Mars Direct: How To Get To Mars With Existing Technology On A Budget We Can Afford!

[Torquemadus]

This is the video of the first public presentation of Mars Direct. This is significant, because this was filmed during the era of VHS tapes! The idea that crewed missions to Mars need to be delayed until far future sci-fi technologies are available, or require prohibitive spending on space infrastructure, is nonsense! This isn't just some daft idea from a deluded dreamer, this mission plan has been adopted by NASA as their Design Reference Mission as their plan to get to Mars. Robert Zubrin can explain this far better than I can!

Does NASA take this kind of thinking seriously?

Apologists for forty years of technological stagnation in Low Earth Orbit are being called into question!

Edited March 6, 2015 by Torquemadus

[Bill Phil]

Politics are what killed space exploration...

[FishInferno]

Politics are what killed space exploration...

For a while, yes, but now you have people like SpaceX, who aren't really effected by politics.

[Bill Phil]

For a while, yes, but now you have people like SpaceX, who aren't really effected by politics.

SpaceX is still dependent on the Government for a large piece of its funding, sadly...

Anyhow, I would rather go with von Braun's later concept that he made in the late 60s. Using two spacecraft to go to Mars.

[FishInferno]

SpaceX is still dependent on the Government for a large piece of its funding, sadly...

They may have gotten $$$ from NASA for the Dragon, but they are developing the BFR/MCT o their own expense.

Anyway, I really like the Mars Direct plan, but I am almost in favor of a 1-way trip and starting a colony because I don't want a repeat of Apollo: "Well, we landed and planted a flag there, and nobody else looks like they can get there too. So lets not bother with any more petty exploration."

[GoSlash27]

Politics are what killed space exploration...

I think it's more accurate to say that politics made the moon landings.

Best,

-Slashy

[Bill Phil]

I think it's more accurate to say that politics made the moon landings.

Best,

-Slashy

Ever hear of say, the cancellation of the Apollo program? In 1968? It was Dead on Arrival. Only funding for the rest of the missions was allocated.

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They may have gotten $$$ from NASA for the Dragon, but they are developing the BFR/MCT o their own expense.

What's the BFR/MCT?

[Newt]

Well, Mars Direct forms part of the basics of the current NASA Manned Mars reference mission (modified but similar).

So, do they take it seriously? It probably is the current most seriously taken Mars landing proposal from what I can tell. Whatever people may say, NASA is not one for one way missions. Most of the people who are going for those, are not exceptionally serious and capable.

EDIT:

As for the whole politics thing, they are both the cause of and the end of space exploration programs; politicians support space when it seems strategic, and they support it in the way that seems most strategic and beneficial for them at the time. It looked good to go to the Moon for a while, then it looked expensive, dangerous, and unnecessary. Currently to the US government, private space flight looks good, so we get the CCDev program and NASA support for Spacex and such, but that can all change very easily, just as it did when Apollo was cancelled.

Edited March 6, 2015 by Newt

[GoSlash27]

Ever hear of say, the cancellation of the Apollo program? In 1968? It was Dead on Arrival. Only funding for the rest of the missions was allocated.

Aye. It is even more true that the authorization of the Apollo program in the first place was strictly political. The continued existence and funding of NASA beyond Apollo was likewise political.

The reduced role and funding weren't the fault of politics, but rather lack of public interest. Politics simply wasn't able to overcome that after we beat the Soviets to the moon.

Best,

-Slashy

[Bill Phil]

Aye. It is even more true that the authorization of the Apollo program in the first place was strictly political. The continued existence and funding of NASA beyond Apollo was likewise political.

The reduced role and funding weren't the fault of politics, but rather lack of public interest. Politics simply wasn't able to overcome that after we beat the Soviets to the moon.

Best,

-Slashy

The moon landings may have been brought about by politics, but politics also killed it. The politicians saw no need to go further with space exploration. They beat the Russians. why go the extra mile? Been there done that.

Anyways, this is against the rules...

Mars Direct is quite the challenge. But if you're going to Mars then you need to go full scale.

[basic.syntax]

. SLS and Orion are just the first step, the pieces needed in their plan to get there (and back) are much bigger and AFAIK - no budget for them.

[Red Fang]

Nice of you t o start this topic, as I have been reviewing Zubrin's speeches for the past couple of days. Too bad I have not been able to a hold of his books by now. I'll see to remedy that asap. Meanwhile, here are my opinions on Mars Direct:

Mars Direct sounds as a solid plan, better than most, semi direct more so, regarding safety. There are some hurdles along the way.

1. Unfortunately, it seems it is to late for quick and dirty development of an STS derived vehicle, suc as Jupiter of the DIRECT proposal, so we are probably stuck with SLS and/or something new, and hopefully cheaper. Up to two or three docking launches might be acceptable: one for Earth departure stage, one for trans-Martian habitat and Mars orbit insertion stage and the third just for the crew. With a bigger launch vehicle, you might get all that launched on one really superheavy launch vehicle such as an SLS BlockII was planed.. (not sure if they still have Block II in the foreseeable future).

2. Sabateur converter has not been tested in Martian atmosphere. It should require a dedicated robotic mission to be done. The part I am most concerned about is supplying enough empty tanks to the converter as well as landing a large volume of liquid hydrogen without rupturing the tank. ~8 tons or about 85 cubic meters! Alternative is an automated system for extracting water from Mars surface and supplying it to the converter which will extract H2 and O2 from it.

3. The mission design calls for a 50-100 kW reactor that should work in Martian atmosphere. AFAIK we do not have a working design for such a machine. OTOH, even with a 25kWe reactor on Mars the mission should be doable, while a smaller design, such as a modified Topaz II with a decent turbine or a Stirling engine might work for a prototype. I do not know enough thermodynamics to judge whether cooling at such low atmospheric pressure should pose a significant problem.

4. The heaviest payload that we have landed on Mars is ~1 ton. How do we land a 20t habitat and a huge Mars Return Vehicle in the same weight class but with a huge volume and height? There might be some significant challenges to developing a heat shield and parachutes for that. There might be some merit in propulsive landing.

5. Radiation. That is a big scarecrow, or as Zubrin would say: "a dragon to be slayed". We do not need much more than several long term missions beyond the Van Allen belts to prove and IMPROVE our knowledge about radiation shielding both from cosmic rays and solar flares.

6. Life support. We need high efficiency to keep the mission weight down. That is especially important for O2 and H2O. Food should not be an issue as it is routinely packed to high nutrition/weight ratio.

7. Doublecheck everything to see if that fits into mass limits of a 20-30ton landing habitat and MAV.

8. Methane engines. No, seriously, liquid methane engines have never been in serial production, so if you want them to be reliable,

Other challenges include selection and development of rovers, making a choice of Habitat+Rover or just a bigass rover, (re)development of NERVas, choice of fuel for EDS depending on the mission architecture (any docking/orbital assembly operation will most certainly be better done with hypergorlics, and a single launch mission would be doable with hydrolox. There is a big mass penalty for hypergorlics. ); building a global survey and navigation network, testing a tether system for artificial gravity to confirm mass and reliability etc. Oh, and one more problem: wee need vehicles with long term storage capability in space.

To sum it up, you need several precursor missions:

1 or 2 - sabateur converter, tanks and reactor test on mars.

2 - Mars landing mission with heavy, bulky payloads

Methane engine testing and development, HLV, and a small station in high Earth orbit with several crews staying up for 6-24 months at a time.

I am certain that all that should be doable within a decade provided sufficient motivation and financing. HLV might be a problem that could only be solved in a CCDEV way. The thing that scares me if the Mars Direct program gets of the ground is becoming to expensive not to be shutting down the program before committing to colonization, the way Apollo got cut.

Edited March 6, 2015 by Red Fang
my spelling was a crime.

[FishInferno]

What's the BFR/MCT?

BRF is Big Fat/Freaking Rocket. It is the unofficial name given to SpaceX's Monster Raptor-powered Mars rocket. MCT is the Mars Colonial Transporter.

There are some things I agree with and some that i disagree with about the Mars Direct plan. Like I said before, the whole goal seems to just be to get there, plant a flag, and say "We did it!". While I do like the attitude of it: "We have the technology, so lets stop trying to muck with politics and make this thinkg happen!"

However, it does only seem to be a short-term plan. One example of this is the rockets. Directs uses a Big Dumb Booster, while SpaceX focuses on reusability to make spaceflight cheaper in the long run. It will be much cheaper to send hundreds of people a year to Mars if everything is reusable from the get-go.

Another thing is the issue of colonization. What I really like about Mars One (I am skeptical about them, but their idea is a good one) and SpaceX is that they are focusing on colonization right from the start, and not wasting time with "flag planting" missions. Sure, eventually we should have ships carrying people going both to and from Mars, but we should start the colonization from the beginning.

Just my 2 cents.

[Bill Phil]

Eh... I think we need more experience colonizing before Mars. The Moon is there, right? It's closer than Mars. But Mars should've been landed on in the 90s at the most.

[billbobjebkirk]

Eh... I think we need more experience colonizing before Mars. The Moon is there, right? It's closer than Mars. But Mars should've been landed on in the 90s at the most.

The problem is, the moon is less like mars than Earth, any experience we gain there is pretty much inapplicable on mars.

[cpast]

Land on Mars to what end? Unfortunately, "because it's cool" generally doesn't convince people with money to part with that money. SpaceX is no exception: they're a for-profit company that pays for its technology development by finding people willing to pay to launch payloads. So what justification will get someone who can afford to pay for a mission to actually pay for it?

[Bill Phil]

The problem is, the moon is less like mars than Earth, any experience we gain there is pretty much inapplicable on mars.

Not necessarily. Mars' big difference from the Moon is that tiny atmosphere and size. And of course distance.

If we could figure out how to better recycle air, water, and so many other things then we could do a lot more regardless of location. This is already done to an extent, but that extent is a few space stations. We should test it and improve on it for a different environment, like, say, the Moon.

Anyhow, any little bit of experience for colonizing is invaluable no matter where you are. Similar equipment could be used, and experience with that equipment would result in a better mission.

[Nibb31]

The problem is, the moon is less like mars than Earth, any experience we gain there is pretty much inapplicable on mars.

That is wrong. Life support techniques, radiation shielding, ISRU, power production, dust mitigation and decontamination, partial gravity... These are all things that are common to Mars and the Moon, and are much easier to study 3 days from Earth than 6 months every 2 years.

People are often tricked by pictures from Mars that make it look a lot like New Mexico or the Australian Outback. They see it as a desert that shares similarities with our own deserts. The colors make it look warm and hospitable. In reality, it is freezingly cold, the atmosphere is for all intents and purposes inexistant and the soil is sterile with no organic matter or minerals that can support vegetation. It has a lot more in common with the Moon than with Earth.

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Another thing is the issue of colonization. What I really like about Mars One (I am skeptical about them, but their idea is a good one) and SpaceX is that they are focusing on colonization right from the start, and not wasting time with "flag planting" missions. Sure, eventually we should have ships carrying people going both to and from Mars, but we should start the colonization from the beginning.

The only thing SpaceX is colonizing is Twitter. Beyond the PR, SpaceX is only going to Mars if somebody (NASA) hires them to. BFR/Raptor "development" is only to demonstrate that they can cater to the HLV market when SLS is cancelled.

There is no market for regular Mars trips, nor will there ever be one any time soon. It will always be expensive, even with reusable MCTs. Colonization is a silly science-fiction induced pipe dream that SpaceX uses for PR purposes, and I really wish people would put a little more thought into it before drinking the Kool Aid.

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This is the video of the first public presentation of Mars Direct. This is significant, because this was filmed during the era of VHS tapes! The idea that crewed missions to Mars need to be delayed until far future sci-fi technologies are available, or require prohibitive spending on space infrastructure, is nonsense! This isn't just some daft idea from a deluded dreamer, this mission plan has been adopted by NASA as their Design Reference Mission as their plan to get to Mars. Robert Zubrin can explain this far better than I can!

It is a vast simplification to say that the technologies required for Mars Direct are available. There is a difference between "theoretical" and "operational", which is why NASA uses a scale called the Technology Readiness Level to rate various technologies.

Systems like SLS or Orion are at TRL8. You need TRL9 before risking human lives on it.

Technologies such as ISRU, which Zubrin's mission relies on, are around TRL3, which means that there is a long way to go before they can be deployed in mission-critical roles with no redundancy. It will take at least a decade or two at current funding levels to reach TRL9. Nobody is going to Mars with operational ISRU in a life depending role before then.

And again, if we wanted to, we could develop the technology. It would be an enormous expense, but then so were Apollo or the Manhattan Project. The question is "why?". "Because we can" is a not a good enough answer when you have to convince millions of taxpayers. Heck, many taxpayers don't even want to pay for schools or hospitals, why would they pay for flags and footprints on another planet? They will pay for entertainment, but Hollywood produces better entertainment for cheaper.

America had reasons for Apollo or the Manhattan Project. It was at war (hot or cold). There is no reason today to launch such a huge effort to go to Mars.

As for the idea of a colony, that is totally premature. Take the ISS. It's Humanity's effort to keep 7 humans alive in space. It took a huge effort and decades of international cooperation to build, yet it needs regular maintenance and logistics flight just to keep those 7 people alive. To make a self-sufficient colony, you would need thousands of people, something on the scale of 150 times the effort that was needed to build the ISS. And you need the resources to fling all that infrastructure not just to 400km above us, but to another freaking planet.

And who is going to pay for a self-sufficient colony on Mars ?

- Elon Musk ? Even his pockets aren't that deep.

- The colonists ? Only the Uber-rich could afford a ticket. But uber-rich people don't like to get their hands dirty and won't give up their lifestyle to spend the rest of their life in a glorified Airstream trailer.

- Governments ? Why would they fund a colony that is bound to either become economically independant and turn its back on them if it succeeds, or become a liability that is going to cost billions just to keep the people alive if it fails. There is no winning scenario.

No, colonies are stupid. The best we can hope for is a science outpost, but even that is a stretch. There simply isn't much science that can be done in a limited science outpost that can't be done for much cheaper, over a much broader area, and over a much longer time, with robots. The only science that you can only get from sending people to live on Mars is to learn how to send people to live on Mars, which is a bit too circular to be a proper justification.

Edited March 7, 2015 by Nibb31

[Rune]

Hey, Marts Direct! It was interestign to see the VHS video of its first presentation. Really puts into perspective how old this plan is!

Anyhow, I've always liked it, but with a big grain of salt. Basically, Zubrin's margin are so razor-tight, and his mass assumptions so optimistic, that I seriously doubt it is realistic. With a bigger booster and doubling most mass figures? Maybe. I still think the ERV to return to Earth is going to be a very tight space to spend month on the way back.

In any case, I think it's biggest merit is to show that you don't really need a "Battlestar Gallactica" approach, with thousands of tonnes launched to LEO in order to get going. Basically, what you really need is the capability to put 20-50mT payloads on a Mars-bound trajectory, and preposition supplies every launch window. In fact, the thing I like the most about it is that is form a true exploration campaign, with a cadence of regular missions that increase the amount of hardware on the ground every two years.

Now, how would I do it? Well, I would launch bigger payloads for starters. A standard of 100mT would probably do, I think you can put in there either a Hab + lander, or a surface hab + ISRU unit (to produce fuel for ascent, that would prove itself before a crewed mission leaves of course). Capturing into a highly elliptical orbit on Mars, delta-v requirements for the orbit-orbit leg of the mission are reasonable, going down to Mars from there is only a matter of using the atmosphere to slow you down, and going back up you can use locally produced fuel. That way you absolutely slash the total delta-v budget for the trip, and still each leg of the trip is within the realm of what a single-stage reusable vehicle could do. Ok, maybe the Earth-Mars leg asks for nukes, but if you make your departure from L2, even chemical engines should be able to do it in a single stage. In any case, even disposable chemical transfer stages would do. You have to launch twice as many? Great, more business to lower the price per kg to low earth orbit... and it will still be cheaper than developing the monster rocket that can do the mission in less launches. That is a mighty important point, imagine the mass that could have been lofted to LEO for what SLS has eaten to date.

That way the whole infrastructure is reusable, and all you have to do to keep on going with the missions is to lift up new payloads and fuel each time to your initial staging point.... with a variety of rockets allowing international cooperation to share the costs. And minimal development costs, mostly for the Mars-dedicated hardwre. Also, note that you can prove the whole orbital thing with a flight to Mars orbit (or an asteroid) before you develop the surface elements.

What NASA should do if they were serious about going to Mars is to develop the long-stay interplanetary Habs that they need to make the trip, and the transfer stages to push them around. Instead, they are following the incredibly expensive ion route, that even in the best of cases won't really solve anything (ion engines don't cut the travel time because their thrust is tiny, and they don't really cut weight either because their powerplants are huge, the only thing that they do well for human spaceflight is to burn a lot of money). If they really wanted to develop the engine that would open the solar system to humans, they would be working of nuclear engines: high isp, high thrust propulsion that allow single stages to... anywhere? It can certainly allows a round trip to Mars in a single stage. In any case, for Mars you don't really need either, the delta-v budget is really not much over what a lunar flight entails.

As to the "dragons" along the way (i.e: radiation and microgravity), there I completely concur with Zubrin: they have been blown completely out of proportion, and are not really show-stoppers... unless you want political justifications to not go. Landing big payloads on Mars is bit of a tougher nut to crack, but F9 actually shows that supersonic retro-propulsion is not an impossible technology.

The point is to start building the things you really need, if you want to do this. An ISRU demonstrator, use it for a sample return mission. Big transfer stages, test them by launching a probe to the outer solar system faster than it could have gotten there otherwise (extra points if you recover it by slowing it down after it accelerates and releases the payload). Long duration habitats, initially test them in LEO where rescue is immediate, then move to cislunar space, then out to NEOs, doing awesome crewed missions with a decent science component along the way.

Those are the things NASA would be doing, if they where seriously thinking about gong to Mars. And they don't even need a much bigger budget that what developing SLS and ORION takes right now.

Rune. Of course, NASA is a political entity controlled by Congress, you have to take everything they say as such.

[Nibb31]

Basically, what you really need is the capability to put 20-50mT payloads on a Mars-bound trajectory, and preposition supplies every launch window. In fact, the thing I like the most about it is that is form a true exploration campaign, with a cadence of regular missions that increase the amount of hardware on the ground every two years.

So much for exploration. Mars has a surface area of 144,798,500 km2 and you are advocating sending regular missions to explore the same area over and over again. Exploration will be limited to a 20-50km radius around the base, depending on the range of the rover and safety constraints (and then only if you have two rovers). If your first mission spends several months exploring that small area, you will have it pretty well covered. What would be the point of sending the next missions to the same place? Wouldn't you want to diversify your science results by exploring a totally different site that might be several thousand km away?

Edited March 6, 2015 by Nibb31

[Bill Phil]

Well, you do a Mars DIRECT combined with the BG approach... Instead of the ERV being used for going from Mars to Earth, you could use the ERV to go to a mothership in orbit.

But if you ask me? I think going anywhere besides Earth Orbit and the Moon is going to take a multi-stage transfer stage, unless it's nuclear. Just look at the average amount of food per year one person needs. It's about a metric ton unless you want to ration it. If you get light astronauts you might be able to get nearly half that. But that's per year. How many years for a round-trip Mars mission? 3 to 5 years? That's a few tons of just the food per person on your voyage. That could translate to a heck of a lot of tons of propellant on your transfer stage. Then you have an entire habitat, with everything that entails. Plus space radiation, micro gravity, and all that jazz. While they are blown out of proportion, they are things that need to be worked on.

That's why I say the BG way is the best way. If you're going to do it, why not just full blown conquer the place? It's not the most friendly environment, but neither was, well, quite a few places on Earth. And the BG way has it's advantages: If one ship has a problem, the others can help. You're not alone anymore. And if you make it so each ship is operating at 3/4 capacity, then quite a few ships could break down and the crew could be saved within minutes. And then maybe the problem can be diagnosed and they can repair it with a supply ship? Sure it's big. But in the long run, it increases success and makes the journey not so scary anymore knowing you have other crews just a few hundred meters away (if they hold formation... which they should).

Mars DIRECT is a plan for, well, something not so grand. And if your transfer vessel screws up there's no one to save you. DIRECT is just another solution to a problem at hand. There are many, and DIRECT shouldn't be considered a savior when it comes to going to Mars.

[Rune]

So much for exploration. Mars has a surface area of 144,798,500 km2 and you are advocating sending regular missions to explore the same area over and over again. Exploration will be limited to a 20-50km radius around the base, depending on the range of the rover and safety constraints (and then only if you have two rovers). If your first mission spends several months exploring that small area, you will have it pretty well covered. What would be the point of sending the next missions to the same place? Wouldn't you want to diversify your science results by exploring a totally different site that might be several thousand km away?

Errr... first, you don't have to land everything in the same place. But if you do, it would be a hell of way to build the infrastucture to, say, support a dedicated rocket hopper to explore the whole panet in suborbital hops, refuelled from the central base. A single spots allows you to develop it much faster into a serious base. Of course, before you settle down for the long haul, you might want to explore a bit to choose the best spot possible. Then again, we already have pretty decent maps of Mars, and by the time the first habitat is landed there, we are probably going to have a pretty good idea about where we want to settle.

Rune. Besides, I'm loosely arguing for the right transport infrastructure. The details of the planetary equipment, I leave as a different problem to be tackled later.

[Bill Phil]

Errr... first, you don't have to land everything in the same place. But if you do, it would be a hell of way to build the infrastucture to, say, support a dedicated rocket hopper to explore the whole panet in suborbital hops, refuelled from the central base. A single spots allows you to develop it much faster into a serious base. Of course, before you settle down for the long haul, you might want to explore a bit to choose the best spot possible. Then again, we already have pretty decent maps of Mars, and by the time the first habitat is landed there, we are probably going to have a pretty good idea about where we want to settle.

Rune. Besides, I'm loosely arguing for the right transport infrastructure. The details of the planetary equipment, I leave as a different problem to be tackled later.

Well, with every few missions you increase the exploration range, right?

You know, most people forget, things look almost completely different when you're close to them. So, rovers should help right? They're extremely slow... And I mean slow. A human could go many kilometers in a day. I mean, come on? Who would use ICEs for remote rovers?

[Rune]

Well, you do a Mars DIRECT combined with the BG approach... Instead of the ERV being used for going from Mars to Earth, you could use the ERV to go to a mothership in orbit.

But if you ask me? I think going anywhere besides Earth Orbit and the Moon is going to take a multi-stage transfer stage, unless it's nuclear. Just look at the average amount of food per year one person needs. It's about a metric ton unless you want to ration it. If you get light astronauts you might be able to get nearly half that. But that's per year. How many years for a round-trip Mars mission? 3 to 5 years? That's a few tons of just the food per person on your voyage. That could translate to a heck of a lot of tons of propellant on your transfer stage. Then you have an entire habitat, with everything that entails. Plus space radiation, micro gravity, and all that jazz. While they are blown out of proportion, they are things that need to be worked on.

That's why I say the BG way is the best way. If you're going to do it, why not just full blown conquer the place? It's not the most friendly environment, but neither was, well, quite a few places on Earth. And the BG way has it's advantages: If one ship has a problem, the others can help. You're not alone anymore. And if you make it so each ship is operating at 3/4 capacity, then quite a few ships could break down and the crew could be saved within minutes. And then maybe the problem can be diagnosed and they can repair it with a supply ship? Sure it's big. But in the long run, it increases success and makes the journey not so scary anymore knowing you have other crews just a few hundred meters away (if they hold formation... which they should).

Mars DIRECT is a plan for, well, something not so grand. And if your transfer vessel screws up there's no one to save you. DIRECT is just another solution to a problem at hand. There are many, and DIRECT shouldn't be considered a savior when it comes to going to Mars.

Pretty much +1. But mind you, you don't really need a huge transfer stage to move large payloads: you just need a lot of small ones, and then you use a bunch of them together, or you launch a small armada in every window. That way you don't have to develop a monster launcher, and you actually amortize you initial development investment sooner. A stage capable of launching a 50mT payload to Mars can probably launch unfueled on top of an EELV-class rocket.

[Bill Phil]

Pretty much +1. But mind you, you don't really need a huge transfer stage to move large payloads: you just need a lot of small ones, and then you use a bunch of them together, or you launch a small armada in every window. That way you don't have to develop a monster launcher, and you actually amortize you initial development investment sooner. A stage capable of launching a 50mT payload to Mars can probably launch unfueled on top of an EELV-class rocket.

I wasn't saying to use a monster launcher, I would prefer building the craft in orbit. But that takes a huge investment.

Wait, is that 50 mega tons? Isn't 50 gigagrams or something? Man that is huge...

There are a lot of ways to go about doing a lot of things. Do you mean using a bunch of smaller transfer stages strapped together to act as a big one?

And here's another thing: Why is payload per launch so important? I mean, for the cost of one SLS launch you could launch almost the same payload with other launch vehicles, all in one year. So, maybe payload per year is better? In that case, SLS would be about 70 tonnes/yr, (the average person eats about that much mass of food in his/her whole lifetime, woah!). If we used the average estimates for SLS launch costs, or about 2.75 billion US dollars per launch (wikipedia data), and assuming one launch per year at 70 tonnes per launch... Then you could launch about 7 DIVHs for that cost. That's 201 tonnes/yr! Of course, this is dependent on future data, which we don't have. And I doubt the DIVH facilities are able to handle that much use. But what if the money used for developing SLS was used instead to allow the much more economical option of revamping the logistics to allow for almost 7 DIVH launches per year? We would be on Mars in a decade, by my estimate.