Author Topic: MCT Speculation and Discussion Thread 4  (Read 618035 times)

Offline Impaler

  • Full Member
  • ****
  • Posts: 1283
  • South Hill, Virgina
  • Liked: 363
  • Likes Given: 0
Re: MCT Speculation and Discussion Thread 4
« Reply #900 on: 10/24/2015 05:50 AM »
Musk has worked out just enough about potential "MCT" approaches that he has a generic requirement for his BFR launcher.  I am certain that he has explored the solution space for Mars transport and wants a launch capability that can support solutions from all chemical solution to SEP/chemical hybrid transport and other possible more exotic solutions.  Technology over a >10 year timeframe does not stay still.  The 1st and  2nd stage need only be able to get the 100mT cargo plus MCT dry weight into appropriate LEO.  If all his broad brush Mars transport solution space fits within these parameters and their evolutionary improvements (e.g.Merlin to Merlin FT), he's good to go.
But why build BFR first? BFR has the most infrastructure requirements. Additionally, you're making the implicit assumption that MCT isn't essentially BFR's second stage. I really, REALLY don't expect SpaceX to make the same mistake NASA is currently making by building a super-expensive-to-develop-and-maintain launch vehicle without really anything to launch.

You can't have it both ways, either SpaceX is a lean and efficient vertically integrated company that's vastly more efficient then 'Old-Space' capable of making a rocket without a huge standing army or they aren't.  If BFR takes huge infrastructure to build and maintain like SLS dose then the prospect of getting to mars is already busted.

I've said a dozen times I expect SpaceX to sell normal commercial flights on BFR for a good long time before it is use for mars, that will build precious flight history before people fly on it.  Two or three large com satellites at a time, Bigelow type space stations, the LEO satellite swarms, and any NASA missions that would have flown on SLS are all potential things to fill the rocket with.  And because these things require a normal 2nd stage that is the configuration that makes sense, it allows a product that can fend for itself in the marketplace and pay for it's own infrastructure without putting that whole cost onto the back of the mars ticket.  Also it doesn't risk completely bankrupting the company in getting to mars turns out to be harder then expected to develop or customers are not ready to buy when the ride is offered. 

As NASA is the only conceivable customer for a first mission they need to be courted to create a mission utilizing SpaceX as the primary contractor.  But NASA will need a decade or more to develop and ready the ground systems.  But to fund that SLS needs to be canceled first and that not going to come until a proven alternative has been fully demonstrated to be reliable.

Were already seeing spiral development from SpaceX when they layed down considerable time and money for Raptor development which was clearly started without the full mars architecture in place, and probably no more then a vague sense of how large BFR would be either.  They just set out to the make the best engine possible and then build the best launch vehicle with and around it.  At each point they are just building the best device they can come up with while utilizing their existing parts, this is how I see the mars bound spacecraft being done as well.


Quote
... So, the Block One MCT will likely again be different from the MCT that lands the first crew on Mars June 2033 following the un-crewed MCT bringing the ISRU equipment May 2031.
I have no doubt MCT will evolve, but your timeline is not the same as SpaceX's timeline. They expect crewed missions much earlier. Which makes sense, as it doesn't make sense to develop a capability and then essentially just let it languish, sucking up money while nothing is accomplished (another mistake NASA is making, though this is mostly Congress's fault).

Which is exactly why an integrated 2nd stage is a bad idea, it makes the launcher too narrow and unable to serve any other role efficiently.  It is also unfeasible on technical grounds but no one seems willing to admit this.

Offline sublimemarsupial

  • Full Member
  • ***
  • Posts: 386
  • Liked: 258
  • Likes Given: 3
Re: MCT Speculation and Discussion Thread 4
« Reply #901 on: 10/24/2015 07:07 AM »

... It is also unfeasible on technical grounds but no one seems willing to admit this.

Can you show us the math that proves this or are you just blowing smoke and speculating like everyone else in this thread?

Offline guckyfan

  • Senior Member
  • *****
  • Posts: 6757
  • Germany
  • Liked: 1790
  • Likes Given: 1766
Re: MCT Speculation and Discussion Thread 4
« Reply #902 on: 10/24/2015 07:46 AM »
You can't have it both ways, either SpaceX is a lean and efficient vertically integrated company that's vastly more efficient then 'Old-Space' capable of making a rocket without a huge standing army or they aren't.  If BFR takes huge infrastructure to build and maintain like SLS dose then the prospect of getting to mars is already busted.

Disagree. Even with much smaller fixed cost it would be a lot for SpaceX. It would also introduce massive slips of the timeline.

I've said a dozen times I expect SpaceX to sell normal commercial flights on BFR for a good long time before it is use for mars, that will build precious flight history before people fly on it.  Two or three large com satellites at a time, Bigelow type space stations, the LEO satellite swarms, and any NASA missions that would have flown on SLS are all potential things to fill the rocket with.  And because these things require a normal 2nd stage that is the configuration that makes sense, it allows a product that can fend for itself in the marketplace and pay for it's own infrastructure without putting that whole cost onto the back of the mars ticket.  Also it doesn't risk completely bankrupting the company in getting to mars turns out to be harder then expected to develop or customers are not ready to buy when the ride is offered. 

Anything that makes design compromises for cisluar space would be less than perfect for Mars. MCT will be designed for Mars and Mars alone. So much was clearly said by Elon Musk and is not some design detail that can be changed when appropriate. It is a part of the basic development philosophy. Which does not say it cannot be used for anything else. Cargo MCT will have large payload doors, similar to the SpaceShuttle. It can deploy satellites and space station modules. Not mass efficient but operationally efficient.

As NASA is the only conceivable customer for a first mission they need to be courted to create a mission utilizing SpaceX as the primary contractor.  But NASA will need a decade or more to develop and ready the ground systems.  But to fund that SLS needs to be canceled first and that not going to come until a proven alternative has been fully demonstrated to be reliable.

If NASA is to be the first customer the concept is dead in the waterspace. It would introduce decades of delay as you yourself state. It is not going to happen.

Were already seeing spiral development from SpaceX when they layed down considerable time and money for Raptor development which was clearly started without the full mars architecture in place, and probably no more then a vague sense of how large BFR would be either.  They just set out to the make the best engine possible and then build the best launch vehicle with and around it. 

Not at all. They see how the best suited engine turns out and then design BFR for it. But the capabilities of BFR do not change by that. Just the number of engines changes. The capabilities of BFR are fixed by what MCT needs.

Which is exactly why an integrated 2nd stage is a bad idea, it makes the launcher too narrow and unable to serve any other role efficiently.

See above. BFR/MCT will not be designed for anything else but Mars.


It is also unfeasible on technical grounds but no one seems willing to admit this.

How do you come to that conclusion?

Offline The Amazing Catstronaut

  • Full Member
  • ****
  • Posts: 1071
  • Arsia Mons, Mars, Sol IV, Inner Solar Solar System, Sol system.
  • Liked: 757
  • Likes Given: 627
Re: MCT Speculation and Discussion Thread 4
« Reply #903 on: 10/24/2015 04:53 PM »

Which is exactly why an integrated 2nd stage is a bad idea, it makes the launcher too narrow and unable to serve any other role efficiently.  It is also unfeasible on technical grounds but no one seems willing to admit this.

Do you think SpaceX, Musk or anybody would bank their reputation and solvency on something which is technically unfeasible? If the BFR/MCT architecture wasn't practical, wouldn't they instead have figured that out by now, especially before they got to the phase of developing the craft's propulsion?

Edit: People have been collectively running math here for years and there's nothing theoretically showstopping about it. Yes, it's tricky engineering, but it's not physics violating engineering. This isn't so much of a quantum leap as the R7 was from the V2.
« Last Edit: 10/24/2015 04:55 PM by The Amazing Catstronaut »
Resident feline spaceflight expert. Knows nothing of value about human spaceflight.

Offline guckyfan

  • Senior Member
  • *****
  • Posts: 6757
  • Germany
  • Liked: 1790
  • Likes Given: 1766
Re: MCT Speculation and Discussion Thread 4
« Reply #904 on: 10/24/2015 05:37 PM »
People have been collectively running math here for years and there's nothing theoretically showstopping about it. Yes, it's tricky engineering, but it's not physics violating engineering. This isn't so much of a quantum leap as the R7 was from the V2.

Designing MCT for Mars EDL will be tricky and in the end they may fail on that. Success is not guaranteed. But I am optimistic about it. As you said, there are years of engineering behind it by top designers. It is not like Elon Musk was on it alone and it is all pipe dreams.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 28361
  • Minnesota
  • Liked: 8209
  • Likes Given: 5436
Re: MCT Speculation and Discussion Thread 4
« Reply #905 on: 10/24/2015 08:32 PM »
People have been collectively running math here for years and there's nothing theoretically showstopping about it. Yes, it's tricky engineering, but it's not physics violating engineering. This isn't so much of a quantum leap as the R7 was from the V2.

Designing MCT for Mars EDL will be tricky and in the end they may fail on that. Success is not guaranteed. But I am optimistic about it. As you said, there are years of engineering behind it by top designers. It is not like Elon Musk was on it alone and it is all pipe dreams.

The biggest questionmark for making a large vehicle like that do Mars EDL was supersonic retropropulsion, which SpaceX has already demonstrated. The rest is stuff that you'd basically already need for a reusable upper stage for an Earth TSTO RLV (vertical landing, heatshield, etc).

I don't think people quite understand here how much these requirements for different segments actually overlap. Going with VTVL and a very good mass fraction for your RLV instead of parachutes or wings for everything means an operationally simpler design that is scalable and applicable to other celestial bodies.
« Last Edit: 10/24/2015 08:37 PM by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline GregA

  • Full Member
  • ****
  • Posts: 492
  • Liked: 255
  • Likes Given: 61
Re: MCT Speculation and Discussion Thread 4
« Reply #906 on: 10/24/2015 10:45 PM »
Yes, one of the misunderstood reasons that Elon is a genius is simply an ability to take existing known quantities and technologies and put them together in ways that other people can't see. In this case he's said from the beginning he believes that travelling to Mars and living on Mars can be done without having to invent something entirely new.

That doesn't mean the solutions are ready to go, just that if you have the vision and the money you can put together something that will work. It's actually not a leap of faith in the technology (though it requires societal support).

There's 2 reasons other people can't do this
1) it's hard to see anything on a huge scale, even for the best people
2) not many people can control the funds to put behind the solution

Because we as humans have difficulties with huge scales we see it as taking a risk. (That doesn't mean there aren't risks in the vision, or in other similar scales, just that it's a type of risk we aren't able to intuitively understand).

He is pushing the limits here though. Supersonic retropropulsion is not a trusted 'known'. And he's pushing the edge in developing the MCT and so on.

Offline philw1776

  • Full Member
  • ****
  • Posts: 1076
  • Seacoast NH
  • Liked: 696
  • Likes Given: 303
Re: MCT Speculation and Discussion Thread 4
« Reply #907 on: 10/24/2015 10:50 PM »
Musk has worked out just enough about potential "MCT" approaches that he has a generic requirement for his BFR launcher.  I am certain that he has explored the solution space for Mars transport and wants a launch capability that can support solutions from all chemical solution to SEP/chemical hybrid transport and other possible more exotic solutions.  Technology over a >10 year timeframe does not stay still.  The 1st and  2nd stage need only be able to get the 100mT cargo plus MCT dry weight into appropriate LEO.  If all his broad brush Mars transport solution space fits within these parameters and their evolutionary improvements (e.g.Merlin to Merlin FT), he's good to go.
But why build BFR first? BFR has the most infrastructure requirements. Additionally, you're making the implicit assumption that MCT isn't essentially BFR's second stage. I really, REALLY don't expect SpaceX to make the same mistake NASA is currently making by building a super-expensive-to-develop-and-maintain launch vehicle without really anything to launch.

You can't have it both ways, either SpaceX is a lean and efficient vertically integrated company that's vastly more efficient then 'Old-Space' capable of making a rocket without a huge standing army or they aren't.  If BFR takes huge infrastructure to build and maintain like SLS dose then the prospect of getting to mars is already busted.

Very confusing. Just where was this said that you're rebutting?  Looks like a strawman arguement to me.
“When it looks more like an alien dreadnought, that’s when you know you’ve won.”

Offline Impaler

  • Full Member
  • ****
  • Posts: 1283
  • South Hill, Virgina
  • Liked: 363
  • Likes Given: 0
Re: MCT Speculation and Discussion Thread 4
« Reply #908 on: 10/25/2015 02:05 AM »
First the idea of a high maintenance cost is inconsistent with SpaceX operations, they shown the ability to build and launch with much less manpower.  It also ignores the intended re-usable nature of BFR, they do not need to manufacture them at a rate of one a month like Falcon, though they will likely make Raptor engines at a few a week with a comparable labor input and assembly-line like production like Merlin manufacturing.

RB is arguing that the whole top to bottom mars transportation system has to come into being simultaneously.  But his argument of 'high maintenance cost' is actually made worse by trying to make the whole system, you would incur both the cost of BFR maintenance along with the cost of the mars transit vehicle aka MCT, claiming that the launcher and transit vehicle are designed to be incapable of operating independently dose not lower the cost.  Your just raising costs while pushing revenue collection further into the future and narrowing it's customer base.  The safe strategy is to do the rocket first, which is the most conventional part of the system and the only part that might be monetized independently of the rest, then push on to the more challenging parts.

Offline philw1776

  • Full Member
  • ****
  • Posts: 1076
  • Seacoast NH
  • Liked: 696
  • Likes Given: 303
Re: MCT Speculation and Discussion Thread 4
« Reply #909 on: 10/25/2015 06:42 PM »
Appreciate the clarification.  I was confused, but I agree.
« Last Edit: 10/25/2015 06:43 PM by philw1776 »
“When it looks more like an alien dreadnought, that’s when you know you’ve won.”

Offline spacenut

  • Senior Member
  • *****
  • Posts: 2391
  • East Alabama
  • Liked: 399
  • Likes Given: 235
Re: MCT Speculation and Discussion Thread 4
« Reply #910 on: 10/25/2015 07:11 PM »
I think they will get the engine built and tested first.  Then design the BFR around the engine or engines.  They also have to determine how big the BFR will be to either use existing infrastructure or to build new infrastructure for the first stage.  Remember existing inland waterway barges are only a certain size.  Falcon was designed to the maximum size of existing road transportation equipment.  Then they will design a reusable 2nd stage.  I think the MCT will be an evolution of the second stage.  I also think it will be designed modular so it could be a second stage for launching large payloads.  The MCT cargo version, and later an MCT human transporter.  I think they will know more when they get the exact specifications for the Raptor engine, power, thrust to weight ration, etc.   Of course this is a speculation thread. 

Offline MikeAtkinson

  • Full Member
  • ****
  • Posts: 1779
  • Bracknell, England
  • Liked: 542
  • Likes Given: 70
Re: MCT Speculation and Discussion Thread 4
« Reply #911 on: 10/25/2015 09:15 PM »
This is my guess at a MCT plan. Note I've separated out the tanker, cargo and crew variants of MCT although they are all based on the same design.

YearElementPhaseNotes
2014Raptorinitial investigations
Q4 2015Architecturerelease
Q1 2016RaptorPDR
2016-7BFR+MCTinitial designsseveral iterations towards a PDR in 2018
Q4 2017RaptorCDR
Q1 2018BFRPDRdepends on Raptor PDR
2018Red dragonsite surveysurface element demos
2019MCTPDRdepends on Raptor PDR
2020BFRCDR
2020Red dragon(s)site survey(s)surface element demos & subsequent synods
2022MCTCDRtanker and cargo versions
2023MCTCDRcrew versions
2023BFRFirst flight1st stage only
2024MCTDemo flightbare bones tanker version
2025BFRDemo flight(s)cargo version & refueling
2026BFRDemo flight(s)crew version - LEO (unmanned)
2027-31BFRDemo flight(s)crew version - LEO long duration (manned)
2028BFRDemo flight(s)cargo version - Mars + crew version - cis-lunar
2031BFRCargo flight(s)cargo version - Mars
2033BFRCrew flight(s)crew+cargo versions - Mars

It would be difficult to meet the 2031 launch window for the first crew flight and just about impossible to meet a Nov 2028 launch window. To meet a Oct 2026 launch window would require Apollo-like resources devoted to it and a fair bit of luck.

Lack of resources or problematic development would delay this schedule by one or more synods.


Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 28361
  • Minnesota
  • Liked: 8209
  • Likes Given: 5436
Re: MCT Speculation and Discussion Thread 4
« Reply #912 on: 10/25/2015 10:48 PM »
First the idea of a high maintenance cost is inconsistent with SpaceX operations, they shown the ability to build and launch with much less manpower.  It also ignores the intended re-usable nature of BFR, they do not need to manufacture them at a rate of one a month like Falcon, though they will likely make Raptor engines at a few a week with a comparable labor input and assembly-line like production like Merlin manufacturing.
SpaceX will lose a huge advantage in per-launch labor efficiency if they only build, say, 1 BFR a year. That is exactly why SLS is ridiculously expensive. SpaceX may beat the industry-standard labor efficiency for rocket manufacture and development by 2-3x, MAYBE, but their main advantage is picking reasonable solutions, i.e. not building a ridiculously expensive rocket using technology half a century old and that will only launch a couple times per year at most.

Also, you're missing a really important point: There isn't actually a market for HLV launch. Nobody* wants more than about EELV Heavy capability (except for exploration, but even then it's not required). There aren't even commercial or military processing facilities for payloads over 5 meters in diameter. There isn't a commercial launch need for BFR, and NASA doesn't even have any payloads that need an HLV. F9 and Falcon Heavy are MORE than enough for all the commercial, civil, and military payloads. I've held this viewpoint for years, I've been vocal about it, and I haven't actually changed my mind on it. The only thing that might make sense for an HLV is if you had some good rationale for flying enough payloads per year that you could take FULL advantage of a full manufacturing line (multiple shifts) /and/ full advantage of full reuse (both first and second stages). To keep a production line busy, you probably need at least 10 flights per year. To do that with multiple shifts, probably about 40 first stage cores per year (and more upper stages). To make first stage reuse make sense, you need to reuse the stage at least ten times. To make full reuse make sense, you need to reuse the first stage at least 100 times and the upper stage 10-30 times. That's roughly a thousand launches per year at a minimum. Partial reuse can get by with maybe 100 launches per year, 40 per year if some are expendable. Otherwise, it's not really the economic optimum. Unless you get to 1000 launches per year, though, you probably aren't launching enough to gain anything by using an HLV. (In fact, you'd reduce your economic efficiency since you wouldn't be reusing as much.)

Only something like large-scale colonization ticks those boxes. Otherwise, put your money into full reuse, not making a mega-rocket.

But let's just pretend that you're right about there being some big market for HLVs out there.

Quote
RB is arguing that the whole top to bottom mars transportation system has to come into being simultaneously.
Ignoring for the moment that you're putting words in my mouth: You mean with Mars transfer vehicle, a lander/ascent vehicle, SEP propulsion, depots and everything? Am I arguing that? No. I'm arguing that a Mars transport system of BFR and MCT as the second stage is basically the same thing as a TSTO RLV BFR.

The requirements between a very large TSTO RLV's second stage capable of higher energy orbits (which is where the real money is), an integrated reusable fairing, and long-loiter capability (essential for cislunar, direct GSO, and multi-plane constellation deployments) is almost entirely overlapping with what an initial cargo MCT would likely do. The only thing different is ability to refuel bidirectionally (this is a thing ULA is working on, so they think it's worth it even though they don't care about Mars much) and long-range comms (both would be very valuable for cislunar). Long-range comms is actually a very easy requirement if you operate at a low data rate.


Quote
...The safe strategy ...
Yeah, no, there's nothing safe about BFR or MCT or SpaceX's Mars plans. If they were merely playing safe, they would still be at Falcon 1 or maybe a Falcon 5. BFR/MCT is not at all a safe strategy.


*I don't take Bigelow's grandiose plans very seriously, and besides, a couple LEO payloads doesn't justify a whole HLV. Bigelow can't carry the cost of a BFR. And if you wanted to put his stations in lunar orbit or on the lunar surface, you'd want something with long-loiter capability like MCT.
« Last Edit: 10/25/2015 11:00 PM by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 28361
  • Minnesota
  • Liked: 8209
  • Likes Given: 5436
Re: MCT Speculation and Discussion Thread 4
« Reply #913 on: 10/25/2015 10:51 PM »
SpaceX may beat the industry average labor cost efficiency, but they aren't magic. Building a huge rocket and a huge factory for it well before they plan on actually using it doesn't make sense. If they build it then mothball it, they will have to relearn it when they want to start it up again. If they build it then keep it operating at a low level, then it will suck up a lot of funds and certainly won't be cheaper than F9 or Falcon Heavy.

No, they will be working on BFR/MCT at the same time. They would be super foolish to do what NASA is doing and building a rocket without anything to launch on it. NASA and SpaceX would both be better served by saving up that money until they're ready to do both. (Though NASA can't really save money from year to year like that, SpaceX can and does... they bought some Solar City bonds when they got a big cash infusion a while back.)
« Last Edit: 10/25/2015 10:56 PM by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline GregA

  • Full Member
  • ****
  • Posts: 492
  • Liked: 255
  • Likes Given: 61
Re: MCT Speculation and Discussion Thread 4
« Reply #914 on: 10/25/2015 11:40 PM »
The only thing that might make sense for an HLV is if you had some good rationale for flying enough payloads per year that you could take FULL advantage of a full manufacturing line (multiple shifts) /and/ full advantage of full reuse (both first and second stages). To keep a production line busy, you probably need at least 10 flights per year. To do that with multiple shifts, probably about 40 first stage cores per year (and more upper stages). To make first stage reuse make sense, you need to reuse the stage at least ten times. To make full reuse make sense, you need to reuse the first stage at least 100 times and the upper stage 10-30 times. That's roughly a thousand launches per year at a minimum. Partial reuse can get by with maybe 100 launches per year, 40 per year if some are expendable. Otherwise, it's not really the economic optimum. Unless you get to 1000 launches per year, though, you probably aren't launching enough to gain anything by using an HLV. (In fact, you'd reduce your economic efficiency since you wouldn't be reusing as much.)

We do keep hearing high numbers from SpaceX. Fleets, scouting the globe for launch locations to move a lot of people. But I don't think we think in the right scale yet.

SpaceX release of plans will help us get the right ball park. Obviously if you're moving 10,000 people a year to Mars ( in 50 years, based on having a million people there in 100 years), that's launching 100 MCTs a year. Add fuel launches and cargo launches and you move up to your 1000 BFR launches a year (in 50 years).

Then one question is how fast they ramp up to that number. I'm not sure how accurate your estimates of cost efficiency are (not saying they are or aren't, I'm just not sure). Elon has previously run factories on single shifts then moved to multiple shifts so that's likely. And they may find making they're making many upper stage fuel tanks etc and less BFRs - or that the number of reuses is lower initially so they have a higher number of new BFRs to start with.

This is my guess at a MCT plan. Note I've separated out the tanker, cargo and crew variants of MCT although they are all based on the same design.

Obviously vastly different scales of approaches.

But in either case - I think an early launch of surface scanning satellites and scouting RD missions in the early 2020s could be added.
« Last Edit: 10/25/2015 11:41 PM by GregA »

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 28361
  • Minnesota
  • Liked: 8209
  • Likes Given: 5436
Re: MCT Speculation and Discussion Thread 4
« Reply #915 on: 10/25/2015 11:50 PM »
Musk mentioned like 80,000 people per year. He didn't specify synod. So that's almost another whole order of magnitude. But my figures are not meant to be taken literally... They are rough +/- order of magnitude only. Main thing to take from them is that you shouldn't build an HLV unless you're doing something on the order of colonization. Nothing else really makes sense.

In many ways, though, MCT is more critical than BFR. MCT serves more roles, as a reusable upper stage that can refuel and loiter and land or do orbital insertion of large payloads just about anywhere in the inner solar system, including Earth orbit/cislunar.
« Last Edit: 10/25/2015 11:55 PM by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline GregA

  • Full Member
  • ****
  • Posts: 492
  • Liked: 255
  • Likes Given: 61
Re: MCT Speculation and Discussion Thread 4
« Reply #916 on: 10/25/2015 11:58 PM »
Musk mentioned like 80,000 people per year. He didn't specify synod. So that's almost another whole order of magnitude.
Really? When was that?

The goal thrown out is 1 million people right? But the timeframe isn't clear.
80,000 a year gets to a million very quickly, unless it's 80,000 a year once the colony is up at the million mark, which makes more sense.

Even with fewer people, the huge scale like you describe will allow them to build large farms, big factories, and start mining - while also dropping the interim resources required in doing that.

I do think it might be the only way to resolve the chicken and egg problem. As long as a few of the world's biggest mining and manufacturing companies decide it's worthwhile.


(ps. yes I've been trying to be careful on years vs synods)

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 28361
  • Minnesota
  • Liked: 8209
  • Likes Given: 5436
Re: MCT Speculation and Discussion Thread 4
« Reply #917 on: 10/26/2015 12:06 AM »
https://twitter.com/elonmusk/status/273483420468932608

Quote from: @elonmusk
Millions of people needed for Mars colony, so 80k+ would just be the number moving to Mars per year
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Impaler

  • Full Member
  • ****
  • Posts: 1283
  • South Hill, Virgina
  • Liked: 363
  • Likes Given: 0
Re: MCT Speculation and Discussion Thread 4
« Reply #918 on: 10/26/2015 05:01 AM »

Also, you're missing a really important point: There isn't actually a market for HLV launch. Nobody* wants more than about EELV Heavy capability (except for exploration, but even then it's not required). There aren't even commercial or military processing facilities for payloads over 5 meters in diameter. There isn't a commercial launch need for BFR, and NASA doesn't even have any payloads that need an HLV. F9 and Falcon Heavy are MORE than enough for all the commercial, civil, and military payloads. I've held this viewpoint for years, I've been vocal about it, and I haven't actually changed my mind on it. The only thing that might make sense for an HLV is if you had some good rationale for flying enough payloads per year that you could take FULL advantage of a full manufacturing line (multiple shifts) /and/ full advantage of full reuse (both first and second stages). To keep a production line busy, you probably need at least 10 flights per year. To do that with multiple shifts, probably about 40 first stage cores per year (and more upper stages). To make first stage reuse make sense, you need to reuse the stage at least ten times. To make full reuse make sense, you need to reuse the first stage at least 100 times and the upper stage 10-30 times. That's roughly a thousand launches per year at a minimum. Partial reuse can get by with maybe 100 launches per year, 40 per year if some are expendable. Otherwise, it's not really the economic optimum. Unless you get to 1000 launches per year, though, you probably aren't launching enough to gain anything by using an HLV. (In fact, you'd reduce your economic efficiency since you wouldn't be reusing as much.)


Customers don't care how big the rocket is they care how much it costs.  In order to get anywhere near the cost structure Musk desires the cost to launch the BFR would need to be well in the range where it would be a cost effective commercial launcher.  While it may cost more then one sat customer would be willing to pay for we already have a NORMAL practice in the industry of launching multiple satellites simultaneously so it is not at all hard to see a viable commercial sat launch market for BFR if it achieved the full reusability which is it's main goal.

The manufacturing of BFR consists of two parts, engines and the tanks, we know the engines will be made in an assembly line like manor similar to Merlin.  If we estimate 36 engines total and a week to make each one then a whole rocket in made under a year with a manufacturing base comparable to that which exists for Merlin now, it would run steadily at full utilization but hardly be huge compared to what's already being done.  The tanks would likely be made at Michoud and if made on a pace to match the engines your looking at a steady state production line as well.

This will not cost billions per year to maintain like SLS which is looking at 2 Billion for maintaining it's work force and half a billion in marginal production costs (giving us a likely 2.5 Billion per year cost for 1 yearly launch).  SpaceX is likely going to do it for 1/10th that much in maintenance (200 million), and one quarter as much to manufacture (125 million).  If the production time is 36 weeks and their are 10 uses out of each rocket initially then you end up with just 14 launches per year and overhead costs are absorbed at around 25 million per launch.  Now of course refurbishment is going to be an unknown factor plus all the non-manufacturing related costs of launch such as pad operations, payload integration etc etc.

Your argument that thousands of launches per year are necessary dose not hold water.  Lots of folks have done lots of speculating on reuse and none of it shows much benefit past 10 uses, if the rocket isn't profitable with 10 uses going to 100 isn't going to change it.  Second their is no way you can find a customers base to purchase thousands of launches per year to immediately soak up this absurd supply suddenly being put onto the market all at once.  That's the kind of volume that would be necessary to achieve the 80K immigrants per year goal.  The system must be viable at a lower initial volume so it can survive to ramp up over decades.

Offline GregA

  • Full Member
  • ****
  • Posts: 492
  • Liked: 255
  • Likes Given: 61
Re: MCT Speculation and Discussion Thread 4
« Reply #919 on: 10/26/2015 05:23 AM »
https://twitter.com/elonmusk/status/273483420468932608

Quote from: @elonmusk
Millions of people needed for Mars colony, so 80k+ would just be the number moving to Mars per year
Thanks for that.

It seems to stem from a misunderstanding though. Musk estimates $36 billion to set up a colony, and calculates it as part of the US GDP.  "Some money has to be spent on establishing a base on Mars. It’s about getting the basic fundamentals in place". The article then talks about $500,000 a colonist, and divides that into $40billion to get the "80,000 colonist" number.

The article uses that in the opening. But it doesn't make sense to have colonists paying the $40 billion if the government is paying it. It also wasn't saying 80,000 total.

So Musk's tweet then clarifies that a bit. He talks about a million people, not 80,000. His throwaway about "80,000 a year" is more likely just trying to emphasise how low that number is.

Tags: