Heavy Lift an unnecessary impediment?

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sftommy

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While there are some obvious savings with regards to mass fraction for heavy lift vehicles, given the design costs and long-term delays one has to ask; “What space objective can we not achieve by building in orbit with smaller parts using our current launch capabilities?”

Appreciate eveyone's ideas!
 
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Gravity_Ray

Guest
There are a couple of basic problems with building with small parts in orbit (obviously there are some good things as well), but since you asked here are the problems:

1. Fuel storage in orbit. This problem needs to be licked before building in orbit can be solved. Fuel just doesn’t do very well in the heat and cold of space. There is no real data on how that fuel will hold up in orbit. Some obviously some work needs to be done to get some data points on this subject.

2. Launch windows. If you are building a space ship (say to get to the Moon), there are certain trajectories that must be met for TLI (trans lunar injection). If I recall correctly you have to launch every 9 days or something like that (correct me if i am wrong). So what happens if you have weather delays? Or, some other technical problem.

There is also some extra fuel needed in changing you deltaV from going from LEO or Lagrange points to TLI. Finally (although not that big of a deal) is the actual construction of the space ship in space. Will it need EVA's? Or all automated? We have seen automated docking problems with the Russian docking system (and that is one of the best systems around) where cosmonauts have had to jump in and take over the docking before something bad happens.

If we can get a heavy lift, that will simplify things a lot (about 70-100 Tons to LEO), or (about 40 to 50 Tons to TLI).
 
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voyager4d

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I don't think it will become economically feasible, to make 70+ tons heavy lift rockets in the near future (next 20 years).
The only thing that makes sense to me, is to evolve existing rockets to 40-50 tons.
I think there is no way arround it, we need to master, how to store fuel in orbit for longer periodes of time.
And of course automatic docking is also a thing we need to master to perfection.
 
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edkyle99

Guest
Gravity_Ray":1c0ztd5g said:
There are a couple of basic problems with building with small parts in orbit (obviously there are some good things as well), but since you asked here are the problems:

1. Fuel storage in orbit. This problem needs to be licked before building in orbit can be solved. Fuel just doesn’t do very well in the heat and cold of space. There is no real data on how that fuel will hold up in orbit. Some obviously some work needs to be done to get some data points on this subject.
Long-term on-orbit propellant storage is a vital need. One solution would be to go all-storable, which has worked just fine for decades on satellites that orbit for, well, decades. Not to mention Soyuz, Shenzhou, Shuttle, and ISS, where storable propellant transfer has been repeatedly demonstrated.
...
If we can get a heavy lift, that will simplify things a lot (about 70-100 Tons to LEO), or (about 40 to 50 Tons to TLI).
Super heavy lift would be terrific. It would make missions easier. One problem is that, while NASA is waiting for the money to develop super heavy lift it cannot start work. Once it starts work, it will takes years to develop. Meanwhile, the U.S. already has a stable of heavy-lift (20-25 tonne to LEO class) rockets and rocket factories and launch pads and launch crews - all bought and paid for - that are proven, but sorely underused. Why not use them? The missions would be a bit trickier, but all of the "tricky" work will be in LEO, where NASA, Russia, Europe, and Japan have managed to prove, by assembling *344+ tonne* ISS from LEO payloads weighing from 2+ to 20+ tonnes, that it can be done.

One nice thing about existing rockets is that, while they are being used their designs can be incrementally "tweaked" to provide more and more performance. The EELV Heavies could get above 30 tonnes to LEO with some reasonable effort, and to 40 tonnes with new upper stages, etc. This type of stair-step improvement has worked well for orbital launch vehicles over the years.

- Ed Kyle
 
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sftommy

Guest
1. Fuel storage in orbit. This problem needs to be licked before building in orbit can be solved. Fuel just doesn’t do very well in the heat and cold of space. There is no real data on how that fuel will hold up in orbit. Some obviously some work needs to be done to get some data points on this subject.
Oxygen and Hydrogen fuel storage seemed to be a natural for the Bigelow inflatables. Temperature regulation technologies would be needed (built into the skins?), and the permeability and chemical tolerances of the Bigelow skins would have to be extensively tested and probably modified. Solid chemical propellants might be more stable. Definitely more research needed generally

2. Launch windows. If you are building a space ship (say to get to the Moon), there are certain trajectories that must be met for TLI (trans lunar injection). If I recall correctly you have to launch every 9 days or something like that (correct me if i am wrong).
TLI could be calculated and achieved from a "LEO launch point" after construction was completed. As could most any launch target.

Finally (although not that big of a deal) is the actual construction of the space ship in space. Will it need EVA's? Or all automated? We have seen automated docking problems with the Russian docking system (and that is one of the best systems around) where cosmonauts have had to jump in and take over the docking before something bad happens.
I would assume EVAs would be required for any larger project. A thought project I mulled over several years ago was designing a satellite that could meet up with it's brethren and build a larger more capable one out of eachs own elements. Robot as space worker does seem to become an even more obvious goal.

I do favor a heavy launch vehicle's development and the advantages it would bring but when I look at the $10B spent on Constellation I think these fuel and construction issues might have been solved with that $10B.
 
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trailrider

Guest
The question with an HLV is not how long it would take to build it, but why wait until 2015 to DECIDE what to build! The thing has been studied to death, and you don't necessarily need a Saturn V class vehicle, if you will be willing to do some assembly in LEO. Where Ares V stubbed its toe was in insisting on using the RS-68, which doesn't have the thrust to lift everything that was envisioned. They finally decided on six, but then realized it would create base-heating, recirculation problems that the ablatively cooled nozzle extension couldn't handle without increasing the spacing to beyond the diameter of the notional tankage.

If they substituted SSME's left over from the Shuttle program, you could get away with fewer engines and closer spacing. By the time you ran out of reusable SSME's you could tool up (fairly cheaply) to build non-reusables that would be cheaper to make.

Perhaps a bigger consideration than the actual size of the booster is the infrastructure that is required to support assembly and launch. This isn't insurmountable, but regardless, Congress is going to have to step up to the plate.

Otherwise, we will wind up as the Portugal of the Space Age!

Ad LEO! Ad Luna! Ad Ares! Ad Astra!
 
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edkyle99

Guest
trailrider":3todt3vk said:
The question with an HLV is not how long it would take to build it, but why wait until 2015 to DECIDE what to build! The thing has been studied to death, and you don't necessarily need a Saturn V class vehicle, if you will be willing to do some assembly in LEO. Where Ares V stubbed its toe was in insisting on using the RS-68, which doesn't have the thrust to lift everything that was envisioned. They finally decided on six, but then realized it would create base-heating, recirculation problems that the ablatively cooled nozzle extension couldn't handle without increasing the spacing to beyond the diameter of the notional tankage.

If they substituted SSME's left over from the Shuttle program, you could get away with fewer engines and closer spacing. By the time you ran out of reusable SSME's you could tool up (fairly cheaply) to build non-reusables that would be cheaper to make.
The "base heating" problem isn't a factor without the big SRBs - and big segmented SRBs are soon going to exist only in history books in the U.S.. RS-68 already flies in a cluster on Delta 4 Heavy. And RS-68 has the thrust - it will produce more than 700,000 pounds of sea-level thrust in its RS-68A form, substantially more than SSME's 400,000 pounds of sea-level thrust. You need *more* SSMEs to produce the same amount of liftoff thrust.

- Ed Kyle
 
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rockett

Guest
I agree with you Ed, if we are going to build new, RS-68's are the way to go. Already proven in the Delta IV.

Also, people like trailrider seem to have the impression that there is a warehouse of SSME's out there somewhere. They don't realize we have a grand total of 15, including the ones mouted on the Orbiters and spares. Depending on the configuration, you wouldn't get many launches of a heavy lift with them before retooling for the RS-68's anyway. So why bother in the first place.
 
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sftommy

Guest
Wikipedia notes the RS-68 as needing 200 upgrades to give it human rated certification (no date on that statement) although United Launch Alliance seems to be well along the way toward human rating the Delta IV and Atlas V courtesy of some of the 2009 Commercial Crew Development funding.
 
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rockett

Guest
sftommy":3jcj72l1 said:
Wikipedia notes the RS-68 as needing 200 upgrades to give it human rated certification (no date on that statement) although United Launch Alliance seems to be well along the way toward human rating the Delta IV and Atlas V courtesy of some of the 2009 Commercial Crew Development funding.
And guess what engine Delta IV uses?
http://en.wikipedia.org/wiki/Delta_IV

:D
 
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Valcan

Guest
rockett":33qjkmyf said:
sftommy":33qjkmyf said:
Wikipedia notes the RS-68 as needing 200 upgrades to give it human rated certification (no date on that statement) although United Launch Alliance seems to be well along the way toward human rating the Delta IV and Atlas V courtesy of some of the 2009 Commercial Crew Development funding.
And guess what engine Delta IV uses?
http://en.wikipedia.org/wiki/Delta_IV

:D
What is involved in these human ratings anywasy is it just saftey stuff?
 
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rockett

Guest
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neutrino78x

Guest
trailrider":1lu7uify said:
The question with an HLV is not how long it would take to build it, but why wait until 2015 to DECIDE what to build!
Well, under Bush's plan, that would have happened in 2017. Moon in 2020, then Mars in 2030. Assuming everything happened on schedule and under budget, which isn't what was happening.

Perhaps a bigger consideration than the actual size of the booster is the infrastructure that is required to support assembly and launch. This isn't insurmountable, but regardless, Congress is going to have to step up to the plate.
Or, you can design all missions to use existing Commercial Off the Shelf rockets, which would probably involve orbital assembly.

Either way, we can go to Mars with the technology we have today. It doesn't have to be in 50 years.

But, I support the Obama Plan of stimulating private space instead of doing everything via NASA. Government needs to fade in the background to a large extent here.

--Brian
 
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neutrino78x

Guest
Gravity_Ray":1dnwzsh8 said:
There are a couple of basic problems with building with small parts in orbit (obviously there are some good things as well), but since you asked here are the problems:

1. Fuel storage in orbit. This problem needs to be licked before building in orbit can be solved. Fuel just doesn’t do very well in the heat and cold of space. There is no real data on how that fuel will hold up in orbit. Some obviously some work needs to be done to get some data points on this subject.
I keep seeing people say that, and it is in the Obama Space Plan, but I wonder, why would you store fuel in orbit? Why not simply wait until it is needed before launching it?

In other words, let's say you are going to assemble a vehicle to go to an asteroid. You put the crew habitation and command module in orbit. Then, you prep another module, which has the propulsion device (chemical rocket, vasimr, whatever), and you put that in orbit. Then, you launch a fuel module containing the fuel. Finally, you launch the people on a space taxi. All these launches are using commercial rockets such as Delta IV or Falcon 9 or whatever.

The module with the fuel should not stay up for more than, say, two or three days before the people go up and you leave.

I don't really see why you would have a fuel depot in LEO unless you're somehow generating the fuel in LEO. Otherwise, you have to launch the fuel to put into the depot, which itself requires fuel.

--Brian
 
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rockett

Guest
neutrino78x":10ju5rz5 said:
trailrider":10ju5rz5 said:
The question with an HLV is not how long it would take to build it, but why wait until 2015 to DECIDE what to build!
Well, under Bush's plan, that would have happened in 2017. Moon in 2020, then Mars in 2030. Assuming everything happened on schedule and under budget, which isn't what was happening.
You might note that Bolden has said between 2020 and 2030 for the HLV to go operational in the first place. I would have taken 2017 compared to that.
neutrino78x":10ju5rz5 said:
Or, you can design all missions to use existing Commercial Off the Shelf rockets, which would probably involve orbital assembly.
More upmass per launch (hence cheaper per pound), it's a matter of scale, like the 747 was more efficient at moving quantity than an equivalent number of 727's. If that's your contention, then keep the shuttles flying...
neutrino78x":10ju5rz5 said:
Either way, we can go to Mars with the technology we have today. It doesn't have to be in 50 years.
We would be better off solving the issues of a colony with a 3 day trip (i.e. lunar). Not so long to get help if needed.
neutrino78x":10ju5rz5 said:
But, I support the Obama Plan of stimulating private space instead of doing everything via NASA. Government needs to fade in the background to a large extent here.
I suspect that there are commercial reasons the traditional suppliers of space hardware are are hanging back and adopting a "wait and see" attitude. Most notably, they have experience in what it takes to make a profit in the space business (think R&D), where the younger companies do not.
 
A

Aggelos

Guest
don't think it will become economically feasible, to make 70+ tons heavy lift rockets in the near future (next 20 years).
The only thing that makes sense to me, is to evolve existing rockets to 40-50 tons.
the Industry I think does studies which say that the sweet spot of commercially viable hlv is 50-60 t...
maybe nasa and Bolden wants the new Hlv to be modular with 50t core.. aand small solids around to go 100 t or greater..lHorisontally assembled like delta 4.... but with Kerosene ofcourse(maybe 5 engines ?)..

some studies show that the future Geo satellites may be even 10t mass..so a 40-50 core launcher can place to of them to geo in the future..
a monolithic Saturn v like launcher will be no usefull..

and the Obama plan says i think in the pdf..that in 2015 the kerosene engine will be ready..and then the rocket will start to be constructed..
 
D

DarkenedOne

Guest
neutrino78x":12y84bji said:
Gravity_Ray":12y84bji said:
There are a couple of basic problems with building with small parts in orbit (obviously there are some good things as well), but since you asked here are the problems:

1. Fuel storage in orbit. This problem needs to be licked before building in orbit can be solved. Fuel just doesn’t do very well in the heat and cold of space. There is no real data on how that fuel will hold up in orbit. Some obviously some work needs to be done to get some data points on this subject.
I keep seeing people say that, and it is in the Obama Space Plan, but I wonder, why would you store fuel in orbit? Why not simply wait until it is needed before launching it?

In other words, let's say you are going to assemble a vehicle to go to an asteroid. You put the crew habitation and command module in orbit. Then, you prep another module, which has the propulsion device (chemical rocket, vasimr, whatever), and you put that in orbit. Then, you launch a fuel module containing the fuel. Finally, you launch the people on a space taxi. All these launches are using commercial rockets such as Delta IV or Falcon 9 or whatever.

The module with the fuel should not stay up for more than, say, two or three days before the people go up and you leave.

I don't really see why you would have a fuel depot in LEO unless you're somehow generating the fuel in LEO. Otherwise, you have to launch the fuel to put into the depot, which itself requires fuel.

--Brian
Your right Brian this is a great idea. It is probably a better and cheaper idea than fuel depots. Truth is what you are describing is what is often referred to as an earth departure stage. It was used on the Apollo missions and was planned for Constellation. The only difference is that without a heavy life vehicle it would have to be launched on separate launch vehicles, which can be done.

The space tourism company space adventures plans to do a lunar flyby mission this way. They plan to launch both a Soyuz with people and a earth departure stage on two separate rockets. Then dock them in space.

Truth is that there are many options for how to integrate smaller payloads from commercial launchers to perform space exploration. To me the biggest challenge is to get NASA out of traditional build one big rocket and send every thing in one haul attitude.
 
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rockett

Guest
DarkenedOne":1en69gzp said:
neutrino78x":1en69gzp said:
Gravity_Ray":1en69gzp said:
There are a couple of basic problems with building with small parts in orbit (obviously there are some good things as well), but since you asked here are the problems:

1. Fuel storage in orbit. This problem needs to be licked before building in orbit can be solved. Fuel just doesn’t do very well in the heat and cold of space. There is no real data on how that fuel will hold up in orbit. Some obviously some work needs to be done to get some data points on this subject.
I keep seeing people say that, and it is in the Obama Space Plan, but I wonder, why would you store fuel in orbit? Why not simply wait until it is needed before launching it?

In other words, let's say you are going to assemble a vehicle to go to an asteroid. You put the crew habitation and command module in orbit. Then, you prep another module, which has the propulsion device (chemical rocket, vasimr, whatever), and you put that in orbit. Then, you launch a fuel module containing the fuel. Finally, you launch the people on a space taxi. All these launches are using commercial rockets such as Delta IV or Falcon 9 or whatever.

The module with the fuel should not stay up for more than, say, two or three days before the people go up and you leave.

I don't really see why you would have a fuel depot in LEO unless you're somehow generating the fuel in LEO. Otherwise, you have to launch the fuel to put into the depot, which itself requires fuel.

--Brian
Your right Brian this is a great idea. It is probably a better and cheaper idea than fuel depots. Truth is what you are describing is what is often referred to as an earth departure stage. It was used on the Apollo missions and was planned for Constellation. The only difference is that without a heavy life vehicle it would have to be launched on separate launch vehicles, which can be done.

The space tourism company space adventures plans to do a lunar flyby mission this way. They plan to launch both a Soyuz with people and a earth departure stage on two separate rockets. Then dock them in space.
The least cost solution is to mine lunar ice, and send it up from a 1/6 gravity well. Split the ice into H2 and O2 as needed in orbit. Water is a very stable storage medium. All you need is a sunshade to keep it frozen.
 
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DarkenedOne

Guest
rockett":r6vwbp6g said:
DarkenedOne":r6vwbp6g said:
Your right Brian this is a great idea. It is probably a better and cheaper idea than fuel depots. Truth is what you are describing is what is often referred to as an earth departure stage. It was used on the Apollo missions and was planned for Constellation. The only difference is that without a heavy life vehicle it would have to be launched on separate launch vehicles, which can be done.

The space tourism company space adventures plans to do a lunar flyby mission this way. They plan to launch both a Soyuz with people and a earth departure stage on two separate rockets. Then dock them in space.
The least cost solution is to mine lunar ice, and send it up from a 1/6 gravity well. Split the ice into H2 and O2 as needed in orbit. Water is a very stable storage medium. All you need is a sunshade to keep it frozen.
That is another great option. It will take longer to get to that point, but it is definitely one to pursue. Like I said before I think that the biggest issue is not the technical challenges, but to get NASA to invest and pursue such options.
 
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rockett

Guest
DarkenedOne":355mcx63 said:
That is another great option. It will take longer to get to that point, but it is definitely one to pursue. Like I said before I think that the biggest issue is not the technical challenges, but to get NASA to invest and pursue such options.
Yes, it will, but sometimes you have to take an incremental approach.

Lunar ice is a real game changer, and orbital refueling the killer app of space exploration. That's where I take issue with the "Obama plan", it ignores this very important step completly. Based on this discovery we need to be focused on getting back to the moon sooner, not later, and staking our claim. Most recent estimates say there are blocks of ice 6 to 10 feet thick:

Lunar Ice Comes in Blocks
http://news.discovery.com/space/lunar-moon-ice-blocks.html

From an engineering standpoint and getting the best return on your investment, it's really the only course that makes sense. I suspect that the other countries that have announced lunar programs have already figured this out, while here in the US we are spinning dreams for political purposes.
 
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Gravity_Ray

Guest
neutrino78x":372dp17c said:
Gravity_Ray":372dp17c said:
There are a couple of basic problems with building with small parts in orbit (obviously there are some good things as well), but since you asked here are the problems:

1. Fuel storage in orbit. This problem needs to be licked before building in orbit can be solved. Fuel just doesn’t do very well in the heat and cold of space. There is no real data on how that fuel will hold up in orbit. Some obviously some work needs to be done to get some data points on this subject.
I keep seeing people say that, and it is in the Obama Space Plan, but I wonder, why would you store fuel in orbit? Why not simply wait until it is needed before launching it?

In other words, let's say you are going to assemble a vehicle to go to an asteroid. You put the crew habitation and command module in orbit. Then, you prep another module, which has the propulsion device (chemical rocket, vasimr, whatever), and you put that in orbit. Then, you launch a fuel module containing the fuel. Finally, you launch the people on a space taxi. All these launches are using commercial rockets such as Delta IV or Falcon 9 or whatever.

The module with the fuel should not stay up for more than, say, two or three days before the people go up and you leave.

I don't really see why you would have a fuel depot in LEO unless you're somehow generating the fuel in LEO. Otherwise, you have to launch the fuel to put into the depot, which itself requires fuel.

--Brian
If you plan on doing multiple launches to do a mission say to the Moon or Mars then we can look at the Augustine report. The report examines how “refueling introduces the idea of critical launches and less critical launches in any given mission.” If it takes several launches, all of which need to be successful to accomplish a given goal, the overall risk of failure climbs significantly. Since launches carrying the fuel can occur long before a final commitment is made to launch critical components (critical component here being the people), the overall risk is reduced, even if the system used to launch fuel has much lower reliability.

No matter what, the fuel must get there before the people. The question does come up; what if there is a delay in launching the people? How long can the fuel last up there? It’s a valid question. So that’s one reason why fuel goes up first (by the way when we say fuel, we must say fuel AND Oxidizers).

Bringing up fuel from Earth is very expensive and dangerous. In my post about my Moon base thought experiment I talk about how making fuel for Earth departure will probably be one of the first Moon base commercial business plans now that we know the Moon has everything you need for fuel and an oxidizer.

For me though I think putting together several launches to do a mission with fueling to be done separately just adds to the complexity of a mission (see my comment about do you do this robotically or do you have to have an EVA to put together your space ship?). That’s why I think it best to have super heavy lift launchers that can simplify the mission. I don’t think getting 100 T to LEO is outside of our capability (hard maybe, but not impossible).
 
R

rockett

Guest
Gravity_Ray":1678of7i said:
If you plan on doing multiple launches to do a mission say to the Moon or Mars then we can look at the Augustine report. The report examines how “refueling introduces the idea of critical launches and less critical launches in any given mission.” If it takes several launches, all of which need to be successful to accomplish a given goal, the overall risk of failure climbs significantly. Since launches carrying the fuel can occur long before a final commitment is made to launch critical components (critical component here being the people), the overall risk is reduced, even if the system used to launch fuel has much lower reliability.

No matter what, the fuel must get there before the people. The question does come up; what if there is a delay in launching the people? How long can the fuel last up there? It’s a valid question. So that’s one reason why fuel goes up first (by the way when we say fuel, we must say fuel AND Oxidizers).

Bringing up fuel from Earth is very expensive and dangerous. In my post about my Moon base thought experiment I talk about how making fuel for Earth departure will probably be one of the first Moon base commercial business plans now that we know the Moon has everything you need for fuel and an oxidizer.

For me though I think putting together several launches to do a mission with fueling to be done separately just adds to the complexity of a mission (see my comment about do you do this robotically or do you have to have an EVA to put together your space ship?). That’s why I think it best to have super heavy lift launchers that can simplify the mission. I don’t think getting 100 T to LEO is outside of our capability (hard maybe, but not impossible).
How about launching lunar ice, and process it in orbit on demand? You could keep a stockpile in orbit, and only split it into H2 and O2 when you you had an upcoming mission. This could be an automated process, and probably not an overly complicated one.
 
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Gravity_Ray

Guest
rockett":37yy9gzg said:
How about launching lunar ice, and process it in orbit on demand? You could keep a stockpile in orbit, and only split it into H2 and O2 when you you had an upcoming mission. This could be an automated process, and probably not an overly complicated one.
Sure Rockett you can do that. However, you need energy to split the ice into its components. So if you have ice in orbit, how will it be split? You will need shade to prevent the ice from sublimating in sunlight and you will need a factory and that is also complicated (that factory will need fuel to stay in one place and energy to split the ice).

I think the best solution is actually making the fuel and oxidizers on the Moon (storing it there cryogenically) and then sending it to LEO as needed. You have a stable lunar base with solar farms to produce enough heat to vaporize the regolith and ice into H2O. You have extreme cold to cryogenically store the fuel there, and you have low gravity to launch or shoot this fuel to LEO as needed.
 
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rockett

Guest
Gravity_Ray":1zgtauk9 said:
rockett":1zgtauk9 said:
How about launching lunar ice, and process it in orbit on demand? You could keep a stockpile in orbit, and only split it into H2 and O2 when you you had an upcoming mission. This could be an automated process, and probably not an overly complicated one.
Sure Rockett you can do that. However, you need energy to split the ice into its components. So if you have ice in orbit, how will it be split? You will need shade to prevent the ice from sublimating in sunlight and you will need a factory and that is also complicated (that factory will need fuel to stay in one place and energy to split the ice).

I think the best solution is actually making the fuel and oxidizers on the Moon (storing it there cryogenically) and then sending it to LEO as needed. You have a stable lunar base with solar farms to produce enough heat to vaporize the regolith and ice into H2O. You have extreme cold to cryogenically store the fuel there, and you have low gravity to launch or shoot this fuel to LEO as needed.
Not necessarily, Ray.
Solar cells are not the only way to generate power in space, but the power issue aside, it may not even be necessary. Maybe all you need is heat and light:
Unique Approach For Splitting Water Into Hydrogen And Oxygen
http://www.energy-daily.com/reports/Unique_Approach_For_Splitting_Water_Into_Hydrogen_And_Oxygen_999.html

Both of these can be easily obtained with solar reflectors, so energy may not be a big issue. As for ice sublimation, all you need is what amounts to a reflective balloon and solar shade to keep it cool. This would end run the volatile storage and transportation issues, which seem to be major problems. Remember space is REALLY cold (almost -270.425 degrees Celsius) in the shade. Also, launching ice from the moon would not require elaborate storage and containment (reducing upmass).
 
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DarkenedOne

Guest
Gravity_Ray":khawku8x said:
Bringing up fuel from Earth is very expensive and dangerous. In my post about my Moon base thought experiment I talk about how making fuel for Earth departure will probably be one of the first Moon base commercial business plans now that we know the Moon has everything you need for fuel and an oxidizer.
I agree with you that once a space

Gravity_Ray":khawku8x said:
For me though I think putting together several launches to do a mission with fueling to be done separately just adds to the complexity of a mission (see my comment about do you do this robotically or do you have to have an EVA to put together your space ship?). That’s why I think it best to have super heavy lift launchers that can simplify the mission. I don’t think getting 100 T to LEO is outside of our capability (hard maybe, but not impossible).
The problem with super heavy lift is that they have proven to be unreliable and very expensive. Relying on a single vehicle presents a single point failure. That is the problem NASA faced with the Shuttle. Luckily the Russians came to our rescue.

At the same time they are very expensive to develop and maintain. The shuttle is the best example of the expense of heavy lift. These systems are very massive, but are used sparingly.
 
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