of them to "pass on the savings".
If they're smart, they're figuring out ways they can own a big part of the infrastructure for an emerging market.
If Musk wanted to maximize his risk-adjusted profit, SpaceX would never have started. Remember, he financed the cashflow out of his own pocket, and went from a 100-millionaire to not being able to afford rent during the process. He himself said SpaceX had less than even chance of success, and he is known to be both very meticulous in preparation, and an incurable optimist.
Would you rather be on the first flight an aircraft makes after leaving the factory, or the tenth?
It could easily be the case that the initial launches have the lowest failure rate.
I wish we had a campus like Raytheon or Northrop have in El Segundo/Redondo Beach. The 60's & 70's were certainly the high points in aerospace campus architecture here in SoCal.
I don't think I've posted anything specifically discussing the merits of the NRA, although I have posted on the subject of gun control and self defense. In any case I'm not sure why discussing that topic and working at SpaceX would be mutually exclusive.
Obviously it should be said that I don't represent SpaceX and the views I express here are my own and not the company's.
Ps: keep up the good work
I'm curious about the etiquette in regards to identifying myself as a SpaceX employee though. I originally joined to relay some of my personal experiences with the company, is it generally a bad idea to identify myself as an employee, or is the bigger issue in your opinion the use of the company name within my username?
Also, if I do identify myself as an employee, do you think it would be wise to maintain two separate accounts, one exclusively for discussing SpaceX/space related matters and another one for other possibly more controversial topics or is it no longer an issue as long as I have a more generic username?
I certainly understand your position and appreciate the advice.
Plus, and I can't speak for everyone, but as a former would-be astronaut, this kind of stuff is tops to me. Info from insiders is always welcome. Consider starting a blog.
Thanks for taking my opinions into account.
I appreciate your sentiment in my starting a blog but I don't think I'd have the time to meaningfully contribute to it and I don't feel comfortable enough in my writing ability to do the kind of long form writing I feel such a topic deserves.
There are certainly many would-be astronauts here as well. Thanks for the kind words in support of the work we're doing.
Are they also testing similar things but we aren't hearing? Or they aren't threatened by the advances?
Ariane 6 is going to be built with a cost effective approach and trying to focus on market needs (3D printing of parts, reusability of the first stage, etc.)
At first, concerning SpaceX, his group of experts told him that the design of the rocket wasn't going to work and was going to explode at high altitude due to fluctuation. They also told him that the first stage would just go through the barge, sinking both the first stage and the barge. Now they are taking new entrants way more seriously.
I hope this is one of those "lost in translation" things, because otherwise I fear for that group of supposed experts.
The energy amount the rocket impacts with is dominated by its speed, not its mass. A small, fast-travelling projectile can make a hole in just about any kind of armour. The terminal velocity is quite low, but that's in part because of the way it is engineered — an ICBM would probably be able to put a hole through a ship deck with ease.
There is a lot of reasoning by analogy vs. reasoning from first principles going on, and the latter seems to be winning. But the main driver of the space industry is governmental funding, not commercial. Much of those statements were probably political; SpaceX have prevailed, and indeed found some champions of their own (John McCain is rabidly behind them, and some of the statements he comes up with are ludicrous in their own right, for example), though not before enduring some setbacks.
While what you've said is true, in practice it isn't a problem.
If the F9 first stage is out of control and going too fast, it will almost certainly miss the barge to begin with. The barge is small, the ocean is big, and the F9 has to maneuver very precisely to reach it.
If it does reach the barge, it will likely be moving relatively slow, and thus is less likely to sink the barge, even it things go crazy at the last moment.
1/2m * v^2
Either way, the relative masses matter. It takes a lot more effort to punch a hole through something much more massive than your projectile! It doesn't make much sense that a light, nearly spent rocket stage would punch all the way through a massive barge. And even if it did, the hole still wouldn't be big enough to sink it.
Would any "expert" really believe SpaceX didn't run the numbers millions of times, and do millions of simulations to confirm they could slow it down before actually spending the money to buy and outfit drone ships, build landing legs onto their rockets, etc. etc. ?
I mean, honestly, while the devil is in the details for an actual landing, they must have been pretty damn sure they could at least slow the thing down sufficiently.
There are several orders of magnitude there.
When shot with a rocket all the air leaks out of the steel barge.
Otherwise, I fear it'll be much too little, much t0o late.
I'm not really playing skeptic here -- SpaceX's progress has been incredible, and I'm inclined to believe them that they can do it -- but it hasn't happened yet.
NASA became boring because they were ordered to become boring and were defunded.
The Chinese have mentioned an effort to recover and reuse first stages by landing them with parachutes.
So far, the Russians seem to think the effort isn't worthwhile.
Closer to home, ULA's new Vulcan rocket is supposed to recover the first stage engines (but again, not the fuel tanks) using a parachute and helicopter.
It remains to be seen whether any of these schemes will work or how long they'll take. They have a lot of catching up to do in any case.
Meanwhile, SpaceX plans to launch a Mars mission in 2018.
Compared to that, Arianeespace's target of 2025 (in nine years!) for Adeline is almost ridiculous.
Just checked: Stephane Israël just raised concerned after SpaceX's latest success: http://www.lemonde.fr/economie/article/2016/05/05/face-a-spa...
Other then subsadising your own industry and for military reasons, their is no argument for making your own rockets. Both those are terrible arguments.
I mean it's not as if Ariane 6 is being built entirely by government money. It's more complicated than that. As a matter of fact, a new company Airbus Safran Launches has recently been created out of the two big aerospace companies and is working mostly on Ariane 6. As I understand it, the CEO of Arianespace is calling for more initiatives like these.
It's a bit like with aerospace, when Boeing started building big airlines, European companies gathered and formed Airbus. They were not government owned but I supposed the government did intervene some way or an other considering it was a strategically crucial economic sector.
Also, whether the government funds an aerospace company is a bit blurry. SpaceX is privately owned but its major client is the government and, as Stephane Israël often complains about, they get extremely advantageous and arguably unfair contracts notably with the US military. It's kind of a government funding in disguise.
That being said, money is not the only issue here. The big thing SpaceX has is passion : since those guys think they're basically saving the world or something, they work much harder than anyone in Europe. I mean it's surely much easier for an engineer to keep working late at night when he thinks that his work will allow man to walk on mars and save the human race from extinction. That's the only way I can explain the extreme speed at which they're making progress when compared to what is done in Europe.
SpaceX actually has to do a lot of work for those government contracts, and they will lose that money if they can not diliver the capability in the required amount of time. They had to carry most devlopment cost themself and they were also always flighing comercial launches. Governemnts are 70% of the launch market, so I don't think any space company can or will live totally without government contracts.
If they can make the Ariane 6 compete within a decent price, I am not against some government contracts going to them. It makes sense not to give all contracts to one company, but Arianspace (or whoever) has to first devlop a rocket without massiv governemnt investment and show that they are in the 20% range of price. If they can not do that, their are other companies who you can go to. Sure its not fair if the rockets from china or russia are subsidised (not saying the are or ar not) but thats good for Europe because we get cheaper launches that are payed for by other governments.
I would guess that European rocket engineers are, or could be, just as passionate, and work just as hard as those in the US. But what saps the passion of engineers is bureaucracy, inefficiency and mismanagement that slows them down and interferes with their work, and by most accounts, these problems infest the aeronautical industry, on both sides of the Atlantic.
SpaceX has managed to build a company that doesn't seem to suffer from these problems. From reading Elon Musk's biography, it doesn't sound to me like the SpaceX engineers are driven by some dream of landing on Mars, even if that's Musk's goal. Rather, they just have a no-nonsense, "get stuff done" attitude. They don't spend weeks doing tests when they can get them all done in one day. They don't spend millions of dollars buying outsourced components when they can build them better and cheaper themselves. They don't thoughtlessly replicate inefficient processes because that's how it's always been done, or it's done everywhere else in the industry.
Put Elon Musk and his management staff in charge of the ESA and I bet they'd install the same no-nonsense attitude in European engineers, and it would be Ariane that was delivering reusability before everyone else. As it is, let's just hope that the example SpaceX sets eventually pays off in changes to the way NASA, the ESA, Boeing, Lockheed Martin, etc. are run.
Although I think that the big US defense contractors would rather get out of spaceflight completely than match SpaceX's costs. Because if they can, then it proves they could have done it all along, and that they've been hugely overcharging the US government for years. And if they've been overcharging for access to space, it might make congress ask questions about all the other pork-barrel military contracts they get, and why they can't deliver those cheaper as well?
I know SpaceX is doing it all more cost effectively, because we have better technology, but have they actually accomplished anything tangible that NASA didn't a generation ago?
The shuttle was the first attempt at re-usability but was far too expensive to be viable. Only the space station is genuinely long term re-useable infrastructure. It's something you can actually use as a platform for further missions beyond it's initial purpose but it also has been excessively expensive. We can't go on like this. Nobody is talking about a replacement space station, the appetite just isn't there. Unless somebody does something, the space station might be the last long term repeatedly occupied human habitat in space.
SpaceX is doing something about that. If they really can reduce launch costs by a factor of 100:1, it will change the fundamental economics of everything we do in space. Suddenly going to the moon stops being a pointless gesture and becomes an economically viable long term proposition. Human habitats in space of the scale of the ISS or bigger become affordable. They're even talking about colonizing Mars and plan to do what's effectively a tech demo of that in 2018.
For the first time the rocket man dreams of the 1970s look like they could actually happen. For a lot of people, that's pretty exciting.
P.S. Downvotes for this question? Really? I'm as much a fan of SpaceX as anyone but it's a fair question, SpaceX haven't even launched one of their recovered rockets yet.
Skylab, not Spacelab.
As you can tell count me excited.
And well, can the "materials" really be recycled without loss of security/quality?
Is the metal more expensive than the carburant/comburant?
>And well, can the "materials" really be recycled without loss of security/quality?
They aren't going to recycle rockets, they're going to refly them. They are aiming for around 100 flights per airframe.
>Is the metal more expensive than the carburant/comburant?
The cost of the metal isn't the major concern, it's the cost of shaping the metal into a working rocket. But yes, fuel costs are a couple hundred thousand, rockets are tens of millions.
SpaceX is exciting because they're doing launches and landings right now, reliably and successfully.
SpaceX (and others) are accomplishing amazing engineering feats aiming at sustainable, repeatable use of their technology, and improving as they go.
Both are amazing accomplishments. But just because "landing a rocket on a barge" is not as sexy as "landing a ship with humans on the moon" doesn't mean it's that much less of an accomplishment. Remember vertical rocket landing is something NASA chose not to attempt because they thought it was going to be too hard. And that's just what SpaceX is doing.
(The exciting part will be much cheaper refurbishment than the STS. But SpaceX haven't actually delivered on that component yet)
it is an important difference when you look beyond earth
the moon, mars, and any future site that has yet to send robots to pave a runaway that is: 4,500 meters long, 91 meters wide, and 40 centimeters thick(o); will necessarily be vertical take off and landing
> That SpaceX's approach will be more suitable to future things is not a good counterargument.
No one is saying that, they're just being positive and looking forward to the future.
How is that bad?
SpaceX took their landed first stage directly over to the test pad to fire the engines multiple times. It's not really apples to apples.
Red Dragon (assuming goes ahead as planned) will be the heaviest payload ever landed on another planet - an incremental improvement to be sure, but a real one. Mars sample return will be a concrete new thing that NASA never managed. Watch this space.
Nailing down the remaining operational workflow and they'll be able to achieve reusable rocketry, and bring down the cost of spaceflight significantly. It truly is the dawn of a new space age.
That's the number of times we landed men on the moon.
Let's not try to downplay NASA's previous successes as "lucky" and "adventurous" in order to make SpaceX seem more advanced in an engineering sense.
Luck did play a pretty big role in Apollo. This is not to discount the huge amount of work and skill that went into making most of those missions a success, but there was sometimes not a whole lot separating them from failure. Apollo 11's landing site ended up being covered with boulders and they nearly had to abort before they found a suitable landing site. Apollo 12 got hit by lightning on the way up, knocking out computers and nearly causing an abort. Apollo 13 came within seconds of exploding on launch, and was saved by a false fuel alarm shutting down the misbehaving engine.
Of course, this is only to be expected when you're doing something so big and new. SpaceX has the benefit of all that experience.
Recovering the second stage is difficult because it's coming in from a much higher speed. The first stage came in doing about 2km/s. The second stage would come in doing 8km/s or more. That means 16x more kinetic energy to deal with and 64x more heating. You need a proper heat shield, not just clever engine burns. There's much less extra margin to play with as well. The second stage does most of the work but is much lighter, and one pound on the second stage is worth ten pounds on the first stage.
SpaceX definitely believes second stage recovery to be feasible at some point, but not on the current Falcon 9.
The dry mass of the first stage is approximately 25,600kg. At 2km/s, its kinetic energy is 51.2 terajoules. The dry mass of the second stage is approximately 3,900kg. At 8km/s, its kinetic energy is 125 terajoules.
So the KE of the second stage is actually about ~2.4x that of the first stage.
Here is were I found the masses of the stages: http://spaceflight101.com/spacerockets/falcon-9-v1-1-f9r/
The Space Shuttle did reuse SRB casings and the orbiter, it was a bit different but a great achievement too.
However this time there is more potential for cost savings. It can still happen that they can't be realized because of some details or even fundamentals we don't understand from the outside.
Does it use fins, or simply engines and whatever those little jets are that, say, the space shuttle had around its nose...
How does the falcon manage to physically orient its body?
Also, is that process completely autonomous? Is there a remote flight engineer steering this to the barge - or is it completely self-guided
I am impressed - but I want to know how this works.
That being said, would you want to be in the nearby path of the rockets if they were going to be ditched?
You also can't land on a ship with parachutes. You don't have enough control. You can still land at sea, but then you have to actually land in the water, which means getting seawater on all your rocket hardware. That causes lots of problems when you want to use that hardware again.
SpaceX did experiment with this approach. Here's a picture of the second Falcon 9's interstage with parachutes packed inside:
But it turned out not to work so well.
NASA had some success with this approach on the Shuttle SRBs. It's easier with solid fuel rockets, because they're less efficient and built tougher. Even then, the cost of recovery and refurbishment ended up roughly breaking even compared to just building new ones each time.
As far as "wasteful" goes, that depends on what you're looking at. Saving fuel for the landing subtracts from payload capacity, which is wasteful in theory... but in practice, many payloads are smaller than the maximum anyway. If you suffer a 30% payload penalty, but you're launching a satellite which is 40% smaller than your maximum, then who cares? The only waste is some extra fuel, which is super cheap. The full fuel load for a Falcon 9 launch is something like $200,000, compare to the total mission price of around $60 million.
"Oh, I'm sure I know a lot better than the accumulated centuries' worth of knowledge from actual rocket scientists, and I can come up with solutions to their problems based on no in-depth knowledge of the field and a minute's thought."
But fragile fuselage is certainly spot on. Parachute-landings still have quite some impact velocity. Strengthening an object the size of a Falcon 9 first stage to survive that impact would require a much stronger and thus prohibitively heavy structure, even if the parachute itself was free. The nice thing about powered upright landing is that all the forces involved are pretty much the same as during launch so that there is little (if any) additional strengthening required.
Note also how the ULA plans for the use of parachutes to recover first stage engine blocks require the parachute to be caught in-flight by a helicopter to avoid any uncontrolled ground contact.
With the powered landing, you already have the engines there, it's just a matter of leaving a bit more fuel. It's not a lot of fuel because you've already dropped a bunch of mass (the whole second stage and a bunch of fuel), and air is helping instead of hindering.
There's also the fact that, unlike parachutes, you can use a powered landing on Mars and the Moon.
But also because a parachute landing actually does a lot more damage than you might expect, and sea water is the last thing you want in your million dollar rocket engine.
They don't want to use cranes, or parachutes or helicopters or complex landing structures, because none of those things will work on Mars in such a way the rocket just needs to be refueled and can fly again.
Airliners could certainly land with parachutes. They could even glide in for unpowered landings. And doing so would save a lot of fuel in either case. But that fuel savings would come at the cost of adding huge operational complexities, and risks. Powered landings are more precise, more predictable, and more reliable. They reduce operational complexities, even if they are costly, and for that reason they are more than worth the fuel costs. An airplane could carry more weight a farther distance if it glided into landing unpowered, but effectively all landings would become emergency situations, and it's just not worth the small benefit of increasing payload.
The same is true in orbital rocketry as well. Parachutes may seem like a good idea, but they increase recovery complexity and costs, they increase the likelihood of damage to the rocket, they reduce predictability, and so on. Powered landings are the most dependable way of ensuring the stage can be returned and of doing so within an operational profile that can be streamlined and optimized until its very reliable and efficient, just like landing a plane. The fact that it comes at some cost of payload capacity is comparatively inconsequential, as it substantially increases the likelihood of recovering the tens of millions of dollars worth of launch vehicle hardware (which over its lifetime will service launches worth hundreds of millions of dollars).