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What might be done

Posted by: Ekkehard Augustin - Mon Jan 07, 2008 11:40 am
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Post What might be done   Posted on: Mon Jan 07, 2008 11:40 am
NASA could list, what's all required to install a permanent lunar base and to operate it.

This list could be broken down to small details. From this detailed list it would become obvious in what order the things have to be done.

The first entry may be exploration of several lunar regions including experiments.

One detail of that entry might be to send equipment into a lunar orbit unmanned and parking it there. The amount of equipment should be higher than what four astronauts can do on the lunar surface within a predetermined period of time. Then it wouldn't be required to limit the tasks.

Each time the astronauts have completed a minimum list of tasks they could call equipment from the lunar orbit down to their location on the surface to do more tasks.

This would enable NASA to make a schedule and to send vehicles on a regular basis - and to apply vehicles that never land on Earth, that are reusable and refuelled.



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Post    Posted on: Mon Jan 07, 2008 9:12 pm
You do know that not everybody agrees that NASA is doing (or going to) do the right thing and/or make the right choices.

But i don't see the point of letting the equipement stay in orbit when you're gonna put it down anyway. I don't see the advantage of it.


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Post    Posted on: Tue Jan 08, 2008 8:02 am
Hello, Stefan,

it would avoid to launch the hardware weight required to go from LEO to the Moon mission per mission again - and thus also the consumption of propellant needed to launch that hardware.

The stresses of reentry as well as erosion and corrosion by weather, oxydation and the like would be avoided also regarding the hardware required to go from LEO to the Moon and thus limited to the vehicles and rockets for getting into LEO from the surface.

It would be more economical by far and help the missions to fit into budget constraints and future reductions of budgets.

I really can imagine that the Congress as a whole would have less problems to agree to NASA-plans if such a concept would be established.



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Post    Posted on: Tue Jan 08, 2008 8:30 pm
Have to go with Stefan...

There's no reason for leaving something that's already been launched in orbit. Wouldn't you be spending more fuel keeping it there until it's needed than setting it down right away?


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Post    Posted on: Wed Jan 09, 2008 11:00 am
Hello, Minthos,

no - given the plan of a permanent lunar station it is no problem to set up a schedule of flights like there is a schedule for flights from Hamburg to New York per flight line and over all floight lines together.

This would eanble the vehicles to return into LEO take new crews of astronauts or/and new payloads and then leave LEO again.

Next please think about the weight of vehicles including tanks. In the case of the Apollo-missions there was the Apollo CSM weighing 5800 kg plus the Saturn IV B weighing more than 11,000 kg - more than 16,800 kg in total. A lot of the 11,000 kg of the Saturn IV B might have been saved if that portion of that weight required to do Translunar Injection would have been launched into space only once and then kept there.

I do not know why you think that the fuel to keep such an object in space would be that much - I didn't find no heavy satellite up to now that required similar amounts of fuel as those amounts required to leave LEO for the Moon or to launch such an object simply.

Last but not least there is the circumstance that all must fit into budgets - which means the economical and monetary aspect and the unescapable fact that this is ruling NASA and its doings. Economically and monetary the fuel is of nearly NO meaning.

So there are several very good reasons to leave something already launched in orbit when it is nearly sure and clear that flights are intended to be repeated again and again.

By the way - I have no problem with parking the vehicle's) in HEO instead of LEO. The altitude of the parking orbit may be 1000 km instaed of 400 km.



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Post    Posted on: Wed Jan 09, 2008 11:55 am
You mean Earth to Moon Cyclers or ferries?

It takes a lot more fuel to send something there and back, than to just send it there. All your engines will need to be a lot more robust because you can't service them, and you will need a super reliable refuelling system.

You would need a significant amount of traffic for this to be more efficient.

Everything that is wrong with the shuttle applies here.

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Post    Posted on: Wed Jan 09, 2008 1:01 pm
Hello, idiom,

I never would think the Space Shuttle to be applied - I have in mind t/Space's CXV, SpaceX's Dragon and the like.

I am calculating this in the Financial Barriers section. There depreciations are taken into account for servicing the engines.

The amounts of propellant are of nearly no meaning really. Assuming LOX/LH2 and taking the price of the more expensive component for the cheaper one (LOX) also shows that 100,000 kg LOX/LH2 cost $ 360,000 maximum.

The refueling system is worked on already - Boeing's orbital propellant depot and the Air Force's refuelling experiment in space are examples of it.

What I am experimentally calculating in the Financial Barriers section up to now indicates that flight rates of one per 6 days or even one per month will be sufficient - and possible. The life-time will be sufficient also as a look to satellites or to the Voyagers shows.

The calculations in the Financial Barriers section will and need to go on and don't take into account yet that tanks and stages can be applied to a lot of different purposes but not only to lunar missions if standardization is done.



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Post    Posted on: Wed Jan 09, 2008 2:17 pm
Ekkehard Augustin wrote:
I never would think the Space Shuttle to be applied - I have in mind t/Space's CXV, SpaceX's Dragon and the like.


What he said was that you take all the things that are wrong with the shuttle, and use them again on this "shuttle", and you're back where you started, if not further behind.


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Post    Posted on: Wed Jan 09, 2008 2:45 pm
Hello, IrquiM,

this argument I have problems to fit into the thing - the problems known from the Shuttle are caused by launching it from the ground as well as by reentry.

If a vehicle is kept in space these problems can't occur - meaning that vehicles going back and forth between Earth and Moon don't have these problems.

t/Space's and SpaceX's vehicles on the other hand aren't launching like the shuttle because they are located on top of the rocket while they aren't reentering like since they don't have wings. t/Space in particular have in mind a reentry at water-cooling and feathering like SSO - according to t/Space and Scaled Composites.

There will be demonstration flights of the Dragon in 2009 - so this part will be tested soon.



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Post    Posted on: Wed Jan 09, 2008 8:55 pm
It is not the cost of the fuel, but the weight of it.

The cost of lifting the return fuel outweighs the cost of an expendable vehicle.

It would need heatshield replaced, computers replaced, engines replaced. And then you might get 20 flights if you completely overhauled it in space every 6 flights or so. It wouldn't be cheaper, but it would keep a lot more people employed.

It might be easier to have a cpomplete manifest of Moon stuff on Earth and simplify the packaging requirement of everything into standard containers. Then just post it one way to the Moon on whatever is available.

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Post    Posted on: Thu Jan 10, 2008 8:00 am
Hello, idiom,

the replacements would be investments which would be depreciated over the flights. Satellites as well as probes like the Voagers show that vehicles kept in space have very long lifetimes - so the depreciations can be very low.

Next a vehicle intented to be kept in space can be constructed without a heatshield, with the proper computers equipped from beginning on and with the proper engines as well - it would be nonsense to first construct it as if would have to land again on Earth later. To get to the vehicle taxi-vehicles can be applied that really land again.

Overhauls like those required for vehicles reentering and being exposed to weather wouldn't be required - so there wouldn't be as much flights be required to do the overhauls. The aspect if vehicles never landing on Earth and never reentering its atmosphere would be a thread fitting into the Technology section where it would have to be considered which overhauls are caused by reentry stresses, gravitational effects, waether, atmospheric oxygen, earthian environment and other factors that don't exist in space. Next it would have to be considered which protections against factors in space might be possible.

From my experiments in the Financial Barriers section it will be much cheaper than would is work on at present. The experiment isn't complete by far - but getting costs/prices per passenger of less than $ 200,000 means that overhaul costs of even 100 times per flight (= $ 20 mio) that result still would keep it extremely economical and better fitting into NASA's budgets.

...



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Post    Posted on: Thu Jan 10, 2008 8:59 am
The heat shield was for Aerobraking not landing.

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Post    Posted on: Thu Jan 10, 2008 11:38 am
Hello, idiom,

in the experimental calculations I use braking rockets like they are used to do lunar orbital insertion.

Next there is developmental work on Aerobraking Technologies but nearly each information about it seems to say or mean that aerobraing can't be applied to manned missions because of the time aerobraking requires.



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Post    Posted on: Thu Jan 10, 2008 11:43 am
So no Ion thruster then Either.

For cargo stuffs Ion thrusters and aerobraking might be enough to make a reusable inter-orbital shuttle practical.

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Post    Posted on: Thu Jan 10, 2008 12:21 pm
The concept used for crewed (or time critical) missions is called Aerocapture.

About "robust" engines and refuelling: The engines of the Salyut and Mir space stations operated for years as well as the refuelling system. There was as far as I remember only on one Salyut space station the need for a repair on the refuelling system.

One problem of "long lifetime" crafts are the electronics. You can't shield them perfectly and a craft e.g. flying Earth-Moon would pass the radiation belts. That was btw the reason for the high weight of the Apollo capsules as Roger E. Bilstein describes in his book "Stages to Saturn" as:

"Recent research on the problem of radiation in space indicated that the spacecraft needed more shielding, which would increase spacecraft weight from the original 6800-kg estimate to 13 600 kilograms."

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Last edited by Klaus Schmidt on Thu Jan 10, 2008 12:22 pm, edited 2 times in total.



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