Author Topic: Maintaining lunar and orbital infrastructure  (Read 2916 times)

Offline Hop_David

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Maintaining lunar and orbital infrastructure
« on: 09/26/2011 04:28 PM »
Let's assume we have propellant mines on the moon as well as tankers that deliver lunar propellant to depots at EML1, EML2, LEO and GEO. Also vehicles that travel between orbits, resupplying their propellant at these depots.

How would this infrastructure be maintained? The tankers, depots, and inter-orbital vehicles would all remain in vacuum. Some of them would dwell above earth's protective magnetic field.

Pressurized hangars with radiation shielding seems one possibility. But some of these vehicles would be large. A hangar big enough to accommodate such vehicles seems implausible, at least in the near term.

Offline Hauerg

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Re: Maintaining lunar and orbital infrastructure
« Reply #1 on: 09/26/2011 04:38 PM »
Those devices would not live forever. There might be some repair capability on module level, but even that may be hard on engines etc. So maybe redundant systems and a tanker is ok if it it does not fall below a defined level of available redundancy.
But you could still fly a tanker with a health you would NOT fly people. But would you risk to let it dock to your depot??

Offline A_M_Swallow

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Re: Maintaining lunar and orbital infrastructure
« Reply #2 on: 09/26/2011 07:54 PM »
To repair the reusable spaceships the spacestation is going to need a vacuum dock.  Here is the concept in Star Trek.


The building would amount to scaffolding with rails for the robotic arms to run along.  A control room and warehouse will also be needed.

Offline Solman

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Re: Maintaining lunar and orbital infrastructure
« Reply #3 on: 09/27/2011 12:40 AM »
Let's assume we have propellant mines on the moon as well as tankers that deliver lunar propellant to depots at EML1, EML2, LEO and GEO. Also vehicles that travel between orbits, resupplying their propellant at these depots.

How would this infrastructure be maintained? The tankers, depots, and inter-orbital vehicles would all remain in vacuum. Some of them would dwell above earth's protective magnetic field.

Pressurized hangars with radiation shielding seems one possibility. But some of these vehicles would be large. A hangar big enough to accommodate such vehicles seems implausible, at least in the near term.

 Well... GEO is the best place to teleoperate a telerobot from the surface of the Earth. The low and constant latency would make this a much cheaper alternative to humans actually in space vs. on the ground.
The robots may or may not be humanoid in their design.
The craft to be repaired would have to have some kind of station keeping system but no dock as such  would it?

Offline gbaikie

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Re: Maintaining lunar and orbital infrastructure
« Reply #4 on: 09/27/2011 02:18 AM »
Let's assume we have propellant mines on the moon as well as tankers that deliver lunar propellant to depots at EML1, EML2, LEO and GEO. Also vehicles that travel between orbits, resupplying their propellant at these depots.

How would this infrastructure be maintained? The tankers, depots, and inter-orbital vehicles would all remain in vacuum. Some of them would dwell above earth's protective magnetic field.

Pressurized hangars with radiation shielding seems one possibility. But some of these vehicles would be large. A hangar big enough to accommodate such vehicles seems implausible, at least in the near term.

It could be they aren't maintained- they have so many used and then they are scrapped.
Anything going to the Moon could maintained on the Moon- but might not much in terms maintenance.
So in short term a lunar lander might designed to make ten trips to the moon. And then retired.
Now lunar mining you going to need a lot maintenance. But in short term you might design your equipment to have a limited life- do as little maintenance as is need but after so many hours, replace them. Later vehicles could designed to last longer and require more maintenance, the cost of maintenance [cost of manhour] could lower in costs.
With fair amount used equipment, you might at some point scrap them to make other things you need.
« Last Edit: 09/27/2011 02:21 AM by gbaikie »

Offline Robert Thompson

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Re: Maintaining lunar and orbital infrastructure
« Reply #5 on: 09/27/2011 08:07 AM »
In a thread within the last 6 months, a Jim I think mentioned some acronym for maximum modularized replaceable components that can be serviced as needs be hands-on inside a pressurized / shirtsleeve area.

Or, a large enough airlock that can accommodate larger removable objects. Perhaps partially pressurize it with nitrogen so that work can be done in suits. Is there a gas that could be most easily recaptured?

At worst, a lot of space walks, so there's a need for spacesuits that require less time to get on.

There may have been a reference to applying spin to an object to make the working environment a bit more stable and faster...

Offline Hop_David

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Re: Maintaining lunar and orbital infrastructure
« Reply #6 on: 09/27/2011 12:16 PM »
In a thread within the last 6 months, a Jim I think mentioned some acronym for maximum modularized replaceable components that can be serviced as needs be hands-on inside a pressurized / shirtsleeve area.

Or, a large enough airlock that can accommodate larger removable objects. Perhaps partially pressurize it with nitrogen so that work can be done in suits. Is there a gas that could be most easily recaptured?

By the Jim aka Night Gator? If you could find that thread, I'd be grateful.

That's just the sort of thing I was hoping to see. Repairing removable modular parts seems more doable than working on an entire space craft. For example, working on an RL-10 engine in a pressurized work place seems more plausible than a pressurized hangar enclosing an ACES 71. 

At worst, a lot of space walks, so there's a need for spacesuits that require less time to get on.

I'd think this would occasionally be needed even if the vehicles were made of modular parts. For example repairing a puncture from space debris to a sun shade or hull of an ACES depot would probably take an EVA.

How doable is EVA maintenance in pressure suits? Am I being too optimistic to hope that improved telerobots might lessen the need for EVAs?

Offline Hop_David

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Re: Maintaining lunar and orbital infrastructure
« Reply #7 on: 09/27/2011 12:26 PM »
It could be they aren't maintained- they have so many used and then they are scrapped.
Anything going to the Moon could maintained on the Moon- but might not much in terms maintenance.
So in short term a lunar lander might designed to make ten trips to the moon. And then retired.

I know a vehicle designed for 5 km/s delta V and no need for TPS or other EDL equipment would have fewer maintenance issues than something like the space shuttle.

But still, is 10 trips with no maintenance plausible?

And if there are only 10 reuses, it would be harder for a lunar propellant mine to become cost effective.

Offline Hop_David

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Re: Maintaining lunar and orbital infrastructure
« Reply #8 on: 09/27/2011 12:34 PM »
Those devices would not live forever. There might be some repair capability on module level, but even that may be hard on engines etc. So maybe redundant systems and a tanker is ok if it it does not fall below a defined level of available redundancy.

Yes, removable modules (as Hernalt also mentioned) seems doable.

Redundancy also seems a way to prolong vehicle life.

 
But you could still fly a tanker with a health you would NOT fly people. But would you risk to let it dock to your depot??

Having humans aboard along with their life support would increase cost enormously, I would think. Hasn't machine docking become as reliable as human docking?

Offline A_M_Swallow

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Re: Maintaining lunar and orbital infrastructure
« Reply #9 on: 09/27/2011 06:50 PM »
{snip}
That's just the sort of thing I was hoping to see. Repairing removable modular parts seems more doable than working on an entire space craft. For example, working on an RL-10 engine in a pressurized work place seems more plausible than a pressurized hangar enclosing an ACES 71. 
{snip}

Repairing the spacecraft by replacing a RL-10 in space may be easier than trying to repair the RL-10.

Offline Andrew_W

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Re: Maintaining lunar and orbital infrastructure
« Reply #10 on: 09/27/2011 08:15 PM »
We discussed repair facilities and the design of vehicles using them here: http://forum.nasaspaceflight.com/index.php?topic=26162.0
I confess that in 1901 I said to my brother Orville that man would not fly for fifty years.
Wilbur Wright

Offline gbaikie

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Re: Maintaining lunar and orbital infrastructure
« Reply #11 on: 09/28/2011 02:54 AM »
It could be they aren't maintained- they have so many used and then they are scrapped.
Anything going to the Moon could maintained on the Moon- but might not much in terms maintenance.
So in short term a lunar lander might designed to make ten trips to the moon. And then retired.

I know a vehicle designed for 5 km/s delta V and no need for TPS or other EDL equipment would have fewer maintenance issues than something like the space shuttle.

But still, is 10 trips with no maintenance plausible?
Rocket engines are inherently simple. But rocket engines aren't.
I think XCOR believes one get a long operational life from rocket engine,
google:
http://www.xcor.com/press-releases/2003/03-12-04_XCOR-2000th-engine-run.html
"XCOR Aerospace passed a significant milestone recently when it logged its 2,000th rocket engine firing. This is the total of the five types of engines the company has designed and built in-house. Cumulative run time is 224.7 minutes, or 13,482 seconds as rocket scientists like to measure run time. "
Not sure what maintenance is involved.
Oh that was in December 04, 2003, so probably have further results out there somewhere.


In general terms I would expect some reduction in efficiency or more exotic parts, and such things would need to be examine and evaluated, but it seems plausible to me

Quote
And if there are only 10 reuses, it would be harder for a lunar propellant mine to become cost effective.
Well, in past I thought rocket fuel would need to sell for $2000 per lb on lunar surface so that it would be $4000 or so at orbit. As rough guess.
So if lift 10 tons [20,000 lb] it's over 20 million per trip at $1000 per lb for lander. So 200 million per lander used 10 times. So it's somewhere in ballpark.
But obviously this area you want to improve, and it might work to design them to have longer life and more maintenance.
But it seems less of a risk to plan on having the least maintenance and few uses and make simply more lunar lander on earth and ship them up, when you talking about the early stages of lunar water mining.

One major problem [the only real problem] of lunar water mining is lack of market. When and if the market increases, you use bigger lander and landers with longer life and can afford the maintenance.

Offline Moe Grills

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Re: Maintaining lunar and orbital infrastructure
« Reply #12 on: 10/03/2011 04:15 AM »
Let's assume we have propellant mines on the moon as well as tankers that deliver lunar propellant to depots at EML1, EML2, LEO and GEO. Also vehicles that travel between orbits, resupplying their propellant at these depots.

How would this infrastructure be maintained? The tankers, depots, and inter-orbital vehicles would all remain in vacuum. Some of them would dwell above earth's protective magnetic field.

Pressurized hangars with radiation shielding seems one possibility. But some of these vehicles would be large. A hangar big enough to accommodate such vehicles seems implausible, at least in the near term.

It could be they aren't maintained- they have so many used and then they are scrapped.
Anything going to the Moon could maintained on the Moon- but might not much in terms maintenance.
So in short term a lunar lander might designed to make ten trips to the moon. And then retired.
Now lunar mining you going to need a lot maintenance. But in short term you might design your equipment to have a limited life- do as little maintenance as is need but after so many hours, replace them. Later vehicles could designed to last longer and require more maintenance, the cost of maintenance [cost of manhour] could lower in costs.
With fair amount used equipment, you might at some point scrap them to make other things you need.

Some very good points.
   But take it further:
For instance, as an Earth analog, there's a site in Arizona where
old aircraft are stored because the place is bone dry?

The Moon would make an excellent place to store spacecraft, vehicles
and any hardware because it is drier, has a weaker gravity (less stress
on larger heavier objects) and lacks free oxygen which can corrode.
And, if you stored vehicles, spacecraft, machinery under a big UNPRESSURIZED lunar "tent", you get the added benefit of eliminating thermal cycling that can repeatedly stress machinery, equipment and
vehicles. Also, the extreme cold temperatures under such a lunar "tent"
would be ideal for storing liquid oxygen, dry ice, liquid methane, etc.

But if you're worried about fine lunar dust being a problem?

Problem solved.....Lunar dust has a high iron content. so magnets
or magnetic devices, would solve that issue both in pressurized & nonpressurized compartments.

And as far as repair and maintenance is concerned on the Moon?

You can have a human mechanic on the Moon doing what they do on Earth, but with the advantage of lower gravity, and avoiding the greasy mess they encounter on Earth (graphite, not grease, would be the lubricant of choice on the Moon for some well-known reasons.)

Or, to save money, and avoid risks, telepresence remote-control
mechanical work can be carried out on the Moon from Earth.

Also, vehicles and machinery on the Moon would have interchangeable parts as much as possible: so if Part(A) breaks on a vital Lunar rover for example, a similar part from a stored aging Lunar vehicle would replace it.
   
Also, it would be logical to make lunar surface vehicles versatile, to fill as many roles as possible simply by replacing parts or attachments, or activating different parts or attachments on such vehicles.
Basically making those vehicles proverbial mobile "Swiss Army Knives".
 
So, for example, if a Lunar rover serving in the role of a regolith digging/moving backhoe breaks down, bring in another Lunar rover, serving (perhaps) in the role of a passenger transport, and temporarily convert it into a lunar backhoe until the other rover is repaired.

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