Speculation thread: intermediate-lift Raptor-derived RLV

[Robotbeat]

...
That's because there isn't one.

IYO

Well, if you can point me at any publicly available documentation that there is one, I am more than happy  to be proven wrong.

The burden of proof is the other way around. You are asserting that no such design exists. The other guy is asserting we don't know that for a fact. So burden of proof is on you.

[QuantumG]

The burden of proof is the other way around. You are asserting that no such design exists. The other guy is asserting we don't know that for a fact. So burden of proof is on you.

Hardly. You can't prove a negative. His claim is that this is all wild speculation and that it should be treated as such. Seeing as that's in the thread title, I think he's on pretty stable ground.

[Robotbeat]

The burden of proof is the other way around. You are asserting that no such design exists. The other guy is asserting we don't know that for a fact. So burden of proof is on you.

Hardly. You can't prove a negative. His claim is that this is all wild speculation and that it should be treated as such. Seeing as that's in the thread title, I think he's on pretty stable ground.

No, that wasn't his claim. You cut off the original quote, which said," That's because there isn't one." That's a strong claim. If he meant to point out it's speculation, he should've said so. Instead he asserted positively that no such design exists.

There are plenty of good reasons why SpaceX would want an intermediate design, and hints that Musk wants a more economical approach to ITS support that idea.

[dror]

One of the reasons I believe a "Raptor 9" based rocket would be beneficial is not only taking advantage of existing infrastructure, but the following:
.
.
.

If you are going to build a completely new rocket to take advantage of existing infrastructure, why just go incrementally better than FH?  So you've obsoleted your own rocket... not a reason to celebrate.

New intermediate-sized Raptor rocket should maximize capability of LC-39A and B.  Build a 12+Mlbf booster (19 engines in three ring -- 1-6-12 -- hex pattern  would be my choice) with both a conventional second stage and fairing, plus a follow-on mini-ITS spaceship second stage.  Core diameter would be around 9m (8-10).  Reusable booster mode payload would be around 200t.

Probably could find a few uses... everything you said x 2.  And obsolete someone else's rocket.

...
An intermediate vehicle needs to serve the later design, not compete with it.
.

I would like to say that I have changed my mind.
Recent publication on Elons "more economic" update expected at IAC17 makes me think that:

It will be ~Nova scale rocket and what AncientU said

It won't be considered as intermediate. It will be ITS although a revised ITS. A new size but one and only.

The timeline won't allow for an intermediate version, although I would very much like it otherwise.

The much smaller version which Sevenperforce suggested could only come later, to replace the Falcon 9\H when it's old, and maybe an upper stage only.

[RocketmanUS]

One of the reasons I believe a "Raptor 9" based rocket would be beneficial is not only taking advantage of existing infrastructure, but the following:
.
.
.

If you are going to build a completely new rocket to take advantage of existing infrastructure, why just go incrementally better than FH?  So you've obsoleted your own rocket... not a reason to celebrate.

New intermediate-sized Raptor rocket should maximize capability of LC-39A and B.  Build a 12+Mlbf booster (19 engines in three ring -- 1-6-12 -- hex pattern  would be my choice) with both a conventional second stage and fairing, plus a follow-on mini-ITS spaceship second stage.  Core diameter would be around 9m (8-10).  Reusable booster mode payload would be around 200t.

Probably could find a few uses... everything you said x 2.  And obsolete someone else's rocket.

...
An intermediate vehicle needs to serve the later design, not compete with it.
.

I would like to say that I have changed my mind.
Recent publication on Elons "more economic" update expected at IAC17 makes me think that:

It will be ~Nova scale rocket and what AncientU said

It won't be considered as intermediate. It will be ITS although a revised ITS. A new size but one and only.

The timeline won't allow for an intermediate version, although I would very much like it otherwise.

The much smaller version which Sevenperforce suggested could only come later, to replace the Falcon 9\H when it's old, and maybe an upper stage only.

The interm could go either way, smaller with 9 engines or it could be more like Saturn V.

SX near term goal is their internet satellites and long term colonizing Mars. The smaller 9/1 could handle the internet launches and exploration missions to Mars. The Raptor based launcher is expected to be cheaper than a Falcon per launch. This could back up Falcon if it is grounded for any reason.The colony launches are more like 20+ years away, so plenty of time to develop the larger vehicles. They first need to see if people can live on Mars ( exploration missions ) before committing to a large vehicle
thats purpose is to launch a colony and not satellites.

[JamesH65]

There is no publically available information that spacex are doing this. Making a claim that they are is what need proving. Just because others think it's a good idea isn't exactly proof. 

[AncientU]

One of the reasons I believe a "Raptor 9" based rocket would be beneficial is not only taking advantage of existing infrastructure, but the following:
.
.
.

If you are going to build a completely new rocket to take advantage of existing infrastructure, why just go incrementally better than FH?  So you've obsoleted your own rocket... not a reason to celebrate.

New intermediate-sized Raptor rocket should maximize capability of LC-39A and B.  Build a 12+Mlbf booster (19 engines in three ring -- 1-6-12 -- hex pattern  would be my choice) with both a conventional second stage and fairing, plus a follow-on mini-ITS spaceship second stage.  Core diameter would be around 9m (8-10).  Reusable booster mode payload would be around 200t.

Probably could find a few uses... everything you said x 2.  And obsolete someone else's rocket.

...
An intermediate vehicle needs to serve the later design, not compete with it.
.

I would like to say that I have changed my mind.
Recent publication on Elons "more economic" update expected at IAC17 makes me think that:

It will be ~Nova scale rocket and what AncientU said

It won't be considered as intermediate. It will be ITS although a revised ITS. A new size but one and only.

The timeline won't allow for an intermediate version, although I would very much like it otherwise.

The much smaller version which Sevenperforce suggested could only come later, to replace the Falcon 9\H when it's old, and maybe an upper stage only.

The interm could go either way, smaller with 9 engines or it could be more like Saturn V.

SX near term goal is their internet satellites and long term colonizing Mars. The smaller 9/1 could handle the internet launches and exploration missions to Mars. The Raptor based launcher is expected to be cheaper than a Falcon per launch. This could back up Falcon if it is grounded for any reason.The colony launches are more like 20+ years away, so plenty of time to develop the larger vehicles. They first need to see if people can live on Mars ( exploration missions ) before committing to a large vehicle
thats purpose is to launch a colony and not satellites.

They have a rocket family, the most economical in the World, to achieve what you call their near term goal.

Long term, you are correct, they want to colonize Mars.  That was the basis for ITS as shown in 2016 IAC presentation.

The immediate challenge in getting to long term goal is establishing a foothold* on Mars -- no small task. 
IAC 2016 ITS is not the optimum vehicle to achieve that because it is too expensive, too large of a leap.

They need a Mars rocket.


* Beach-head may be a more apt term -- like the warfare equivalent, this will be a difficult and dangerous task.  There will almost certainly be fatalities.

There is no publically available information that spacex are doing this. Making a claim that they are is what need proving. Just because others think it's a good idea isn't exactly proof.

All correct.

[M.E.T.]

One of the reasons I believe a "Raptor 9" based rocket would be beneficial is not only taking advantage of existing infrastructure, but the following:
.
.
.

If you are going to build a completely new rocket to take advantage of existing infrastructure, why just go incrementally better than FH?  So you've obsoleted your own rocket... not a reason to celebrate.

New intermediate-sized Raptor rocket should maximize capability of LC-39A and B.  Build a 12+Mlbf booster (19 engines in three ring -- 1-6-12 -- hex pattern  would be my choice) with both a conventional second stage and fairing, plus a follow-on mini-ITS spaceship second stage.  Core diameter would be around 9m (8-10).  Reusable booster mode payload would be around 200t.

Probably could find a few uses... everything you said x 2.  And obsolete someone else's rocket.

...
An intermediate vehicle needs to serve the later design, not compete with it.
.

I would like to say that I have changed my mind.
Recent publication on Elons "more economic" update expected at IAC17 makes me think that:

It will be ~Nova scale rocket and what AncientU said

It won't be considered as intermediate. It will be ITS although a revised ITS. A new size but one and only.

The timeline won't allow for an intermediate version, although I would very much like it otherwise.

The much smaller version which Sevenperforce suggested could only come later, to replace the Falcon 9\H when it's old, and maybe an upper stage only.

The interm could go either way, smaller with 9 engines or it could be more like Saturn V.

SX near term goal is their internet satellites and long term colonizing Mars. The smaller 9/1 could handle the internet launches and exploration missions to Mars. The Raptor based launcher is expected to be cheaper than a Falcon per launch. This could back up Falcon if it is grounded for any reason.The colony launches are more like 20+ years away, so plenty of time to develop the larger vehicles. They first need to see if people can live on Mars ( exploration missions ) before committing to a large vehicle
thats purpose is to launch a colony and not satellites.

They have a rocket family, the most economical in the World, to achieve what you call their near term goal.

Long term, you are correct, they want to colonize Mars.  That was the basis for ITS as shown in 2016 IAC presentation.

The immediate challenge in getting to long term goal is establishing a foothold* on Mars -- no small task. 
IAC 2016 ITS is not the optimum vehicle to achieve that because it is too expensive, too large of a leap.

They need a Mars rocket.


* Beach-head may be a more apt term -- like the warfare equivalent, this will be a difficult and dangerous task.  There will almost certainly be fatalities.

There is no publically available information that spacex are doing this. Making a claim that they are is what need proving. Just because others think it's a good idea isn't exactly proof.

All correct.

I don't understand this argument. What is the point of establishing this "beach head"? Other than being a symoblic achievement, how does it make long term Mars colonization more feasible? I thought the goal was to achieve the required economies of scale to make Mars colonization affordable.

The key distinction here is that an intermediate Mars rocket - which allows boots on the ground, but does not solve the cost challenge - is meaningless. If however an intermediate rocket can be built which can generate funds for the eventual massive ITS which makes mass transit to Mars possible, then such an intermediate rocket makes sense. But crucially, this intermediate rocket might have nothing to do with Mars, and everything to do with generating massive amounts of money from orbital launches.

So its main justification would be that it earns SpaceX lots and lots of money in the medium term. Money with which the planned ITS can then be built. The net effect of such a rocket, therefore, might be that the first manned Mars trip that has the funding it needs might only occur in the mid 2030's, once those funds have been generated closer to home.

So in short, the intermediate rocket won't be for Mars. It will be for earning money in Earth orbit. Money with which to build the BIG Mars rocket. The ITS. That's the revised approach that I expect from Elon's imminent revelation. Not some downscaled ITS that is still aiming for Mars in the short term. Because that does not provide anything other than a symbolic boots on the ground, Zubrin type solution.

The above assumes that an intermediate rocket is even in consideration, which I'm not sure about at all.

[AncientU]

Cost is one immediate challenge.
Technical challenges that are just as immediate include:
Raptor engine performance demonstration
Carbon fiber construction of large vehicle
On-orbit refueling
Mars EDL
Mars ISRU propellant production
Mars refueling
Mars Departure and Earth return
Earth EDL
Human rating booster and spaceship

Doing these with a 550t-capable vehicle (designed for colonization) is insanity.  (Right back where we started in Fall 2016 after IAC.)

Landing 100-200t payloads on Mars and establishing a beach-head producing ISRU propellant, water, etc. is not your Father's flags and footprints, one-off 'mission'.

Waiting until 2030s is not a viable option.

[M.E.T.]

Cost is one immediate challenge.
Technical challenges that are just as immediate include:
Raptor engine performance demonstration
Carbon fiber construction of large vehicle
On-orbit refueling
Mars EDL
Mars ISRU propellant production
Mars refueling
Mars Departure and Earth return
Earth EDL
Human rating booster and spaceship

Doing these with a 550t-capable vehicle (designed for colonization) is insanity.  (Right back where we started in Fall 2016 after IAC.)

Landing 100-200t payloads on Mars and establishing a beach-head producing ISRU propellant, water, etc. is not your Father's flags and footprints, one-off 'mission'.

Waiting until 2030s is not a viable option.

Ok. I accept that all of those are major challenges.  However, maybe I don't quite understand why all of those challenges would be dramatically easier to solve with an SLS sized rocket than with an ITS sized one.

Secondly, let's say this beach head is established with this intermediate rocket - which presumably will also cost in the billions of dollars range to develop. What would the cost per kg be to transport people and cargo to Mars, compared to ITS? Presumably the entire reason behind ITS's size was that this provided the only means by which to get the cost per passanger down to this theorized $200k range. In order to achieve full reusability with say an SLS sized rocket, you would sacrifice a lot of payload, and the cost per kg landed on Mars would be much higher. So how would you then support the beach head economically, let alone expand it to achieve full colonization?

I guess the answer to the above would be that it won't happen with the intermediate rocket, but with a successor rocket of ITS size. But then, if the cost of establishing the beach head was already much greater due to the higher cost/kg, where will the money for a whole new rocket come from? And this while still having to support the fledgling base on Mars at high cost at the same time?

To me, intermediate might mean that the full scale ITS remains the only rocket being constructed, but that it comes online in stages. With its first years of operation focusing on orbital cargo only, perhaps even lunar deliveries, in order to generate money for the eventual Mars landing.

And then all the other challenges you mentioned, such as ISRU, propulsive landings on Mars, long term life support systems and power generation on Mars can be solved incrementally. That means ITS is still the only rocket being invested in, it still starts operating in the early 2020's, and it starts earning money from non-Mars related missions immediately, all the while proving itself and gradually expanding its capabilities until the fully fledged Mars vehicle is finally ready, maybe around 2030 or thereabouts.

But it seems that size is critical to the economies of scale that Musk has in mind. Building a smaller rocket defeats that purpose completely.

[Semmel]

Frankly, the reason I believe is economical. A smaller vehicle can place the Internet constellation into orbit cheaper than F9 or full scale ITS. Also an SLS sized rocket can launch from the Cape, I believe the full scale it's would need an offshore launch platform. Which would be much more expensive. Again all economic reasons.

[M.E.T.]

Frankly, the reason I believe is economical. A smaller vehicle can place the Internet constellation into orbit cheaper than F9 or full scale ITS. Also an SLS sized rocket can launch from the Cape, I believe the full scale it's would need an offshore launch platform. Which would be much more expensive. Again all economic reasons.

Two comments on that spring to mind.

Firstly, I agree with you on using such a rocket for generating money from the internet constellation and other orbital services. But then its intention is not to be a Mars rocket. Just a rocket that generates money, with which the eventual Mars rocket will be built. That makes sense. But it also requires that we accept a significant delay in the Mars rocket being constructed.

(Edited to add that it also assumes that F9 and FH cannot also deliver the satellite constellation with sufficient economy to generate vast amounts of funding for the Mars endeavour.)

Regarding the second point, I thought Musk laid that issue to rest in one of his comments, where he stated that LC39A was over developed for Saturn V, and could in fact handle the thrust of the ITS? So that seems to be a non-issue? But I might have misunderstood that point, I must confess. Maybe someone can clarify it for us.

[guckyfan]

We will have to see which size this new vehicle will have.

I have expected something in the range of New Glenn. 7 Raptor first stage, maybe 9, would be totally adequate for lifting everything in cislunar space. Assuming the upper stage is not only reusable but refuellable it could land on Mars too and be more capable than RedDragon without being much more expensive.

But I read the new announcements as being for making money as well as advancing Mars, beyond something similar to Red Dragon. Which could be a vehicle that maxes out the flame trench capability of the LC-39 pads. As Tom Mueller said it would make every other rocket obsolete. It could do everything in cislunar space, including moon landing and return to earth, at least with a tanker in lunar orbit. It could also land about 100t on Mars. Enough to build a fuel ISRU plant and supply a base.

The second would firmly establish SpaceX for interplanetary manned exploration. Decision makers could no longer ignore the SpaceX challenge. IMO it could be implemented much faster than the full size ITS. My concerns about ITS were always centered around how and in what timeframe a pad for it can be built, including EIS and building permit.

[guckyfan]

Regarding the second point, I thought Musk laid that issue to rest in one of his comments, where he stated that LC39A was over developed for Saturn V, and could in fact handle the thrust of the ITS? So that seems to be a non-issue? But I might have misunderstood that point, I must confess. Maybe someone can clarify it for us.

My speculation is, that the size of the LC-39 pads allows for ITS, but not the flame trenches. This is the only thing I can see that would reconcile older statements that LC-39 are too small for ITS and the newer statements. I can not believe, that they now suddenly have discovered, the flame trenches are powerful enough, to handle ITS full size.

[M.E.T.]

We will have to see which size this new vehicle will have.

I have expected something in the range of New Glenn. 7 Raptor first stage, maybe 9, would be totally adequate for lifting everything in cislunar space. Assuming the upper stage is not only reusable but refuellable it could land on Mars too and be more capable than RedDragon without being much more expensive.

But I read the new announcements as being for making money as well as advancing Mars, beyond something similar to Red Dragon. Which could be a vehicle that maxes out the flame trench capability of the LC-39 pads. As Tom Mueller said it would make every other rocket obsolete. It could do everything in cislunar space, including moon landing and return to earth, at least with a tanker in lunar orbit. It could also land about 100t on Mars. Enough to build a fuel ISRU plant and supply a base.

The second would firmly establish SpaceX for interplanetary manned exploration. Decision makers could no longer ignore the SpaceX challenge. IMO it could be implemented much faster than the full size ITS. My concerns about ITS were always centered around how and in what timeframe a pad for it can be built, including EIS and building permit.

Would this be used for long term colonization, or would that require an ITS-sized follow up rocket, to be developed down the line?

[Robotbeat]

If SpaceX can use the same rocket to launch the constellation AND to settle Mars, then they can afford to do the latter FAR sooner than otherwise.

Also, I want to point out that a smaller ITS should still be more than sufficient for getting prices low enough, IF you believe the original numbers.

If the full sized ITS can get $200,000 per person, then a vehicle 1/3rd the size should still be capable of, say, $250,000 or $350,000 per person, especially if you use a little cleverness. Scale helps cost, but definitely not 1 to 1.

And being able to share infrastructure for the constellation, other commercial launches, and Mars settlement would ITSELF reduce ticket prices versus keeping the Falcon line up while having ITS only for Mars. Shutting down the partially expendable Falcon line will have huge cost benefits.

Mars will probably always be a secondary source of income for SpaceX. So being able to piggyback on their main source of income will enable a huge cost reduction for Mars, since they could basically do Mars missions at marginal costs (instead of needing to generate profit to pay back a big investment in ITS and continuing infrastructure), essentially subsidize Mars settlement. You can essentially just use extra launch capacity for Mars at-cost. This is a very good hack for enabling Mars settlement to be affordable.

As their main revenue-generating constellation and commercial launches grow in size (in response to a huge reduction in per-kg cost), they'll eventually be able to grow ITS to full size and beyond. ...without having that cost be a burden on Mars settlement.

[guckyfan]

Would this be used for long term colonization, or would that require an ITS-sized follow up rocket, to be developed down the line?

I would expect, when they move from a base to a settlement they will want and need the bigger ITS. My guess, without time pressure they would go straight to 15m diameter, but the same number of engines. It would help landing larger payloads on Mars or a larger number of settlers without raising cost a lot. All speculation, of course.

[M.E.T.]

If SpaceX can use the same rocket to launch the constellation AND to settle Mars, then they can afford to do the latter FAR sooner than otherwise.

Also, I want to point out that a smaller ITS should still be more than sufficient for getting prices low enough, IF you believe the original numbers.

If the full sized ITS can get $200,000 per person, then a vehicle 1/3rd the size should still be capable of, say, $250,000 or $350,000 per person, especially if you use a little cleverness. Scale helps cost, but definitely not 1 to 1.

And being able to share infrastructure for the constellation, other commercial launches, and Mars settlement would ITSELF reduce ticket prices versus keeping the Falcon line up while having ITS only for Mars. Shutting down the partially expendable Falcon line will have huge cost benefits.

Mars will probably always be a secondary source of income for SpaceX. So being able to piggyback on their main source of income will enable a huge cost reduction for Mars, since they could basically do Mars missions at marginal costs (instead of needing to generate profit to pay back a big investment in ITS and continuing infrastructure), essentially subsidize Mars settlement. You can essentially just use extra launch capacity for Mars at-cost. This is a very good hack for enabling Mars settlement to be affordable.

As their main revenue-generating constellation and commercial launches grow in size (in response to a huge reduction in per-kg cost), they'll eventually be able to grow ITS to full size and beyond. ...without having that cost be a burden on Mars settlement.

Well, if the cost/kg does not drop dramatically with greater size, I guess it changes the equation somewhat. Interesting. I wonder what the reduced diameter and reduced payload would mean for the size of the habitable area that the 100 settlers (or are we talking only 30 setllers now) would spend 3-5 months in on the way to Mars.

[AncientU]

Frankly, the reason I believe is economical. A smaller vehicle can place the Internet constellation into orbit cheaper than F9 or full scale ITS. Also an SLS sized rocket can launch from the Cape, I believe the full scale it's would need an offshore launch platform. Which would be much more expensive. Again all economic reasons.

Two pads at the Cape to be exact.  Maybe Boca Chica, too, in time.

The comparison with SLS stops there, though.  This will be a fully reusable rocket, capable of launching monthly, weekly, whatever Mars development (and Lunar, ConnX, DoD, etc.) demands.  Reuse plus refueling on orbit will allow this system to gain most of the cost advantages of the 2016 IAC version.

This is a buildable rocket now -- assuming Raptor is flight qualified in the next 1-2 years, even if they need to make the first boosters of Li-Al and use landing legs.  The workforce is assembled and qualified, assembly line engine production is proven, pad(s) available, reuse technology proven, ..., and NASA is currently all hot on going to Mars, but is launcher constrained.  When would timing be better?

I still believe that the first of these boosters could fly in 2020... New Glenn, Vulcan-Centaur, SLS EM-1 timeframe.

[M.E.T.]

Frankly, the reason I believe is economical. A smaller vehicle can place the Internet constellation into orbit cheaper than F9 or full scale ITS. Also an SLS sized rocket can launch from the Cape, I believe the full scale it's would need an offshore launch platform. Which would be much more expensive. Again all economic reasons.

Two pads at the Cape to be exact.  Maybe Boca Chica, too, in time.

The comparison with SLS stops there, though.  This will be a fully reusable rocket, capable of launching monthly, weekly, whatever Mars development (and Lunar, ConnX, DoD, etc.) demands.  Reuse plus refueling on orbit will allow this system to gain most of the cost advantages of the 2016 IAC version.

This is a buildable rocket now -- assuming Raptor is flight qualified in the next 1-2 years, even if they need to make the first boosters of Li-Al and use landing legs.  The workforce is assembled and qualified, assembly line engine production is proven, pad(s) available, reuse technology proven, ..., and NASA is currently all hot on going to Mars, but is launcher constrained.  When would timing be better?

I still believe that the first of these boosters could fly in 2020... New Glenn, Vulcan-Centaur, SLS EM-1 timeframe.

Ok, this is sounding intriguing. So what do you envisage, roughly? A single stack, two stage, SLS sized, Raptor based, fully reusable rocket that is refuellable in LEO? With more or less what diameter and what  fully reusable payload to LEO?