SpaceX set to launch ‘used rocket’
bbc.com
bbc.com
https://www.reddit.com/r/spacex/comments/62aqi7/rspacex_ses1...
https://www.reddit.com/r/spacex/
Here's the SpaceX press kit:
http://www.spacex.com/sites/spacex/files/finalses10presskit....
I can name many subs that attract some of the top members in the world in that field. If you are fascinated by rocketry, then yes /r/spacex is going to really impress you.
There are knitting subs attended by the top knitters in the world that write the knitting books everyone else uses. But I think it less likely to impress you if you don't value knitting as a skill, like you value rocketships.
I don't know why you think my opinion of r/SpaceX is driven by some obsession with rocketry. I am much less interested in SpaceX than in a dozen other hobby topics, but that subreddit stands out in the objective quality of the moderation and community. Likewise, HackerNews is one of the higher quality places for discussion on the internet even though I do very little programing.
(and now you know those are both things)
The most popular great subreddit is probably askhistorians.
I don't subscribe, but I browse "best of last week" occasionally.
EDIT: Happily, in the last hour some people have made at least 3 specific recommendations. (Anime doesn't personally interest me, and I think /r/TrueReddit is highly overrated, but /r/syriancivilwar looks very interesting.)
(I do remember that the mod had a very hands-off attitude that IMO didn't work very well, with clickbait headlines to bad articles frequently getting upvoted.)
Historians is very well moderated (strict) and has users have expert tags.
The civilwar sub always has the newest information tagged with the needed facts about the sources. Lots of different people and sometimes pretty high level discussions. They are literally producing their own magazin now.
There are some of the best.
I find /r/teslamotors mediocre, most posts are uninteresting and the comments can be ridiculously naive and optimistic. Many people there are convinced that Tesla has the most advanced self-driving tech and hugely exaggerate the importance of crowdsourced fleet learning.
Perhaps it's got good discussion but I'd be willing to bet it's probably heavily censored too.
I was under the impression that SpaceX was trying to make the first re-usable rocket stage, but I've recently found out that that isn't true. The space shuttle already holds that title.
I'm also kindof curious why they decided to go with a vertical-landing-design, instead of putting some wings on it and having it glide home like the shuttle did. Is that a weight-concern? Aerodynamics, mabye, but couldn't the wings be articulated in the same way that the landing legs are right now?
(I will admit some ignorance in this field. I'm definitely a fan, but I'm definitely not a historian or a rocket scientist)
As for gliding back: the Falcon booster does not actually achieve orbit-- when the main engine cuts off, it is on a ballistic trajectory back to the ocean. While it may be possible to design some sort of gliding apparatus to "save" a booster on a sub-orbital trajectory, it is (again, as I understand it), much simpler to simply adjust that trajectory via a boostback burn that reverses or slows that trajectory, and to then perform a suicide burn[2] to recover the stage, either on a barge or (on lower orbit missions) back on a land-based pad.
I am not a rocket scientist, nor do I have experience in the space industry-- these thoughts are just based on what I've read following the SpaceX reusability program as closely as I can for the past few years.
I do play a lot of Kerbal Space Program, though.
[1] https://en.wikipedia.org/wiki/Criticism_of_the_Space_Shuttle...
[2] http://space.stackexchange.com/questions/10307/what-is-a-sui...
They also have no other option. Even one engine at lowest throttle (70 %) is powerful enough to lift the almost empty booster again, so they cannot hover (which would make things a bit easier, at the expense of needing more fuel).
(If someone can confirm/deny this? I'm seeing approx 28T dry mass, thrust per engine of 66T and min thrust of 70%, but that dated guess work from http://space.stackexchange.com/q/4466/ )
SpaceX rockets use a much simpler engines, that burn oxygen and kerosene. The main cost is in the first stage of the engine - think two rockets on top of each other, the first stage is the bottom rocket that first first. When the first rocket is done, it falls away. This first stage accounts for the majority of the cost of the launch. Think of it was being equivalent to the main tank and 2 boosters of the shuttle.
What SpaceX manages, which no-one has done before, is to retrieve that big + expensive first stage for reuse.
http://www.gettyimages.com/detail/news-photo/solid-rocket-bo...
All that stress + salt water meant a fairly extensive refurb process.
Could one conceivably use different materials (that maybe didn't exist back then) resistant to aquatic stress and salt, to have made the old plan much more cost effective?
Following this line of thought I think you wind up with something close to what SpaceX does. Because the next largest save-able cost would be the boat crew to go recover it. So attach a propeller to the rocket to have it come back on its own. Then you want to save that cost and complexity so have it come to your boat with no crew and touch down gently.
The vertical landing design is actually really smart because it allows a relatively un-aerodynamic object to get back to the ground without adding heavy wings and fairings. Rockets don't actually like having fins when they go up since the dynamic pressures get to be extremely high. Rather, they opt for gimbaled engines to steer (this also helps when there's no atmosphere to steer with). The only downside to this approach is that some of the fuel has to be retained for the return trip, though this is a relatively small fraction. The other huge issue you have to deal with when gliding back is having some sort of landing gear in addition to the control surfaces. You can put wheels on it but that's a lot of weight and if you land it horizontally, without the pressure of the propellant keeping the body rigid, it will most likely crumple.
The SSME are special and specially efficent because they burn fuel-rich and have multible pre-burners. They were very highly optimized but that made them complex.
Full-staged combustion has a better max performance for a given fuel and promises to be simpler in design.
Basically, the physical and aerodynamic stresses of decelerating vertically are fairly similar to those of accelerating vertically. Whereas designing something which can work as a rocket and a plane would be a lot more difficult, and probably more expensive to produce.
It's more difficult to control vertically, but if you can get it right you save a lot of complexity in the physical engineering.
Vertical landing for the Falcon 9 made sense because it meant they only had to add a small amount of extra weight and new systems (landing legs, grid fins, etc.) in order to achieve powered precision landings. In contrast, adding wings, landing gear, other aerodynamic components, and potentially other engines (in order to achieve powered landings) adds a lot of extra complexity and weight. Additionally, the stage is already designed to handle vertical flight and forces, making it strong enough to handle strong aerodynamic forces while flying horizontally is no small change. And vertical landing enables barge landings out at sea as well as dramatically reducing the size of the landing facilities (a small pad versus a landing strip). All of which saves costs, complexity, and enables a higher percentage of the vehicle's performance to be used by the customer versus for recovery.
Early on they tried parachutes but ditched them, iirc.
At this point you have traded several tons of parachutes and many more points of failure which could cause loss of mission (parachutes are complex mechanisms) for a smaller weight of fuel and exactly the same points of failure as a rocket always has. Then SpaceX added grid fins, since purely propulsive landing was not going to be anywhere near accurate enough.
Classic example of working to your strengths, where the greatest strength of a rocket is acceleration along its primary axis :D
They could do something like the Russians do with Soyuz - small solid rocket boosters that fire right at landing. But yeah, that's a lot more things that have to go right.
Also even with the rocket motors Soyuz hits the ground pretty hard.
And yes, Soyuz hits pretty hard. But Soyuz was developed over fifty years ago. I'll bet we could do better today.
I'm not sure what advantage additional solid landing rockets would provide over just slightly bigger fuel tanks for the main engines.
I was originally thinking about solid rockets in context of a parachute system, but the more I think about the more I believe truly gentle landings aren't really a feature of the current design.
I'm not sure how much weight it would add, but it seems like having the ability to fine-tune the thrust at the very end would allow them to land much more gently and feel better about not introducing metal fatigue or other damage. Of course the addition of a smaller LF engine probably makes the most sense.
For RTLS launches, it would do approximately as good as their current approach, the fuel for landing burn+legs will approximately weight as much as wings and wheels. But would definitely cost more to develop.
A winged stage also having a jet engine, allowing it to fly back as a powered airplane, not a glider, would solve both issues, and will whole lot more efficient than current SpaceX approach for RTLS, and about as good as ASDS, but a lot, a lot more expensive to develop. They would have to become an aircraft company in addition to being a rocket company.
SpaceX ITS video:
Shuttle boosters are solid-fuel, so they can't restart, can't land, and were ditched in the ocean and refurbed. In contrast the 1st stage of spacex rockets can land itself.
I was under the impression that SpaceX was trying to make the first re-usable rocket stage, but I've recently found out that that isn't true. The space shuttle already holds that title.
For certain values of re-usable. It was pretty much stripped and refurbed for each mission, at enormous cost. The costs of spacex are orders of magnitude smaller.
I'm also kindof curious why they decided to go with a vertical-landing-design,
This design works everywhere, not just earth.
And of course, there was John Glenn, monitored inside and
out, blood tested, urine sampled, entire organism analyzed
for signs of accelerated aging. Close observation of the
Senator suggested that there might not be any medical
obstacles to launching the entire legislative branch into
space, possibly the most encouraging scientific result of
the mission.As tempting as it is to picture a blood-spattered Canadarm flinging goat carcasses into the void,...
> The Soviet Shuttle, the Buran (snowstorm) was an aerodynamic clone of the American orbiter, but incorporated many original features that had been considered and rejected for the American program, such as all-liquid rocket boosters, jet engines, ejection seats and an unmanned flight capability. You know you're in trouble when the Russians are adding safety features to your design.
[0] https://en.wikipedia.org/wiki/List_of_space_shuttle_landing_...
Of course, the Earth rotates underneath the Shuttle while it's in orbit, so when the Shuttle comes back around in a polar orbit it's quite some distance to the west of the launch site, so it needs to be able to make significant maneuvers for this to work.
Vandenberg never ended up hosting Shuttle launches, of course. It was nearly ready, with mission planned and everything, when Challenger exploded. This caused a reevaluation of the whole idea, and it ended up being scrapped. But the design consequences remained part of the vehicle until the end.
The SSMEs (Space Shuttle Main Engines - Aerojet Rocketdyne RS-25), required an almost complete rebuild after every launch. It was nominally reusable in that the parts could be reused, but it took a long time to refurbish and re-test the engines. Also, the first stage of the Space shuttle included the solid rocket boosters and the hydrogen fuel tank. The boosters were absolutely reusable (I seem to remember reading that of all the SRBs, all but four were reused - two from the first launch were never recovered, and two from the Challenger disaster that couldn't be recovered). But the Space Shuttle wasn't fully reusable like the Falcon first stage.
To me, the difference between the Space Shuttle and the Falcon 9 is kind of like the difference between a doctor of mechanical engineering and a mechanical engineer. The Space Shuttle was an amazing (and complex) piece of tech - the engines used liquid hydrogen and liquid oxygen, which is incredibly efficient but notoriously difficult to work with (cooling hydrogen to a liquid sate and keeping it cooled is not trivial). It was a long (~10 years) process to develop the Space Shuttle from the existing tech we already had. The result was a highly tuned and complex engine that was incredibly efficient. It makes you feel a bit warm and fuzzy at how efficient and well engineered the engines are.
SpaceX went the other way - they said we'll use a slightly less efficient set up (RP-1 (refined kerosene) and liquid oxygen) as our fuel, but we'll make up for it by making each individual launch much much cheaper. So while they may not have the fuel efficiency of the Space Shuttle, for the cost of a single Space Shuttle launch (~$400M per launch according to wikipedia), SpaceX could launch 6 or 7 Falcon 9s (~$60M per launch). The SSMEs are very efficient engines. The Falcon 9 is a very efficient platform. It's kind of like a big picture vs micro optimization sort of thing. (There is no judgement here - the Space Shuttle was developed by a government with much different concerns and constraints than the private business developing the Falcon 9).
Having a fixed wing aircraft come down from space really doesn't make that much sense when we get down to it. It's a really great and interesting concept, but the realities of it make it not worth the trouble. Sure the Space Shuttle glided, but even a brick going 17,000 miles an hour will glide for a long while. This video (https://www.youtube.com/watch?v=B3JZtY7bcbM) gives a great overview into the complexities of a plane-shaped spacecraft hitting the atmosphere at 7 km/s. When a capsule (like the Apollo Command Module) hits the atmosphere, you only need to protect one side of it, and you just let the thing fall like a stone then slow it down with parachutes. The Space Shuttle Orbiter had to have different materials with different heat shielding properties all over its body because it would glide through the air at different angles. The bottom of the orbiter had an enormous surface area, and it needed to be thermally insulated. But heat shields are very heavy, and that amount of weight would make the launches impractical and landing impossible. So NASA had to develop new, light materials that were incredibly strong and also heat resistant.
The Falcon 9's first stage is not going nearly as fast as the Space Shuttle Orbiter when it hits the atmosphere, so it's not really appropriate to make a direct comparison about the complexities there. But this is to me another part of the brilliance of SpaceX looking at the big picture - it's much easier to reuse the first stage (which is typically the most expensive part of a launch vehicle) which doesn't reach orbital velocity and capture as big a chunk as the savings as possible rather than being totally 100% efficient.
I would not be surprised if NASA was 50 or 60 years ahead of its time with the Space Shuttle. It seems like private industry is catching up to where NASA was with the Saturn V in the 60s just now (we're still not close to a rocket as powerful as the Saturn V). We may see that in 20 or 30 years, the industry uses the materials and knowledge gained from the Space Shuttle to develop new and novel spacecraft.
Again, I'm just a programmer who loves rocketry and space - I apologize if there are any technically inaccurate bits in this post.
It's sort of apples vs oranges to compare the Shuttle main engines vs the Falcon 9 engines, because the Shuttle main engines were on the the crewed upper stage of the Shuttle stack and the Falcon 9 booster is the boost stage of the Falcon 9 stack.
The direct comparison is comparing the Falcon 9 booster (first stage) with the solid rocket boosters of the Shuttle stack, and comparing the Shuttle with the Dragon. Dragon v1 has a heat shield (like Shuttle) and then parachutes (unlike Shuttle). Dragon 2 will have reusable engines to land propulsively, which means it will land on land like the Shuttle.
The Falcon 9 booster is much, much more sophisticated than the Shuttle boosters. The Shuttle boosters were solid fueled; once lit they could not be turned off or throttled. They just burned at maximum thrust until they ran out of fuel, which is why they needed parachutes to land in the ocean.
Unfortunately NASA learned that salt water is terrible for engines, even if they land gently, and the cost of refurbishing the boosters after each launch (and the amount of time it took) was much higher than anticipated. Falcon 9's Block 5 booster should (hopefully) reach a point where it can land, get refueled, and immediately take off again, like a 747.
> I was under the impression that SpaceX was trying to make the first re-usable rocket stage, but I've recently found out that that isn't true. The space shuttle already holds that title.
For the reasons I have above, you were right the first time. SpaceX is trying to make the first reusable booster that achieves orbit. Both Shuttle and Blue Origin's New Shepard are reusable, but neither of them can reach orbit by themselves.
> I'm also kindof curious why they decided to go with a vertical-landing-design, instead of putting some wings on it and having it glide home like the shuttle did.
Scaling laws. Vertical take-off, vertical landing (VTVL) rockets scale to any size. Wings don't. The Falcon 9, the Falcon Heavy, and future mega-rockets will all be able to use the same basic technology. Wings don't scale well at all.
You are correct about the disadvantages of wings, but wrong about why SpaceX isn't using them.
SpaceX has always had the goal of landing on Mars and returning home. All their rockets have been developed with this in mind. They tested their first rocket, and got it to work. They sold it to Nasa and the like (and even developed it with some of their requirements in mind), but the goal was always to learn how to make bigger rockets that can get to Mars, that Nasa is willing to pay for the smaller ones is a side benefit. Mars does not have enough atmosphere for wings to work, therefore SpaceX is not interested in Wings.
Even if reuse of the rocket was clearly more expensive that building a new one each time (it isn't) SpaceX would be working on reusable rockets now because when they get to mars they need to land the rocket and latter reuse it to return back to earth.
The Solid Rocket Boosters are strictly speaking doing exactly what the Falcon 9 booster is doing: being recoverable. However, the Falcon 9 boosters have much greater capability to be re-used without refurbishment, since they don't encounter salt water.
The Space Shuttle's engines were extremely complex beasts that begat the most advanced alloys at the time – very much bleeding edge, with the tightest tolerances possible, to squeeze out performance that wasn't thought possible before, using highly aggressive propellants (hydrogen embrittlement was a huge problem). As a result, they only had a tenth of their planned life expectancy (average of 5-6 instead of 55 flights), and needed an 80% refurbishment between every flight to replace cracked turbine blades etc. pp.
Falcon 9's Merlin engines, meanwhile, are best described as "boring": They're firmly a 60s design made cheaper than dirt thanks to modern manufacturing technology, and highly reliable thanks to a simple design and safe fuels (kerosene). SpaceX already demonstrated on the ground that Merlins can perform multiple missions without needing refurbishment.
Or, in car analogies: The Space Shuttle is a Jaguar, Falcon 9 is a Ford. While you can, on the paper, drive a Jaguar twice without seeing a workshop, nobody managed it yet.
> I was under the impression that SpaceX was trying to make the first re-usable rocket stage, but I've recently found out that that isn't true. The space shuttle already holds that title.
Kinda, sorta, in theory: While the orbiters did refly a lot of times, the engines (the most expensive part of the Shuttle) barely did, only in the "Ship of Theseus" sense. Same for boosters (fishing steel tubes out of the ocean and hammering out the kinks was a pure work creation measure), and the huge external tanks were made anew each time.
> I'm also kindof curious why they decided to go with a vertical-landing-design, instead of putting some wings on it and having it glide home like the shuttle did. Is that a weight-concern?
Precision and weight: Wings are dead weight for a vertically launched rocket, and increase drag (especially supersonic) further than folded-up landing legs do. Hoverslam point landings need very little added mass on the rocket, and you expose a far smaller surface to re-entry heating etc.
> In response to a question whether the discount was closer to potential figures publicly disclosed by SpaceX’s Shotwell and SES chief executive Karim Sabbagh — who discussed possible reusability discounts of 30 percent and 50 percent, respectively — Halliwell said: “It certainly came out closer to Gwynne than to Karim.”
> The figures, while stated as unofficial and somewhat arbitrary, illustrated the behind-the-scenes negotiation on the real price of a reused Falcon 9.
> Halliwell did not confirm whether the ultimate price for the SES 10 launch fell between the 30 percent and 50 percent discount figures.
> “We did receive a good discount on the baseline price,” he said. “It’s not as crazy or spectacular as you might think, and that makes sense. SpaceX has to supply an awful lot of equipment, and they have to do an awful lot of refurbishment.
> “It is an interesting price, and it’s something which we believe will be meaningful going forward, and will be meaningful for the industry in the longer term,” he said.
> SES says there was “no material change” to the insurance coverage or the company’s premium payment after cinching the agreement to launch SES 10 on a “flight-proven” rocket.
https://spaceflightnow.com/2016/09/13/ses-stands-by-spacex-a...
Right, they've already stated that with the current rocket there's no economical way to recover the second stage, which aren't cheap, and so far nobody knows how many launches the cores will be good for. Also the infrastructure for supporting the recovery efforts, including the drone ships and their operations, can't be cheap. I expect the SpaceX re-use project will probably be in the red economically for years before it starts paying off it's setup costs.
I don't think refurbishment is going to cost all that much. They fired their "max damage" core eight times without any refurbishment and it did alright. The upcoming Block 5 version of the rocket is supposed to incorporate lots of changes to help with reusability.
Lessons from the Shuttle are commonly brought up, but may not apply very much. Aside from being very different craft (with the Shuttle running on much thinner margins), a huge difference is that SpaceX is able to rapidly and strongly iterate as they learn. The Shuttle that first launched in 1981 was not all that different from the one that last launched in 2011. The design was not entirely set in stone when it started flying, but it was pretty close. That's what happens when your vehicles cost multiple billions of dollars each. SpaceX is continuing to build new rockets and that makes it a lot easier to make changes to react to experiences with older designs.
I doubt the ships are all that expensive in the grand scheme of things. I'm sure the cost is more than what you or I could afford, but I don't think it's a particularly large fraction of the booster's multi-dozen-million-dollar cost.
In any case, it will be great to see how it works out, rather than just talking about how it might work out!
https://www.reddit.com/r/spacex/comments/61walr/why_are_f9_b...
I didn't find many of the comments enlightening, but the general argument seems to be this: expert consensus (by both SpaceX and the insurance company) is that the risk of failure is simply not that much higher than a normal launch. So it doesn't make sense to waste a probably-safe trip to LEO; you might as well get paid. Even in the extreme limit where there was a 50-50 chance of failure, it's clear that there would be some payload that would be worth attaching (e.g., a standard satellite design with a low marginal construction cost, or even a high school satellite project).
So it's not just the engines that have been tested. Also, they had to put some sort of beanie cap on top to simulate flight loads.
SpaceX will no doubt discover new failure modes that nobody has thought of up till now (and thus were not looking for, and thus did not detect).
Other parts that failed had been successfully used in flight so a "dummy launch" would have provided no certainty other than "everything worked this time."
It would be really interesting if that happens. I wonder how people would react. Here's hoping we don't have to find out.
Another flight would just show there are unlikely to be failures on a second launch, but wouldn't say anything about a 3rd launch. So would you do a 3rd test launch to check that? When do you stop testing and just launch something worthwhile?
> SES says there was “no material change” to the insurance coverage or the company’s premium payment after cinching the agreement to launch SES 10 on a “flight-proven” rocket.
https://spaceflightnow.com/2016/09/13/ses-stands-by-spacex-a...
Any part can undergo fatigue damage for a given loading if it is designed to be weak enough.
Similar to the machines used to inspect shipping containers. I would not be surprised if SpaceX had at least considered if not obtained equipment for the ability to X-ray the entire assembled rocket for any internal defects.
Anyone curious can take a look at the equipment from Yxlon (http://www.yxlon.com) for examples of COTS X-ray based inspection that's available. And Yxlon and most others in this industry do custom work, making a robotic full sized rocket inspection setup, quite a realistic concept when the costs of failure are considered.
Source: a good friend of mine is a structural engineer for Aerospace Corporation (a rocket scientist if you will) and I'm an avid r/SpaceX reader.
Perhaps it's just British?
Together this has led them to success, but any space-faring nation or organization with a few billion dollars sitting around could have achieved the same thing, they just didn't have the courage or foresight to do so. Indeed, Blue Origin will probably follow along and reproduce the same achievement in orbital rocketry within the next 5 or 10 years or so. And I expect others to follow as well, once a model that can be easily copied has become established and its advantages proven.
And, well, as long as no cheaper competitor comes along it doesn't matter if launch prices are high since whoever needs to launch something just has to pay them.
There are a few reasons why this is "hard" but few of them are actually underlying engineering issues, most of them are at higher levels. A big problem is that, as I alluded to, the natural and traditional optimizations for expendable rockets lead you away from reusability. Those optimizations tend to push you toward lowering the number of engines on each stage and also concentrating more cost on the upper stages. Incremental rocket development tends to be easiest by improving the upper stage, because that takes lower upfront costs and is sometimes less complex (lower R&D costs, smaller capital investment, able to leverage existing launch and rocket processing infrastructure). But the result of those optimizations tends to be rockets (like the Delta IV, Atlas V, Ariane 5, etc.) that are difficult and costly to reuse (due to an inability to throttle the first stage thrust enough, among other reasons) and where reuse of the first stage, the easiest stage to reuse, is not advantageous because that's not where the costs are concentrated. Indeed, if you look at the Shuttle system, that involves reuse of the upper stage, at extraordinary cost and with extraordinary complexity. It takes intentional choice to design a rocket, like the Falcon 9, which is both highly amenable to first stage reuse and also where that reuse has the most benefit (due to that stage being most of the cost of the launcher). It's even more difficult to achieve that without being vertically integrated the way SpaceX is.
The Falcon 9 is fundamentally based on a 1950s era rocket design, and the main design goals aren't high performance or technical achievement but low costs. Using well-proven basic designs (LOX/Kerosene open cycle engines, two stage rockets) meant that SpaceX could concentrate a significant amount of their development efforts on working on reusability alone. That's actually surprisingly difficult for traditional rocket development orgs to do. For one, using a "simpler" basic design would seem like "going backwards". For another, doing the basic engineering to develop reusability would seem rudimentary. More importantly, any perceived failure would be very, very difficult for those orgs to accept. Experimental rockets are hard to get right, and often anytime things don't work exactly as expected on the first flight can easily be perceived by the public as a "failure". This was true even for SpaceX when they took several attempts to achieve first stage landings even though those stages already achieved their main purpose and normally they'd just get thrown away. NASA and traditional rocket makers are enormously prideful and sensitive about perceptions of failure.
This pushes those orgs to avoid "messy" development projects and to also tend to focus on "beyond the state of the art" developments. This protects those orgs from injuries to their pride because it helps avoid messy failures but also gives them an excuse if things don't work out, because they were working on something innately challenging. This is how we got the Shuttle, for example, which was a typical "beyond the state of the art" development effort. It's also how we got the X-33/VentureStar which relied on several key beyond the state of the art technologies.
It's also why we turned away from the DC-X design, which demonstrated VTVL sub-orbital flight in the 1990s. But something as simple and clunky as a 2-stage launcher using old rocket engine technology and lower stage reusability wasn't sexy enough for NASA et al back then, they had to have something like an RLV SSTO that was sexy enough to justify any risk of program failure.
If you could go back in time to the 1960s/'70s and tell them what to build you could absolutely produce a system similar to SpaceX's. It wouldn't have the same performance margins, it wouldn't have the same capabilities, it probably wouldn't be able to do barge landings, but you could absolutely build a reusable rocket using contemporary technology. And we'll see in the near future how many others copy the design once it's proven. The hard part isn't really the technology, it's the risk taking and the dogged pragmatism.
I think this is really the key thing. Many of the big leaps forward are about challenging deeply rooted or held assumptions. Elon Musk seems to be very good at that.
I don't have the details, but in his presentation of the Tesla solar roof tiles, he mentioned, a couple of times, how inefficient the whole supply chain was for roofing today. His body language implied that it was shockingly inefficient.
So when he made the claim that solar roof tiles will be about the same price as old school roof tiles, maybe that's why. Challenging a bunch of assumptions, and even looking in places that few others thought to look.
PS: I know this is a simplifications, and I'm sure others have looked into this space before, so I'm not sure what caused others not to push forward.
If this launch is successful, how much money SpaceX would have saved by using a 'used rocket' instead of a new one?
Since they took four months to refurbish this stage it may have cost quite a bit to do so for now. But they're learning and Block 5 to debut later this year will have lots of changes based on what they learned.
On an expendable architecture the priority is saving weight on the second stage, because every kilogram saved there saves many kilograms for the first stage. So pound for pound the second stage usually costs more than the first stage. Also the cheapest way to build a first stage is with one or just a few big engines. Both these optimization criteria are reversed for a re-usable design. In the Falcon 9 the first stage is re-used while the second stage isn’t, so that’s the stage you want to spend your money on. Also a few big engines can’t be throttled low enough or gimbaled precisely enough for a landing burn. Even the using just one of the relatively small engines in the Falcon 9 can’t be throttled low enough to hover. Hence the Falcon 9 has many smaller engines to give it a much greater range of thrust settings and better attitude control.
United Launch Alliance's Vulcan (15-30 tons payload to low orbit, depending on if solid rocket boosters are added) will, using two of Blue Origin's BE-4 methane engines.
Blue Origin's reusable (initially partially, eventually fully reusable) New Glenn (40 tons payload to low orbit) will be using the same engines but 7 of them for the first stage and I think one of them for the second stage.
SpaceX's fully reusable ITS (300 tons payload to orbit reusable, 500 tons expendable) will use 42 Raptor engines, full-flow staged combustion engines at ridiculously high chamber pressure. On just the first stage. 9 more Raptor engines on the spaceship portion (which is like a spacecraft/second-stage combination).
Additionally, Masten Space Systems is developing a small-sat (1 ton or maybe 300kg, depending on if they're picked under DARPA's XS-1 program) launcher that would be highly reusable called Xepthyr that will use their Broadsword methane engine.
BTW, Masten Space Systems actually inspired SpaceX to pursue vertical landing recovery years ago (SpaceX had previously tried using parachutes on Falcon 1 and the Falcon 9 first stages, without success) with this video that Elon Musk reportedly emailed to the whole company:
https://www.youtube.com/watch?v=kqm48D5WZ6A
(And Masten also has been pursuing using a launch cradle instead of legs for landing, similar to what SpaceX pursued for ITS. And I think SpaceX got that idea from Masten, too.)
we could extract this before it get's into the atmosphere.
I highly doubt that reusable rockets would be economically viable at our current state of material technology. We need better materials for the engines and the tanks to make them reusable. Even airplanes have to be retired when they still look new just because they've been through multiple pressurization/depressurization cycles and accumulated microfissures. Of course they are not even close to the levels of stress sustained by rockets.
SpaceX has had trouble getting approved for Air Force launches in the past because they "tweak" the design of Falcon 9 too often. They had to commit to NASA to fly seven launches of a "fixed" design (what SpaceX is calling "Block 5") before they will be allowed to fly crewed missions (for NASA).
Better than which target? Yes there is a lot of stress, but what make you say with such certainty that the stress levels are not suitable for 2, 3, 10 or 50 launches? Just reusing a rocket a single time would be a huge cost saver. I don't see how this is not "economically viable".
> When you launch single-use rockets every next one is more advanced and reliable than the previous one
Let's not forget that we have been using russian engines build in 1960 and stored in a hangar for decades in siberia on the Atlas and Antares...
Well, we're about to find out for sure later today, bar a scrubbed launch.
Typical airplane lifespans are measured in tens of thousands of flights. It's not really comparable.