SpaceX: Mars Colonial Transporter "MCT" -- Speculation (not Raptor)

[meekGee]

One more counter-intuitive hint on how I found out that this mission profile was not only doable, but desirable: Start at Mars!

Tinker - I'm all for speculating, but when you say "I found out" - are you implying that you have some corroboration for any of this?

Or are you basing all of this on Elon comment regarding your diagram?

--

There are several posts above that argue that equal dV does not mean that the same vehicle just goes back and forth.  You should address that instead of dropping hints on how you went about constructing your theory.

IMO, since the vehicle going out is heavier, and get less aerobraking at the end, then  IF you want it to "just go to Mars turn around and come back" you need to give it a much stronger kick, so it has less dV on the way out.  This is hard to do without a second stage that stays behind, or with an in-orbit refueling scheme.

[Patchouli]

I've always thought it would make sense for MCT to be a single vehicle that launches from Earth, refuels in LEO, travels to Mars, lands on Mars, refuels, and then returns to Earth.  It seems like it would simplify the whole architecture a lot.

I think the best way to tackle large scale Mars transport would be to split the architecture into three vehicles.

One that does nothing but launch things into LEO.
Try to make this one reusable.

The next is a space only vehicle whos job is to take the payload from LEO to Mars.
If it does not reenter reuse should be easy.

The last is a lander optimized for Mars EDL.
This might be best used in an expendable fashion early on until there's a mining industry on Mars.
At first it probably would be more cost effective to recycle it on Mars vs send it back.
Think like the covered wagons used by the American pioneers during the 19th century.
They were reused at their destination vs sent back.

[meekGee]

I've always thought it would make sense for MCT to be a single vehicle that launches from Earth, refuels in LEO, travels to Mars, lands on Mars, refuels, and then returns to Earth.  It seems like it would simplify the whole architecture a lot.

I think the best way to tackle large scale Mars transport would be to split the architecture into three vehicles.

One that does nothing but launch things into LEO.
Try to make this one reusable.

The next is a space only vehicle whos job is to take the payload from LEO to Mars.
If it does not reenter reuse should be easy.

The last is a lander optimized for Mars EDL.
This might be best used in an expendable fashion early on until there's a mining industry on Mars.
At first it probably would be more cost effective to recycle it on Mars vs send it back.
Think like the covered wagons used by the American pioneers during the 19th century.
They were reused at their destination vs sent back.

This was always my thought too.  It's a basic engineering thing, right?  split the problem into tasks that differ from each other, and optimize each part of the solution to that task.

Except I'm coming around to seeing it a bit differently.

The mass of the propellant is the bulk of the problem. You're going to have to lift it to orbit anyway. The only reason to do it in multiple runs is if you're planning on going only once, and you don't want to build a rocket that flies only once.  But if you're planning on flying many times, there's something to be said for the inherent efficiency of size, and the simplicity of single launch.

You do want to take advantage of aerobraking, especially on the way back to Earth.  Yes, you can leave the interplanetary stage in orbit, but then you need to retro-brake it, and you'll need to refuel it for next time, so you're going to haul up the fuel anyway, and then - complexity again.  If it's just an empty stage - bring it down and relaunch.  It not absurd.

So overall, for a system that will be used many times, I can see the "monolithic" scenario panning out, especially since we know that SpaceX is thinking about a really BFR.

However, unlike Tinker's diagram, I don't see the problem as symmetric, and I don't see everything coming back to Earth.

First, because of all the reasons laid out in previous posts, the vehicle going out needs to be given a much larger dV then is assumed in Tinker's reasoning. So IMO two stages will stay behind.

Second, the payload compartment will stay on Mars (habitat).   What's coming back is just a minimally fueled tank and the engines.  Maybe not even all of the tanks.  (Tanks are also useful on Mars)

So if you "start on Mars" as Tinker said, you end up with something else: what's the minimal vehicle that can be launched back from Mars and land on Earth w/o any payload?  That's the reusable component.  Now size the earth-bound booster section around it.

Only my 2c of course.

[CriX]

tinker:  I think people are just jealous they didn't get to share a word with Elon, themselves.

That schematic illustrates the best way for a private business to go.  Optimized for simplicity and getting your entire ship back and only having to spend money on fuel.

The only thing I'd change on your picture is that likely the central CCB first stage will not be recoverable, at least for the first iteration of the F9HR, due to the crossfeeding and higher speed that it will attain.

[CriX]

Although one item:  While that schematic shows the general architecture of the launches and landings, it does not include details on arguably the most interesting part which will be the actual person-transporting spacecraft that will sit on top.  Whether or not MCT refers to just this upper spacecraft or the whole shebang is ... well, its pretty pedantic now that I think of it, lol.

[RocketmanUS]

I've always thought it would make sense for MCT to be a single vehicle that launches from Earth, refuels in LEO, travels to Mars, lands on Mars, refuels, and then returns to Earth.  It seems like it would simplify the whole architecture a lot.

I think the best way to tackle large scale Mars transport would be to split the architecture into three vehicles.

One that does nothing but launch things into LEO.
Try to make this one reusable.

The next is a space only vehicle whos job is to take the payload from LEO to Mars.
If it does not reenter reuse should be easy.

The last is a lander optimized for Mars EDL.
This might be best used in an expendable fashion early on until there's a mining industry on Mars.
At first it probably would be more cost effective to recycle it on Mars vs send it back.
Think like the covered wagons used by the American pioneers during the 19th century.
They were reused at their destination vs sent back.

This was always my thought too.  It's a basic engineering thing, right?  split the problem into tasks that differ from each other, and optimize each part of the solution to that task.

Except I'm coming around to seeing it a bit differently.

The mass of the propellant is the bulk of the problem. You're going to have to lift it to orbit anyway. The only reason to do it in multiple runs is if you're planning on going only once, and you don't want to build a rocket that flies only once.  But if you're planning on flying many times, there's something to be said for the inherent efficiency of size, and the simplicity of single launch.

You do want to take advantage of aerobraking, especially on the way back to Earth.  Yes, you can leave the interplanetary stage in orbit, but then you need to retro-brake it, and you'll need to refuel it for next time, so you're going to haul up the fuel anyway, and then - complexity again.  If it's just an empty stage - bring it down and relaunch.  It not absurd.

So overall, for a system that will be used many times, I can see the "monolithic" scenario panning out, especially since we know that SpaceX is thinking about a really BFR.

However, unlike Tinker's diagram, I don't see the problem as symmetric, and I don't see everything coming back to Earth.

First, because of all the reasons laid out in previous posts, the vehicle going out needs to be given a much larger dV then is assumed in Tinker's reasoning. So IMO two stages will stay behind.

Second, the payload compartment will stay on Mars (habitat).   What's coming back is just a minimally fueled tank and the engines.  Maybe not even all of the tanks.  (Tanks are also useful on Mars)

So if you "start on Mars" as Tinker said, you end up with something else: what's the minimal vehicle that can be launched back from Mars and land on Earth w/o any payload?  That's the reusable component.  Now size the earth-bound booster section around it.

Only my 2c of course.

The hab and propulsion stage would be coming back ( Elon wants the whole think back for cost savings ). It would be refueled on Mars by ISRU. The question is are they planning on bring it to EML1/2, LEO, or back to Earth?

If the BFR is a super sized FH RLV then the 2nd stage would not be part of the MCT. The MCT would have it's own propulsion stage designed around it's performance needs.

So from above posts the MCT would most likely not be brought back to Earth. So that leaves EML1/2 and LEO. Trying to design it to aero brake in Mars and Earth atmosphere would mean it would not be optimized for one of them. So that leaves EML1/2, however the MCT would need to be refuel and supplied, a lot harder to do out at EML1/2 compared to LEO and cost more. SpaceX does not want to go to the moon so I don't think they would be looking for Lunar propellants to supply their MCT out at EML1/2. So the best compromise might be to return the MCT to LEO by aero capture with active thermal cooling of the heat shield with the propellant(s).

What will have the greater delta v, LEO to Mars surface or Mars surface to LEO? That will size the propulsion stage after we also know the mass of the rest of the MCT.

If the MCT is to return to LEO for the next mission then the BFR only needs to be able to lift the mass of an empty MCT to LEO. Human rating then would be able to stay with the F9/Dragon. Added flights of BFR could bring propellant or the supplies needed for a mission.

Could the hab part of the MCT be a larger version of the Dragon capsule. If so for a crew of eight how large would it need to be? What would the mass be of air, crew, food, water, ect. need to be for a 210 day journey from LEO to Mars surface plus 10 extra day supply ( assuming air, food , water already on Mars surface for mission stay )?

[Michael Bloxham]

Perhaps the Mars *Colonial* Transport is just the bare-boned crew capsule part, with attached second stage being the necessary size for single-stage direct ascent from Mars' surface to Earth entry?

So what Tinkers diagram shows is the crewed element. Cargo to Mars' surface would be accomplished with a cargo-optimised vehicle and may not return?

 Or perhaps the propulsion element of the cargo version would perform a free-return trajectory to Mars, while the cargo element detaches for EDL? That might make a lot more sense than having *everything* return to Earth. :-)

[Roy_H]

I think the best way to tackle large scale Mars transport would be to split the architecture into three vehicles.

One that does nothing but launch things into LEO.
Try to make this one reusable.

The next is a space only vehicle who's job is to take the payload from LEO to Mars.
If it does not reenter reuse should be easy.

The last is a lander optimized for Mars EDL.

I agree 100%. The interplanetary stage could be VASIMR powered, and would not have to depend on aero-braking to achieve orbit around Earth or Mars.

[Patchouli]

Perhaps the Mars *Colonial* Transport is just the bare-boned crew capsule part, with attached second stage being the necessary size for single-stage direct ascent from Mars' surface to Earth entry?

So what Tinkers diagram shows is the crewed element. Cargo to Mars' surface would be accomplished with a cargo-optimised vehicle and may not return?

 Or perhaps the propulsion element of the cargo version would perform a free-return trajectory to Mars, while the cargo element detaches for EDL? That might make a lot more sense than having *everything* return to Earth. :-)

Early on a Mars colony would need as much raw materials as it can get so anything the ends up on Mars probably should stay there until there's metal refining going on.
Each added person will probably need to come with a few tons of raw materials.
As for how to re-purpose parts of the lander tanks could become ISRU storage the electronics could be salvaged,any valves would be useful etc.
Very large tanks could even become hab sections but anything smaller then a Centaur is unsuitable for this.

Even a small lander could provide lots of useful parts for a colony.
If the lander uses a crew cab similar to the SEV then this could be reused on a rover.

[Occupymars]

Folks:
In other words, no refueling anywhere, no stopping in either orbit, a 'roll on, roll off' ferry from Earth surface to Mars surface and back. Period, Finite. That's all she wrote!

But that must be wrong because MCT has a number attached to it tinker and that number is 500,000 dollar's per ticket which mean's MCT need's to transport a lot of people per trip to meet that number. Likely one hundred people per trip! and that can't be done without in space rendezvouses i.e Habitation Module.

No no no. $500,000 was not attached to MCT.

Read this and listen to the recording. MCT is not linked with $500,000.

http://www.bbc.co.uk/news/health-17439490

It's the only mars architecture in town! Unless there's another "fully reusable rocket transport system between Earth and Mars that is able to re-fuel on Mars" that is not MCT. He doe's not say MCT in that interview because that Interview was in march 2012 when he hadn't come up whit the MCT name yet.

[Rabidpanda]

But that must be wrong because MCT has a number attached to it tinker and that number is 500,000 dollar's per ticket which mean's MCT need's to transport a lot of people per trip to meet that number. Likely one hundred people per trip! and that can't be done without in space rendezvouses i.e Habitation Module.

No no no. $500,000 was not attached to MCT.

Read this and listen to the recording. MCT is not linked with $500,000.

http://www.bbc.co.uk/news/health-17439490

It's the only mars architecture in town! Unless there's another "fully reusable rocket transport system between Earth and Mars that is able to re-fuel on Mars" that is not MCT. He doe's not say MCT in that interview because that Interview was in march 2012 when he hadn't come up whit the MCT name yet.

$500,000 is the ultimate goal, I don't think Musk expects to reach that for a long time.  MCT is probably just the first generation vehicle and I doubt it will carry anywhere close to 100 people.

[Dave G]

It's the only mars architecture in town! Unless there's another "fully reusable rocket transport system between Earth and Mars that is able to re-fuel on Mars" that is not MCT. He doe's not say MCT in that interview because that Interview was in march 2012 when he hadn't come up whit the MCT name yet.

Quote from Musk:
http://shitelonsays.com/transcript/elon-musk-lecture-at-the-royal-aeronautical-society-2012-11-16

[How many people on a flight?] "In the beginning you'd go with a smaller number of people and you'd have a higher proportion of cargo and emergency equipment and that kind of thing. Once you really got rolling, you'd increase the number of people on the flight because you'd have supplies there. So you wouldn't need to worry about carrying with you all the supplies for the journey there, the stay on the surface and coming back. So initially you start off with maybe a handful of people, less than 10, just trying to give orders of magnitude here, but then you'd go to 100 or more in steady state, down the road."

I believe the $500,000 price tag corresponds to that "down the road" number of passengers. 

To be clear, Musk wants to get people on Mars within 10-20 years, but that's nowhere near the $500K ticket price. 

Musk also mentioned there would be a lot of investment required to build a Mars base large enough to support normal passengers at $500K each.  I believe this would require many years to come to fruition.

So we're talking 25 to 50 years from now before this $500K price has a chance of becoming real.

According to SpaceX, the MCT architecture is aimed at putting a colony on Mars within the next 10-20 years.

So logically, it seems that MCT is for the initial colony, and there would be some other architecture that would support $500,000 per person with a hundred people per flight.

[Occupymars]

But that must be wrong because MCT has a number attached to it tinker and that number is 500,000 dollar's per ticket which mean's MCT need's to transport a lot of people per trip to meet that number. Likely one hundred people per trip! and that can't be done without in space rendezvouses i.e Habitation Module.

No no no. $500,000 was not attached to MCT.

Read this and listen to the recording. MCT is not linked with $500,000.

http://www.bbc.co.uk/news/health-17439490

It's the only mars architecture in town! Unless there's another "fully reusable rocket transport system between Earth and Mars that is able to re-fuel on Mars" that is not MCT. He doe's not say MCT in that interview because that Interview was in march 2012 when he hadn't come up whit the MCT name yet.

$500,000 is the ultimate goal, I don't think Musk expects to reach that for a long time.  MCT is probably just the first generation vehicle and I doubt it will carry anywhere close to 100 people.

But that's my point if $500,000 is the ultimate goal then MCT need's to be "capable" of carrying around one hundred people per trip to make that $500,000 number viable!

[cro-magnon gramps]

But that must be wrong because MCT has a number attached to it tinker and that number is 500,000 dollar's per ticket which mean's MCT need's to transport a lot of people per trip to meet that number. Likely one hundred people per trip! and that can't be done without in space rendezvouses i.e Habitation Module.

No no no. $500,000 was not attached to MCT.

Read this and listen to the recording. MCT is not linked with $500,000.

http://www.bbc.co.uk/news/health-17439490

It's the only mars architecture in town! Unless there's another "fully reusable rocket transport system between Earth and Mars that is able to re-fuel on Mars" that is not MCT. He doe's not say MCT in that interview because that Interview was in march 2012 when he hadn't come up whit the MCT name yet.

$500,000 is the ultimate goal, I don't think Musk expects to reach that for a long time.  MCT is probably just the first generation vehicle and I doubt it will carry anywhere close to 100 people.

But that's my point if $500,000 is the ultimate goal then MCT need's to be "capable" of carrying around one hundred people per trip to make that $500,000 number viable!

Initial MCT to Mars for set up of colony

10 passengers at 500,000 each
Cargo at 45 million dollars
 top price of 50 million dollars for a MCT to Mars and return

say 3 cargo plus passengers for 30 people in "Mayflower" like voyage
with 2 fully loaded cargo MCTs. Settlers would live in the MCTs while unloading. Unloading and return would be the priority until there was only 1 MCT left, when Martian Housing would be established...

for total cost of 250 million... with return of MCTs within 18 months (launched as unloaded, from Mars) for refurb and packing for relaunch 6 months after return...

total speculation, but based on airline style pricing and rotation; now with the passage of time, either more MCTs are built, or only the first 5 are used... my inclination would be that more are built, but at what rate, that is WAGs and beyond speculation... but I would presume that within 5 years, there would be at the minimum 500 settlers on Mars... and growing (first Martians to be born on Mars within that time frame )

Gramps

[ClaytonBirchenough]

But that's my point if $500,000 is the ultimate goal then MCT need's to be "capable" of carrying around one hundred people per trip to make that $500,000 number viable!

No.

And if MCT has to carry 100 people to Mars and back, the launch costs have to be ridiculously low.

Say to get 100 people to Mars and back, you need a conservative 1,000,000 kg to be launched into LEO. At a cost of $500,000 dollars, that would mean:

$500,000 x 100 = $50,000,000 per mission.

$50,000,000 mission cost / 1,000,000 kg  = $50 per kg to LEO.

That's an extremely low launch cost. Not to mention you have development costs and all that other stuff. No; it's going to take something truly remarkable to get a person to Mars for $500,000. NOT MCT.

[Space Frog]

I would assume the long-term $500,000 ticket goal would leverage a cycler-type infrastructure where the transit ship is roomy, permanent, and doesn't do any major trajectory changes.  You'd be crazy not to, since that's essentially a space station which we're (at least fundamentally) able build and maintain now.  Prior to that you'll probably have a smaller in-space transit vehicle that loiters at Mars.  I don't know which the term "MCT" refers to. 

[ClaytonBirchenough]

There's a thread for the $500,000 to Mars topic here:

http://forum.nasaspaceflight.com/index.php?topic=28418.0

If the $500,000 relates to MCT, continue on... 

[Joel]

I think the key is developing a system with a minimum number of components. If *MCT* could fill the roles of a reusable upper stage, Earth departure stage, Mars descent and ascent vehicle, etc., you'd certainly minimize the development costs and ensure high flight rates. Exactly how you would use it (rendezvouses, refuelings in space, etc.) is probably secondary and subject to change.

The same "multi-purpose" spacecraft could probably be used to ferry people or sats to LEO/GTO/GEO, eventually replacing both the F9 upper stage and Dragon.

Being able to land it on Earth is probably important since servicing it in space could be prohibitively expensive/difficult.

[oldAtlas_Eguy]

Using some simple cost modeling for the per person to LEO price an Earth to LEO transport portion of the full MCT 200mt to LEO system would be about $500K / person. If that vehicle system is flying weekly it would be possible for the price to drop to half of that or $250K per person with 155 people per launch, a true airline to space system. Although you could transport 7,500 people per year from Earth into Space, the market for tourism would probably not support that amount, but mix that with other commercial work manpower transport and permanent settlement travel and it may come to that high.

So this next vehicle system MCT (at least the to LEO portion) could support the $500K to Mars price tag. Most likely the $500K price tag would be the next vehicle / system after that. Time frame for MCT first operations and then full operational would be similar to the start of the F9 design development (2005) to the operational capability of FH (2015) or 6 years to test and possibly initial single core like operations followed by Heavy operations at 10 years, to use a similar SpaceX development cycle. That puts initial MCT single core flight tests at about 2019 and heavy flight operations at about 2023.

If this occurs say goodbye to SLS.

[Robotbeat]

I think the key is developing a system with a minimum number of components. If *MCT* could fill the roles of a reusable upper stage, Earth departure stage, Mars descent and ascent vehicle, etc., you'd certainly minimize the development costs and ensure high flight rates. Exactly how you would use it (rendezvouses, refuelings in space, etc.) is probably secondary and subject to change.

The same "multi-purpose" spacecraft could probably be used to ferry people or sats to LEO/GTO/GEO, eventually replacing both the F9 upper stage and Dragon.

Being able to land it on Earth is probably important since servicing it in space could be prohibitively expensive/difficult.

The $500k was in context of, I think, tens of thousands of colonists every year and what was /physically/ possible (not how much would be most realistic). I think the number was 80,000 per year. $40 billion per year. The launch frequency would dwarf the current launch market in frequency and mass. Several launches per day of super-HLVs or launches every half-an-hour for Falcon Heavy-class vehicles. Except, accelerate that by quite a bit because of orbital mechanics.

If it were to ACTUALLY happen at that scale and cost, you'd have to find a way to smooth the launch rate so you don't have several hundred large launch vehicles used just a few times every year. That would be too expensive. My guess is you'd launch propellant and consumables and mass-produced habitats into LEO constantly (using a smaller number of extremely reusable launch vehicles) and launch the people in a few months every orbital window scrunched together like on commercial jet liners. The departure stages would return themselves to LEO or wherever after every departure burn and so would be able to be used a dozen times or so every window. The habs would travel by themselves most of the trip with only the very minimum in propulsive capability (maybe attitude-control with warm-gas thrusters).

Other stages would "catch" each hab at Mars, refuel in Mars orbit, also being able to be used multiple times each window. Then, highly-reusable Mars landers would capture the mass-produced habs in low Mars orbit and bring them to the surface, perhaps over a period of weeks, thus allowing just a few dozen landers to bring hundreds of habs to the surface. The habs would stay on the surface.

During the off-season (when not during a capture window), the landers would shuttle propellant to low Mars orbit.

The trick is that every element except perhaps the habs (which would be permanently used at all times) needs to be reused at least one or two hundred times in its lifespan (which can't be more than 25-30 years, realistically) to get the cost down low enough for the project to be viable at the given price.

There are some simplifications possible. For instance, the launch vehicle upper stages could be refueled and do the work of departure stage during the launch window. And similarly on the Mars side, the landers could be refueled and do the work of capture stage. This is probably preferable and could allow each component (besides the hab) to be used over a thousand times. Even the habs could be reused, but not more than about ten times (unless you count the return trip as separate). But the colonists need someplace to live anyway.


That said, I really don't think Musk is thinking of this sort of plan. I bet he's counting on reusing the habs and just hand-waving (for the moment) the issue of colony space. I also bet he's considering ways to incorporate solar-electric propulsion (for cargo, for instance).

Most launch vehicles are used just 1 time. Shuttle was used about 30 times per airframe, one and a half orders of magnitude better on first pass, but much of each vehicle was discarded (i.e. the ET) or remanufactured (the SRBs and to some extent the SSMEs) each flight and is the best we've done so far. To get to colonization of that scale, we need around 1000 flights per airframe without needing to essentially remanufacture it except maybe every 100 flights. It needs to be essentially gas-and-go and needs to fly at least once a week for twenty years. And we need LOTS of them, even if they're big. Over the course of a few decades, we'll need to build dozens of them even if they're 50-100mT. And if they're F9-class, we'll need hundreds. Like if all the Delta IIs were reusable and more.