Amortizing reusable Mars Transports

SpaceNut · 2014-11-20 21:36:58

Human exploration missions to Mars could require up to 20 tons of cargo on the surface

Mars split mission concept

NASA plans to send bulky cargo and equipment to Mars via solar electric propulsion, with transit times of two to three years. Crew vehicles and habitat modules would be depart from lunar DRO using faster chemical rockets

Planetary exploration with SLS

Boeing is marketing the Space Launch System as a multipurpose rocket capable of launching ambitious science missions. From left: Uranus Orbiter (with probe), the 16-meter Advanced Technology Large Aperture Space Telescope (ATLAST), and Interstellar Explorer

GW Johnson · 2014-11-21 09:55:49

Hi Spacenut:

What you posted about landers, split missions, and SLS capabilities is intriguing. I cannot say I have digested and understand it all yet.

To answer your question, the 3-ship fleet in my posting is an orbit-to-orbit manned transport and two unmanned vehicles. The manned vehicle has the habitat, engines, and core structure which are are reused for other missions. It never lands anywhere. You just add loaded propellant tanks and go. The other two unmanned vehicles are propellant tank farms pushed by a Mars lander. That's unmanned one-way stuff, and can be sent first. This fleet has to rendezvous in low Mars orbit. This is actually the old 1950's picture of a manned Mars mission.

Landing operations with single-stage reusable landers draws on the in-orbit propellant tank farm. The landers are more-or-less conical capsule shapes, and they are the surface habitat for crews on the surface. One crew stays in orbit doing science while the other spends about a week at a site. Rotating surface crews provides the safety of rescue capability with the other lander. You do this during about the first half of the stay at Mars, visiting as many sites as can be supported by the tank farm you have bought. More money is more real exploration, pure and simple.

In the second half of the stay at Mars, all the crew goes to the surface with both landers at the "best" site for surface ISRU propellants, etc. If ISRU propellant manufacture works well enough, it can support suborbital trips to yet more sites to explore. If not, at least the baseline mission gets accomplished. Between the two landers and maybe a couple of inflatables, there should be plenty of living space for a few months on the surface.

The crew ascends in the landers to low orbit, for rendezvous with the tank farm and orbit-to-orbit vehicle. Landers and empty tanks are left in orbit for use later by the "next mission" whenever and whoever that might be. The orbit-to-orbit transport returns to LEO for recovery and reuse. I include small free-return-capable entry capsules in that vehicle for an engine failure accident returning to LEO. But they should never have to be used.

The orbit-to-orbit transport as I envision it is a baton shape with the hab at one end and the engines at the other. It spins end-over-end for artificial gravity in the habitat section. I always use chemical rockets for departure and arrival burns. One could add electric thrust during transit to shorten trip times, though. Locate it at the spin center, and direct its thrust perpendicular to the spin plane.

GW

Last edited by GW Johnson (2014-11-21 09:59:31)

Impaler · 2014-11-21 22:31:44

I'd like to stick more to the original thrust of the thread, which is examining how SpaceX could/would/should set up an ongoing conveyance of cargo to Mars. Perhaps we should split off the discussion of the multiple landing site initial scouting mission into another thread as their is like a gulf of decades between between these two things happening and were badly mixing time-scales to discuss them in the same breath.

Forget about all other rockets from other companies such as ULA, or international partners, SpaceX won't succeed unless it achieves huge launch cost reductions, at which point they will own the market outright (unless maybe Skylon but it's payload is so small I think it will just be a fuel tanker).

Your own launch cost math seems to show how staggeringly inefficient the other launchers are. If the F9H is used for everything then I would save nearly 4 Billion in launch costs. I find it inconceivable that 12 and 20 ton launch vehicles that have higher cost per pound are going to be used for assemble pieces of a larger mission. What kind of things are you imagining these launchers hold? Why can't we just stack 4 cargoes that would have been F9 onto a F9H and turn three launches into one and save oh around 60%. The Ariane 5 launches 2 Satellites at a time to fully utilize it's capacity, the same can be done here. Even If I can only fit 3 or even 2 cargoes that would have flown on F9 on a F9H I'm still coming out ahead using 1 F9H because it costs less then 2 F9. Caveat All based on projected costs.

Any huge monolithic piece needs a big launcher period.
Any infinitely divisible cargo (propellent) will go on the lowest cost per pound launcher, and we expect their to be more then enough propellent to fill any launcher many times over. Bigger generally leads to cheaper per pound so long as the developer is the same (NASA SLS vs SpaceX F9H breaking the trend)

Only very limited scenarios incentive using small launchers, if the small launcher cheaper per pound, has a higher safety for mission critical asset launch (crew), if their is a SINGLE medium sized piece that can very efficiently use a small launcher but not a big one.

GW Johnson · 2014-11-22 11:00:27

Impaler:

Looking at published launch prices and max payload capabilities (to LEO) for all the launchers (every country) produces a very interesting curve. The commercial launchers (subject to price competition) are all in the vicinity of $2500/lb at 10-20 tons. Spacex's published data for Falcon-Heavy falls in the vicinity of $1000/lb at 53 tons. If you extend/extrapolate that trend, the unit price should be at or under $500/lb at around 100 tons. It's probably nonlinear, but still, way under $1000/lb.

Yet NASA's best estimates for SLS fall in the vicinity of $2500/lb, which you have to take with a very big chunk of rock salt. Their history of estimating costs is abysmal. That's the difference between a government-run design and commercially-competitive designs.

From all that I conclude SLS will never be cheap: what's the cost difference between 100 tons launched to LEO at $2500+/lb on SLS, and 100 tons launched in five 20 ton chunks at $2500-2400/lb on ULA and F-9 rockets, and docked together? Not much. Not much at all.

The noncompetitive historical government missile-derived launchers like Titan-IV fall 4+ times higher than the commercial curve. The one-and-only routine spaceplane (shuttle) delivered about 15 tons for a $1B launch price: around $30,000/lb.

Skylon might (maybe someday) do better, but its inherently small payload fraction will preclude “cheap” commercially-competitive use as a tanker, which needs to be lots of tonnage. Spaceplanes will have a niche for small payloads only. Like crews.

So Spacex, ULA, their foreign counterparts like Ariane, and maybe(!!) NASA's SLS are what you have to work with for missions to Mars or anywhere else outside cis-lunar space, now, and for the foreseeable future. Period.

And, you have to consider achievable flight rates. Falcon-Heavy will be cheaper, yes, but not very many of them will be available for a long time yet. Spacex is having trouble keeping up with the Falcon-9 business it has already booked. This shows in slipped launch dates.

There might (or might not ever) be an SLS flight rate of 1 per year.

ULA actually has the highest flight rate, primarily because it has two rockets built in two different factories. But that won't last. ULA will soon have to replace the Russian engines on Atlas-5, due to the bad international relations we will be having for the foreseeable future.

The space station was a $10B+ item precisely because most of it was assembled from 15-ton items launched at near $30,000/lb. The same job could be done commercially today with 15-20 ton items at $2500/lb, which would slash the launch price by more than a factor of 10.

Looking at that overall picture of what's available and flight rates for the foreseeable future, I don't see any future in waiting for SLS which will most likely be several times more expensive than we have right now, or for the inexpensive Falcon-Heavy, whose flight rates cannot sustain a large effort. To me, that picture says use what you have now, or you'll never fly at all.

So, I disagree with your statement that current commercial rockets are "staggeringly inefficient". They are quite demonstrably the most cost-efficient means that we have. Further, smaller launchers will never be cheaper per pound. If you add Falcon-1 to the curve, it's above $4000/lb at 1 ton size. So bigger really is better, but you must use what you have. And the commercial unit prices are simply the very best available, by at least a factor of 4.

GW

louis · 2014-11-22 20:35:12

From everything I have ever read on this subject, I agree with GW.

I suggest you follow Elon Musk if you want the cheapest way to launch. He is completely devoted to delivering the cheapest possible launch system...he's not looking to maximise profit from that point of view.

If his reusable launcher systems go to plan we should see some further substantial falls in launch costs. I think Musk thought he could get it down to $500 per pound. He may be right.

When you compare that with $30,000 per pound for Space Shuttle launches we can see we are in game changer territory as regards getting to Mars.

GW Johnson wrote:

Impaler:
Looking at published launch prices and max payload capabilities (to LEO) for all the launchers (every country) produces a very interesting curve. The commercial launchers (subject to price competition) are all in the vicinity of $2500/lb at 10-20 tons. Spacex's published data for Falcon-Heavy falls in the vicinity of $1000/lb at 53 tons. If you extend/extrapolate that trend, the unit price should be at or under $500/lb at around 100 tons. It's probably nonlinear, but still, way under $1000/lb.
Yet NASA's best estimates for SLS fall in the vicinity of $2500/lb, which you have to take with a very big chunk of rock salt. Their history of estimating costs is abysmal. That's the difference between a government-run design and commercially-competitive designs.
From all that I conclude SLS will never be cheap: what's the cost difference between 100 tons launched to LEO at $2500+/lb on SLS, and 100 tons launched in five 20 ton chunks at $2500-2400/lb on ULA and F-9 rockets, and docked together? Not much. Not much at all.
The noncompetitive historical government missile-derived launchers like Titan-IV fall 4+ times higher than the commercial curve. The one-and-only routine spaceplane (shuttle) delivered about 15 tons for a $1B launch price: around $30,000/lb.
Skylon might (maybe someday) do better, but its inherently small payload fraction will preclude “cheap” commercially-competitive use as a tanker, which needs to be lots of tonnage. Spaceplanes will have a niche for small payloads only. Like crews.
So Spacex, ULA, their foreign counterparts like Ariane, and maybe(!!) NASA's SLS are what you have to work with for missions to Mars or anywhere else outside cis-lunar space, now, and for the foreseeable future. Period.
And, you have to consider achievable flight rates. Falcon-Heavy will be cheaper, yes, but not very many of them will be available for a long time yet. Spacex is having trouble keeping up with the Falcon-9 business it has already booked. This shows in slipped launch dates.
There might (or might not ever) be an SLS flight rate of 1 per year.
ULA actually has the highest flight rate, primarily because it has two rockets built in two different factories. But that won't last. ULA will soon have to replace the Russian engines on Atlas-5, due to the bad international relations we will be having for the foreseeable future.
The space station was a $10B+ item precisely because most of it was assembled from 15-ton items launched at near $30,000/lb. The same job could be done commercially today with 15-20 ton items at $2500/lb, which would slash the launch price by more than a factor of 10.
Looking at that overall picture of what's available and flight rates for the foreseeable future, I don't see any future in waiting for SLS which will most likely be several times more expensive than we have right now, or for the inexpensive Falcon-Heavy, whose flight rates cannot sustain a large effort. To me, that picture says use what you have now, or you'll never fly at all.
So, I disagree with your statement that current commercial rockets are "staggeringly inefficient". They are quite demonstrably the most cost-efficient means that we have. Further, smaller launchers will never be cheaper per pound. If you add Falcon-1 to the curve, it's above $4000/lb at 1 ton size. So bigger really is better, but you must use what you have. And the commercial unit prices are simply the very best available, by at least a factor of 4.
GW

SpaceNut · 2014-11-23 16:14:49

With it being 3 legs to a mars mission it is probably the end and work backwards to what needs to be launched that will be what we will need. This also depends on the preloading of mars surface as well as for what design will be used for Earth return.

Out going leg:
We do know what the mission on Mars surface needs are for a crew of 4 but the amounts change when we start looking at adding a greenhouse versus taking all the food we would need, giving a greater mobility for science as well as exploration, using more than just the atmosphere for insitu materials to ensure crew safety and all these impact the power souce we would want to bring. even when we say the grand total number us x we are then working to say how to land that value for x. Of course once we do know tha mars orbit vehicls value for x we can then work it back to earth orbit and further back to what it will take to launch it to earth orbit for the chunk sizes that can be used to assemble the vehicle for mars.

Return leg;
This one is dependant on mars direct launch to home from its surface or an rendevous in orbital link up with a fully stocked ship. Either case could have an earth orbit link up for the heavy heatshield for earth entry as a way to shave off mass.

Impaler · 2014-11-23 18:12:56

GW: I've said 10 times already that SLS is a boondoggle, stop beating that horse cause I AGREE, you keep pretending it is the only vehicle that will ever exist in that size class and your turning it into a straw-man.

SpaceX is committed to making IT'S OWN 100+mt launcher. THAT is the vehicle I am saying will be cost effective for Mars, it will continue the cost curve of F9, F9H and may hit that $1000/kg. When you compare commercial to government launchers your comparing across two cost curves and the bigger=cheaper effect is swallowed up. If a mission needs X tons IMLEO you always want the SMALLEST, SINGLE rocket, smallest so you use all the capacity, single so you minimize assembly and complexity, Mars missions are still likely to need several hundred ton IMLEO, but 100mt looks to be the limit of ground operation practicality (if it blows up on the pad it's preferable to have a sub-nuclear explosion), if you want to say 50-70 'medium' sized launches + assembly in orbit are adequate and we don't need 100mt launchers then I concur, but 20mt is just not practical, you you need to wait at least for F9H.

Russians are also working on Angara which in it's largest configurations will be in the 35mt range, Chinese are rapidly building bigger versions of Long-March which should be comparable and if the Chinese are really going to the Moon they will exceed 100mt. I don't think 35mt is big enough but I suspect that if F9H propellent cross-feeding works it will become industry standard and we will see a bump-up in what multi-core rockets can do into that ~50 range.

The staggering inefficiency I was referring to is between ULA & NASA vs SpaceX & Russians. When AtlasV is used without boosters it has a comparable payload to F9 and only costs TWICE as much, after the Air-force buys in bulk in the range of >40 launches AND 1 Billion dollars of overhead are subsidized by government. Delta Heavy can exceed 25mt but it is burning through 3 cores and costs 350 million. These commercial launchers actually have cost curves much like the SLS (aka 10x worse then claimed), which should be no surprise because the same companies are building both and they built them under similar cost-plus contracting for government bodies aka NASA and US Airforce, they are effectively not commercial because they don't compete for commercial satellite launches, the only real commercials now are SpaceX, Russians, Ariana, Chinese. SpaceX basically gets the kind of cost curve that the Russians achieved with Soyuz, cause Falcon9 is really when it comes down to it a redesigned Soyuz, and SpaceX engineers everything as the Russians would (and the Chinese just steal the Russian tech outright). Ariane is expected to fall out of commercial viability and become the European equivalent of ULA, launching government loads with massive subsidies.

Their is absolutely NO mission planned or budgeted right now for Mars and their won't be for decades, saying "To me, that picture says use what you have now, or you'll never fly at all." is Zubrinist impatience at it's highest, even he knew to wait for vehicles >20mt. When SLS is done their MIGHT be money freed-up for development of the Mars mission hardware, before that no chance, everything else is on a shoe-string right now. Best case is SLS flies once, is moth-balled, NASA instead uses F9H and later the SpaceX super-heavy-rocket and Congress finally lets NASA stop making rockets and concentrate on mission hardware.

Last edited by Impaler (2014-11-23 18:43:40)

SpaceNut · 2014-11-23 20:49:19

Yes paying for a standing army that has a very union restricted view of what is there job which means they are idle waiting for there narrow amount of work to come down the line. Space x does not have that problem...

GW Johnson · 2014-11-28 12:53:33

Sorry to have been absent several days. I have been very ill. Hopefully, that is coming to an end.

Impaler:

You and I agree about SLS being a boondoggle, yes. NASA is particularly susceptible to them, as we-the-people have allowed its extreme politicization. I don't see an end to that anytime soon. I don't see NASA doing anything productive about sending men to Mars or anywhere else outside cis-lunar space until that politicization does end. So no one should be holding their breath.

On the other hand, I do know about Spacex's intent to build its own giant rocket. I just don't think they will do anything in that area for some time to come. Their hands are busy coping with an accelerating launch manifest for Falcon-9, and getting Falcon-Heavy flying, plus building another spaceport in south Texas. The spaceport won't start until the test site on Texas can handle Falcon-Heavy (an effort coming to an end, I believe), and Falcon-Heavy won't fly until they can wring-it-out on the ground at the test site. On top of all that, they cannot divert engineers to the point that Falcon-9 starts failing. No, it'll be a long time yet before they make any significant start on their giant rocket. That's why I usually don't say much about it.

GW

Impaler · 2014-12-11 22:01:42

Looks like SpaceX is looking at Solar Electric Propulsion per recent interview with Gwynne Shotwell.

https://www.youtube.com/watch?v=EoCDLUHb0y4

GW Johnson · 2014-12-12 15:43:05

If it was me, I'd do a conventional-burn escape, not a slow electric spiral, with men. With cargo, a slow electric spiral is fine.

With men, I'd use the electric to raise average speed during transit, after the escape burn. And to reduce speeds before the capture burn. That is, until a really high power density electric source becomes available.

GW

Impaler · 2014-12-12 18:27:43

Yes spiraling through the Van Alen belts with passengers on-board is a no-no. But I'd just do the spiral out with the cargo and empty habitation modules and then send the passengers directly to dock with the vehicle immediately before it leaves the Earth. You can really pack people tightly on a 3 day transit, almost air-liner densities. The habitats that they need for the long transit (which Gwynne estimated at 8 months each way) are probably 10x the mass of the Taxi craft. So you might be looking at 20 launches for assembling the SEP vehicle and power system, 50 launches of cargo, 10 Argon propellent launches, 10 launches to put habitat modules in place and or stock them with provisions and water for radiation shielding (now spiral out) and then 1 taxi launch, all in that order so your departing as soon as passengers are boarded.

GW Johnson · 2014-12-14 11:21:18

I find it very interesting how these mission approaches are slowly iterating away from the Apollo-based concepts of rocketing packages directly to Mars (mostly one-way), and toward the ion-thruster orbit-to-orbit transport with landing craft idea. This was proposed in the early 1950's by Ernest Stuhlinger and Werner von Braun, et al. The modern nuance is to have the crew sent to rendezvous with fast transport, so as not to have to spend months spiraling. Especially through the Van Allen belts.

The nuance not generally discussed yet is to equip the manned orbit-to-orbit transport (separate from any unmanned orbit-to-orbit cargo transports) with both kinds of propulsion. Do the escapes and captures with high-thrust rocketry, use the ion propulsion to speed up the long transits to and from Mars. No spiraling. No chasing around all over the place with extra launches and manned vehicles trying to rendezvous. Of course, unmanned cargo just goes earlier, ion powered with spiraling, on the long trip. Time matters not, to dead hardware.

If you pick a low parking orbit with the right inclination at Mars, you relieve your landers of enough delta-vee so that one-stage reusable chemical landers become feasible. That way, multiple landings at multiple sites become possible with a minimal number of landers. All you need is to send the propellant, not so many vehicles. Visiting multiple sites was also a concept in the 1950's mission design that was very scientifically attractive then, and still today. Plus we get to try out ISRU at different sites with different resources available.

That kind of mission offers a whole lot more return than the Apollo-like stuff. But, you must spend more up front. No such thing as a free lunch.

GW

Last edited by GW Johnson (2014-12-14 11:23:13)

SpaceNut · 2014-12-14 13:13:59

How low is a Mars parking orbit to make single stage possible?

Impaler · 2014-12-14 14:37:13

Well it depends on how much high-atmospheric drag we are willing to tolerate. ISS is higher then it really 'needs' to be to because we want to avoid all the re-boost that would be necessary if it was at lower orbit, the main cause of Drag on ISS is the solar array. If your only staying briefly in orbit like the shuttle did then something like 100 km is fine and you get a considerable performance improvement by staying at lower altitude, I recall the shuttle lost about 20-25% of it's payload capability when delivering to ISS rather then it's intended lower altitude and lower inclination, how much each factor was responsible I don't know but it shows that any surface-2-orbit vehicle benefits greatly from having the target orbit be minimalistic.

Mars atmosphere is thinner then Earths, but the lower gravity means what it is 'fluffier' so Mars high atmosphere densities are likely to be closer to Earths then a direct extrapolation from surface density would indicate. On the other hand the speed of a vehicle in Mars orbit is less then that of one at Earth, and drag is proportional to velocity squared, so drag should be reduced by that. I can't say what the time for an orbit to decay on Mars is and if it is better or worse then Earth. The numbers I can recall hearing for Mars parking orbits are on the order of 200km which is ISS like, if that can be pushed down I don't know.

If we were talking about a massive brick of time-insensitive cargo modules then it doesn't need any significant panel arrays and it would have a very high density, it can also be long an thin and present a very small cross-section to the atmosphere. That means it will have very slow orbital decay and could be placed at a lower orbit. Your Mars assent/decent cargo capsule just goes up for a brief stay to load up and then comes right down again so it's own orbit will not decay significantly in the time it takes to do the load/unload. So the limiting factor is how quickly you can disassemble and transport down the the surface the cargo brick vs how long it takes to decay. If deliveries of cargo to Mars are every 26 months then it makes sense to space the dis-assembly over that long so our Mars infrastructure both ISPP and capsules is fully utilized. When the brick is fully disassembled all you have left is a truss-frame work that can be boosted back up to a more stable orbit where it can be picked up and brought back to Earth by the next SEP drive unit to depart.

SpaceNut · 2015-02-15 18:19:12

Void wrote:

However, if SpaceX can launch for $1000.00/pound, and the tanks for storing the methane are lighter, a bigger fuel budget is possible, than for using the SLS.

SpaceNut wrote:

The cost of reuse is not really a 100% as for the case of a single launch its really cost is just that; since no parts are from recycling but on the next launch the costs are only true if you know how many times you can reuse it before its junk. That could be 1 time or many but in either case there is also the incurred inspection and repair costs to add back in as well as the transportation costs in order to figure out the payload costs on a specific flight out of what numbered location in the reuseability count one might be at.

Void wrote:

They will have to profile their system, to find out what the actual expectations can be.
Yes they will have to inspect, and sometimes replace parts.
It is not a totally free booster to reuse.
I would think that they might phase them. Use the newest best ones to launch more critical loads, and if there is such, use the old ones to launch less critical loads. Less critical loads might be fuel and Oxygen to low Earth orbit. Storage of such to a purpose not yet defined, but perhaps to come.
And then I have been thinking about it because of your response, what about the Moon? As these things become less qualified for flight, perhaps use a falcon heavy without a payload, the middle booster being the marginal one. The notion being that that one could be outfitted with a different set of landing legs, which would only be folded up once. Send it to the Moon, where it's use would no longer involve passing through the atmosphere up and down, and also where it's engines could be operated at a lower thrust level to compensate for their marginal trust levels.
So I presume the would be lifting loads like LOX manufactured on the Moons surface. The tanks perhaps could be wheeled over and attached to the landing legs, to make the assembly less tipsy?
Similarly of course perhaps metals could be lifted, perhaps materials suitable for a 3D printing process?
I think there would be less options for repairs, perhaps if one was no longer suitable for that purpose, it would just go to junk on the Moon, or if it could it might lift itself to a "L" location to serve a purpose. Maybe even still as a booster that does not land. But that would only apply if it could still do valuable work. It seems less likely that that 3rd option would be workable.
So SpaceX might just have the Moon in it's pocket as well, if they prove their system.
I don't think they will wait for the Moon LOX to go to Mars however, but eventually it might be a part of a larger transport effort.
I am trying to use your acronyms. Perhaps that will please the hosts.

SpaceNut · 2015-02-15 18:45:24

The reuse of recovered first stages from high point of return for the triple barrel has net be tried yet only the low one has as there is a 40% fuel penalty to land it back on any surface to allow for less work to need to be done to it.

It is interesting to make use of it for a moon concept....

louis · 2015-02-15 20:06:54

I think perhaps you are overstating the amount of cargo that needs to be exported to Mars, once a functioning base is established.

With ISRU on Mars, you can:

1. Manufacture Earth-like air.

2. Generate electricity from concentrated solar heating and steam engines built on Mars or from methane driving steam engines, with the methane also manufactured on Mars.

3. Create soil and grow food or plants to produce raw materials for clothing.

4. Construct buildings out of Mars bricks.

5. Manufacture rocket fuel.

6. Fulfil your water needs.

Mars colonists can live very frugally. They want be requiring huge resource inputs for home furnishings, private automobiles or many sets of clothes.

Some of the key cargo requirements will probably be:

Medicines and medical equipment.

Rovers and other vehicles - although electric motors can probably be built on Mars from an early stage.

Replacement space suits.

Void · 2015-02-16 09:18:35

I suppose you are correct. Once they have raw materials for 3D printers and other manufacturing methods, electronic exports from Earth to Mars, will satisfy most needs. I would think bringing in the equipment to be able to obtain those raw materials would be the extravagant part.

GW Johnson · 2015-02-16 09:21:21

This ISRU thing also leads back to an orbit-based mission with multiple landers exploring multiple sites. If you do that the first half of your stay at Mars, you can find the site where your ISRU is most effective in terms of actual ground truth. Remember, ground truth has always been at variance with remote sensing, everywhere we have ever sent probes.

The second half of your stay is where you land everything and everybody at the "best" site (likely the one sitting on top of the buried glacier, where you can mine water with hot water down a simple well). Put your base complex there, where it can succeed, and either mothball it or leave it running on automatic when you leave. I say that, because I really do believe there will only be one government-sponsored mission to Mars. It'll get cut off just like Apollo. If the base is there, visionaries like Musk will go back sooner.

If you have an orbit-to-orbit vehicle that can keep a crew alive for the long transit, why throw it away for the return? That vehicle could take crews to any destination inside the main asteroid belt, including the NEO's. So, re-use it. Build and launch the one, use it to visit the many places.

We keep iterating back to that 1950's concept of a orbit-to-orbit ship(s) plus landers, when we look at these issues from first principles, unconstrained by who has been building what. Because it has made sense for half a century now.

I hope Musk builds his giant rocket. Think $500/lb to LEO in 100 ton modules. Not the $1000/lb with 50 ton modules to LEO with Falcon-Heavy. Not the $2500/lb with the current commercial launchers in the 10-20 ton class to LEO.

GW

Last edited by GW Johnson (2015-02-16 09:23:03)

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#26 2014-11-20 21:36:58

Re: Amortizing reusable Mars Transports

#27 2014-11-21 09:55:49

Re: Amortizing reusable Mars Transports

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#31 2014-11-23 16:14:49

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#34 2014-11-28 12:53:33

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#35 2014-12-11 22:01:42

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#36 2014-12-12 15:43:05

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#37 2014-12-12 18:27:43

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#38 2014-12-14 11:21:18

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#39 2014-12-14 13:13:59

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#40 2014-12-14 14:37:13

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#41 2015-02-15 18:19:12

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#43 2015-02-15 20:06:54

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