Use commercial to get to moon

[rockett]

Of course, if we did want to go back just for a quick visit, there is always HLR.
Human Lunar Return (HLR)
http://www.nss.org/settlement/moon/HLR.html

 

[neutrino78x]

Of course, if we did want to go back just for a quick visit, there is always HLR.
Human Lunar Return (HLR)
http://www.nss.org/settlement/moon/HLR.html

I've seen that, and it is a good idea, although I think we want to have common modules which can be used on Mars, an asteroid, or the Moon. Mars Direct modules are what I have in mind. As few parts specific to one destination as possible, yet also use indigenous resources to the greatest extent possible.

--Brian

 

[rockett]

I've seen that, and it is a good idea, although I think we want to have common modules which can be used on Mars, an asteroid, or the Moon. Mars Direct modules are what I have in mind. As few parts specific to one destination as possible, yet also use indigenous resources to the greatest extent possible.

--Brian

Actually, Brian, my ideal would be quite different. I personally think we need to exploit a modular approach.
1. In orbit assembled vehicles out of reusable modular components (habs, tank assemblies, engine clusters, etc.)
2. In orbit refueling and depots.
3. Minimal additions brought up to Earth orbit, for specific missions (such as a lunar lander, and so on).

Advantages are:
1. Making use of what we have learned in the assembly of the ISS. (If we can design, ISS modules, we can design spacecraft modules. It is purely an engineering problem.)
2. Minimal upmass per mission, with the exception of fuel replenishment.
3. Uprating individual components (not the entire vehicle), engines for instance.
4. Maximum lifetime use of any components orbited (unless uprated).
5. Replacement only of individual components that have reached the end of their service lifetimes (not the whole vehicle).

 

[DarkenedOne]

Those "commercial" outfits will have their own fixed program costs. ULA, for example, gets something like $1-ish billion per year just to keep its launch pads and rocket factories open, whether it launches or not. (The Air Force said this week, BTW, that those fixed costs are going to increase significantly in the wake of the Constellation Cancellation.) The Shuttle program fixed costs are not just for the launch, but also for the astronauts, etc., something that ULA doesn't have to worry about (yet).

True. The difference is that the fixed costs of the commercial rockets are spread over multiple sectors. That is part of the rational behind rockets like the Falcon 9 and a man-rated Atlas or Delta is that unlike Ares the fixed costs would be spread across multiple industries. This sharing of cost brings both cost and reliability benefits over rockets like the Orion, which would have a very low launch rate.

In broad, general terms, it costs X dollars to put a kilogram into orbit, regardless of who does the launching. NASA's real problem is that each Shuttle launch sends a lot of kilograms (more than 100,000 of them) into orbit, and thus costs a lot of dollars. The real reason that "commercial" crew launch would, or should, cost less is that ISS crew spacecraft are going to weigh one-tenth as much as a Shuttle orbiter. They should therefore cost one-tenth as much to launch, but that remains to be seen. NASA does not, for example, have to build a brand new Shuttle orbiter for each flight.

It is true that the weight savings alone should cost less. However there are also cost benefits to simply having a simpler vehicle. Lets not forget that the Shuttle was the most complex vehicle ever constructed. The Soyuz and the commercial alternatives by comparison are far simpler, but they get the job done.

Also delivering cargo by unmanned vehicles also decreases costs since unmanned cargo spacecraft are simpler for the reasons I previously stated.

 

[DarkenedOne]

The cargo can be launched from cheaper, less reliable, commercial rockets. Cargo does not require life support. Cargo does not require radiation shielding. Cargo does not require artificial gravity. Cargo does not require any consumables. There is no problem with cargo in space for long durations.

Exactly, that's one of the major advantages of a Mars Direct, ISRU approach. You could use automated missions to set up the solar power and a robotic device to scoop up the lunar soil and generate fuel. Then you could send humans, with fuel for only one way, and they would use the fuel generated on the moon to go back.

Although this author on The Space Review feels that Lunar ISRU would not work well.

Still, even if you don't use the ISRU method, your idea is sound, in my opinion. We can take our time sending automated machines to set things up, then the humans are sent afterward.

--Brian

That is definitely the strategy that NASA needs to pursue.

The problem is that I think NASA has not taken this strategy is that splitting the mission up like that is risker. However I think it really is the only way to economically do space travel.

The idea of shipping everything in one huge rocket/spacecraft like Apollo did is simply so expensive.

 

[neutrino78x]

modules are what I have in mind.
--Brian

Actually, Brian, my ideal would be quite different. I personally think we need to exploit a modular approach.

Clearly, we both want a modular approach, lol.

2. In orbit refueling and depots.

This part, I am still not sold on. I seem to be in the minority on here, but I think fuel depots defeat their own purpose. You still have to bring the fuel up there to put in the depot, so if you have something that needs more fuel, you might as well add the fuel on Earth, or send an autonomous device ahead of time which can generate the return fuel from the environment.

Mars Direct calls for a heavy lifter because it allows the crew delivery and habitation module to go up at the same time, with no orbital assembly. Under Mars Direct, you send an autonomous vehicle to generate the fuel for the return trip on the surface of Mars.

To me, a fuel depot only makes sense if the fuel is being made at the depot.

--Brian

 

[rockett]

This part, I am still not sold on. I seem to be in the minority on here, but I think fuel depots defeat their own purpose. You still have to bring the fuel up there to put in the depot, so if you have something that needs more fuel, you might as well add the fuel on Earth, or send an autonomous device ahead of time which can generate the return fuel from the environment.

Mars Direct calls for a heavy lifter because it allows the crew delivery and habitation module to go up at the same time, with no orbital assembly. Under Mars Direct, you send an autonomous vehicle to generate the fuel for the return trip on the surface of Mars.

To me, a fuel depot only makes sense if the fuel is being made at the depot.

--Brian

Actually, fuel depots make a lot of sense.
In the "Mars Direct" architecture I have read about, you haul the spacecraft+fuel up every time. In my thinking, it makes more sense to haul up the reusable spacecraft modules 1 time as components. These would remain in orbit, never to return, except when deorbited when they had reached the end of their service lifetimes.
It would work like this:
1. Engine modules. These would consist of standard engines that could be easily be coupled and clustered clustered together for the desired mission.
2. Tankage modules. Once again, fuel tankage groups of various sizes that could be clustered and and coupled together, based on the mission and engine modules required.
3. Life support modules. These also could be grouped together based on mission duration, crew size, and crew module(s) required.
4. Crew modules. these would be grouped and custered like the ISS modules, but they would consist of various "mission module" types.
Finally, add a lunar lander, Mars lander, or any other modules required based on the mission.

The assembled module group would comprise the "mother ship". Once the mission was completed and they returned to LEO, it could be disassembled and reconfigured for different missions.

The economy here is only hauling that mass for these modules up 1 time, for multiple missions, the moon, Mars, Venus, asteroids, L1, or whatever else required. The only thing to replenish is replacements, fuel, and resupply, much as the ISS is resupplied. Crew would be ferried to the ISS for transfer to or from orbit. That way you are not hauling an entire spacecraft for a single use, each time you plan to go somewhere.

 

[pathfinder_01]

modules are what I have in mind.
--Brian

Actually, Brian, my ideal would be quite different. I personally think we need to exploit a modular approach.

Clearly, we both want a modular approach, lol.

2. In orbit refueling and depots.

This part, I am still not sold on. I seem to be in the minority on here, but I think fuel depots defeat their own purpose. You still have to bring the fuel up there to put in the depot, so if you have something that needs more fuel, you might as well add the fuel on Earth, or send an autonomous device ahead of time which can generate the return fuel from the environment.

Mars Direct calls for a heavy lifter because it allows the crew delivery and habitation module to go up at the same time, with no orbital assembly. Under Mars Direct, you send an autonomous vehicle to generate the fuel for the return trip on the surface of Mars.

To me, a fuel depot only makes sense if the fuel is being made at the depot.

--Brian

Propelent depots can make the whole trip more manageable. You can send the fuel ahead via slower methods like ION or plasma or use lower energy slow trajectories. Now your craft only needs to Carry enough propellant to make it to the next depot instead of all the propellant to make it to it's destination.

It is sort of like Apollo, if they had went with the original idea it would have required an even bigger rocket than the Saturn V, a Nuclear thermal EDS, and A huge lander to hold enough fuel for the return. I don't think they could have made it in 8 years if they went that route. Heck could you imagine the problems with parking a lander like that on the moon and getting out.

Lunar orbit rendezvous made it more more manageable. Now the lunar lander only has to hold enough fuel to make it to the surface and back. And the command module only needs enough fuel to brake into and leave lunar orbit. Massive savings that allowed a rocket like Saturn V to do the job without needing a Nuclear thermal EDS or Huge Lander.


Also I don't think that dr. zubrin has worked a day in his life at a factory. I do think that fuel can be made automatically, However I do think that the depot will probably need some human intervention from time to time. (i.e. Clearing a clogged pipe roboticaly from earth at mars is going to take a long time).

Here is how it can make things more manageable. You could refuel a chemical rocket at L1\L2, leave and break into a high mars orbit. Refuel again and get into a lower mars orbit. This will cut down on the mass of your craft allowing a faster trip if using electric or possibly even chemical. This could allow less inspace construction due to the smaller craft. This could allow use of smaller cheaper launchers due to the smaller size of the craft and so on. You could then leave your earth departure craft in mars orbit and board a lander to the surface. Now your lander only needs to be big enough to land on mars. Instead of being big enough to land on mars and contian all of the fuel for the return trip.

When you can make propellant on site you can use the propellant to replenish the depots. For instance a lunar tug could carry lunar oxygen to L1 and possiblly Hydrogen, and bring back supplies to the moon or a moon base. Now earth no longer needs to send proplent for inbound craft and can replace that mass with something more useful.

At mars now you only need a craft big enough to hold fuel for a return trip to earth and it needs only to get to low mars orbit. That simplfies the engineering. In addition having propelent on hand in space could make a powered decent to mars an attractive option.

 

[neutrino78x]

Actually, fuel depots make a lot of sense.
In the "Mars Direct" architecture I have read about, you haul the spacecraft+fuel up every time.

Yes, but you only bring the fuel required to go one way to Mars. The fuel for the return trip is generated on the planet, converted from the atmospheric CO2.

The economy here is only hauling that mass for these modules up 1 time, for multiple missions, the moon, Mars, Venus, asteroids, L1, or whatever else required. The only thing to replenish is replacements, fuel, and resupply, much as the ISS is resupplied. Crew would be ferried to the ISS for transfer to or from orbit. That way you are not hauling an entire spacecraft for a single use, each time you plan to go somewhere.

But you still have to continually replenish these depots. Since you have to do that, you might as well bring your fuel with you, assuming you are going beyond Earth Orbit.

I would say this, however: one major benefit of doing things this way maybe be that it eliminates the need for a Heavy Lift Launcher. But I could be wrong on that.

--Brian

 

[pathfinder_01]

Actually, fuel depots make a lot of sense.
In the "Mars Direct" architecture I have read about, you haul the spacecraft+fuel up every time.

Yes, but you only bring the fuel required to go one way to Mars. The fuel for the return trip is generated on the planet, converted from the atmospheric CO2.

True but in mars direct you need to be able to land a craft big enough to generate and hold the fuel for a return mission. That does not sound trivial. He gives a dry mass of 8.1 tonnes(which I think is way the beep too optomistic). Landing such a craft on unprepared ground wont be easy. Esp, as on mars you have winds to cope with(i.e. will the wind knock my mostly empty craft down after it lands?). True the winds are not quite as forcful as on earth, but it doesn't take too much to knock something down if it has enough surface area for the wind to work on and is light(i.e. sounds like an empty mars craft). What effect will sitting on a slant do to my craft as it fills with fuel? How will the ground behave as my craft gets heavier?

It would be much simpler to just land a craft that only needs to carry part of the fuel home. It would be much smaller. It also might be smart to restrict the use of methane to the lander and to the mars equipment. That way your plant does not have to be so big or work so hard. In fact a smart move might be to generate argon for a vasmir engine in orbit and methane for your lander. You would need to move a lot less argon than you would methane for a return trip.

The economy here is only hauling that mass for these modules up 1 time, for multiple missions, the moon, Mars, Venus, asteroids, L1, or whatever else required. The only thing to replenish is replacements, fuel, and resupply, much as the ISS is resupplied. Crew would be ferried to the ISS for transfer to or from orbit. That way you are not hauling an entire spacecraft for a single use, each time you plan to go somewhere.

But you still have to continually replenish these depots. Since you have to do that, you might as well bring your fuel with you, assuming you are going beyond Earth Orbit.

I would say this, however: one major benefit of doing things this way maybe be that it eliminates the need for a Heavy Lift Launcher. But I could be wrong on that.

--Brian[/quote]

You do have to replenish, but I think the advantage of not carrying along all the proplent might be better. All the unuesed propelent in a rocket counts as mass. That is one big mass savings.

 

[rockett]

True but in mars direct you need to be able to land a craft big enough to generate and hold the fuel for a return mission. That does not sound trivial. He gives a dry mass of 8.1 tonnes(which I think is way the beep too optomistic). Landing such a craft on unprepared ground wont be easy. Esp, as on mars you have winds to cope with(i.e. will the wind knock my mostly empty craft down after it lands?). True the winds are not quite as forcful as on earth, but it doesn't take too much to knock something down if it has enough surface area for the wind to work on and is light(i.e. sounds like an empty mars craft). What effect will sitting on a slant do to my craft as it fills with fuel? How will the ground behave as my craft gets heavier?

It would be much simpler to just land a craft that only needs to carry part of the fuel home. It would be much smaller. It also might be smart to restrict the use of methane to the lander and to the mars equipment. That way your plant does not have to be so big or work so hard. In fact a smart move might be to generate argon for a vasmir engine in orbit and methane for your lander. You would need to move a lot less argon than you would methane for a return trip.

Design is actually the easy part.
Your mars fuel ship is actually nothing more than a processing plant. So, I would design it this way:
1. Large flat cone (think a huge flattened Apollo capsule shape, maybe, takes care of wind problem). No landing legs.
2. Reactor in the bottom, for stability. (unless you landed on the side of a cliff, it would be stable)
3. Internal bay, carrying small "bulldozer bots". These would retrieve and return material for processing, remove material after processing.
4. Processed gas stored in inflatable bladders. It would not be liquified until transfer to the Mars lander. This would simplify the design a great deal, because you would not have to store it in cryogenic vessels.

The difference from Mars direct, is that the processing and return vehicles would be separate. The processing unit would be a permanent Mars lander.

But you still have to continually replenish these depots. Since you have to do that, you might as well bring your fuel with you, assuming you are going beyond Earth Orbit.

Save a lot of cost and fuel. Load up water from the moon and process it in orbit using solar, then transfer it to your fuel depots. The moon has .168 G, and no atmosphere. It's MUCH cheaper than hauling fuel up from Earth.

I would say this, however: one major benefit of doing things this way maybe be that it eliminates the need for a Heavy Lift Launcher. But I could be wrong on that.

Actually, it does. You could launch these components using:
1. The Shuttle
2. Any number of existing rockets, Atlas 5, Ariene 5, Russian launchers.
3. Commercial for the smaller components (thinking Space X)

You do have to replenish, but I think the advantage of not carrying along all the proplent might be better. All the unuesed propelent in a rocket counts as mass. That is one big mass savings.

That is exactly what I am getting at.

 

[neutrino78x]

3. Internal bay, carrying small "bulldozer bots". These would retrieve and return material for processing, remove material after processing.

Well the fuel generator does not do anything with the martian soil, it just processes gases from the atmosphere. It takes in CO2 and reacts that with hydrogen to get water, then electrolysis to get oxygen.

The difference from Mars direct, is that the processing and return vehicles would be separate. The processing unit would be a permanent Mars lander.

hmm, Mars Direct has two launches for each mission, this is assuming that you are going to have several different areas where you land people. I suppose that if you already decided one spot for a permanent colony, you would have a permanent gas processor.

Save a lot of cost and fuel. Load up water from the moon and process it in orbit using solar, then transfer it to your fuel depots. The moon has .168 G, and no atmosphere. It's MUCH cheaper than hauling fuel up from Earth.

Well, yes, if you are making the fuel on the Moon, and then sending it to Earth orbit, that would probably help. My understanding, however, is that the fuel depots being proposed would be refueled by sending the fuel up from the Earth. That's the part I didn't support.

Still, for craft going directly to Mars, I would give them the fuel to go one way, on the Earth. No need to stop in Earth Orbit. Orbital assembly just puts the Mars colony off to "The Future" when we have a lot of infrastructure in space.

I think the Direct 3.0 Shuttle Derived Heavy Lifter concept is a good one for missions beyond LEO.

--Brian

 

[DarkenedOne]

Apollo-class doesn't mean "flags and footprints". It means sortie missions. These missions can be longer-duration efforts than Apollo. There are good reasons to do such exploration missions. Humans have only seen six areas, all near the equator on the Earth-facing side of the Moon. Only one of the moon walkers was a geologist. The rest were essentially test pilots.

In case you haven't noticed, NASA isn't going to be given enough money to do a lunar base, let alone start mining the place! I would prefer sortie over nothing at all, which is the current post-Constellation plan.

- Ed Kyle

When it comes to human space flight sortie mission do not really make any sense. There is little Apollo did that a robot can do for a fraction of the cost.

What human space flight really excels in is advanced capabilities like building a base and etc.

 

[neutrino78x]

Speaking of Robert Zubrin's estimate of the mass of the Earth Return Vehicle, which would generate the fuel to return home for a Mars mission, pathfinder wrote:

He gives a dry mass of 8.1 tonnes(which I think is way the beep too optomistic).

I believe you are mistaken. See the Wikipedia article on Mars Direct.

Earth Return Vehicle

The Earth Return Vehicle is a two-stage vehicle. The upper stage comprises the living accommodation for the crew during their six-month return trip to Earth from Mars. The lower stage contains the vehicle's rocket engines and a small chemical production plant.
Round trip payload
Crew compartment 7,100 kg
Reaction control system 400 kg
Biconic brake 2,450 kg
Stage 1 (dry) 6,330 kg
Stage 2 (dry) 1,770 kg
Mars-bound payload
Hydrogen for propellant production 5,810 kg
SP-100 Reactor 4,500 kg
Earth-bound payload
Crew 450 kg
Suits 300 kg
Consumables (dry food) 2,000 kg
Soil Samples 150 kg
Stage 1 propulsion system
Usable propellant (methane / oxygen) 70,160 kg
Dry mass 8,850 kg
Total engine thrust 85,237 kgf (835.89 kN)
Specific impulse 373 s (3.65 kN·s/kg)
Stage 2 propulsion system
Usable propellant (methane / oxygen) 25,000 kg
Dry mass 2,560 kg
Total engine thrust 9,059 kgf (88.84 kN)
Specific impulse 373 s (3.65 kN·s/kg)

So, add up all those masses, you get a little more than 8.1 tonnes. You get more like 58 tonnes, or something like that. The chemical plant itself is only 8 tonnes, but the whole thing is a lot more than 8 tonnes.

The Earth Return Vehicle is also the vehicle which the Crew would return in. They would get in the upper stage of it. The ERV also has all the food etc they would need on the return.

The only thing I don't really like about Zubrin's plan is that he wants to use nuclear reactors, and I am not convinced that it is safe to have a reactor in a chemical rocket launch. However, I do admit that it would be more difficult to have 100 kW of solar panels (especially given the lower level of sunlight on Mars) on it.

Here is a web site about the SP-100 reactor, which is a 100 kW nuclear reactor design for space.

--Brian

 

[rockett]

So, add up all those masses, you get a little more than 8.1 tonnes. You get more like 58 tonnes, or something like that. The chemical plant itself is only 8 tonnes, but the whole thing is a lot more than 8 tonnes.

The Earth Return Vehicle is also the vehicle which the Crew would return in. They would get in the upper stage of it. The ERV also has all the food etc they would need on the return.

The only thing I don't really like about Zubrin's plan is that he wants to use nuclear reactors, and I am not convinced that it is safe to have a reactor in a chemical rocket launch. However, I do admit that it would be more difficult to have 100 kW of solar panels (especially given the lower level of sunlight on Mars) on it.

Here is a web site about the SP-100 reactor, which is a 100 kW nuclear reactor design for space.

--Brian

Seems awfully wasteful to throw away you processing plant after only one use.

 

[neutrino78x]

Seems awfully wasteful to throw away you processing plant after only one use.

Well, if you start building up a base at one spot, you would have multiple redundant processors, under Mars Direct. Although, as I said, you could always send over one large one, if the redundancy wasn't important. Zubrin's idea is that, while you can connect the modules to make one large base, each module would be independent.

--Brian

 

[edkyle99]

When it comes to human space flight sortie mission do not really make any sense. There is little Apollo did that a robot can do for a fraction of the cost.

Robots can't do this:
http://www.youtube.com/watch?v=HKdwcLytloU&feature=fvw

- Ed Kyle

 

[rockett]

Well, if you start building up a base at one spot, you would have multiple redundant processors, under Mars Direct. Although, as I said, you could always send over one large one, if the redundancy wasn't important. Zubrin's idea is that, while you can connect the modules to make one large base, each module would be independent.

--Brian

So if I understand you correctly, the very first one would be there solo, right?

 

[neutrino78x]

So if I understand you correctly, the very first one would be there solo, right?

Sounds right... It would provide return fuel for a solo habitat module.

--Brian

 

[rockett]

So if I understand you correctly, the very first one would be there solo, right?

Sounds right... It would provide return fuel for a solo habitat module.

--Brian

What happens if something goes wrong with it while the explorers are in transit to Mars? An Apollo 13 style abort would not be possible, because you are relying on it for return fuel.

 

[neutrino78x]

So if I understand you correctly, the very first one would be there solo, right?

Sounds right... It would provide return fuel for a solo habitat module.

--Brian

What happens if something goes wrong with it while the explorers are in transit to Mars? An Apollo 13 style abort would not be possible, because you are relying on it for return fuel.

You don't send them until you confirm that the return fuel is ready. The device will sit there nice and stable until the humans arrive to use it.

--Brian