I've also heard that fuel is not the main cost contributor to a rocket launch. In fact, it is a really insignificant portion of the cost. It is the vessel that contains giant amounts of fuel that is costly. Hence reusability from SpaceX makes sense and so does launching the rocket from high altitude to avoid building the first stage all together.
There's a reason we don't throw away a 747 after one flight.
Fuel is only a couple percent of the cost of a rocket launch. Rockets are expensive, and on the Falcon 9 the first stage is 80% of the cost of the rocket.
In the early days of SpaceX I saw claims that expendables were more economical because you could build them cheaper, but then SpaceX went and build reusable rockets that are also cheap; their rockets cost less than competitors even without reuse.
They're getting government business because they charge the government less than their competitors charge. The subsidy argument doesn't make sense unless it's only the commercial launches that are cheap.
There are a lot of vested interests in this industry that are strongly incentivized to say reusable rockets are no big deal. I think they'll continue to say that until the BFR flies and SpaceX drops their rates to levels far below what disposables could ever achieve.
Yeah, and with much higher required dv and more required stages this would be a huge problem. But we only need two stages to orbit when launching from Earth, so it's really not that big of a deal, and it turns out that optimizing for reusability ends up being a lot cheaper than optimizing for minimum fuel use. For example, it only costs $200k for a fuel load of Falcon 9 fuel. If you got rid of reusability you'd need less fuel and could save tens of thousands of dollars ... but at the cost of needing to build a new $54M spacecraft with each launch. Clearly that trade-off isn't worth it.
When you throw away the entire rocket every flight you throw away tens of millions of dollars in hardware. If you can recover and re-fly stages you can get away with a lot of compromises elsewhere. Especially since the first stage, for SpaceX anyway, represents 3/4 of the hardware cost of the launch vehicle.
Even reusing the first stage once means cutting the overall hardware cost of a flight by nearly 1/3. For SpaceX that translates to about $20 million per flight in savings. And that's from one and only one reuse flight of the first stage. In comparison the fuel is nothing. In comparison even a massive payload hit is acceptable. As long as the payload reduction is less than the cost reduction, everything is golden, and the rest is profit margin. For 2 reuses (3 total flights) the hardware cost per launch drops to 1/2 of current costs. For 5 or more uses per first stage the cost drops below 40%.
SpaceX's launches are already cheaper than the competition, dropping below 1/2 of their current cost floor makes it impossible for the competition to keep up and would enable them to own the launch market.
That's a good point, but then it is an odd thing for them to care about the fuel savings vs. their claim of not needing the first stage and allowing for single stage to orbit with a plane type launcher, which is a far bigger deal in terms of cost savings.
E.g. consider that Musk a few years ago estimated the fuel and oxidizer costs for a Falcon 9 v1 at ca $200k per launch, with a list price for the launches at $54m to $59.5m. Cutting the cost of the rockets themselves on the other hand, whether by reuse or making them smaller/cheaper will matter much more.
I guess whether eliminating the first stage entirely vs. reuse will matter much will depend on how many times recovered stages can be reused and how much it will cost to prepare them for reuse, as the potential fuel savings are basically rounding errors.
Fuel is super cheap, only a few hundred thousand for each Falcon launch and a full Starship/Superheavy stack launch is estimated at only a half million. But it's going to be many decades before launch costs come down close to fuel costs.
Right now it's been estimated that SpaceX's launch cost of new Falcon 9 is around $45M, and their cost for launching a re-used Falcon is around $25M, a far cry from the $200k cost of Kerosene & LOX.
Re-use is great, but they are still in the early stages. Their goal for Falcon was ten launches per first stage, but they just lost their first attempt at a 5th first stage launch (albeit after it successfully put it's cargo in orbit), after suffering several major anomalies with it's engines.
Falcon first stage re-use takes over a month because there is still some re-furbishment and re-testing, and that costs money too. The second stage and fairings also cost around $15M together, and they are destroyed every launch (though they keep attempting fairing recoveries, they haven't been very successful at).
SpaceX won't be able to significantly lower launch costs until Starship is successfully completed. Starship gives you have a system designed for up to 100 re-uses, and a re-usable second stage without a fairing. At that point they might be able to lower launch costs to the $10M range, but it's going to be hard to get much lower. There are still a ton of people involved in every launch, and those people need to get paid.
Well, if you go to the extreme case (the entire rocket is reusable with _no_ refurbishment) the cost of rocket fuel is $200,000 while the approximate cost of the hardware is in the range of $60M. So, in the extreme case it would be _massively_ cheaper. On the order of 99% savings.
At the moment, SpaceX is only reusing a portion of the rocket (the first stage, not the second stage or the fairings). And that re-used portion requires some refurbishment. SpaceX estimates it's 30% cheaper per launch right now.
Over the next few years SpaceX will probably bring that cost down (though they won't necessarily pass that cost on to the consumer — they could very well just enjoy the extra margins). I'm guessing they can realistically get to 50-70% cost savings per launch over the next few years.
though they are working on recovering the fairing, and attempting something related to that today.
SpaceX is very, very far ahead of the field, although it's not quite obvious at the moment, though it will be soon.
You see, there are two ways to build reusable rockets. One way is to build a purely reusable vehicle from the ground up, but this is extraordinarily expensive because of all the testing involved before it can be used commercial. The other is to build an expendable/reusable hybrid. A rocket that can be used in an expendable configuration but has all of the needed elements to allow for reusability down the road. This is vastly easier because it means you can bootstrap development on the back of commercial launch business, and do testing that is largely subsidized by paying customers. And this is what SpaceX has been doing.
However, there's a problem. You have to head into reusability from the get go, you can't just modify any old rocket for reusability, you need to design from a place of suitability for reuse from square one. And while that's not an enormous difficulty it is very much non-trivial, and imposes a substantial overhead on R&D and manufacturing costs. This is because most of the optimizations for building a purely expendable rocket drive the design away from the optimizations you'd want for a reusable rocket. In an expendable design it's common for there to be a mix of propellants and a diversity of engine designs between the first and upper stages, it's also common for the upper stage to be more expensive than the first stage, because that stage is more critical for payload performance and launch precision. Also, it's common to minimize the number of engines on the first stage. Even the Saturn V had only 5 first stage engines. And generally there'd be no reason to add first stage engine restart capability on an expendable vehicle.
All of those things results in an expendable vehicle that is completely unsuited to reuse. It leads to a first stage that is very difficult to modify for reuse, and an overall rocket design that does not reward the easiest type of reuse (of the first stage) because most of the cost is in the upper stage anyway. SpaceX went to a great deal of effort to ensure that they built a rocket that could serve the expendable launch market immediately (and pull in hundreds of millions of dollars in revenue) while also being suitable for reuse with comparably moderate modifications. The first stage has 9 engines, so throttling down to a thrust level suitable for precision landings of a mostly empty stage is possible by using only one engine. The first stage use restartable engines (using onboard TEA/TEB igniters). And the first stage is about 3/4 of the hardware cost of the vehicle, since the 2nd stage uses only one engine and is also LOX/Kerosene fueled.
That foresight has allowed SpaceX to be in the launch business for several years, proving the capability of the company and gaining much needed experience in building and flying rockets while also poising the company to bring to market a reusable launcher. In comparison, every other established launch provider in the world could only do reusability by designing a new launcher from scratch.
You raise a few good points. Falcon 9 launches could be 30% cheaper if fully reusable but that only reduces a launch cost down to $25M.
I am skeptical of the claim that they will just be able to refuel and go. Every reusable space vehicle has had that goal and always cost more than expected to refurbish for the next launch. Yes, we may get there eventually but not in the next few decades, the risks of a catastrophic component failure are too high to do no refurbishment.
The starship and super heavy are certainly cheaper to construct but that has more to do with fabrication techniques than the material cost.
Methane is less dense than kerosene so needs larger tanks but it does have more energy per unit mass. The overheads of using cryogenic fuel are reduced on a larger rocket but the performance gain is probably only 10% or so.
I am not aware of any significant insulation between tanks on the Falcon 9 and it certainly isn't a major cost factor.
That's a very worthwhile point but there are a few major reasons why it's a more problematic strategy.
First, reliability. When you engineer a vehicle as large and as complex as an orbital launcher which only operates once in its entire lifetime you typically need to over-engineer a lot of key parts of the thing in order to ensure a high level of overall reliability. This runs counter to the sorts of optimizations necessary to bring production costs down by orders of magnitude. More so, when a full up test inevitably results in the destruction of the vehicle (because it is expendable) and tests cost as much as a launch (tens of millions of dollars) it makes it very, very difficult to evolve the design of the vehicle extensively.
That leads to a catch-22, you have to run a lot of launches to make the vehicle design significantly cheaper to manufacture. Buuuut, now you've vastly increased the development cost of the vehicle so you've erased all of the cost gains you've made.
But, if you design for reusability then you can actually increase reliability because the cost of the vehicle is amortized over multiple flights, so you can have a more expensive vehicle.
Also, while a lot of aerospace components (like fuel tanks, electronics, etc.) can be mass produced with the right design, this is a lot more difficult with rocket engines which have a very high number of precision machined parts made out of special alloys. This makes the engines the long-pole in the costs of a rocket, and it's very difficult to reduce those costs. Right now SpaceX is already the world's largest manufacturer of high-power rocket engines, so if there was a way to cut costs on them they would already be on top of them.
Now, back to reusability. Another thing that you get from reusability is that testing can be much cheaper, since you can make incremental changes to a vehicle design and then re-test it.
With reusability you have the best of all 3 worlds. You have reliability, you have low per-flight costs, and you have an enhanced ability to prove out potential vehicle redesigns economically.
Now, if the size of the launch market were much larger and reusability were more difficult then the equation could change, because it might be easier to recoup expensive cost-saving efforts over a shorter period of time.
NASA's big project for launch is a disposable rocket using Space Shuttle technology. It will cost at least a billion dollars per launch.
SpaceX's project is a fully reusable rocket, with rapid turnaround because it uses methane fuel in the world's first clean-burning full-flow engine. They expect to be able to launch three times per day. On top of that the rocket is built of cheap stainless steel instead of carbon fiber.
With that amount of reuse, each launch basically pays for fuel and ground support, each of which costs about a million dollars per launch. Given their payload of at least 100 tonnes, that's $20/kg. They've already done a single-engine hop test, and hope to reach orbit within six months.
"Reusing the first stage three times halves the overall cost of launch. Reusing 9 times cuts the cost to 1/3. However, there is little benefit to first stage reuse beyond that… Reusing both stages just once halves the total cost of launch. In addition, reusing both stages four times reduces the cost to 1/4, and reusing eight times reduces to 1/8."
As you touched upon a lot of things in space are expensive because launch vehicles aren't reusable, once they are it makes sense to create cheaper and expandable payloads rather than multi-billion dollar payloads strapped to rockets that can't be allowed to fail.
What, exactly, do you think is a reusable rocket? You can't just land it, refuel, attach it to a second stage, and fire it up again. Everything has to be retested and tons of stuff replaced because the forces during launch, let alone reentry, are extreme. Until they have lots of data on failure modes in the reusable stage, they are probably ultraconservative with what parts they replace so I wouldn't be surprised if the cost of reuse is ~40-50% of the cost of a new one (on mobile so I'm too lazy to look up spaceX's official numbers).
I'm not so sure the economics works so well for reusables. Flying a reuseable LV requires (as far as anybody's managed, we'll see with SpaceX) far more work than just fuel & go. Typically you'd need a lot of maintenance work and repairs between each flight, not to mention the added complexity to the vehicle required for recovery. That's largely why the Shuttle wound up pushing a billion per launch, instead of the $10 million initially targeted, or the $110 million marginal cost of a launch.
Their goal is to allow the rocket to ignite at 200k ft. Thats only a bit lower than the altitude SpaceX ignites its second stage, which is not reusable
Rocket reuse is not a panacea. There is a very real expendable cost advantage in choosing SpaceX but rocket reuse will not reduce rocket costs significantly. There might be another -50% costs to be had once they iron out all the kinks but what Elon musk promises will not happen because he always overhypes everything.
The point mlindner is making is that the cost of launch vehicles is in the vehicle, not the propellant. So full rapid reuse, so you can refly the entire vehicle a lot, drives the cost per launch way down.
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