NASA, CNES Warn SpaceX of Challenges in Flying Reusable Falcon 9 Rocket - <AUTHOR> http://aviationweek.com/blog/nasa-cnes-warn-spacex-challenges-flying-reusable-falcon-9-rocket?sfvc4enews=42&cl=article_4 <comment><USER2> They know nothing about reusability. Not even NASA has operated a truly reusable vehicle, the "reusability" of Shuttle was a joke (it still cost >$1 billion per flight) and they made every mistake possible when designing the vehicle. In contrast, Falcon 9 is an enormously simple launcher and reusability should be not only fairly straightforward but also advantageous. Moreover, because reusability of the F9 will actually save money (as opposed to the Shuttle where it required a massive ongoing operational cost) it will allow _more_ money for ongoing development of improved vehicles (which SpaceX is _already_ working on).

Additionally, SpaceX isn't dumb, they've already tested running their engines through multiple cycles on test stands, they know the issues they'll run into and they have a reasonable idea how long they can expect to use them (spoilers: lots). And SpaceX has been operating reusable rockets over the course of several flights in the form of the the Grasshopper and F-9R-Dev vehicles which they've used for test flights.

<comment><USER3> Honestly, their criticism sounds like the kind of thing any jealous nay sayer would say. They're trying to make it sound like an honest warning, but in reality, they're just afraid of having their crown stolen. They're basically telling SpaceX that their new approach has unforeseen risks. It's never been done before, hence it's risky, and it could well fail, it shouldn't even be tried.

They're saying the NASA people had a working model for decades, and hence people should trust NASA's expertise more, not the new guy taking big risks trying new things. In reality, they can see that SpaceX knows what they're doing, and NASA has been falling behind for a long time, but that's really hard for NASA to accept. Still makes me sad to see this kind of attitude. Risk taking is necessary for innovation, and calculated risks often pay out big time, but the establishment is still always too afraid to take the said risks... And then when somebody else is there to take those risks, they try to discourage them.

<comment><USER2> More or less. Here's the thing, SpaceX is almost certainly going to demonstrate partial launch vehicle reusability within the next year. And they're going to make it look easy. What's more, for the most part it _will_ be easy.

The damning bit is that what SpaceX ends up doing will be the sort of thing that could have been done back in the '80s or maybe even the '70s. But nobody had the right combination of pragmatism and vision to make it happen. But they could have, and there were bread crumbs all along the way.

So why didn't they? A lot of it ultimately comes down to a few factors. Group think and bureaucracy. And fads. Yup, fads. One problem that orbital aerospace has been constantly afflicted with is the coolness factor problem. When pushing new projects it can be difficult to do so unless there is some sort of coolness factor, some way in which the new project is demonstrably more advanced than previous generation efforts. This is anathema to actual progress because most progress comes from copying, perfecting, and incremental innovation. The coolness factor is how we ended up with Shuttle (so cool), and X-33/VentureStar (much, much cooler). But look at the Falcon 9, it's just a 2 stage LOX/Kerosene booster, they've been building those since the '50s/'60s, it's the definition of _uncool_. But what it lacks in coolness it more than makes up for in usefulness.

In terms of fads you can look to the Hydrogen rocket fad that still has a grip on a lot of engineers. LOX/LH2 undoubtedly has a very high Isp, and Isp is supremely important in the rocket equation. But it's not everything, and LH2 has a crapload of very serious downsides when it comes to using it in rocketry, many of which add significant cost to the system. The Hydrogen fad is why the Shuttle had SRBs (because the SSMEs couldn't generate enough thrust on their own to get off the pad) and thus is partially responsible for the Challenger disaster. It's also responsible for the Delta IV, which is an extremely expensive launcher.

But back to breadcrumbs. They were there. In the early '90s the DC-X program demonstrated vertical takeoff/vertical landing was a feasible technology, and it did so using LOX/LH2 even. But the program was largely ignored because NASA was too dumb to see the promise of a reusable _stage_ , since it wasn't cool enough relative to the idea of an SSTO RLV (in the same year as the last flight of the DC-X NASA got the X-33 program rolling).

If NASA was just a little bit smarter and more practical it would have been easy to see the promise of the DC-X, easy to see the practicality of partial reusability, and easy to see the advantages of simpler launchers. But they didn't. Instead they pursued cool idea after cool idea, dumping around a billion dollars into X-33 alone. And when their overly ambitious cool ideas didn't pan out they ended up with nothing. And it was only through the comparative pragmatism of the defense department and the EELV program (which developed a couple boring 2-stage launchers) that the US had any reasonable launch capability whatsoever after the Shuttle program ended. Now it will be through the comparatively superior pragmatism (not to diminish the genius of SpaceX) that we'll end up with even greater launch capability and unprecedented reusability.

<comment><USER4> " _The Hydrogen fad is why the Shuttle had SRBs (because the SSMEs couldn 't generate enough thrust on their own to get off the pad)..._"

Errr, not to my memory.

Back when it was being thought about, Single Stage To Orbit (SSTO, [https://en.wikipedia.org/wiki/Single-stage-to- orbit](https://en.wikipedia.org/wiki/Single-stage-to-orbit)) was beyond the foreseeable state of the art, and the initial plans were to have to complete, reusable stages, a 1st stage big monster that would get the 2nd stage high and fast enough, and then would land "normally".

But NASA just didn't get enough money to do it right (the '70s were a particularly bad time to be trying to do such a thing in the US, and in things like the SSMEs just plain screwed up ([https://news.ycombinator.com/item?id=7711061](https://news.ycombinator.com/item?id=7711061)). So at practically every turn, they sacrificed true reusability, operating costs, and ultimately safety (not a coherent design, but a series of compromises, and of course no provision for failure) to keep development costs within their budget.

</comment></comment></comment></comment><comment><USER5> _"We tried to make the engines reusable for 55 flights," he said in Paris last month. "Look how long and how much money it took for us to do that, and we still weren 't successful for all parts."_

Sour grapes, much?

This is why it's important to have different groups of engineers trying different things--you get a chance to pull off things previously thought impossible or prohibitive.

<comment><USER6> Let's wait and see how it will actually work. The guys who designed Space Shuttle also expected much more reusability than what they managed to achieve. There are serious physical limits that you just can't be even aware of until you actually try.

<comment><USER7> The Space Shuttle was a political football whose design was dictated by the whims of Congress and the meddling of the military first, and by engineering second.

The Shuttle was required to be reusable as a political goal. However, it was not given the funding it needed to actually accomplish it in any reasonable fashion.

The Air Force put some tough requirements on it, such as the requirement for enough cross-range capability when landing to be able to launch into a polar orbit from Vandenberg, deploy a satellite, and land back one orbit later. This is purely a wartime requirement. No peacetime mission needs this. This required much bigger wings (and thus much more weight), even though the Shuttle never once launched out of Vandenberg, let alone on one of these crazy single-orbit missions.

Politics screwed up other stuff too. The solid rocket boosters, for example, were manufactured on the other side of the country, largely because of Congressional pork. The long and difficult transport process required the boosters to be built segmented, and that design directly lead to the loss oF Challenger.

Similarly, budget constraints dictated the cheaper SRB-plus-external-tank design rather than a more sophisticated and more reusable (and more expensive) reusable booster. This design directly lead to the loss of Columbia.

The net result was that the Shuttle had a very narrow engineering margin. The SSMEs are engineering marvels in terms of how light they are and how much power they put out. But putting out a lot of power for little weight is a really bad plan for something you want to reuse. Reusability means robustness, and robustness means extra weight and less power.

The Shuttle is what you get when you say, "How much will it cost for a reusable launch system? $10 billion? Too much, we'll give you $5 billion." (Numbers in the ballpark but mostly made up for illustration.)

On the other hand, the Falcon 9R is what you get when a for-profit space launch company wants to make more money. It's not a prestige project, it's not a political project, it's not a military project dictated by thoughts of all- out war with the USSR, it's not subject to Presidential grandstanding or Congressional pork. It's just a bunch of smart people thinking of ways to save their customers money and turn a better profit while doing it.

The Shuttle was an extremely ambitious design that did everything differently. Ultimately, everything was too ambitious to be reusable.

Falcon 9R, on the other hand, is deeply _un_ ambitious. The rocket is a pretty standard design. They don't even try to use liquid hydrogen for any stage, even though it's theoretically more efficient, instead favoring easier-to- handle kerosene. Their rocket engines are high performance but not on the bleeding edge. And when they decided to go for reusability, instead of building a whole new system with wings and ceramic tiles and all sorts of other extreme innovations, they just said, let's slap some legs on the first stage and give it some extra fuel. It's a completely different approach that pretty much only shares the word "reusable".

I don't think the Shuttle really has many lessons to offer when evaluating the potential of Falcon 9R.

<comment><USER4> " _and the meddling of the military_ "

" _The Air Force put some tough requirements on it, such as the requirement for enough cross-range capability when landing to be able to launch into a polar orbit from Vandenberg, deploy a satellite, and land back one orbit later._ "

That's not what I remember at the time this was happening, nor was it e.g. the story in a good study published in _Science_. Sure, the DoD/intelligence community wouldn't have minded such a capability, but NASA insisted on it to make the shuttle more attractive to them and _to help justify the monopoly_ NASA obtained on these sorts of launches.

Something the DoD didn't like _at all_ , and was partly freed from after the _Challenger_ disaster. Which also prompted a closer look at the safety of Vandenberg launches and the canceling of them.

<comment><USER7> Here's a source for you:

[http://history.nasa.gov/SP-4221/ch5.htm](http://history.nasa.gov/SP-4221/ch5.htm)

Quote: "However, it meant that if a shuttle was to execute a one-orbit mission from Vandenberg, it would return to the latitude of that base after 90 minutes in space only to find that, due to the earth's rotation, this base had moved to the east by 1100 nautical miles. Air Force officials indeed expected to launch the Shuttle from Vandenberg, and they insisted that the Shuttle had to have enough crossrange to cover that distance and return successfully."

It goes into quite a bit of detail on the Air Force's involvement and reasoning.

I'd be interested to see them if you had sources that say otherwise.

<comment><USER4> You don't suppose the official, house NASA history of the Shuttle might be a bit unreliable on these issues???

My sources are what I contemporaneously learned and remembered in the '70s, and that paper in _Science_ (the world's #2 science journal after _Nature_ , not that it wasn't back then very political, just that this claim cuts against their politics). It would have been published in the '80s, very possibly after the _Challenger_ disaster prompted a lot of second looks, but I can't be more specific.

<comment><USER7> Yes, an official NASA history is certainly going to be biased.

On the other hand, you've given me no reason whatsoever to believe you over them. Your ??? is completely out of line. I merely gave a source for what I said and asked if you had one. I understand if you don't, but don't be surprised if I then don't necessarily believe your claim.

<comment><USER4> But I do have a source; it would be behind a paywall if I could find it/went to the trouble of trying to find it (the search would probably cost money to make sure I found the right article). At best I hoped to plant a seed of doubt about yet another archetypal bashing of the military; clearly I've failed.

My "???" indicates I think it's quite possible the author's sources lied to him. You're welcome to believe that NASA people, when talking about their greatest and most expensive in every way failure---these decisions killed two complete crews of 7 each---are more honest than I am, but I'm not entirely sure how much company you'll have, the world has seen rather a lot of post- Apollo NASA by now....

(This alone should give one serious pause: [https://en.wikipedia.org/wiki/Rogers_Commission_Report#Role_...](https://en.wikipedia.org/wiki/Rogers_Commission_Report#Role_of_Richard_Feynman)).

<comment><USER7> It's not "bashing of the military". The Air Force didn't _want_ the Shuttle, but once they were forced into it, they wanted to make it useful to them. The fault lies with the people who forced two organizations with widely different goals to come up with a single vehicle that worked for both of them.

I don't understand your incredulity at my reaction. What exactly did you _think_ was going to happen when you showed up making an effectively anonymous comment saying, "no, that's wrong, believe my 30-year-old memories over the official history"?

<comment><USER4> You're contradicting yourself: first you said:

" _The Space Shuttle was a political football whose design was dictated by the whims of Congress and the meddling of the military first...._ "

Then you note the military didn't want it, but wanted it to be useful if forced. I would add the _Science_ article specifically addressed the single orbit polar mission, saying the Air Force didn't see a great need for that and would have been happy with gentler flight profiles. It explicitly said NASA insisted on it, and that's consistent with their post-Apollo institutional biases, much the same produced the hot-rod SSMEs.

"Meddling", when it wasn't, qualifies as bashing in my book, especially in the full context of your sentence.

As for my incredulity, maybe start here: [https://en.wikipedia.org/wiki/Historiography](https://en.wikipedia.org/wiki/Historiography)

I was a History minor in college....

<comment><USER7> I don't see the contradiction. They were forced into the project and then they screwed with it.

However, if you insist on taking offense at my comment, I'm not going to fight it that hard. I'm not really interested in what offends you.

What I _am_ interested in is some sort of external source for the stuff you're saying. Pseudonymous internet comments from "hga" and vague references to "the _Science_ article" don't count.

</comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER8> > Christophe Bonnal of the launcher directorate at French space agency CNES, > agrees. "If you reuse, you stop producing, depending on the level of > reusability," he says. "So you end up with a permanent prototype, and to > keep costs down you need to have a high rate of production."

I am not a rocket scientist. So someone please explain to me why this quote isn't the single stupidest thing I've read all day.

<comment><USER9> I think what he means (using a software library analogy): if you have a reusable component that is not worked on but satisfies your needs now, you're going to work around all problems and implement hacks to keep using the reusable component, instead of improving it - improving/maintaining that component could cost you another development team. You get technical debt / bitrot instead.

If they keep component X too long, they'll need to reimplement / rebuild X from scratch in a few years when the original factory/production line doesn't exist anymore. This would require a lot of up-front cost that may be higher than just producing a new element of that type for every launch.

I don't think the message was completely negative though: "depending on the level of reusability" sounds more like "this is hard, but if you pull it off with cost of restarting production << cost of reusability over N years, that's an achievement"

Edit: many words

<comment><USER10> SpaceX has already stated that the lifetime of the reusable rocket is 50 launches maximum, assuming it is recovered intact every launch.

If the cost of those launches drops by a significant margin (such as a 90% reduction as suggested), there will be many more launches as every country with two pennies to rub together launches communications and land monitoring satellites.

</comment></comment></comment><comment><USER11> Tangential thought:

It really seems to me that only companies with the "California tech startup mentality" (whether they're in Cali or not) can actually do _anything_ today. I'm starting to refer to the rest of the economy as the "legacy economy," "legacy industry," etc.

I understand some of the reasons: bottom-up engineer-led engineering teams, lean operations, little or no bureaucracy compared to large older institutions, etc. But there seems to be something else too, some kind of difficult to quantify attitude or mentality. I get it, but I find it hard to describe except to say it's about believing in the future, believing that things are actually possible. Everyone else everywhere else seems to be looking backward and thinking of all the reasons things can't be done.

Like this, for example. "Here, we're NASA, and here's why it can't be done." The NASA of the 50s and the 60s is rolling in its grave!

Legacy economy indeed. Disrupt everything. Ditch it all and start over.

<comment><USER2> Indeed. There are folks who see disruption as valuable and those who see it is as risky, dangerous.

As to the NASA of the 1960s, that was a NASA who developed 4 different manned spacecraft in a 10 year period (Mercury, Gemini, Apollo CM & Apollo LM) and flew them on 4 different rockets (Atlas, Titan, Saturn I, Saturn V). That's the sort of activity that looks similar to what SpaceX is doing today and very dissimilar to what NASA is doing today (sinking billions per year into masses of bureaucratic BS and very little hardware).

<comment><USER4> _Five_ different rockets! The first suborbital Mercury flights used Redstones, V-2 descendants that used alcohol and LOX.

Followed by the Atlas that used kerosene and LOX like Space X, the Titan which used fuels that could be stored in the rocket for long terms, making it a practical ICBM (taken out of service in the mid-80s).

All those were adopted from military missiles, and were followed by the purpose built Saturn I and V, and both of their first stages also used kerosene and LOX.

Am I seeing a pattern here ^_^?

(Quibbles: the "kerosene" used in rockets is actually highly refined stuff: [https://en.wikipedia.org/wiki/RP-1](https://en.wikipedia.org/wiki/RP-1) and the Saturn upper stages used liquid hydrogen and LOX.)

<comment><USER2> Hydrogen was used for the Saturn upper stages for performance reasons, since at the time that was more important than cost. If cost is a concern it's generally cheaper just to build a larger rocket and use LOX/Kerosene everywhere. The fascinating thing about rocket development throughout history is that almost none of it has ever been truly cost sensitive.

The big advantage for SpaceX in using the same propellant and mostly the same engine in the 2nd stage on the Falcon 9 is that the 2nd stage is dirt cheap. In any other rocket they'd see the opportunity to build a small little LOX/LH2 stage and improve the payload tremendously. But then you'd end up with a lot of cost in the 2nd stage, which is precisely what SpaceX doesn't want. With the Falcon 9 design 3/4 of the manufacturing cost is in the first stage. Which means that reusing _just_ the first stage (by far the easiest reusability prospect) nets huge gains. This is what you call low lying fruit. And it's fruit that would have been there for anyone else to pick except they kept making the tree taller without thinking about it, instead of just picking the fruit.

So now instead of a more expensive rocket with more payload SpaceX ends up with a vastly less expensive rocket with slightly less payload (easily worked around with the Falcon Heavy configuration). Even just 2 reflights of the first stage translates to an overall reduction of 50% in the capital cost of each flight (or 60% in the case of the FH).

<comment><USER4> " _easily worked around with the Falcon Heavy configuration_ "

I'm a little concerned about the propellant crossfeed aspect of the Falcon Heavy (the liquid boosters on the sides feed propellant to the core, which will be mostly full when they separate ... and that's much sooner than a normal Falcon 9 first stage is finished boosting, might make reusability easier).

If they pull it off they'll be the first ever, right?

Not saying they can't, but unlike almost everything else they're doing, this is new "rocket science" to my limited knowledge.

<comment><USER2> It's not crazy complicated. And the Shuttle was fed by an external tank as well. The way it will work with the Falcon Heavy (when that much payload capacity is desired) is that the 3 engines on each side in the center booster will each feed from the nearest outer cores during liftoff. When those cores are empty the feed will be stopped, those 6 engines will shut down, the outer cores will separate, and then the 6 engines will come online again fueled by the center core. It's mostly just valve work, to be honest. Also, even if it doesn't work it's not a huge deal long term. It means that we'll be deprived of the highest payload capacities for an expendable Falcon Heavy but we'll still have a fairly high (20+ tonne to LEO) capacity booster in a reusable configuration, which will probably be more impactful in the long run than the expendable configuration.

<comment><USER4> Ah ha! In the back of my mind I _knew_ this wasn't entirely unprecedented, just couldn't remember where.

The scheme, as described in more details by you, is a lot simpler, and less concerning than I was envisioning (figures, given this is Space X). There's no cross tanking, that is, feeding the tanks of the central core from the sides.

Hmmm, although as I remember, when they had to shut down one engine during an ascent, it shed debris because of the pressure imposed by the adjacent engines. But I note the Merlin 1D, while producing significantly more thrust at sea level (nearly 50%), can throttle between 70-100 percent. Obviously they've thought through these stresses, and of course there are structural implications in making them highly reusable, they're willing to trade off weight penalties for durability, and therefore likely strength.

Anyway, thanks for the details, and all the contributions you've made to this topic!

<comment><USER2> That's a good point about the engine problem after it was shut down. However, there are a few important issues that are relevant. On further investigation the engine damage was due to fuel leakage, it wouldn't necessarily be expected that a healthy engine would react the same way if shut down under the same conditions. Also, that failure occurred at Max-Q (maximum dynamic pressure), and normally it would be expected that the stage separation would occur under much, much less strenuous aerodynamic conditions (farther down range and higher altitude, much lower atmospheric pressure).

</comment></comment></comment></comment></comment></comment></comment></comment><comment><USER12> "We'd pick them out of the ocean, but we spent a lot of time cleaning those things up when we got them back"

And there's the rub. SpaceX is working on having reusable components land on solid ground.

<comment><USER13> That quote is respect to the Shuttle Solid Rocket Booster - a part completely incomparable to the Falcon. It's really a throw away line about establishing an absolutely silly baseline.

The meat of the 'argument' (and really, I don't believe it's an argument) is that the Shuttle Main Engines (the ones mounted on the tail of the Shuttle, the ones that land like a plane) had similar expectations of reusability, and ended up being absolutely terrible at reusablility. That's the point to address, not the throw away line.

<comment><USER14> Right but they were awful because they were built and tested and qualified top-down, not bottom up. Feynman wrote about this idiocy at length: [http://science.ksc.nasa.gov/shuttle/missions/51-l/docs/roger...](http://science.ksc.nasa.gov/shuttle/missions/51-l/docs/rogers- commission/Appendix-F.txt)

<comment><USER11> I also wonder about the use of hydrogen and how this impacted reusability. From what I've read hydrogen causes things like metal embrittlement, which is why SpaceX is completely avoiding it despite the higher specific impulse it yields.

<comment><USER2> LH2 is also super cryogenic. LOX and even liquid methane have boiling points higher than LN2. You can build launchers with them without even bothering to insulate the tanks, because the boiloff is so marginal over the duration of the launch. Whereas LH2 absolutely requires a lot of insulation, because it needs to be much, much colder. Worse yet, because of the super low density of LH2 you can't afford even a small amount of boiloff because that hurts your mass fraction immensely, and if you have a LOX/LH2 vehicle you've probably scraped and scrabbled for what meager mass fraction you've managed to achieve (through advanced alloys and so forth). One particular consequence of the use of LH2 with the Shuttle was that it resulted in an ice covered and foam insulated enormous external tank cheek-by-jowl with the delicate TPS coated underbelly of the orbiter during launch, as the vehicle rammed through the air at transonic then supersonic then hypersonic speeds.

Another consequence of the LH2 choice for the Shuttle is that it didn't have enough thrust at sea level to get off the pad, so it needed high-thrust, low- cost boosters as a 0th stage. Solid rockets being the obvious go-to solution, those got used.

In a very real way the choice to use LH2 resulted not just in much of the cost and complexity of the Shuttle system but also the death of 2 crews and the loss of 2 orbiters.

<comment><USER11> Hydrogen rockets sound like a classic case of narrow over-optimization for one or a few dimensions of performance at the expense of the overall picture.

The methane direction SpaceX is taking going forward strikes me as almost a no-brainer. It gives you a higher isp than kerosene, is about as easy to handle as LOX, and is super-abundant and cheap. In addition to being basically 95% of natural gas it can also be made electrochemically/thermochemically from water and CO2 or trivially obtained from biomass digestion. The latter options are all possible on Mars. It's also a renewable fuel if you get it from non- fossil sources on Earth.

<comment><USER15> Hydrogen can make sense, but not really as the Shuttle used it. The second and third stages of the Saturn V used hydrogen, which was in part responsible for the much greater mass to TLI than the N-1 would have had (despite having a first stage with more thrust).

</comment></comment></comment></comment></comment></comment></comment><comment><USER16> There have been very few reusable delivery systems (1? sorta?). That is too low of a sample size to draw conclusions. SpaceX has shown itself to be much more efficient than NASA and NASA's usual vendors, who is to say this will not build a better reusable delivery system? After all the last one was designed 40+ years ago by a very bureaucratic/political organization. Not to mention that Space uses Kerosene rather than Hydrogen for materials related reasons.

Also, while some comparisons to the shuttle's main engine are warranted, refurb costs of the shuttle's solid boosters will not be comparable as they landed in the ocean rather than on dry land. Ocean water is nasty stuff for hitech equipment.

</comment><comment><USER17> I'm not sure that landing is more dangerous than takeoff. It's true that the thing is pointed towards the earth, but on the other hand there is a lot less fuel to explode.

<comment><USER18> The problem is that on launch the rocket is moving away from inhabited areas and out toward uninhabited areas during launch. On Landing it's going towards more densely populated areas. I wonder if maybe the solution is to land them on some uninhabited island, like the one the USAF targets ICBMs with dummy warheads on it from time to time.

<comment><USER15> From what I have heard, the first stage will come in aimed away at the landing, or anything else, and then perform the divert maneuver that they've been testing with Grasshopper/F9R-Dev to put itself over the landing site at the last moment. That way if anything goes wrong before the last few seconds, the rocket won't fall where it was suppose to land.

They are definitely planning on doing boost-back to the general area of the launch site though, not aiming for a target down-range. The launch this weekend will have them bringing the stage back closer to land than the previous attempt.

</comment></comment></comment><comment><USER19> shoud we remind NASA and CENS that in the 1980s USSR had a shuttle launched by remote control and land under the same computer control..</comment>