Author Topic: MCT Speculation and Discussion Thread 2  (Read 217728 times)


Offline guckyfan

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Re: MCT Speculation and Discussion Thread 2
« Reply #1 on: 08/17/2014 01:13 PM »
So I ran two sets of numbers of the available DV with different cargo masses.

The first is a single BFR launch with partial fuel. So the fuel would be 250 MT-(35MT+Cargo). example. 30 MT cargo flight would launch with 250-(35+30) = 185 MT of fuel.

The second estimate is fully fueling the MCT with the refueling BFR after a partial burn to a higher orbit to maximize DV. This can add approximately .75 km/s of additional DV.

All calculations are based on no refueling after leaving LEO.

MissionDV Req (km/s)Partial Fuel Cargo (MT)Full Fuel Cargo (MT)Notes
LEO->EML1->Earth4.145115Round Trip Cargo
LEO->EML2->Earth3.7655115Round Trip Cargo
LEO->EML4/5->Earth4.833085Round Trip Cargo
LEO->GEO->Earth3.93095Drop Cargo at GEO
LEO->LLO->Earth4.042590Drop Cargo at LLO
LEO->EML2->EML1->Earth4.8830115Round Trip Cargo
LEO->Moon->Earth8.67N/A8Return Cargo 2 MT
LEO->SEL1->Earth5.52065DV Correct??
LEO->SEL2->Earth5.52065DV Correct??


Base on the above, my conclusion is that the MCT can serve some very useful missions in cis-lunar space.

Cargo MCT would be unmanned, while Crew/cargo MCT could perform the mission with crew.

Landing on the Moon cargo capability was a disappointing 8 MT, and other Moon specific requirements may not be worth it.

The MCT could be a very powerful and capable for cis-lunar space and the local solar system.

Here is a link to my spreadsheet: https://docs.google.com/spreadsheets/d/1e7uz5Tt8Y_duvBvFXkPxhj0IuNQD-as6bZqghScQM2E/edit?usp=sharing

I hope you find this interesting and if I have made any obvious mistakes.

Very interesting post, thank you. I want to comment to the moon landing part.

I think I still like that capability even if you say it is disappointingly low. It would be enough for supply and crew runs to maintain an existing base.

For initial installation of a base refuelling beyond LEO would help a lot with payload to lunar surface. The easiest way of doing that would be to send a tanker along with MCT. The tanker would be refuelled to capacity in LEO parallel to MCT. They would fly in tandem TLI. Fuel would then be transferred during flight to the moon. MCT lands and the tanker returns to earth after a loop around the moon. It would be interesting to calculate the cargo capacity in this scenario. Would it reach the full 100 tons?

Worst case refuelling fails, MCT and tanker could still land back on earth after a loop around the moon. The tanker would have to vent the excess fuel for a safe landing though.

Edit/CR - simplifying reference to post in closed thread
« Last Edit: 08/18/2014 08:13 AM by CuddlyRocket »

Offline J-V

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Re: MCT Speculation and Discussion Thread 2
« Reply #2 on: 09/18/2014 08:46 AM »
I don't know if this should be - or is - discussed in another thread, so mods move this if needed please.

Raptor is generally considered to be too powerful engine for MCT to land with. But how about the just announced BE-4 http://forum.nasaspaceflight.com/index.php?topic=35655.0  from Blue Origin? It has about fourth of the thrust of one Raptor, is reusable, and runs on LNG. ISP hasn't been revealed, and I'm not certain about restarts, but otherwise it sounds like possible match for MCT.

Offline guckyfan

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Re: MCT Speculation and Discussion Thread 2
« Reply #3 on: 09/18/2014 09:12 AM »
I don't know if this should be - or is - discussed in another thread, so mods move this if needed please.

Raptor is generally considered to be too powerful engine for MCT to land with. But how about the just announced BE-4 http://forum.nasaspaceflight.com/index.php?topic=35655.0  from Blue Origin? It has about fourth of the thrust of one Raptor, is reusable, and runs on LNG. ISP hasn't been revealed, and I'm not certain about restarts, but otherwise it sounds like possible match for MCT.

SpaceX using an engine not made inhouse and from Blue Origin, of all possible sources, is that even a remote option?

But you are not alon in thinking that with all the recent increases of Raptor thrust figures it is too large for MCT unless MCT scales up with Raptor for a capacity way beyond 100t or 100 settlers.


Offline J-V

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Re: MCT Speculation and Discussion Thread 2
« Reply #4 on: 09/18/2014 09:15 AM »
SpaceX using an engine not made inhouse and from Blue Origin, of all possible sources, is that even a remote option?

Well.. a possibility from technical point of view at least ::)

Offline Ben the Space Brit

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Re: MCT Speculation and Discussion Thread 2
« Reply #5 on: 09/18/2014 09:30 AM »
SpaceX using an engine not made inhouse and from Blue Origin, of all possible sources, is that even a remote option?

Well.. a possibility from technical point of view at least ::)

Agreed.

However, in the end, Musk and Bezos are both successful businessmen and money talks. If they can come to a commercial arrangement that benefits them both, I doubt they'd be sufficiently self-absorbed to block it for petty personal reasons.

That said, remember that LCH4 staged combustion as a propulsion option came out of left-field for SpaceX. So, it isn't beyond possibility that plans already exist for some exotic in-space propulsion system that is currently a closely-guarded commercial secret. After all, Musk keeps talking about flights to Mars with time-frames in the weeks rather than months; that's beyond even a high-performance hydrolox engine's capabilities.
« Last Edit: 09/18/2014 09:32 AM by Ben the Space Brit »
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Offline guckyfan

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Re: MCT Speculation and Discussion Thread 2
« Reply #6 on: 09/18/2014 10:00 AM »

Well.. a possibility from technical point of view at least ::)

True, from a technical standpoint.

Agreed.

However, in the end, Musk and Bezos are both successful businessmen and money talks. If they can come to a commercial arrangement that benefits them both, I doubt they'd be sufficiently self-absorbed to block it for petty personal reasons.

Yes but I would really rule out outsourcing any engines, especially for their long term goal MCT and making themselves that dependent on a sole source supplier.

That said, remember that LCH4 staged combustion as a propulsion option came out of left-field for SpaceX. So, it isn't beyond possibility that plans already exist for some exotic in-space propulsion system that is currently a closely-guarded commercial secret. After all, Musk keeps talking about flights to Mars with time-frames in the weeks rather than months; that's beyond even a high-performance hydrolox engine's capabilities.

I heard Elon talk about 3 months, clearly in the context of MCT and methane. But weeks?


Offline CyclerPilot

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Re: MCT Speculation and Discussion Thread 2
« Reply #7 on: 09/19/2014 03:36 AM »
Hey all.  First time poster.

I think this MCT speculation thread has been great.  My favorite so far on NSF, which is saying a lot on this excellent forum.

Assuming this whole BFR, MCT thing works out, I bet the BO metholox Engine will make it to Mars.  I doubt it will be on the SpaceX MCT though.  Elon has stated he doesn't want to do it alone, so how sweet would it be to have a BO MCT riding up to orbit on a SpaceX BFR?  8)

I agree that having 6+ smaller Methane/LOX engines would be better for the Mar Lander for several reasons, minimize G-forces, provide engine-out redundancy, ability to hover, more maneuverable, etc.  There are many excellent designs for such a vehicle in the first thread (I even started exploring one myself involving the inner 10m-dia of the MCT to be hollow and having a hoist on top able to lower all the modules straight to the surface, but a digress... :) )

Has anyone came up with a passable design for the MCT that incorporates the big 4.4 mega-newton thrust Raptor?  It seems like that is the way SpaceX is heading.  Given the constraints of 4 months transfer, landing 100+MT on Mars, ISRU fill-up on surface, and returning fully reusable, what can we design using at least one 4.4MN Raptor?

One option I explored a little deeper is using Super Dracos to provide the low thrust Martian landing.  This offers several advantages over the 4.4MN Raptor alone:
-Already on the shelf and qualified (this can't be over stated).
-Excellent reliability and engine out redundancy
-Already "man rated" (or will be by the time MCT flies)
-Excellent maneuverability for a controlled and aimed landing on the rocky surface (throttling and having several all around the MCT)
-Fuel does not boil off over 4 month
-Martian Debris kick-up reduced (this may be THE show stopper for a 100% Raptor landing).
-High thrust to weight (I can't find quoted numbers though).
-Can double as the crew escape system during launch from Earth.
-Can possibly reduce or eliminate the need for insulating the Metholox tanks.

The disadvantages are many as well:
-Increased mass for more Engines
-2nd fuel system (although the MCT will likely have Dracos for maneuvering anyways).
-Low ISP (Can it be improved with larger nozzle?)
-No ISRU of fuel (at least not at first)
-Toxic Fuel, no getting around this, and it may require heavier tanks that can survive a micro-meteor, but then again one hit to the metholox tanks could mean LOM/LOC, and they will be a much bigger target).
-Increased noise for crew/colonists (I am picturing these up top, near the crew for use in the launch abort system)

What will it take?
Assuming 100MT landed on Mars, some sort of aerobraking, and using the Raptor(s) for most of the braking Delta-V.
100MT = 371,100 N weight on mars (980,000 N Earth)
Super Draco has 68,170 N Thrust
Thrust reduced to 61,353 N assuming a 10% cosine loss (25.8 degrees)
You would need about 12 Super Dracos to provide a t/w of 2 on Mars.  (12! That is much fewer than I expected, so I hope my math isn't wrong).

Is 2 a good t/w to shoot for for a gentle landing?  A number like 16 SD's would be about ideal for redundancy and to make Earth landings easier (The MCT should be about 50 MT by then, so close to a 2 t/w ratio there).

The next question would be the amount of fuel required for those SD's.  I did not try to model the whole EDL system, so I couldn't begin to estimate the delta-V required by the SD's.  I think nominally there should be enough to perform a soft landing on Mars and Earth, no ISRU.  I also think there should be enough to provide all the non-aero capture delta-V for the MARs EDL in case there is a problem with the Raptor or the metholox tanks.  This scenario would have to be a brown-pants and make a subsequent earth landing impossible without refueling in Earth orbit.  Jettisoning the metholox and some non-essential cargo may be necessary.   In a catastrophic emergency, they could use the launch abort and dump most of the MCT, but this would only help after a Mars colony has been established and could mount a rescue.

Thoughts?

Offline Owlon

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Re: MCT Speculation and Discussion Thread 2
« Reply #8 on: 09/19/2014 04:21 AM »
Hey all.  First time poster.

I think this MCT speculation thread has been great.  My favorite so far on NSF, which is saying a lot on this excellent forum.

.....

The issues that, to me, would disqualify using Superdracos:

1) For the MCT to work even on paper, you'll need pretty extreme mass efficiency. Adding extra engines and another fuel system adds a lot of mass. Ideally, your landing engine(s) would also be your launch engine(s), and your RCS thrusters would use Methane/LOX

2) You really don't want to carry your Earth landing propellant all the way to Mars and back, as that would add a huge mass penalty due to the exponential nature of the rocket equation. You want to be able to produce your Earth landing propellant on Mars, which restricts you to Methane (really a few other options, but Methane gets a major bonus for being the ascent fuel already)

As a super rough estimate of the needed landing delta-V on Mars, I get 500-1000 m/s. So, using a 380 isp engine means you need (at 750m/s) a bit over 20 tons to land a 100 ton MCT. Using Superdracos with an isp of 250 (this is a wild guess) I get more like 35 tons of landing propellant.

Offline ncb1397

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Re: MCT Speculation and Discussion Thread 2
« Reply #9 on: 09/19/2014 05:07 AM »
Hey all.  First time poster.

I think this MCT speculation thread has been great.  My favorite so far on NSF, which is saying a lot on this excellent forum.

.....

The issues that, to me, would disqualify using Superdracos:

1) For the MCT to work even on paper, you'll need pretty extreme mass efficiency. Adding extra engines and another fuel system adds a lot of mass. Ideally, your landing engine(s) would also be your launch engine(s), and your RCS thrusters would use Methane/LOX

2) You really don't want to carry your Earth landing propellant all the way to Mars and back, as that would add a huge mass penalty due to the exponential nature of the rocket equation. You want to be able to produce your Earth landing propellant on Mars, which restricts you to Methane (really a few other options, but Methane gets a major bonus for being the ascent fuel already)

As a super rough estimate of the needed landing delta-V on Mars, I get 500-1000 m/s. So, using a 380 isp engine means you need (at 750m/s) a bit over 20 tons to land a 100 ton MCT. Using Superdracos with an isp of 250 (this is a wild guess) I get more like 35 tons of landing propellant.

How much could a super-draco pair and the associated carbon fiber wrapped titanium spheres weigh? SpaceX rolled them out during the Dragon v2 reveal and unless both are made out of solid lead, they couldn't weigh very much. MCT might have one Raptor which doesn't exactly lend itself to fine grain control for landing, but you could get close to zero velocity and zero altitude and then use the Super Dracos for the fine grain control after that using very minimal fuel. That being said, this would require some kind of crazy flip over manuever to orient the raptor because it won't have canted thrust to fire around the heat shield. Your ISP based calculation doesn't take into the account the additional mass and effort required to store liquid oxygen and liquid methane for a 6 month journey. 15 tons of payload for propellant might have to be sacrificed for the safety and simplicity of hypergols.

Anyways, what is the key ingredient for hypergols that can be sourced on Earth but not on Mars? It may not be the most efficient process or the simplest process to produce like the sabatier reaction but you can make all kinds of fuels on Mars. Carbon monoxide, corn based ethanol, hydrogen, etc. The key is to not need very much of the more costly fuel which if the MCT lands back on Earth, it probably won't need very much landing fuel to be loaded on Mars for earth landing because of the thick atmosphere, the lightness of the unloaded MCT and the fact that an unmanned return MCT could do a very aggressive high-g landing reducing gravity losses.

edit: It could actually turn out that Monomethylhydrazine is less costly on Mars than methane because of the scarcity and high demand for hydrogen although it wouldn't really have the ISP for single-stage-to-earth.

MMH hydrogen mass fraction: ~13%
methane hydrogen mass fraction: ~25%
« Last Edit: 09/19/2014 05:23 AM by ncb1397 »

Offline guckyfan

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Re: MCT Speculation and Discussion Thread 2
« Reply #10 on: 09/19/2014 05:34 AM »

How much could a super-draco pair and the associated carbon fiber wrapped titanium spheres weigh?

Let's say as a first approximation they have no weight at all. It is the propellant that kills the idea. You have to bring the earth landing propellant to Mars and back. No, it must be methane.

BTW I don't think the landing engine can have ISP 380. IMO the vacuum engine bell wil need to be retracted, reducing ISP and thrust. It would be destroyed by the airflow before ignition. It won't be enough reduction though, to land with Raptor.

Offline nadreck

Re: MCT Speculation and Discussion Thread 2
« Reply #11 on: 09/19/2014 05:37 AM »
Reliquefaction systems exist today (though are a new technology) for LNG tankers. They have existed for a while (but at a much larger scale) for LNG storage facilities. While the MCT will be a much smaller system than current LNG tankers, I don't think it is unreasonable to visualize methane reliquefaction capabilities.  Simply shading the tank from ambient sunlight with a shade that has vacuum between it and the tank, and if the shade is also a solar panel, it can easily power the reliquifaction of the modest amount of boil off you would have after that shading.  On tankers that float on oceans >160 degrees warmer than liquid methane, before they had reliquefaction capabilities boil off was approximately 0.1 to 0.25% a day.
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Offline CyclerPilot

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Re: MCT Speculation and Discussion Thread 2
« Reply #12 on: 09/19/2014 06:00 AM »
I agree that methane/LOX is the fuel of choice.  Given the constraint of a single 4.4MN Raptor, I was trying to brainstorm a better landing method.

Even if can be throttled to, say 25%, Raptor still has a high t/w.  Issues I see are:
-debris obscuring the landing, digging a hole, and damaging the MCT.
-Engine failure means LOM/LOC.
-inability to accurately select a landing site

I am not suggesting using super dracos for the entire EDL delta-V.  Just for the last 100 m or so of decent.  Assuming the Raptor brings it to a stop at that altitude, the SD's would only need to provide about 30 m/s Delta-V (rough guess from 8 sec drop).  Round that up to 100 m/s for site selection.  In this scenario, I think a 1.5 nominal t/w for the Dracos would be enough.  How much would this cost in mass?

12 SD's at 500kg each (total guess)
At 250 isp, that takes 4,200 kg of propellant.  Double the prop if attempting a SD landing on earth as well, though for Earth it makes less sense (no debris, more gravity to make Raptor more doable)

10,200 kg.  Worth it?  Can this be trimmed more?  For all I know, SD's are even lighter.  To me, the propellant is nothing, it's just a question of how much the SDs weigh.

Offline ncb1397

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Re: MCT Speculation and Discussion Thread 2
« Reply #13 on: 09/19/2014 06:04 AM »

How much could a super-draco pair and the associated carbon fiber wrapped titanium spheres weigh?

Let's say as a first approximation they have no weight at all. It is the propellant that kills the idea. You have to bring the earth landing propellant to Mars and back. No, it must be methane.

BTW I don't think the landing engine can have ISP 380. IMO the vacuum engine bell wil need to be retracted, reducing ISP and thrust. It would be destroyed by the airflow before ignition. It won't be enough reduction though, to land with Raptor.

The Olin Raschig process for the production of hydrazine requires ammonia and hypochlorite feed stocks. You are going to want to be able to produce ammonia anyways because:

Quote
Ammonia, or azane, is a compound of nitrogen and hydrogen with the formula NH3. It is a colourless gas with a characteristic pungent smell. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or indirectly, is also a building-block for the synthesis of many pharmaceuticals and is used in many commercial cleaning products.
http://en.wikipedia.org/wiki/Ammonia

As far as hypochlorite, another chemical with industrial uses like water treatment, the biggest problem would be finding chlorine, but various landers have found chlorine compounds on Mars.

Offline DJPledger

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Re: MCT Speculation and Discussion Thread 2
« Reply #14 on: 09/19/2014 07:14 AM »
I agree that methane/LOX is the fuel of choice.  Given the constraint of a single 4.4MN Raptor, I was trying to brainstorm a better landing method.
Raptor is now 6.9MN SL thrust with the vacuum version to produce 8.2MN vacuum thrust according to Tom Mueller. It's thrust figures may still go through further refinement as the development process goes along.
« Last Edit: 09/19/2014 07:26 AM by DJPledger »

Offline Lampyridae

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Re: MCT Speculation and Discussion Thread 2
« Reply #15 on: 09/19/2014 07:48 AM »
Has anyone came up with a passable design for the MCT that incorporates the big 4.4 mega-newton thrust Raptor?  It seems like that is the way SpaceX is heading.  Given the constraints of 4 months transfer, landing 100+MT on Mars, ISRU fill-up on surface, and returning fully reusable, what can we design using at least one 4.4MN Raptor?

One option I explored a little deeper is using Super Dracos to provide the low thrust Martian landing.  This offers several advantages over the 4.4MN Raptor alone:
-Already on the shelf and qualified (this can't be over stated).
-Excellent reliability and engine out redundancy
-Already "man rated" (or will be by the time MCT flies)
-Excellent maneuverability for a controlled and aimed landing on the rocky surface (throttling and having several all around the MCT)
-Fuel does not boil off over 4 month
-Martian Debris kick-up reduced (this may be THE show stopper for a 100% Raptor landing).
-High thrust to weight (I can't find quoted numbers though).
-Can double as the crew escape system during launch from Earth.
-Can possibly reduce or eliminate the need for insulating the Metholox tanks.

The disadvantages are many as well:
-Increased mass for more Engines
-2nd fuel system (although the MCT will likely have Dracos for maneuvering anyways).
-Low ISP (Can it be improved with larger nozzle?)
-No ISRU of fuel (at least not at first)
-Toxic Fuel, no getting around this, and it may require heavier tanks that can survive a micro-meteor, but then again one hit to the metholox tanks could mean LOM/LOC, and they will be a much bigger target).
-Increased noise for crew/colonists (I am picturing these up top, near the crew for use in the launch abort system)

In all probability, the *reusable MCT* (as opposed to a pathfinding type spacecraft based off of Dragon or a Falcon Heavy upper stage) will be a true "spaceliner" and not an exploration craft. That means, it will land at a prepared concrete (or Martian equivalent) pad. Long before reusable MCTs start landing, there will be ISRU, pads and established infrastructure. The large cargo landers which precede it will not need to worry about damaging their nozzles on the way down... if this is a problem then there could easily be a workaround... skycrane, gimballing engines etc.
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Offline CuddlyRocket

Re: MCT Speculation and Discussion Thread 2
« Reply #16 on: 09/20/2014 09:19 AM »
Hey all.  First time poster.

Welcome to the forum; good first post! :)

Quote
One option I explored a little deeper is using Super Dracos to provide the low thrust Martian landing.

What would be involved in modifying SDs to use Methalox propellant?

Offline baddux

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Re: MCT Speculation and Discussion Thread 2
« Reply #17 on: 09/20/2014 06:58 PM »
I wonder what would be the way to fund MCT/BFR development? Options:
1. Will they fund building BFR and MCT from Elon Musk's pocket and start selling tickets like Virgin Galactic is doing?
2. Will they ask NASA to fund those?
3. Something else, what?

My speculation is that it could be the option 3. in following way:

- They will build BFR with 1. and 3. core variation, ~55mT and ~150mT LEO
- First they will build BFR1core and replace Falcon Heavy with that, that would be ready in ~2020, will get cash flying satellites with that
- They build MCT mk1 without some needed parts like heatshield and radiation protection in ~2025, probably partly funded by NASA
- They will launch MCT mk1 with BFR 1core to LEO and after 2025 and use it as replacement of the ISS, making money with government and space tourist customers
- If the previous is success they will proceed developing BFR 3core and MCT mk2 which can be launced to Mars, could happen ~2030

Offline The Amazing Catstronaut

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Re: MCT Speculation and Discussion Thread 2
« Reply #18 on: 09/20/2014 09:17 PM »
I wonder what would be the way to fund MCT/BFR development? Options:
1. Will they fund building BFR and MCT from Elon Musk's pocket and start selling tickets like Virgin Galactic is doing?
2. Will they ask NASA to fund those?
3. Something else, what?

My speculation is that it could be the option 3. in following way:

- They will build BFR with 1. and 3. core variation, ~55mT and ~150mT LEO
- First they will build BFR1core and replace Falcon Heavy with that, that would be ready in ~2020, will get cash flying satellites with that
- They build MCT mk1 without some needed parts like heatshield and radiation protection in ~2025, probably partly funded by NASA
- They will launch MCT mk1 with BFR 1core to LEO and after 2025 and use it as replacement of the ISS, making money with government and space tourist customers
- If the previous is success they will proceed developing BFR 3core and MCT mk2 which can be launced to Mars, could happen ~2030

Apologies for my lack of citations - they're taken mostly from Musk interviews and the general grapevine and probably do not count as Space X canon (makes a mental memo to start storing links). Regard everything typed below as merely well-researched hearsay until Space X releases whatever MTC official statement they have planned for the future.

From what Musk has insinuated in the past, there is going to be some sort of pay-to-fly element on the MCT. MCT is going to require a reusable BFR or the whole thing isn't going to work financially. The max play load of the BFR has been approximated, but is not set. Whoever gets to go will need to be at a fair state of psychological perfection, if he's going to squeeze around a hundred human sardines onto his brainchild. The MCT may utilise a water-based anti-radiation shield, which would imply one end of the craft is going to stay permanently orientated towards the sun during transit - perhaps the engine or cargo block. The BFR may carry all the way up to 400 tonnes plus to LEO in its largest configuration, which sounds fairly stupendous. It is fairly stupendous.

MTC propulsion (at least in space) is going to be orientated around a three-raptor triad layout, optimised for in-space use (larger engine bells, fuel pump alterations, ecetera) The positioning of these engines on the MTC is uncertain, as is the design shape of the MTC itself. A tri arrangement bears an element of sense to it, but also unbalances the MTC's centre of thrust if one or more of the engines fails in-flight. For this reason, we can thus assume the engines are going to be mounted as close to the ship's centreline as possible.

Conditions aboard the MTC are going to be claustrophobic, with probable segregation of passengers into small compartments. The psychological ramifications of this are apparently negative from the http://en.wikipedia.org/wiki/MARS-500 Mars 500 test carried out in Moscow; severe behavioural changes in four out of six (professional) astronauts locked within simulated deep space conditions (communications time delay, ecetera), although  Elon's emphasis on halving the travel time through a significant amount of propellant should reduce the problem - let's hope these in-space Raptors aren't too thirsty for the job they have to do; present statistical data appears promising.

The MTC will feature backup system after backup system; remember this is more than a capsule - it'll have to be a flying arcology, comparable in self-dependency to a modern nuclear submarine, but with none of the regular attributes such as being immersed in an oxygen rich environment, earth like gravitation, orů well, we all know the list.

As for landing, there are implications that the whole several hundred tonne starship may actually attempt martian landing, ISRU refuelling, before an Earth return. If this happens, I'll eat my telescope.

Essentially, all we can assume about the MTC is that it is going to be revolutionary, and will probably prove every single hypothesis we could ever type about it completely wrong, me included.
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Online Robotbeat

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Re: MCT Speculation and Discussion Thread 2
« Reply #19 on: 09/20/2014 09:26 PM »
I hope SpaceX makes MCT first. It's more important than BFR. Empty (or by using part of its own delta-v), it should be launchable by Falcon heavy into orbit where it can be refueled.
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

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