Europe joins the re-usability bandwagon?

[Lars-J]

In other words, it is a science fiction rocket...
Why wouldn't they go with Skylon instead? That is much closer to being doable and would still be a novel and potentially competitive approach. Also much closer to reality.

That should tell you all you need to know about how feasible/practical Skylon really is. (hint: It is not)

[Hobbes-22]

It's worth noting this is an Arianespace study, not ESA.

[Alpha_Centauri]

While the UK is still a member of ESA, a more relevant point is that it is not currently involved in funding launcher development, neither does it have a stake in Arianespace. So it's hardly surprising that these organisations look for 'European' (a.k.a. French, with a dash of Italian and German) solutions. E.g. the funds for the 'ESA' studies on SABRE/Skylon came from the UK contribution, it didn't imply buy-in from other countries.

[zubenelgenubi]

Moderator: Thread has veered off-topic, in more than one direction.  Posts deleted.

[saliva_sweet]

So, if Europe really wants to compete with Starlink....let a private company do it.

But therein lies the rub. Why isn't SpaceX european? You'd think we were in a good position back when Spacex started. Or Facebook or google, Amazon, Microsoft, Apple (I know this one is technically european lol) ... companies that changed the world. US will control the flow of information. Barriers to private enterprize - regulatory, social, mental, are too high here. There is nothing we can do about this unless something fundamental changes in EU. European government led megaconstellation is a Buran project.

[rakaydos]

So, if Europe really wants to compete with Starlink....let a private company do it.

But therein lies the rub. Why isn't SpaceX european? You'd think we were in a good position back when Spacex started. Or Facebook or google, Amazon, Microsoft, Apple (I know this one is technically european lol) ... companies that changed the world. US will control the flow of information. Barriers to private enterprize - regulatory, social, mental, are too high here. There is nothing we can do about this unless something fundamental changes in EU. European government led megaconstellation is a Buran project.

As someone who lives in the US, you could also say that the barriers to public enterprise is too high here, as seen by the fight over something as basic as infrastructure.

[su27k]

So, if Europe really wants to compete with Starlink....let a private company do it.

But therein lies the rub. Why isn't SpaceX european? You'd think we were in a good position back when Spacex started. Or Facebook or google, Amazon, Microsoft, Apple (I know this one is technically european lol) ... companies that changed the world. US will control the flow of information. Barriers to private enterprize - regulatory, social, mental, are too high here. There is nothing we can do about this unless something fundamental changes in EU. European government led megaconstellation is a Buran project.

As someone who lives in the US, you could also say that the barriers to public enterprise is too high here, as seen by the fight over something as basic as infrastructure.

SLS has entered the chat...

Seriously, the US has its own share of government funded boondoggles, the difference seems to be the US has been able to encourage and support private innovations at the same time (so far at least).

[edzieba]

Having said that I fully agree with you that "Europe" does not need its own internet satellite constellation.

gimme a break... the point of Starlink, Kuiper and others is global broadband Internet access - I mean, for the unfortunate 2 or 3 billion people living in poor countries not rich enough to get the same high broadband Internet via ground networks.

Now if we agree on this point, indeed, Europe has an ultra-dense and up-to-date ground network perfectly able to bring broadband internet into european smartphones anywhere on the continent... no ? for example in france, the 5G certainly goes through updated ground networks - people are even protesting or even going conspiracy nut about it.

Or maybe it is just a matter of not staying behind a potential revolution that are spaceborne megaconstellations (think Concorde or... Ariane or Eutelsat or Galileo) ?
Don't forget Galileo is not only "a GPS for Europe" but also a soft power tool "You don't like America and GPS ? go Galileo !" China is doing the same, they are creating their own GPS (Beidu ? can't remember) just for the technology, the jobs, and soft power.
Does this apply to broadband internet mega-constellations ? Does europe needs a "broadband Internet Galileo or Eutelsat" ?
There is certainly an old tradition of creating an "European matching capability" as far as satellites systems and markets go: Inmarsat (at sea) , Eutelsat (TV), Meteosat (weather), SPOT (remote sensing), Galileo (GPS)... 

Two things:

- You left out my disclaimer: "Or at least, not one initiated and paid for by European governments."
- All the "European matching capability" stuff you mentioned is government-initiated. Starlink isn't.

European governements initiating Galileo, to match the US goverment-initiated GPS, makes perfect sense.
European governments initiating Meteosat, to match the US government-initiated NOAA sats, makes perfect sense.
European governments initiating SPOT, to match the US government-initiated LandSat, makes perfect sense.

However, European governments initiating a European satellite internet constellation, to match the SpaceX PRIVATELY initiated Starlink constellation, makes no sense at all.

What the EU and ESA are proposing to do, is to compete with a PRIVATE COMPANY instead of other nations. That is silly. Not to mention a downright stupid way to spend European taxpayers' money.
So, if Europe really wants to compete with Starlink....let a private company do it.

The US is very concerned about private and public entities competing. Elsewhere, that isn't often a concern. If something can be done better by a public entity than a private one (in general, public infrastructure is a good example) then just do that. Practicality trumps ideology.

An 'EU megaconstellation' would be more of a shared backbone that individual providers could offer service via, similar to how fixed-line broadband infrastructure is handled outside the US via Local Loop Unbundling - one entity handles building and operating the actual cabling from end users to demark points (and usually to datacentres and to trunk connections too), and other entities are in the business of selling that service to consumers. Those service providers compete with each other, but over a common infrastructure (some private providers also build out their own infrastructure, but usually this will end up being an entity operating a DOCSIS network, and several entities operating over a shared DSL and/or fibre network). Or how some nations organise GSM service: multiple network operators sell service to the public, but in terms of the actual PHY layer everyone gets to talk to everyone else's sites because they use the same standard and interlink (e.g. if I buy service for Provider A, and Provider B is the operator of the nearest cell site, then my device talks to the cell site operated by Provider B and traffic then gets routed back to Provider A for onward carry. Vice versa the other way around) to allow overage without redundant cells and reduced rollout costs. This keeps barrier to entry low and increases consumer choice of provider (and thus competition between providers) while keeping total infrastructure cost across all providers lower than duplicated redundant.

A bit more detail on Ariane Ultimate, via Parabolic Arc:

    reflections for the post-2040 are well underway with the Ariane Ultimate project . At this stage, it is still only a concept, that is to say a pool of new technologies which are in an embryonic state but which we want to make mature by this time, in order to develop a launcher that must be carbon neutral, fully reusable and at almost zero marginal launch cost. It is also a question of projecting on the new uses of space in the coming decades as we can imagine them on this horizon: for example the need for high speeds to reach the low orbits which could serve as hubs of exchange towards the Moon or towards Mars.


        Ariane Ultimate will represent a departure from previous generations of launchers. It is about finding the ideas and technologies to meet these objectives and these future uses.

    Cheaper, simpler, more efficient, easier to recover: this type of single-stage launcher would be the holy grail! However, it is not currently possible, especially because the materials we use are too heavy. We must therefore find a way to lighten the structures,” explains Nathalie Girard.

    Initial research is therefore oriented towards the development of new, lighter and extremely resistant materials such as carbon nanotubes, graphene, or architectural materials made possible by 3D manufacturing. Another avenue is to work on propulsion, with new high energy density propellants which would make it possible to drastically reduce the mass and the cost on the launcher. Ariane Ultimate finally incorporates reflections on avionics and software that will benefit from emerging technological advances, such as “many cores” processors or the quantum computer.

Sounds less like a launcher design and more like a tech dev program: here's 5 impossible things to do before lunch, maybe one of them will turn out to be possible and spin out into useful products.

[mupp]

The EU itself is starting to make moves...




Bit more info at the link.
https://ec.europa.eu/info/funding-tenders/opportunities/portal/screen/opportunities/topic-details/horizon-cl4-2021-space-01-21

[su27k]

https://twitter.com/pbdes/status/1447918860032790532

French President @EmmanuelMacron: France 2030 goal is a reusable min-launcher by 2026 and a stronger French participation in smallsat constellations. @ESA @defis_eu @CNES.

[Rik ISS-fan]

I think this topic is the right place to discuss a question I've got.
What is the best approach to develop reusable launchers in Europe?

I think Callisto is a right start. But I think Themis as next step is a leap to far. It's to large for a demonstrator, thus to expansive. I also think there are multiple roads to Rome / methods to recover a stage). Thus different recovery methods need to be tested. Parachute recovery, landing legs, landing catch mechanism.
The engine used on the testbed/demonstrator needs to be proven/qualified/certified before the reusable demonstrator can be developed. Otherwise engine reliability risks, harm the reusable stage demonstrator.
Thus developing the engines is the first priority. I think a liquid engine is required.

I think the first stage of Sirius Space Services; Sirius 1 could be a nice step after Callisto. It uses a simple 38kN pressure-feed LOx LNG engine.
Other options are the first stages of micro launchers. I really like the Skyrora XL, but UK ain't EU any longer.
PLD space could us Miura 1 or make a demonstrator with a cluster of Teprel-B (pressure feed) engines.
ISAR could use the first stage of their Spectrum launcher, RFA the first stage of RFA One.
Several Avio M10 engines could be used in a demonstrator, ? Avio / Maia Space?

A reusable first stage could be use for suborbital express (experiments) and as lander demonstrator. (Blue Origin; New Sheppard / Masten; Xogdor).
I think both (Suborbital and Diamond sites) CSG, France Guiana and SSC Esrange, Sweden are launch sites where a reusable suborbital rocket could be operated. I think SSC Esrange LZ-3 is the primary launch site for a reusable stage demonstrator.
Europe also needs to mature (lunar/mars) lander technologies, also for this purpose the launch sites and reusable stages are required. I think a nearly decade long development plan is required.

Another scenario is that P120C(+) production will soon become limiting in launching Vega C/E and Ariane 6. several 1000kN Prometheus or the Avio proposed 6xM10 thrust (600kN ? Romeo) engines could be used on a reusable stage that replaces the P120C. This reusable stage is very similar to the Themis demonstrator.
I think Themis as demonstrator is to large, if higher launch rates is enabled by a affordable liquid booster. They could use it on decent to develop stage recovery. But initially they will likely expend this liquid booster. So it's a development approach with high material costs. 

I'm interested in other views/ thoughts about how Europe can develop reusable stages.

Spacenews Avio Q&A

...
How else is Europe’s Recovery Plan helping Italy’s space industry?

Another good chunk of money from it is going toward developing rocket technology. We will use this funding to create a demonstrator of a new rocket using our liquid oxygen-methane engine. {A demonstrator stage that uses M10 engines, or the VUS Vega E upperstage  }

And also to develop a new liquid oxygen methane engine that will be six times more powerful. So that paves the road for the next generation launchers that we will likely have in the 2030s.

[Zed_Noir]

I think this topic is the right place to discuss a question I've got.
What is the best approach to develop reusable launchers in Europe?
<snip>
I'm interested in other views/ thoughts about how Europe can develop reusable stages.
<snip>

Before hardware considerations. Decide what the reusable launcher is going to be use for and from which launch sites. Also decide if the upper stages is to be recoverable.

Program have to prioritizes less production cost and ease of assembling the launcher. Not a jobs program in other words.

On the propulsion hardware side. Some sort of pump fed semi-cryogenic liquid engine that can landed the booster stage or allows the booster stage to reentry the atmosphere from orbit.

Finally, Europe doesn't have much time to field a reusable launcher before window of opportunity to gain market share in the commercial reusable launch market closes.

[DanClemmensen]

I think this topic is the right place to discuss a question I've got.
What is the best approach to develop reusable launchers in Europe?
<snip>
I'm interested in other views/ thoughts about how Europe can develop reusable stages.
<snip>

Before hardware considerations. Decide what the reusable launcher is going to be use for and from which launch sites. Also decide if the upper stages is to be recoverable.

Program have to prioritizes less production cost and ease of assembling the launcher. Not a jobs program in other words.

On the propulsion hardware side. Some sort of pump fed semi-cryogenic liquid engine that can landed the booster stage or allows the booster stage to reentry the atmosphere from orbit.

Finally, Europe doesn't have much time to field a reusable launcher before window of opportunity to gain market share in the commercial reusable launch market closes.

You are describing a competitor to Falcon 9. But Falcon 9 is now a decade old. By the time a new design is operational, Falcon 9 will be used only for legacy missions because it will have been superseded by Starship. Your new design will only serve customers that are forced by policy or law to use it.  In 2022, Falcon 9 will reach its highest launch rate, because half its launches are Starlink and Starlink will migrate to Starship in 2023, and by 2024 F9 will carry only those payloads (Crew dragon, perhaps) that cannot or will not migrate to Starship.

[Timber Micka]

I think this topic is the right place to discuss a question I've got.
What is the best approach to develop reusable launchers in Europe?

I think Callisto is a right start. But I think Themis as next step is a leap to far. It's to large for a demonstrator, thus to expansive. I also think there are multiple roads to Rome / methods to recover a stage). Thus different recovery methods need to be tested. Parachute recovery, landing legs, landing catch mechanism.
The engine used on the testbed/demonstrator needs to be proven/qualified/certified before the reusable demonstrator can be developed. Otherwise engine reliability risks, harm the reusable stage demonstrator.
Thus developing the engines is the first priority. I think a liquid engine is required.

I think the first stage of Sirius Space Services; Sirius 1 could be a nice step after Callisto. It uses a simple 38kN pressure-feed LOx LNG engine.
Other options are the first stages of micro launchers. I really like the Skyrora XL, but UK ain't EU any longer.
PLD space could us Miura 1 or make a demonstrator with a cluster of Teprel-B (pressure feed) engines.
ISAR could use the first stage of their Spectrum launcher, RFA the first stage of RFA One.
Several Avio M10 engines could be used in a demonstrator, ? Avio / Maia Space?

A reusable first stage could be use for suborbital express (experiments) and as lander demonstrator. (Blue Origin; New Sheppard / Masten; Xogdor).
I think both (Suborbital and Diamond sites) CSG, France Guiana and SSC Esrange, Sweden are launch sites where a reusable suborbital rocket could be operated. I think SSC Esrange LZ-3 is the primary launch site for a reusable stage demonstrator.
Europe also needs to mature (lunar/mars) lander technologies, also for this purpose the launch sites and reusable stages are required. I think a nearly decade long development plan is required.

Another scenario is that P120C(+) production will soon become limiting in launching Vega C/E and Ariane 6. several 1000kN Prometheus or the Avio proposed 6xM10 thrust (600kN ? Romeo) engines could be used on a reusable stage that replaces the P120C. This reusable stage is very similar to the Themis demonstrator.
I think Themis as demonstrator is to large, if higher launch rates is enabled by a affordable liquid booster. They could use it on decent to develop stage recovery. But initially they will likely expend this liquid booster. So it's a development approach with high material costs. 

I'm interested in other views/ thoughts about how Europe can develop reusable stages.

Spacenews Avio Q&A

...
How else is Europe’s Recovery Plan helping Italy’s space industry?

Another good chunk of money from it is going toward developing rocket technology. We will use this funding to create a demonstrator of a new rocket using our liquid oxygen-methane engine. {A demonstrator stage that uses M10 engines  }

And also to develop a new liquid oxygen methane engine that will be six times more powerful. So that paves the road for the next generation launchers that we will likely have in the 2030s.

In my opinion, as soon as Ariane 6 is operational, ESA and CNES should immediately begin the active development phase of the Ariane Next reusable LV (which means canceling the development of Ariane 6 upgrades like the Astris upper stage). I also think they should cancel the development of Vega-E except for the M10 engine, which might be useful to them later.

I think that they should skip one of the two demonstrators because having two demonstrators does not seems necessary to me. I understand why they want to have two demonstrators but that's too incremental (and therefore slow) of an approach compared to what SpaceX and China are doing.
In terms of design, I think Ariane Next should be a Falcon 9 clone. They should use the Prometheus engine similarly to the Merlin, with a vacuum-optimized version for the upper stage. It's a tried and tested design that can put around 20 metric tons into low orbit, a payload capacity roughly equivalent to that of Ariane 5 and 6.
If Europe has a Falcon 9 clone by the second half of the decade that would be a major win. Ariane Next could compete with Rocket Lab's Neutron, which will enter service around the same time. (They could also develop a high-energy upper stage based on the M10 engine to compete with ULA's Vulcan Centaur)

The experience gained should allow them to begin the development of a heavy reusable LV in the 2030s (either by slapping 3 Ariane Next cores together Falcon Heavy-style, or by developing a new design from scratch).

That would be an ideal timeline I think, but I'm 100% sure things won't go that way at all IRL.
France has recently ceased to be the main financial contributor to the Ariane 6 program. Germany took that role, and Germany wants Ariane 6 to become ESA's workhorse launcher for the next ten years, so they are pushing for the development of A6 upgrades like the Astris kick stage. The whole Ariane Next/MaiaSpace thing is a French-led effort that's radically different from Germany's vision of the future. Anyway, it will be interesting to see how it all plays out.

[floss]

It would be far better to do something else rather than reinvent the wheel again.

[TrevorMonty]

I think this topic is the right place to discuss a question I've got.
What is the best approach to develop reusable launchers in Europe?

I think Callisto is a right start. But I think Themis as next step is a leap to far. It's to large for a demonstrator, thus to expansive. I also think there are multiple roads to Rome / methods to recover a stage). Thus different recovery methods need to be tested. Parachute recovery, landing legs, landing catch mechanism.
The engine used on the testbed/demonstrator needs to be proven/qualified/certified before the reusable demonstrator can be developed. Otherwise engine reliability risks, harm the reusable stage demonstrator.
Thus developing the engines is the first priority. I think a liquid engine is required.

I think the first stage of Sirius Space Services; Sirius 1 could be a nice step after Callisto. It uses a simple 38kN pressure-feed LOx LNG engine.
Other options are the first stages of micro launchers. I really like the Skyrora XL, but UK ain't EU any longer.
PLD space could us Miura 1 or make a demonstrator with a cluster of Teprel-B (pressure feed) engines.
ISAR could use the first stage of their Spectrum launcher, RFA the first stage of RFA One.
Several Avio M10 engines could be used in a demonstrator, ? Avio / Maia Space?

A reusable first stage could be use for suborbital express (experiments) and as lander demonstrator. (Blue Origin; New Sheppard / Masten; Xogdor).
I think both (Suborbital and Diamond sites) CSG, France Guiana and SSC Esrange, Sweden are launch sites where a reusable suborbital rocket could be operated. I think SSC Esrange LZ-3 is the primary launch site for a reusable stage demonstrator.
Europe also needs to mature (lunar/mars) lander technologies, also for this purpose the launch sites and reusable stages are required. I think a nearly decade long development plan is required.

Another scenario is that P120C(+) production will soon become limiting in launching Vega C/E and Ariane 6. several 1000kN Prometheus or the Avio proposed 6xM10 thrust (600kN ? Romeo) engines could be used on a reusable stage that replaces the P120C. This reusable stage is very similar to the Themis demonstrator.
I think Themis as demonstrator is to large, if higher launch rates is enabled by a affordable liquid booster. They could use it on decent to develop stage recovery. But initially they will likely expend this liquid booster. So it's a development approach with high material costs. 

I'm interested in other views/ thoughts about how Europe can develop reusable stages.

Spacenews Avio Q&amp;A

...
How else is Europe’s Recovery Plan helping Italy’s space industry?

Another good chunk of money from it is going toward developing rocket technology. We will use this funding to create a demonstrator of a new rocket using our liquid oxygen-methane engine. {A demonstrator stage that uses M10 engines  }

And also to develop a new liquid oxygen methane engine that will be six times more powerful. So that paves the road for the next generation launchers that we will likely have in the 2030s.

In my opinion, as soon as Ariane 6 is operational, ESA and CNES should immediately begin the active development phase of the Ariane Next reusable LV (which means canceling the development of Ariane 6 upgrades like the Astris upper stage). I also think they should cancel the development of Vega-E except for the M10 engine, which might be useful to them later.

I think that they should skip one of the two demonstrators because having two demonstrators does not seems necessary to me. I understand why they want to have two demonstrators but that's too incremental (and therefore slow) of an approach compared to what SpaceX and China are doing.
In terms of design, I think Ariane Next should be a Falcon 9 clone. They should use the Prometheus engine similarly to the Merlin, with a vacuum-optimized version for the upper stage. It's a tried and tested design that can put around 20 metric tons into low orbit, a payload capacity roughly equivalent to that of Ariane 5 and 6.
If Europe has a Falcon 9 clone by the second half of the decade that would be a major win. Ariane Next could compete with Rocket Lab's Neutron, which will enter service around the same time. (They could also develop a high-energy upper stage based on the M10 engine to compete with ULA's Vulcan Centaur)

The experience gained should allow them to begin the development of a heavy reusable LV in the 2030s (either by slapping 3 Ariane Next cores together Falcon Heavy-style, or by developing a new design from scratch).

That would be an ideal timeline I think, but I'm 100% sure things won't go that way at all IRL.
France has recently ceased to be the main financial contributor to the Ariane 6 program. Germany took that role, and Germany wants Ariane 6 to become ESA's workhorse launcher for the next ten years, so they are pushing for the development of A6 upgrades like the Astris kick stage. The whole Ariane Next/MaiaSpace thing is a French-led effort that's radically different from Germany's vision of the future. Anyway, it will be interesting to see how it all plays out.

I'd allow for adding 4 SRBs from A6 for high performance missions which would be expendable.

[Zed_Noir]

I think this topic is the right place to discuss a question I've got.
What is the best approach to develop reusable launchers in Europe?
<snip>
I'm interested in other views/ thoughts about how Europe can develop reusable stages.
<snip>

Before hardware considerations. Decide what the reusable launcher is going to be use for and from which launch sites. Also decide if the upper stages is to be recoverable.

Program have to prioritizes less production cost and ease of assembling the launcher. Not a jobs program in other words.

On the propulsion hardware side. Some sort of pump fed semi-cryogenic liquid engine that can landed the booster stage or allows the booster stage to reentry the atmosphere from orbit.

Finally, Europe doesn't have much time to field a reusable launcher before window of opportunity to gain market share in the commercial reusable launch market closes.

You are describing a competitor to Falcon 9. But Falcon 9 is now a decade old. By the time a new design is operational, Falcon 9 will be used only for legacy missions because it will have been superseded by Starship. Your new design will only serve customers that are forced by policy or law to use it.  In 2022, Falcon 9 will reach its highest launch rate, because half its launches are Starlink and Starlink will migrate to Starship in 2023, and by 2024 F9 will carry only those payloads (Crew dragon, perhaps) that cannot or will not migrate to Starship.

Huh. Where did you get the idea that I was proposing a Falcon 9 clone?

Only stated that Europe don't have much time and couldn't be a decentralized jobs program approach. Europe have to decide the roles to be fulfilled with a reusable or a partially-reusable launcher.

IMO. The Europeans need an interim reusable launcher with limited service life to have some experience before trying to compete with the large reusable launchers from SpaceX and maybe Blue Origin.

[DanClemmensen]

I think this topic is the right place to discuss a question I've got.
What is the best approach to develop reusable launchers in Europe?
<snip>
I'm interested in other views/ thoughts about how Europe can develop reusable stages.
<snip>

Before hardware considerations. Decide what the reusable launcher is going to be use for and from which launch sites. Also decide if the upper stages is to be recoverable.

Program have to prioritizes less production cost and ease of assembling the launcher. Not a jobs program in other words.

On the propulsion hardware side. Some sort of pump fed semi-cryogenic liquid engine that can landed the booster stage or allows the booster stage to reentry the atmosphere from orbit.

Finally, Europe doesn't have much time to field a reusable launcher before window of opportunity to gain market share in the commercial reusable launch market closes.

You are describing a competitor to Falcon 9. But Falcon 9 is now a decade old. By the time a new design is operational, Falcon 9 will be used only for legacy missions because it will have been superseded by Starship. Your new design will only serve customers that are forced by policy or law to use it.  In 2022, Falcon 9 will reach its highest launch rate, because half its launches are Starlink and Starlink will migrate to Starship in 2023, and by 2024 F9 will carry only those payloads (Crew dragon, perhaps) that cannot or will not migrate to Starship.

Huh. Where did you get the idea that I was proposing a Falcon 9 clone?

Only stated that Europe don't have much time and couldn't be a decentralized jobs program approach. Europe have to decide the roles to be fulfilled with a reusable or a partially-reusable launcher.

IMO. The Europeans need an interim reusable launcher with limited service life to have some experience before trying to compete with the large reusable launchers from SpaceX and maybe Blue Origin.

I did not say you proposed an F9 clone. I said you proposed to compete with F9.

[Zed_Noir]

<snip>
Before hardware considerations. Decide what the reusable launcher is going to be use for and from which launch sites. Also decide if the upper stages is to be recoverable.

Program have to prioritizes less production cost and ease of assembling the launcher. Not a jobs program in other words.

On the propulsion hardware side. Some sort of pump fed semi-cryogenic liquid engine that can landed the booster stage or allows the booster stage to reentry the atmosphere from orbit.

Finally, Europe doesn't have much time to field a reusable launcher before window of opportunity to gain market share in the commercial reusable launch market closes.

You are describing a competitor to Falcon 9. But Falcon 9 is now a decade old. By the time a new design is operational, Falcon 9 will be used only for legacy missions because it will have been superseded by Starship. Your new design will only serve customers that are forced by policy or law to use it.  In 2022, Falcon 9 will reach its highest launch rate, because half its launches are Starlink and Starlink will migrate to Starship in 2023, and by 2024 F9 will carry only those payloads (Crew dragon, perhaps) that cannot or will not migrate to Starship.

Huh. Where did you get the idea that I was proposing a Falcon 9 clone?

Only stated that Europe don't have much time and couldn't be a decentralized jobs program approach. Europe have to decide the roles to be fulfilled with a reusable or a partially-reusable launcher.

IMO. The Europeans need an interim reusable launcher with limited service life to have some experience before trying to compete with the large reusable launchers from SpaceX and maybe Blue Origin.

I did not say you proposed an F9 clone. I said you proposed to compete with F9.

You might be right. But the Europeans have to start with baby steps first.

What I proposed could be applicable for a Starship scale reusable launch system as well as a much smaller reusable launch system. IMO.

[Solarsail]

I'm a bit shy on my math here but:

What would be the implications of a (reusable) first stage with a slightly ad-hoc tripropellant combination?  Say, an engine cluster containing both Prometheus and Vulcain engines?  The Prometheus engines can do much of the thrust at the start of flight, light the A5 / A6 do with solids, and then swap to Vulcain only later in the primary flight, improving the specific impulse of the stage over all?  Then use the Prometheus engines for landing, and the boost back and / or re-entry burns, if those exist?  Would this help to reduce the extreme wet mass requirements of re-usability from an all Prometheus stage?  Would using hydrogen in a first stage make it unacceptably high volume?