Who in European space will ask the impertinent question: How much would it cost to add a second Vulcain to the Ariane 5/6?

 Copyright 2023 Robert Clark

 

ArianeSpace Needs to Transition to Reusability to Survive.

 European space advocates have been lamenting that there seems to be no near term route to keeping up with SpaceX, getting reusable launchers, and towards achieving manned space flight. However, in point of fact ESA already has the components to form a launcher comparable to the Falcon 9 and at lower price, while keeping pace with SpaceX in reusability, and in manned spaceflight.

 All it would require is someone, anyone in the Europeans space community to ask the impertinent question, "How much would it cost to add a 2nd Vulcain to the Ariane 5/6?"

  For once that question is asked, and ArianeSpace forced to answer honestly, they would have to admit it could be done for only a development cost in the range of only ~$200 million. But then it would become obvious how to proceed.

 First, note that the Ariane 6 that was planned to compete with the SpaceX Falcon 9 has been pushed back to 2024, when its original launch date was in 2020, extending the time where SpaceX is cornering the market. Note also the Ariane 6 will not be reusable. In fact ArianeSpace has admitted they won't be fielding a reusable launcher until the 2030's. 

 ULA was driven to the brink of bankruptcy by denying the importance of reusability. There is little doubt the same will happen to ArianeSpace if they wait a decade to field a reusable vehicle. Independent European space observers have also made this point about the choice of the non-reusable Ariane 6:

Europe’s lack of rocket ‘audacity’ leaves it scrambling in the space race
European policymakers want to stop SpaceX from dominating the launch market.
BY JOSHUA POSANER
JANUARY 15, 2021 12:28 PM CET 6 MINUTES READ
That 2014 decision haunts French Economy Minister Bruno Le Maire, who keeps a warning of that moment on his desk.
“The European space adventure is magnificent, but in 2014 there was a fork in the road, and we didn’t take the right path,” Le Maire told a conference last September. “We should have made the choice of the reusable launcher. We should have had this audacity.”
https://www.politico.eu/article/europe-arianespace-rocket-space-race/

 The Fast Route to Reusability.

 The problem with reusability for the Ariane 5 and 6 is they use solids for a large portion of their takeoff thrust. These large side boosters also make up a large portion of the cost. In fact, the situation has actually gotten worse with the Ariane 6. But the Space Shuttle program demonstrated you don't save on reuse with solid side boosters. By the time you fish the SRB's out of the ocean, tow them to port, transport them from port back to the manufacturing facility, clean them out from all the burnt on combustion products, and then finally refill them with propellant, the cost is no better than just using new ones to begin with. A little thought makes it easy to see why. Solid side boosters are just a filled in metal pipe. The cost of that metal pipe is small compared to all the processing involved in making the SRB. Keeping the same metal pipe but increasing all the needed steps for processing does not reduce the cost of the SRB.

 So to get the low cost reusable rocket you have to dispense with the SRB's. Necessarily that means you have to use additional liquid-fueled core engines. Then is adding an additional core engine a multi-billion dollar, or euro, development? 

 No! I was quite startled to find JAXA was able to add an additional hydrolox engine to the H-II first stage for only an approx. $200 million development cost.

 See the highlighted passage in this article where the cost to add another engine to the H-II was only 27 billion Yen, about $200 million: 

 

 But that means instead of the multi-billion current development cost of the Ariane 6, the same could have been accomplished for just a few hundred million and would also have been reusable! I made this point here:

Multi-Vulcain Ariane 6.

https://exoscientist.blogspot.com/2018/02/multi-vulcain-ariane-6.html

 Thus the importance of asking that impertinent question of ArianeSpace, "How much to add an additional Vulcain to the Ariane 5/6?"

WHY Are the Far More Expensive SRB's Used Rather then the Cheaper Liquid-fueled Engines? 

 Knowledgeable ESA observers have been aware for awhile now that the ESA policies for distributing funds and costs to the differing member states do not result in the most cost effective vehicles. It’s a policy called geographical-return that requires member states costs to be apportioned by some set proportion of the billion dollar development costs. So if some member states have been contributing some large proportion of the costs through solid side boosters, that cost continues to be part of the development for new rockets or upgrades.

 The governments of the member states regard this as a good thing because it helps to keep active, and paid, the space industries and space industry employees in their countries. But another key reason why some member states like the funds for the ESA to go to develop solid rocket side boosters is because those funds help also to develop solid rockets for their defense programs. So rather than those countries having to pay the entire cost of the solid rocket missiles in their defense programs on their own, some portion of that is actually paid for by the ESA in developing solid rocket side boosters for space launchers.

 You can see why there is a great incentive for those member states, which have great influence on the direction and funding choices for the ESA, to continue to want to use solid rocket boosters in all launchers produced by the ESA.

 But the stunning fact is how much more expensive the solids are for the Ariane 6 than just adding another Vulcain engine! The latest cost figures for the Ariane 6 are the €75M for the two SRB version and €115M for the four SRB version. 

 This suggests, as a first order estimate, that we can take the cost of two SRB’s as €40M. But the cost of a single Vulcan is only €10 million! So the two SRB’s on the Ariane 6 base version costs 4 times more than an additional Vulcain! Therefore, again as a first order estimate, we can take the cost of a two Vulcain Ariane 6 with no SRB’s as only €45 million, ~$50 million. This compares quite favorably to current $67 million cost of the Falcon 9.

 The reason why this isn’t done can not be attributed to some supposed multi-billion development cost to add an additional Vulcain to the Ariane core. Actually, it’s the current plan for the Ariane 6 with the newly developed solids, new upper stage, and new Vinci engine whose development cost is in the $4+ billion range. It’s really quite stunning to realize the same could have been accomplished at only a ~$200 development cost simply by adding another Vulcain to the Ariane 5 core, using the same original cryogenic upper stage. Nearly a factor of 20 times cheaper!

 But nobody knows this because nobody asks that one simple question, “How much would it cost to add a second Vulcain to the Ariane 5/6?”

 Now, once you have the all-liquid Ariane 6 that costs even cheaper than the Falcon 9, you can also keep up with SpaceX in reducing price by reusability by also reusing the core stage via powered landing a la the F9 booster. Again, the solids in the current Ariane 6 version would not save on reusing them as the Space Shuttle program abundantly showed. So that huge €40 million cost just for the SRB’s on the Ariane 6(more than the cost of the entire rest of the rocket!) out of the total  €75 million would be fixed no matter how many times you wanted to reuse the core.

 It might be argued that even a fully throttled down single Vulcain would have too much thrust for a hovering landing. Actually, this is the case also with the Falcon 9. It uses what SpaceX calls "hover-slam" for landing. The thrust is precisely timed so the booster just reaches 0 velocity as it touches down. Actually, I'm not a fan of "hover-slam". Much better for the Ariane case would be to use two Vinci engines for the landing only. It is designed to be air-startable and restartable. It weighs without the nozzle extension for vacuum use only 160 kg. So two would weigh only 320kg on the first stage. It's use would allow true hovering landing for the first stage.

Three Vulcains on the Ariane 5/6 Match the Falcon 9 in Payload at a Lower Price.

 The two Vulcain Ariane 5/6 would have lower payload than the Falcon 9. But it would be quite competitive for the lucrative geosynchronous transfer orbit(GTO) used by many communications satellites, at ~6,000 kg to GTO at lower price than the F9. The F9 is at about 8,000 kg to GTO. But most satellites don't need this full capacity anyway.

 However, if we used three Vulcains we could then match the Falcon 9 in payload and still be at lower price. This comes from again using the first order estimate of €40 million for the two SRB's. So the Ariane 6 with no SRB's would be €35 million, as a first order estimate. So adding on two Vulcains would be €55 million, as a first order estimate. But this is still less than the $67 million price for the Falcon 9.

 In an upcoming blog post I'll discuss further the three Vulcain case showing it can match the Falcon 9 in payload. Intriguingly, by using multiple copies of such 3 Vulcain cores, I estimate 4 to 6, you can also get a 'superheavy' lift vehicle capable of 100-tons to LEO, a 'moon rocket'. Using multiple copies  of already existing cores allows you to get the 'superheavy' lift at far less development cost than the $20 billion of the SLS, or the $10 billion of the ill-conceived Superheavy/Starship.

 Manned Launchers.

 Finally, in regards to manned launchers, just use the all-liquid Ariane 6 since you no longer have the safety issues of using SRB’s on manned launchers.

 

  Robert Clark

Possibilities for a single launch architecture of the Artemis missions.

 Copyright 2022 Robert Clark

 In the blog post ESA Needs to Save NASA's Moon Plans I noted that the original plan SpaceX submitted to NASA for a lunar lander required 16 launches due to multiple refueling flights, with the refueling flights to orbit requiring a time of 6 months to accomplish. I argued in the blog that if instead NASA used an Ariane 5/6 as the upper stage of the SLS rocket replacing the current Interim Cryogenic Propulsion Stage(ICPS) then it could be done in just a single launch of the SLS, with no launches of the Starship required at all.

 After their proposal was submitted by SpaceX and accepted by NASA, Elon Musk, stung by the criticism it would take so many launches, suggested it probably could be done in only 4 refuelings since a stripped down Starship for a lunar lander mission would weigh much less.

 SpaceX needs to be open about what the mass would be for such a stripped down Starship since that would directly affect how much NASA, and the U.S. taxpayers, would have to pay to SpaceX for refueling launches. See discussion here, 

The nature of the true dry mass of the Starship. 

 My suggestion to use the Ariane 5/6 as an SLS upper stage was critiqued on political acceptability grounds for a such a large contract to be taken from a U.S. company and given to a European company. 

 Here I'll propose a solution using existing, pretty much, American upper stages for the SLS. It's the ULA Centaur V upper stage coming into service next year. I considered using the Delta IV common core stage but at a 40 meter height it might be too tall for this use.

 

Architecture.

 The Centaur V has a 54 ton propellant load. Following the approx. 10 to 1 gross mass to dry mass ratio of the original Centaur, I'll take the dry mass to be ~5 tons. Then I'll examine  two options: 1.)2 Centaur V's combined into a single stage, and 2.)2 separate Centaur V's.

 The current Block 1 version of the SLS gets about 27 tons to trans-lunar injection(TLI). This is the speed needed to get a spacecraft once in orbit to reach the Moon. The 27 tons is just enough to get the Orion capsule and its service module to TLI. 

 However, the current approach is not to put the Orion in low lunar orbit around the Moon. Instead, it will be placed in a higher altitude orbit of Earth-lunar space called a near-rectilinear halo orbit(NRHO). The reason is the current version of the SLS did not have enough power to put the Orion in low lunar orbit and for it to be able to escape again.

 Our plan then is to first increase the payload capacity of the SLS so that enough additional propellant can be given the Orion service module so the Orion can actually reach and leave low lunar orbit. 

 The Orion with its fully fueled service module has a mass of 26.5 tons. The propellant load of the service module is ~10 tons, with 16.5 total tons dry mass of the Orion and service module. We'll add an additional 10 tons propellant to the service module to bring the total mass to 36.5 tons, including 20 tons of propellant.

 The AJ-10 engine used has a vacuum ISP of 319s. We'll assume a lunar lander of size ~15 tons, comparable in size to the Apollo missions lunar lander. In a following blog post we'll describe it in more detail. So, 16.5 + 15 = 31.5 tons dry mass needs to be put in low lunar orbit.

 For the delta-v calculation, after the SLS places the Orion/Service Module/lunar lander stack in trans-lunar injection(TLI) towards the Moon, we need .9 km/s to put the stack into low lunar orbit. This requires 13 tons of propellant, leaving 7 tons remaining:

319*9.81Ln(1 + 13/(31.5 +7)) = .910 km/s. The lunar lander will then be launched to land on the Moon while the Orion and service module remain in lunar orbit.

 After the lander mission is completed, the lander returns the astronauts to the Orion in lunar orbit, and the lander is then jettisoned. The Orion's service module is then fired to bring the Orion back to Earth. After lander jettison, the dry mass of the Orion and service module will be 16.5 tons. Then the 7 tons of remaining propellant is sufficient to perform the trans-Earth injection(TEI) burn of 900 m/s to escape lunar orbit and place the spacecraft back onto the free return trajectory back to Earth:

319*9.81Ln(1 + 7/16.5) = 1,100 m/s.

Calculations for Earth escape stage to TLI.

 That's the plan if we can upgrade the SLS to carry sufficient payload to give the Orion service module that extra 10 tons of propellant. The total mass that needs to be put into TLI is 36.5 + 15 = 51.5 tons. Here's a calculation for the first approach of two Centaur V's combined into a single stage. I'll use the payload performance calculator of Dr. John Schilling, on Silverbirdastronautics.com. The specifications for the 5-segment SRB's are taken by scaling up the numbers from the 4-segment SRB's used on the Space Shuttle system.

 I'll give this stage 4 RL10 engines instead of the Centaur V's 2 because of the larger size, in effect just transferring two of the RL10's from the second Centaur's to the first. The input page looks like this:

                                                               

 The payload estimator then gives the payload to LEO of ~127 tons:

 

  And the for the payload to TLI we'll use a C3 of -1.00km2/s2.

 This gives a payload to TLI of about ~52 tons:

  It is notable though the Schilling payload estimator has rather large error bars. These numbers need to be confirmed by more accurate payload estimators.

 The payload can be increased by using instead of the RL10's, a single Blue Origin BE-3U, the vacuum optimized version of the BE-3 engine used on the New Shepard. This engine has a vacuum optimized thrust of 710 kilonewtons. Placing this in for the upper stage thrust gives a payload to LEO of 136 tons, and to TLI of 54.7 tons. Again this needs to be confirmed by more accurate payload calculators.

 The intent here is to find a low cost approach to an upper stage that would allow a single launch architecture for the Artemis lunar lander missions. A combination of adding additional engines and also combining two tanks would ratchet up the costs.

  The second approach would use two separate Centaur V's. However, because of the large mass that needs to be carried by the either Centaur as payload we'll give both Centaurs 4 RL10's. The input screen looks like this on the Schilling calculator:

  And the LEO payload is ~129 tons:

 And the TLI payload is ~54.7 tons:

  Again, these payload estimates would have to be confirmed by more accurate payload estimators.

 This second approach would not incur the extra costs of combining two Centaur V's into a single stage, but it would require 4 additional RL10's. As before though we could get increased payload by replacing the RL10's by the BE-3U, and likely lower cost.

 We still need to come up with that lunar lander of comparable gross mass as the Apollo lander, ~15 tons. In a following blog post I'll show our European partners can come up with such a lander at low cost and at a relatively short time frame.

  Robert Clark

 

ESA Needs to Save NASA's Moon Plans.

Copyright 2022 Robert Clark

 The SLS was planned to have a large upper stage called the Exploration Upper Stage(EUS). This would take the SLS Block 1 to the SLS Block 1B, needed for a single flight lunar architecture. However, the multi-billion dollar cost for development of a large upper stage from scratch means it’s unlikely to be funded.

 NASA is proposing a solution using the Starship making separate flights. But this plan takes 6 flights total or likely more of the Superheavy/Starship for the Starship to fly to the Moon to act as a lander. One look at this plan makes it apparent it’s unworkable:

 Actually, it’s likely to be more complex than portrayed in the figure, needing 8 to 16 refueling flights. This is what SpaceX submitted to NASA in proposing the plan, requiring 6 months to complete the Starship refueling:

SpaceX CEO Elon Musk details orbital refueling plans for Starship Moon lander. By Eric Ralph Posted on August 12, 2021
First, SpaceX will launch a custom variant of Starship that was redacted in the GAO decision document but confirmed by NASA to be a propellant storage (or depot) ship last year. Second, after the depot Starship is in a stable orbit, SpaceX’s NASA HLS proposal reportedly states that the company would begin a series of 14 tanker launches spread over almost six months – each of which would dock with the depot and gradually fill its tanks.
…
In response to GAO revealing that SpaceX proposed as many as 16 launches – including 14 refuelings – spaced ~12 days apart for every Starship Moon lander mission, Musk says that a need for “16 flights is extremely unlikely.” Instead, assuming each Starship tanker is able to deliver a full 150 tons of payload (propellant) into orbit after a few years of design maturation, Musk believes that it’s unlikely to take more than eight tanker launches to refuel the depot ship – or a total of ten launches including the depot and lander.
https://www.teslarati.com/spacex-elon-musk-starship-orbital-refueling-details/

 Everyone, remember the Apollo missions where we could get to the Moon in a single flight? In fact, this would be doable with the SLS given a large upper stage. Then the suggestion is for the ESA to provide a Ariane 5 or 6 as the upper stage for the SLS. It would save on costs to NASA by ESA paying for the modifications needed for the Ariane core.  

 As it is now ESA is involved in a small role in the Artemis lunar program by providing the service module to the Orion capsule. But it would now be playing a major  role by providing the key upper stage for the SLS.  

 The argument might be made that the height of the Ariane 5/6 is beyond the limitations set forth by NASA for the EUS. However, if you look at the ca. 30 m height of Ariane 5 core compared to the 14 m height of the interim cryogenic upper stage now on the SLS, this would put the total vehicle height only a couple of meters beyond the height that had already been planned for the SLS Block 1B anyway:

 

 See discussion here:  

Budget Moon Flights: Ariane 5 as SLS upper stage, page 2.   

https://exoscientist.blogspot.com/2013/09/budget-moon-flights-ariane-5-as-sls.html

 Coming up: ESA also could provide a low cost lander for the Artemis program.

Payload Estimates

 Here’s the Silverbird Astronautics estimates for the payload capacity using the Ariane 5 as the upper stage. The vacuum Isp used for the Ariane 5 is taken as 462 s since it it known by the example of the RL10 engine that a hydrogen engine can have its vacuum Isp raised to this level by a nozzle extension. Specifications shown below, with the 5-segment SRB data estimated by 25% scale up of the Space Shuttle SRB’s data.

 And the results for the LEO payload:

 The estimated payload for TLI is found by putting -1.0 in for the hyperbolic C3 value for “Escape trajectory” field. This is a number that indicates it’s just below escape velocity for a free return trajectory around the Moon in case the mission has to be aborted.

 So both the LEO payload of 150 tons and the TLI payload of 60 tons are above even the Block 2 payload capacity that would use advanced carbon fiber casing for the SRB’s.

 Input data taken from: 

 

 

   Robert Clark

A Reusable SLS? UPDATED: July 31, 2022.

 Copyright 2022 Robert Clark

 The SLS is now projected to cost $4 .1 billion per flight. Because of that severe cost it is projected to only fly once per year. This can not form the basis of a sustainable Moon colonization plan. But suppose we could make the SLS reusable? It’s already known the side boosters can be made reusable as with the shuttle program. The engines on the SLS core stage were derived from the shuttle engines which were intended to be reused up to 100 times. However, since the SLS was intended to be expendable the shuttle-derived engines on the core were designed cheaper to be expendable. However, any rocket engine even an expendable in reality is reusable at least 10 times or more. This is because they have to be certified for several firings for testing purposes. This is described by the well-regarded space expert Henry Spencer:

____________________________________________________________________________

From: Henry Spencer <henry@zoo.toronto.edu>

Newsgroups: sci.space.tech

Subject: RLV engines (was Re: X-33 Concepts: Lockheed, Mac Dac, Rockwell)

Date: Wed, 19 Jun 1996 13:03:12 GMT

In article <4q6am4$46s@ns.hcsc.com> andyh@hcxio.hdw.hcsc.com (Andy Haber) writes:

>I think this is an area where critics can speak the loudest.  Today's 

>existing engines all leave something be be desired as true, good SSTO engines.

>This is mostly due to history.  Most engines (other than SSME's) were 

>designed for ELV's, not SSTO's.

Actually, this does not have a lot of bearing on their suitability for

RLVs.  Most ELV engines are, despite their application, reusable, because

they have to be developed and tested.  The F-1 was specified for 20 starts

and 2250s of life, the J-2 for 30 and 3750s.  Six F-1s ran over 5000s each

as part of the service-life tests.  DC-X's RL10s looked "pristine" after

20 starts; the RL10 is nominally rated for 10 starts and 4000s of firing.

>...In terms of using SSME's, sure those can used,

>although doing something to reduce the required level on maintenance on

>the existing engines is quite desirable...

Unfortunately, it probably can't go far enough.  Rocketdyne's own estimate

was that, with a *lot* of work, you could probably get SSME maintenance

costs down to $750k/engine/flight, which is unsatisfactory if you're aiming

for really large cost reductions.

-- 

If we feared danger, mankind would never           |       Henry Spencer

go to space.                  --Ellison S. Onizuka |   henry@zoo.toronto.edu

_____________________________________________________________________________

https://yarchive.net/space/rocket/engine_reusability.html

 Then even reusing the vehicle 10 times could result in a factor of 10 reduction of launch cost, if the maintenance cost could be kept relatively low. That quote about $750, 000 maintenance cost after a lot of work may seem low but from memory I recall it being in the range of $1 million to $2 million per engine after several years into the shuttle program.

LANDING.

 But how to land the SLS core? Starting the SSME’s is a complex process. Modifying them to be air-startable would not be trivial. Instead, I suggest using the method proposed for making the Centaur a lunar lander, multiple pressure-fed side thrusters for a horizontal landing. 

Robust Lunar Exploration Using an Efficient Lunar Lander Derived from Existing Upper Stages. 

 Note then that for a stage reentering to Earth broad-side almost all the reentry velocity is burned off aerodynamically just by air drag so that the stage reaches terminal velocity at approx. 100 m/s. For a stage nearly empty of fuel, this low amount of velocity could be cancelled relatively easily by pressure-fed thrusters with the thrusters running on just the residual of propellant left in the tanks.

 About the landing, there would be additional development cost for the horizontal landing thrusters.  But pressure-fed thrusters are a relatively simple technology. Compare for example the time SpaceX spent developing the Draco thrusters on the Dragon to the time developing the Merlin engine. And from discussion of the thrusters on the Starship they seem more like an afterthought compared to the cost, time, and complexity put into the Raptor engines.

 How about giving the RS-25’s on the SLS core restart capability? Again I’ll refer to the redoubtable Henry Spencer:

___________________________________________________________________________

Newsgroups: sci.space.shuttle

From: henry@spsystems.net (Henry Spencer)

Subject: Re: One part Oxygen, two parts Hydrogen and BOOM!

Date: Sat, 14 Oct 2000 03:37:23 GMT

In article <slrn8ue2f1.bv2.zaitcev@js006.noname.ru>,

Pete Zaitcev <zaitcev@yahoo.com> wrote:

>> The SSMEs use "torch" igniters, little oxygen/hydrogen burners firing into

>> the preburners and chambers.  The igniters themselves are ignited by,

>> essentially, high-tech spark plugs.

>

>I see... obviously there cannot be a spark in a vacuum.

Not entirely true, but irrelevant -- when the igniter fires up, there's an

oxygen/hydrogen gas mixture there for the spark to travel through.

>Is the plug the reason engines cannot be restarted in orbit or

>there is more to the story?

There's nothing *fundamental* in the SSME which makes an in-space restart

impossible -- no one-shot parts or anything like that -- but it's a

complicated engine which has to be set up exactly right for a successful

start, and ground equipment (and gravity!) helps out with that.  It would

not be difficult to develop a variant which could start itself in space,

but there has been no reason to do that.

--

Microsoft shouldn't be broken up.       |  Henry Spencer   henry@spsystems.net

It should be shut down.  -- Phil Agre   |      (aka henry@zoo.toronto.edu)

________________________________________________________________________

https://yarchive.net/space/shuttle/ssme_ignition.html

 So likely it could be done by Aerojet, but I have no confidence they could do it in an affordable manner. Or more precisely, I have no confidence they would do it at an affordable price charged to NASA. For instance the RS-25 engine used on the SLS is derived from the SSME. It was expected to be cheaper than the SSME as it it used a lower parts counts and was not required to have the 100 times reusability of the SSME. But instead Aerojet charged more for this engine than the SSME even when accounting for inflation:

NASA will pay a staggering $146 million for each SLS rocket engine. The rocket needs four engines, and it is expendable. ERIC BERGER - 5/1/2020, 6:55 PM https://arstechnica.com/science/2020/05/nasa-will-pay-a-staggering-146-million-for-each-sls-rocket-engine/

 About the payload lost on reusability, a stage that goes to LEO can remain in orbit for a few orbits to come back over the landing site so minimal propellant is burned to return to launch site. 

 If we do use a large upper stage, then the SLS would not go to orbit and as SpaceX showed you would need minimal fuel burned if landed down range, and so minimal payload lost, rather than returning to launch site. However, there is then the cost of the upper stage. If it were the Ariane 5/6, the cost of the Ariane 6 being as low as $77 million, it should be even lower than that without the Ariane side boosters or upper stage. 

ARIANE 6 VS. SPACEX: HOW THE ROCKETS STACK UP The European Space Agency is planning to use the Ariane 6 for a variety of missions. ESA MIKE BROWN 1.24.2022 2:00 PM In January 2021, Politico reported that the Ariane 6 could launch for as little as $77 million. That’s a steep discount from the $177 million price tag for the Ariane 5. https://www.inverse.com/innovation/ariane-6-vs-spacex

  About the landing thrusters, I wouldn’t give a contract for it to any of the usual aerospace companies under NASA’s cost-plus contracts. Instead I would prefer doing it “in house”, so to speak. I was quite impressed by a team at Johnson Space Center led by chief NASA engineer Stephen Altemus developing an unmanned lunar lander for only $14 million development cost:

The Morpheus lunar lander as a manned lander for the Moon. http://exoscientist.blogspot.com/2014/06/the-morpheus-lunar-lander-as-manned.html

  The approach the NASA team used on saving costs was likely analogous to that used by commercial space in cutting costs.  No doubt also the pressure-fed engines being used rather than complex turbo-pump engines contributed to the low development cost.

ECONOMICS

 This report estimates the launch market as approx. $48 Billion per year by 2030:

Global Space Launch Services Market is projected to reach at a market value of US$ 47.6 Billion by 2030: Visiongain Research Inc October 05, 2021 09:33 ET | Source: Visiongain Ltd https://www.globenewswire.com/news-release/2021/10/05/2308874/0/en/Global-Space-Launch-Services-Market-is-projected-to-reach-at-a-market-value-of-US-47-6-Billion-by-2030-Visiongain-Research-Inc.html

 At a going rate of approx. $10,000 per kilo to LEO that would amount to 4,800 tons to orbit.  For a SLS lofting nearly 100 tons to orbit even in SLS 1 form, that’s quite a lot of launches it could take part in per year IF it could do it at a competitive price. If  it could do 10 reuses, that could bring the price down to $400 million per flight, or $4,000 per kilo, about the price of the reusable F9 when new, or a bit more than $3,000 per kilo of the used F9. But IF it could do 20 reuses, within the capabilities of some expendable engines, it would be $2,000 per kilo which would beat even the F9 used reusable price.

 In point of fact though the first four SLS vehicles would all use original Space Shuttle engines. Then likely each has dozens of uses left in their operational lifetimes:

Apr 6, 2021
RS-25 Rocket Engines Return to Launch NASA’s Artemis Moon Missions.
https://www.nasa.gov/exploration/systems/sls/rs-25-rocket-engines-return-to-launch-artemis-moon-missions.html

 

   Robert Clark