In 2016 SpaceX has bookings for ~$1.3B of rockets (22 at $57m via Google and the US launch schedule thread). They receive about $650M annually from the CCtCap award ($2.6B through 2019) and about $200M from CRS, that's about $2.15B in revenues. A very cursory search suggests that Tesla and Google both have 25% profit margins so let's assume that SpaceX gets the same and makes a profit of ~$550M. Suppose half that profit goes into funding private Mars work, so that 1/8th of all revenue is being spent on internal Mars R&D and mission costs. That's a $275m annual budget for Mars efforts, on the order of half their yearly costs on the CCtCap award.>
Quote from: guckyfan on 06/17/2015 05:50 pmQuote from: Lobo on 06/17/2015 04:29 pmQuote from: fast on 06/17/2015 01:48 pmAnd back to design concepts, it is the most fun What if BFR and MCT will be the essentially same thing? Kind of universal module sized similar to S-IC, 9 Raptors at the bottom, with lending legs, around 1900mt. Than all thing will be three core (I know, Elon said one-core, but look at F5), MCT in the center will have less fuel load replaced by cargo bay and improved thermal protection, and probably have less than 9 Raptors(3?).Just a thought to standardize and reduce cost...Setting aside Elon's actual words aside for a moment about it being single core, the 2-piece concept myself and a few others have been debating about would do what you are doing, but with just two pieces rather than 3. One big monolithic RTLS booster, and one combo upperstage/spacecraft that can get itself to LEO where it will be refueled prior to going to Mars. Actually this looks to me like the first innovative new idea for a while.Elon Musk said single core. But the idea behind that was to my understanding, not a 3 core heavy configuration because the central core would go too fast for easy RTLS and would incur heavy payload loos for reuse. This concept avoids that problem.This concept would be like a first stage in two parts, something completely different. The "central core" would be the MCT. The vac engine problem might be solvable with a retractable engine bell extension. The mechanism shown in that Falcon Heavy animation seems to allow fast efficient reconnection so should not be a major problem for simple operation.Two side cores with 9 engines each plus a central core with 5? engines would give a total number of engines 23 for lift off. Most of them would be switched off as soon as the T/W ratio allows it to retain fuel for reaching orbit.It is innovative (good job fast). And it could work for the reason you say. It eliminates the central core that's staging too fast. There's also be a booster core for the intermediate size LV that's been discussed over on the SFR thread.But, I just don't know that it has advantages over an in-line wider core? Do you see where this would be an advantage? Maybe if they weren't planning to build the cores near the launch facility, this concept would result in thinner cores that are more easily transported. But that's really not a problem unless SpaceX changes from what they've stated.And it'd result in a tall and skinny MCT. That's probably the major issue with it vs. monolithic, that I see.
Quote from: Lobo on 06/17/2015 04:29 pmQuote from: fast on 06/17/2015 01:48 pmAnd back to design concepts, it is the most fun What if BFR and MCT will be the essentially same thing? Kind of universal module sized similar to S-IC, 9 Raptors at the bottom, with lending legs, around 1900mt. Than all thing will be three core (I know, Elon said one-core, but look at F5), MCT in the center will have less fuel load replaced by cargo bay and improved thermal protection, and probably have less than 9 Raptors(3?).Just a thought to standardize and reduce cost...Setting aside Elon's actual words aside for a moment about it being single core, the 2-piece concept myself and a few others have been debating about would do what you are doing, but with just two pieces rather than 3. One big monolithic RTLS booster, and one combo upperstage/spacecraft that can get itself to LEO where it will be refueled prior to going to Mars. Actually this looks to me like the first innovative new idea for a while.Elon Musk said single core. But the idea behind that was to my understanding, not a 3 core heavy configuration because the central core would go too fast for easy RTLS and would incur heavy payload loos for reuse. This concept avoids that problem.This concept would be like a first stage in two parts, something completely different. The "central core" would be the MCT. The vac engine problem might be solvable with a retractable engine bell extension. The mechanism shown in that Falcon Heavy animation seems to allow fast efficient reconnection so should not be a major problem for simple operation.Two side cores with 9 engines each plus a central core with 5? engines would give a total number of engines 23 for lift off. Most of them would be switched off as soon as the T/W ratio allows it to retain fuel for reaching orbit.
Quote from: fast on 06/17/2015 01:48 pmAnd back to design concepts, it is the most fun What if BFR and MCT will be the essentially same thing? Kind of universal module sized similar to S-IC, 9 Raptors at the bottom, with lending legs, around 1900mt. Than all thing will be three core (I know, Elon said one-core, but look at F5), MCT in the center will have less fuel load replaced by cargo bay and improved thermal protection, and probably have less than 9 Raptors(3?).Just a thought to standardize and reduce cost...Setting aside Elon's actual words aside for a moment about it being single core, the 2-piece concept myself and a few others have been debating about would do what you are doing, but with just two pieces rather than 3. One big monolithic RTLS booster, and one combo upperstage/spacecraft that can get itself to LEO where it will be refueled prior to going to Mars.
And back to design concepts, it is the most fun What if BFR and MCT will be the essentially same thing? Kind of universal module sized similar to S-IC, 9 Raptors at the bottom, with lending legs, around 1900mt. Than all thing will be three core (I know, Elon said one-core, but look at F5), MCT in the center will have less fuel load replaced by cargo bay and improved thermal protection, and probably have less than 9 Raptors(3?).Just a thought to standardize and reduce cost...
But, I just don't know that it has advantages over an in-line wider core? Do you see where this would be an advantage?
In 2016 SpaceX has bookings for ~$1.3B of rockets (22 at $57m via Google and the US launch schedule thread). They receive about $650M annually from the CCtCap award ($2.6B through 2019) and about $200M from CRS, that's about $2.15B in revenues. A very cursory search suggests that Tesla and Google both have 25% profit margins so let's assume that SpaceX gets the same and makes a profit of ~$550M. Suppose half that profit goes into funding private Mars work, so that 1/8th of all revenue is being spent on internal Mars R&D and mission costs. That's a $275m annual budget for Mars efforts, on the order of half their yearly costs on the CCtCap award.A doubling of commercial sales -- 50 launches a year -- adds about $170m to this estimate and puts the effort at $450M yearly. A great success of reuse might drastically affect profit margins, or it might not, since now you need to build fewer rockets for the same flight rate, but you also need to maintain reflown stages, and you might end up discounting your launch price anyways. Imagining a 50% profit margin and doubled sales, SpaceX can spend $900M on Mars work yearly.What I am getting at is that the scale of SpaceX's commercial rocketry business is borderline in terms of building and operating individual exploration craft. Fleets of $500M MCTs are beyond SpaceX's independent means, even under optimistic expectations.I am also skeptical of SpaceX trying to switch horses in midstream between kerolox Falcon and methalox BFR architectures with this cost structure. Before they had an order book and DoD certification, they had a lot of freedom to change rocket configurations. Now, they have an ongoing business of maintaining Falcon service and associated Falcon costs. If SpaceX tries to leap directly to methalox and BFR in one go, that adds on Raptor costs and BFR costs and MCT costs all at once. These are going to be Large Rocket Costs, much larger than those incurred for Falcon. I am skeptical that the existing business can bear them. SLS costs are $2.2b/year, and BFR is larger than SLS. I don't see how SpaceX can develop a rocket larger than SLS and a very advanced upper stage / spacecraft capable of Mars EDL/ascent for a small fraction of the price.I think Musk's comments about a "single monster boost stage" can encompass a range of monstrosity. A single core equivalent of Falcon Heavy would, after all, be at least a smidge monstrous. A craft that delivers "100 metric tons of useful payload to the surface of Mars" can be assembled in Earth orbit and does not need to launch intact from Earth's surface.Ultimately I think that SpaceX might well achieve a manned Mars landing, but I am doubtful of their ability to independently fund a major colonization architecture. It does make me wonder if SpaceX might try to get into the satellite business to scale up their revenues in order to better follow up on the Mars goal.
In 2016 SpaceX has bookings for ~$1.3B of rockets (22 at $57m via Google and the US launch schedule thread). They receive about $650M annually from the CCtCap award ($2.6B through 2019) and about $200M from CRS, that's about $2.15B in revenues. A very cursory search suggests that Tesla and Google both have 25% profit margins so let's assume that SpaceX gets the same and makes a profit of ~$550M. Suppose half that profit goes into funding private Mars work, so that 1/8th of all revenue is being spent on internal Mars R&D and mission costs. That's a $275m annual budget for Mars efforts, on the order of half their yearly costs on the CCtCap award....
Assembly in LEO is not feasible in my opinion, it has proved extremely expensive to do any assembly in space.
Thanks for the link, this seems to be the key quote.“And then one of the key questions is can you get to the surface of Mars and back to Earth on a single stage. The answer is yes, if you reduce the return payload to approximately one-quarter of the outbound payload, which I thought made sense because you are going to want to transport a lot more to Mars than you’d want to transfer from Mars to Earth. For the spacecraft, the heat shield, the life support system, and the legs will have to be very, very light."It's largely as I suspected, Musk is describing what COULD be done and the constraints he would face in doing it, but it is by no means a commitment that this is how he will proceed even with the initial design. I think the incredible lightness necessary to make it work will prove too risky of a development challenge, he could end up in Venture Star territory if just one of his lightening strategies fails to work the whole thing could collapse.By setting low bars like Mars surface to Low Mars orbit and low entry velocity the whole design process becomes a much less risky and cutting edge. SpaceX has traditionally not done high risk designs so I think it is far more likely that in the end he chooses the safer design even if it dose require a second SEP vehicle to function and a good deal of rendezvous in space for refueling.Quote from: Robotbeat on 06/18/2015 02:22 amAnd? You've done better? Musk and occasionally Shotwell are basically the ONLY source for anything about MCT. So like it or not, that's all we've got right now.Actually their is a LOT of information on rocketry out their on the inter-webs and we can and should do our own research if we expect to speculate with any kind of informed way. If Musk & Shotwell quotes were the only permissible source material then this thread would be nothing more then a religious war between the SpaceX fan-boys and the SpaceX haters. If my analysis disagrees with anyone else's, even Musk's I have every right and indeed the responsibility to point that out and I will not heckled by you or anyone else simply because I don't own a rocket company.
And? You've done better? Musk and occasionally Shotwell are basically the ONLY source for anything about MCT. So like it or not, that's all we've got right now.
In 2016 SpaceX has bookings for ~$1.3B of rockets (22 at $57m via Google and the US launch schedule thread). They receive about $650M annually from the CCtCap award ($2.6B through 2019) and about $200M from CRS, that's about $2.15B in revenues. A very cursory search suggests that Tesla and Google both have 25% profit margins so let's assume that SpaceX gets the same and makes a profit of ~$550M. Suppose half that profit goes into funding private Mars work, so that 1/8th of all revenue is being spent on internal Mars R&D and mission costs. That's a $275m annual budget for Mars efforts, on the order of half their yearly costs on the CCtCap award.
What I am getting at is that the scale of SpaceX's commercial rocketry business is borderline in terms of building and operating individual exploration craft. Fleets of $500M MCTs are beyond SpaceX's independent means, even under optimistic expectations.
I am also skeptical of SpaceX trying to switch horses in midstream between kerolox Falcon and methalox BFR architectures with this cost structure. Before they had an order book and DoD certification, they had a lot of freedom to change rocket configurations. Now, they have an ongoing business of maintaining Falcon service and associated Falcon costs. If SpaceX tries to leap directly to methalox and BFR in one go, that adds on Raptor costs and BFR costs and MCT costs all at once. These are going to be Large Rocket Costs, much larger than those incurred for Falcon. I am skeptical that the existing business can bear them. SLS costs are $2.2b/year, and BFR is larger than SLS. I don't see how SpaceX can develop a rocket larger than SLS and a very advanced upper stage / spacecraft capable of Mars EDL/ascent for a small fraction of the price.
Ultimately I think that SpaceX might well achieve a manned Mars landing, but I am doubtful of their ability to independently fund a major colonization architecture. It does make me wonder if SpaceX might try to get into the satellite business to scale up their revenues in order to better follow up on the Mars goal.
Actually, you probably want to dump the water shielding before Mars entry. Mars has lots of water, and it will be absolutely essential to tap that water for any of this to work.Additionally, clever arrangement of propellant tanks (and surface tension devices) could use your propellant as shielding. Methane is actually significantly more efficient than water for radiation shielding (Water has an average atomic mass of 6, while methane has an average of ~3). Only hydrogen is superior.That would probably shift the expected fuel:oxidizer ratio to be more fuel rich than it otherwise would be (if you could adjust that ratio on the fly, you may depart EML1/2 with a more stoich ratio but do final burn above Mars with significantly more fuel rich).
So I guess it might be a good idea to jettison the water before the final injection burn to Mars orbit, that might reduce the fuel required for that manoeuver. A linked question is would we want to jettison the waste, or is the compost value higher than the value of fuel saving? Is the injection burn a large part of the overall fuel use for Mars transfer? My understanding is the faster we go, the more fuel is required to stop at Mars, but for a 6 month mission, is the Mars burn a large portion of the deltaV requirement?
From Statements made by SpaceX representatives:- 100mt payload delivery to Mars- 1/4 payload SSTO return to Earth from mars surface- prop density 1m^3 for 1mt (LOX and CH4)- 15m diameter vehicle (this was hited at not actually specified by SpaceX- Raptor engines 380-385 vacuum ISP 500klbfA vehicle like this results:- Vehicle structure+engines+ shield =40mt- Max propellant load 900mt- propulsion section (engines and tanks) cylindircal or nearly cylindrical section at base 15m diameter and 6m tall- bi-conal payload section (first section 15m to 10m diameter 10m tall) (second section 10m to 0m 10m tall) ~1800m^3 volume-MCT can be its own 2nd stage on the BFR (BFR is basically just the 1st stage) would have ~7.5km/s delta v capability with a 100mt payload+40mt vehicle dry weight +900mt propellant load-An MCT tanker variant would be a Cargo MCT without any cargo which could deliver ~150mt of propellant to LEO would have 6km/s delta v capabilityIn order to get to Mars 6-9 tankers docking in LEO-MEO are required Edit Added: BTW An MCT cargo used as the 2nd stage going just to LEO would be capable of delivering 180mt of payload. Note the 1st stage needs to be capable of ~3km/s delta v with a fully loaded MCT + 180mt of payload on top ~1120mt MCT+payload GLOW
Quote from: oldAtlas_Eguy on 06/18/2015 02:39 pmFrom Statements made by SpaceX representatives:- 100mt payload delivery to Mars- 1/4 payload SSTO return to Earth from mars surface- prop density 1m^3 for 1mt (LOX and CH4)- 15m diameter vehicle (this was hited at not actually specified by SpaceX- Raptor engines 380-385 vacuum ISP 500klbfA vehicle like this results:- Vehicle structure+engines+ shield =40mt- Max propellant load 900mt- propulsion section (engines and tanks) cylindircal or nearly cylindrical section at base 15m diameter and 6m tall- bi-conal payload section (first section 15m to 10m diameter 10m tall) (second section 10m to 0m 10m tall) ~1800m^3 volume-MCT can be its own 2nd stage on the BFR (BFR is basically just the 1st stage) would have ~7.5km/s delta v capability with a 100mt payload+40mt vehicle dry weight +900mt propellant load-An MCT tanker variant would be a Cargo MCT without any cargo which could deliver ~150mt of propellant to LEO would have 6km/s delta v capabilityIn order to get to Mars 6-9 tankers docking in LEO-MEO are required Edit Added: BTW An MCT cargo used as the 2nd stage going just to LEO would be capable of delivering 180mt of payload. Note the 1st stage needs to be capable of ~3km/s delta v with a fully loaded MCT + 180mt of payload on top ~1120mt MCT+payload GLOWThanks, this is a great summary. I guess this means not much water based radiation shielding? And if as Guckyfan proposes there is no final injection burn, not much fuel at the end for radiation protection either?
- Vehicle structure+engines+ shield =40mt
The MCT is not a small vehicle. It could conceivably reach Earth orbit as an SSTO with a little payload about 20mt.
Quote from: Darkseraph on 06/18/2015 03:20 amI've extremely high doubts that once the BFR/MCT package is complete, SpaceX will just cancel its breadwinning Falcon9/Falcon Heavy lines and launch all commercial satellites on a Saturn V class rocket. .. and assuming that's the case, what's BFR for? Annual (at best) launches of MCTs?
I've extremely high doubts that once the BFR/MCT package is complete, SpaceX will just cancel its breadwinning Falcon9/Falcon Heavy lines and launch all commercial satellites on a Saturn V class rocket.