Mars Colonial Transporter: What will it look like?

[Nibb31]

30 minutes ago, ShotgunNinja said:

100 tons is an awful small mass for a 'colony ship', the project seem way overoptimistic in general. If only we insisted with the orion, we could do direct surface-to-mars launches of 10 million tons. That is more like a colony ship. And the technology has been available for 50 years.

No it hasn't. There is a difference between "This might work on paper" and "We have the technology". The difference is called engineering, and it's subject to all sorts of real-life practicality roadblocks such as cost, regulations, environmental impact, politics, materials, supply chain, safety, etc...

Now it would be great if this thread didn't turn into yet another "If only had built Orion" discussion. We had them all before. kthxbye.

[tater]

39 minutes ago, ShotgunNinja said:

100 tons is an awful small mass for a 'colony ship', the project seem way overoptimistic in general. If only we insisted with the orion, we could do direct surface-to-mars launches of 10 million tons. That is more like a colony ship. And the technology has been available for 50 years.

The NASA Mars DRA 5 has the habitat at 30 mt. The lander is also about 30mt, and the transfer vehicle is closer to 40. That's 100mt. For a mission with 6 crew. So yeah, "colony ship" is a little hyperbolic, it's basically a Manned Mars mission ship all up in one package.

[ShotgunNinja]

@tater I see, that is realistic. Was reading the wikipedia article and seem that at least in the mind of Musk it is supposed to be a one-way only 'colony ship'. IMO it is a very unrealistic mission.

Quote

The Mars colony envisioned by Musk would start small, with an initial group of fewer than ten people. With time, Musk hopes that such an outpost could grow into something much larger and become self-sustaining, at least 1 million people.

 

@Nibb31 First the Nuclear Test Ban Treaty and then you: why everybody hate orion so much? It always fascinated me as a leap forward in term of propulsion. And besides, I was just using it as contrast.

Edited August 26, 2016 by ShotgunNinja

[kerbiloid]

2 hours ago, Nibb31 said:

Red Dragon will not be manned. They will be using it for collecting data, development and prototyping.

I see. I just find it strange to worry about bacteries on Red Dragon when the next would be Colonial Transporter with crew. As several years between them play any role.

[Rakaydos]

1 hour ago, tater said:

SpaceX apparently has around 5000 employees (wiki). If the average wage is 40k a year (the median wage in the US is 51k), each launch right now includes about 18 Million $ of payroll. That can give us a lower limit on costs with a launch a month (2/mo and you can half that figure).

The whole Mars nonsense requires billions (with zero RoI), and even making 10s of millions per satellite launch, that's still chump change. The satellite market is finite, and in other threads people (including me) have done the math looking at the last few years of launches to see what % SpaceX could possibly take. The reality is that there are a small number of possible customers per year, and that is unlikely to change significantly.

 

18 mil in payroll, sure. Probably a few million more for pad rental, and workshop rental, and material costs.

So call it 30 million profit per launch. Plus any research and development contracts they can snag on the way, like the airforce "Raptor upper stage" contract.

do you really think that, if spaceX builds a BFR, Nasa and the like wont pay to fly on it? Even with simlar markup?

[tater]

Just now, Rakaydos said:

do you really think that, if spaceX builds a BFR, Nasa and the like wont pay to fly on it? Even with simlar markup?

What will they fly on it?

You're talking about SLS sized payloads. They have SLS, and fallacy or not, they will consider "sunk cost." Not to mention the jobs program aspect. 

SLS is alreay in a situation where there are not enough payloads, and the marginal cost of launch is only really a thing if they launch at some reasonable rate, otherwise it's bet to look at total cost. Could SLS get cancelled? Sure, but it won't happen very quickly, or without a fight, as many people are employed in SLS related work, and they are intentionally in as many districts as possible. It;s like military base closures. The Pentagon has wanted most bases closed for as long as I can remember, but every time one is suggested, it becomes "critical" to national security as far as that State and it's representatives are concerned. The same will be true of swapping BFR for SLS.

[Frozen_Heart]

2 hours ago, ShotgunNinja said:

100 tons is an awful small mass for a 'colony ship', the project seem way overoptimistic in general. If only we insisted with the orion, we could do direct surface-to-mars launches of 10 million tons. That is more like a colony ship. And the technology has been available for 50 years.

Considering the record amount we have ever put on Mars is 2 tons, I think 100 tons is plenty of improvement from there.

[CptRichardson]

4 hours ago, Nibb31 said:

One way to work out the minimum requirement for the BFS, you need to look for the dV requirements for each leg of the journey. Assuming it uses for the BFR and its own propellant load to get into LEO,  the other minimum requirements are:

LEO to Mars intercept and LMO to Earth intercept = 4260m/s

Mars surface to LMO =3800m/s

So assuming that the BFS is refueled in LEO and LMO by another BFS, and assuming it needs a few hundred m/s for propulsive landing and manoeuvering, the BFS needs to have at least 5000 m/s of dV with a payload of 80 metric tons.

In order to support 100 tons after landing, the dry mass of the vehicle will have to be at least 40 tons, including landing gear, structure, life support, heatshield, etc... (I think that's optimistic). So when you plug this data into the rocket equation with an average Isp of 320s, you get a total mass of 591 mt. Which is about the weight of a fully loaded A380.

To get the BFS to LEO; the BFR first stage is going to need to spend 4000 m/s and land. The Falcon 9 separates at Mach 10, which is 3430m/s, so it might be possible to push the envelope a bit more, but this means that the tanks of the BFS are empty when they reach orbit with its 80 ton payload. If you want to go anywhere, you need to fill it up. We've calculated that the BFS tanks are going to need to carry nearly 600 tons of propellant, and since the BFS has a 80 ton payload, you are going to need 5 BFS tanker flights in LEO and in LMO to fill it up for the journey.

As for plugging the requirements of the BFR into the rocket equation, to get 4000m/s out of a 150-ton single stage with a 591-ton payload, you're rocket is going to weigh 2650 metric tons fully loaded. And that's without counting drag and gravity losses. Basically, that puts you in the Saturn V size category, with a BFR equivalent to the S-IC and S-II, and a BFS equivalent to the S-IVB and CSM/LM stack. The trick is in making the BFR and BFS reusable, which makes orbital refueling feasible.

Of course, to make this scheme work, SpaceX has yet to demonstrate:

• 1st stage reusability
• Powered landing from orbit
• Orbital spacecraft reusability
• Orbital refueling and propellant storage
• Fast turnaround of the above
• Long duration life support
• Mars reentry
• Mars powered landing
• Automated ISRU and ground refueling
• Mars launch
• Reentry from Mars

That really is an awful lot of technology to be developed by a single company.

Uh, you list is at least partially pretty freaking wrong.

They HAVE proven that their 1st stages are robust enough to relaunch and are currently testing their most-worn 1st stage to destruction to see how many times they can reuse one before failure. They have not outright relaunched them due to paperwork, but have demonstrated that they can still withstand the forces of launch several times after landing.

They HAVE demonstrated powered landing from orbit, also known as 'every single landed F9 ever'.

They have not demonstrated orbital craft reusability, but will be demonstrating this within approximately a year.

They have not demonstrated orbital refueling.

They have demonstrated the ability to refuel and immediately refire their landed stages after recovery, showing their ability to ramp into fast turnaround.

Long-duration life support is still being worked on by everyone, so not a particularly pressing need, and can be countered by lifting ungodly oodles of current-tech life support.

Mars reentry is theoretically proven and possible with their currently existing landing tech.

Mars powered landing is theoretically proven and possible with their currently existing landing tech.

Automated ISRU and ground refueling is still being worked on by everyone, and once more has the potential counter of 'launch some as tankers to land on Mars.

Mars Launch... yeah, that one needs some thinking.

Reentry from Mars: Current reentry gear, just oodles more of it.

 

And all of this discounting that they're sending the so-called 'Red Dragon' to Mars first as a testbed for Mars landing, reentry, and deep space tasks, likely pressurized and prepared as the greenhouse to Mars concept that Musk originally founded SpaceX just to do, and that at least the first BFR to Mars will be unmanned and carrying around 20 to 100 tons of probe cargo. Or that they'll almost certainly be using the BFR in Cislunar space to build the rest of the BFR infrastructure for a proper cycler ship or transport to Mars and back, and god knows how many other things that I can't even think of off the top of my head right this second.

[tater]

16 minutes ago, CptRichardson said:

Uh, you list is at least partially pretty freaking wrong.

They HAVE proven that their 1st stages are robust enough to relaunch and are currently testing their most-worn 1st stage to destruction to see how many times they can reuse one before failure. They have not outright relaunched them due to paperwork, but have demonstrated that they can still withstand the forces of launch several times after landing.

Proving it means relaunching one. It;s very likely going to happen soon, but it is not proved, or proved reliable/cost effective until they actually do it a few times.

16 minutes ago, CptRichardson said:

They HAVE demonstrated powered landing from orbit, also known as 'every single landed F9 ever'.

F9 Stage 1s that have landed have never been to orbit. That's a lot more velocity than they have.

16 minutes ago, CptRichardson said:

They have not demonstrated orbital craft reusability, but will be demonstrating this within approximately a year.

No, they won't, F9 stage 1 is not an orbital craft.

16 minutes ago, CptRichardson said:

They have demonstrated the ability to refuel and immediately refire their landed stages after recovery, showing their ability to ramp into fast turnaround.

Hardly fast, but certainly relatively fast.

16 minutes ago, CptRichardson said:

Long-duration life support is still being worked on by everyone, so not a particularly pressing need, and can be countered by lifting ungodly oodles of current-tech life support.

Until it exists it's not proven.

16 minutes ago, CptRichardson said:

Mars reentry is theoretically proven and possible with their currently existing landing tech.

Theoretical and mature enough to use for people are 2 different things. Red Dragon will be the first largeish payload to Mars ever.

16 minutes ago, CptRichardson said:

Mars powered landing is theoretically proven and possible with their currently existing landing tech.

We will not know until they do it. Possibly after multiple tries.

 

 

[Findthepin1]

58 minutes ago, tater said:

Theoretical and mature enough to use for people are 2 different things. Red Dragon will be the first largeish payload to Mars ever.

What about Curiosity? It's the size of an SUV and it weighs 2000 pounds.

[tater]

54 minutes ago, Findthepin1 said:

What about Curiosity? It's the size of an SUV and it weighs 2000 pounds.

Dragon 2 is about 6 tons. 

[Rakaydos]

Just now, tater said:

Dragon 2 is about 6 tons. 

Same order of magnitude.

[Nibb31]

1 hour ago, Findthepin1 said:

What about Curiosity? It's the size of an SUV and it weighs 2000 pounds.

It was a totally different landing method. Powered landing of a manned 150 ton vehicle is whole different matter.

 

 

All of the points tater pointed out are true. As I said above, there is a huge difference between a concept that works on paper, and actual engineering. And with a launch window every two years, maturing technology through iterative development is going to take time.

 

Edited August 26, 2016 by Nibb31

[Nibb31]

2 hours ago, CptRichardson said:

Or that they'll almost certainly be using the BFR in Cislunar space to build the rest of the BFR infrastructure for a proper cycler ship or transport to Mars and back, and god knows how many other things that I can't even think of off the top of my head right this second.

If the orbital refueling architecture proves correct, the BFS isn't going anywhere until they have at least 2 vehicles.

To demonstrate Mars return, they need at least 3: one for the journey, one to refuel in LEO, and one to refuel in LMO. The return trip is only possible if the ISRU works well enough to produce enough propellant for 4 launches, 450x9 = 2700 tons of propellant in 2 years. That's a lot to expect from an autonomous system, and you'll need some huge storage tanks too.

Edited August 26, 2016 by Nibb31

[tater]

15 minutes ago, Rakaydos said:

Same order of magnitude.

Completely different landing modality, however. Remember that it's more than just mass, there is also g load to consider. A robot is far more amenable to harsher EDL forces than people are.

The reality is that NASA is extremely interested in Red Dragon precisely because they have never landed anything even roughly analogous to landing people, and RD would actually be flying that sort of manned EDL profile.

[magnemoe]

14 minutes ago, tater said:

Completely different landing modality, however. Remember that it's more than just mass, there is also g load to consider. A robot is far more amenable to harsher EDL forces than people are.

The reality is that NASA is extremely interested in Red Dragon precisely because they have never landed anything even roughly analogous to landing people, and RD would actually be flying that sort of manned EDL profile.

And that red dragon is an standard you could stuff anything who fit into. You could probably get an larger hatch who make it more suitable for rovers. 
An issue with lots of the current space program is that its way to much one off stuff, you use years designing something then use it once and design something else. The development cost is probably higher than construction an launch cost for many of them. 

[RedKraken]

33 minutes ago, Nibb31 said:

If the orbital refueling architecture proves correct, the BFS isn't going anywhere until they have at least 2 vehicles.

To demonstrate Mars return, they need at least 3: one for the journey, one to refuel in LEO, and one to refuel in LMO. The return trip is only possible if the ISRU works well enough to produce enough propellant for 4 launches, 450x4 = 1800 tons of propellant in 2 years.

I dont think they will need to refuel at LMO. That 100 tonne payload to surface will shrink to 10(?) for the trip home, frees up lot of dv. They can get home for 7000m/s(?) from mars surface. 

I agree with your list Nibbs. Cheers! 

Edited August 26, 2016 by RedKraken

[Emperor of the Titan Squid]

Well, I found a perfect name. MCT  Andy Weir

[tater]

18 hours ago, RedKraken said:

I dont think they will need to refuel at LMO. That 100 tonne payload to surface will shrink to 10(?) for the trip home, frees up lot of dv. They can get home for 7000m/s(?) from mars surface. 

I agree with your list Nibbs. Cheers! 

I'm unsure what % actually gets left, honestly. I doubt anything like 90% of the payload is left at Mars. The vehicle itself is the payload. 

[Rakaydos]

25 minutes ago, tater said:

I'm unsure what % actually gets left, honestly. I doubt anything like 90% of the payload is left at Mars. The vehicle itself is the payload. 

If you're bringing enough supplies to keep people alive to the next synod, presumably you arn going to be bringing those supplies home. That's got to be some pretty significant mass. Drop the entire cargo comparment to save on dry mass, and it may actually approach the 90% figure.

[tater]

46 minutes ago, Rakaydos said:

If you're bringing enough supplies to keep people alive to the next synod, presumably you arn going to be bringing those supplies home. That's got to be some pretty significant mass. Drop the entire cargo comparment to save on dry mass, and it may actually approach the 90% figure.

They have talked about large doors, but the bulk of the craft is leaving, so it would be supplies. The first one would likely be left on the surface anyway. There is no way 90% is left on Mars. The craft itself is likely at least 30t. In the Mars DRAs, the lander/ascent vehicle is 30t. The transfer vehicle is 30t.

[Rakaydos]

55 minutes ago, tater said:

They have talked about large doors, but the bulk of the craft is leaving, so it would be supplies. The first one would likely be left on the surface anyway. There is no way 90% is left on Mars. The craft itself is likely at least 30t. In the Mars DRAs, the lander/ascent vehicle is 30t. The transfer vehicle is 30t.

I cannot parse the bolded line (Mainly the last bit about supplies). Can you please clarify?

I havnt seen the Mars DRAs, but I strongly suspect they ran numbers based on monoprop or hypergolic propellants. Methane engines are a new field, ISRU is theoretically sound but untested, so they would have stuck to the less efficent but storable propellant types that require every bit of fuel be carried both ways.

If the dry mass of the ship is cut even 70%, combined with the more efficent engines, they should be able to at least get on a hoffman return without martian orbit refueling.

 

-------------------------------------------------------------------------------------------------

Mirroring from (the non-pay forums at) NASAspaceflight.com:

Quote

Approaching 30 days from what (we hope) is the big reveal, I thought it a good time to revisit and post revised BFR/MCT speculation before any info leaks out.  Trying to stay within the parameters of what Musk has said as I best understand.  A TSTO vehicle launched by a re-useable, single core BFR that puts the BFS a.k.a. the MCT into LEO where it is re-fueled, travels to and lands on Mars where it is again refueled for the journey back to Earth carrying a quarter of the outbound “cargo” mass.  The outbound cargo masses 100 tonnes which I assume means either cargo or people or a combination thereof.  BFS/MCT mass not included in the 100T.

Myriad unknowns led by the dry mass of the BFS.  Rocket equation dictates various mass assumptions here can produce wildly different answers.

My predictions, metric unless otherwise stated:
1.   Entire launch vehicle BFR+BFS masses under 5,000T.  Guestimate ~4,500T.
2.   BFS dry mass < 100T, my pick is 85T carbon composites BUT heavier than some predictions because ruggedized to allow for minimal maintenance.
3.   BFR absolutely > 10m diameter to fit enough engines. Likely between 12.5 and 15m.  My guess 15m.  Allows addition of more engines in the future.
4.   My guestimate BFR+BFS stack <100m height.  Certainly <125m.
5.   Sticking with the “over 230T” Raptor thrust Elon mentioned, I get 25-27 engines.  My guestimate is 26 with “over 230T” as 235T in my spreadsheet.  Around 13.5 million Lbs force.
Engine # most likely wrong because…
6.   Predict that Raptor engine design goal thrust changed to higher than 230T previously stated, but only by several 10s of tonnes, not hundreds.
7.   BFS with 5 Rvac engines
8.   RTLS minimizes cost, turnaround time, effort.  Changed my opinion from max payload ASDS for those reasons.  Just make the BFR bigger. Stages low and slow ~2.2 Km/sec.  “Easy” recovery & re-flight vs F9 GTO flights.
9.   Initial BFR test flights likely equipped with less engines and less payload.
10.   Large crew volume design >2,000m3.  Initial flights with less people & people space but more cargo space.
11.   Initial crewed Mars mission will carry 6-12 people.  10 is my latest #. Why?
NASA & other nations will buy seats. 
http://forum.nasaspaceflight.com/index.php?topic=40683.msg1557261#msg1557261
12.   SEP still under development awaits later opposition cargo transits
13.   BFS will have “exotic” upper mounted engines for rough terrain Mars landing &takeoff (just echoing others’ analysis here)
14.   BFS will be a lifting body for EDL, but not a scaled up Dragon capsule shape.  It will look badass.

You know we’re totally screwed trying to predict Musk because he already warned us,
“When it looks more like an alien dreadnought, that’s when you know you’ve won.”

 

Edited August 27, 2016 by Rakaydos

[tater]

SpaceX people mentioned large doors... at some point (a few meters) for hauling cargo out.

Regardless, the craft itself (MCT) is huge, and must mass more than 10 tons just for its own structure, fittings, LS, etc. They're not claiming 100 mt of cargo landed, they are talking about landing a 100 mt spacecraft on Mars, some of which some is cargo. Basically, as a reality check, MCT is a Shuttle Orbiter (which had a max liftoff weight 109 mt, with a useful cargo load of ~25% of that).

If MCT mass is not included in the 100 mt to the surface, the craft itself will mass nearly 100 mt alone... maybe total mass 180? (that's a 4% payload fraction to LEO assuming the 4500 mt guesstimate for the stack total)

So 55% cargo.

Edited August 27, 2016 by tater

[tater]

If the stack is 5000t, then it's under 50% cargo (F9 puts about 4% launch mass in LEO)

[RedKraken]

31 minutes ago, tater said:

SpaceX people mentioned large doors... at some point (a few meters) for hauling cargo out.

Regardless, the craft itself (MCT) is huge, and must mass more than 10 tons just for its own structure, fittings, LS, etc. They're not claiming 100 mt of cargo landed, they are talking about landing a 100 mt spacecraft on Mars, some of which some is cargo. Basically, as a reality check, MCT is a Shuttle Orbiter (which had a max liftoff weight 109 mt, with a useful cargo load of ~25% of that).

If MCT mass is not included in the 100 mt to the surface, the craft itself will mass nearly 100 mt alone... maybe total mass 180? (that's a 4% payload fraction to LEO)

So 55% cargo.

Im thinking dry masses of ~150t. Cargo 100t.  Total 250t to the surface. Have I made a rookie mistake?

Or is it  an 85t dry + 15t cargo for total 100t to surface?

Back to the VAB RedKraken!

 

 

Edited August 27, 2016 by RedKraken