Author Topic: About reusable LM  (Read 1294 times)

Offline carmelo

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About reusable LM
« on: 02/13/2017 02:17 AM »
In case of reusable lunar module,how is possible do maintenance of this vehicle in space?
Reusables vehicles must be reviewed between a a flight and the other; you not can simply putting fuel and starting.
Generally maintenance of reusable space vehicles is very complex,and requires a specialized staff...
How you can make this in lunar orbit in a little orbital outpost,with the LM supposedly docked outside in  the vacuum of the space?

Offline Space Core

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Re: About reusable LM
« Reply #1 on: 02/13/2017 02:46 AM »
If ITS, New Armstrong or some equivalent happens, you might not need to service it in space.  If the lander could be made to fit in a reusable vehicle's cargo area, you could cycle it back to Earth for maintenance.

Offline MATTBLAK

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Re: About reusable LM
« Reply #2 on: 02/13/2017 03:18 AM »
Maintenance of a reusable LM is going to be very difficult in zero g in spacesuits; unless it were designed from scratch to be serviceable and upgradable, as the Hubble telescope was - but that is not an apples-to-apples comparison. But when we are dealing with a 'reusable' LM in the near-ish future; it will a first generation 'Version 1.0' reusable LM, with all those inherent challenges and difficulties. It's likely one of three scenarios will occur:

1: Reusable LM's will be kicked down the road for a long time - put in the too-hard basket - in favor of a lightweight, cheap as possible expendable vehicle that can get small crews or modest cargo down to the Moon. It would likely use storable, hypergolic propulsion.

2: If the new LM is single-stage reusable craft (my preference), it will likely have ton-toxic RCS systems and propulsion. Propellants will (likely) be LOX/CH4, LOX/Kerosene, or LOX/Propane. The Main Descent/Ascent Engine set could be a removable module that can be replaced with another engine module brought occasionally from Earth when the engine develops flaws or wears out. Spacewalking Astronauts could install the module and hook it up to the propellant tank plumbing. I should think that the propellant tanks could be unbolted and replaced in a similar manner. The pressure cabin could have modular, replaceable life support systems and the main flight avionics can be designed to be replaced as complete electronic 'boxes'. Modularity; always...

3: Two-stage, partially reusable. In some ways, this would be the easiest design. How? Well, the Descent stage could be an expendable, hypergolically fueled module designed for one-way descent use. But we could get a bit cunning with it: It's doesn't have to be a 'deadweight' bit of hardware after descent. If the stage could have one or two retractable solar array sets mounted on it, once the Ascent Stage leaves, the solar arrays could be deployed to provide power for a small Outpost - just plug in a heavy-duty extension cable and enjoy a couple kilowatts of power. During an Outpost buildup, if the Outpost was surrounded by a few descent stages, instead of a solar array set, perhaps a couple of those Descent Stages could have a metric ton or so of RTG power units mounted aboard to give long Lunar night power supplies.

The Ascent Stage: A reusable craft that is designed for 5 or 10 (whatever) reuses. It is mated with a fresh Descent Stage brought from Earth with each new arriving crew. The Ascent Stage could also have a modular, replaceable Ascent engine module - or at least a replaceable nozzle extension for each time that nozzle erodes past usefulness. I would recommend that the RCS and main propulsion be LOX/CH4, LOX/Propane or LOX/Kerosene. Propellant supplies to fill the Ascent stage could be brought from Earth by Commercial suppliers or as a 'Tanker Module' brought with Orion Astronauts for each landing mission.

For the second and third options, we can assume that the reusable lander is operating out of a Lunar Orbital station or Depot staging point. For the expendable option, a Lunar space station is not strictly needed. Such a vehicle depending on the exact configuration and propulsion design, could mass anywhere between 25 and more than 30 metric tons.
« Last Edit: 02/13/2017 03:25 AM by MATTBLAK »
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Offline A_M_Swallow

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Re: About reusable LM
« Reply #3 on: 02/13/2017 03:40 AM »
{snip}
For the second and third options, we can assume that the reusable lander is operating out of a Lunar Orbital station or Depot staging point. For the expendable option, a Lunar space station is not strictly needed. Such a vehicle depending on the exact configuration and propulsion design, could mass anywhere between 25 and more than 30 metric tons.


Anything that stays in orbit for more than 6 months and is visited at least twice is a space station. Propellant depot, staging post, repair hanger or full function are just the type of spacestation.

Offline brickmack

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Re: About reusable LM
« Reply #4 on: 02/13/2017 03:56 AM »
A lunar lander operates in a MUCH less stressful regime than a launch vehicle. Theres no reentry forces whatsoever. The engines produce orders of magnitude less thrust and usually burn for less time per mission. G forces are lower. Pressure differential is constant throughout the flight. Etc. If you can make a rocket that can reliably last 1 earth-launch mission before needing refurbishment (ie, the bare minimum for a reusable vehicle), and magically put that rocket on the moon, it should last several flights before receiving the same level of damage.

Offline A_M_Swallow

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Re: About reusable LM
« Reply #5 on: 02/13/2017 04:02 AM »
The Centennial Challenger 'Lunar Landers' required to be able to take off again within a hour. Masten's entry Xombie has had 227 flights. Their records may show the sort of servicing landers will need.
http://masten.aero/vehicles-2/xombie

NASA's Project Morpheus lander was also reusable. There may be some very interesting information in its repair logs.


I see 4 categories of repairs and replacements:

a. Consumables, like propellant, food and air. Replaced every trip.

b. Mechanical consumables, items that need replacing every 2 or 3 flights. If they cannot be made to last a long time require them to be easy to change. I suspect that the heat protection on the feet may fit this category along with spark plugs.

c. Normal, things like engines that last several flights. They may have to be specified to be reused 10 or 50 times. Space walks and robots may be needed to repair or replace them.

d. Unfixable, one or more of these break - possibly in a crash - and the lander is scrapped.

Offline Paul451

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Re: About reusable LM
« Reply #6 on: 02/20/2017 11:15 AM »
If ITS, New Armstrong or some equivalent happens, you might not need to service it in space.  If the lander could be made to fit in a reusable vehicle's cargo area, you could cycle it back to Earth for maintenance.

Errr, if ITS is possible, then why would you need a separate lunar lander? ITS would be the reusable, refuellable lunar lander.

Offline Space Core

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Re: About reusable LM
« Reply #7 on: 02/20/2017 01:53 PM »
If ITS, New Armstrong or some equivalent happens, you might not need to service it in space.  If the lander could be made to fit in a reusable vehicle's cargo area, you could cycle it back to Earth for maintenance.

Errr, if ITS is possible, then why would you need a separate lunar lander? ITS would be the reusable, refuellable lunar lander.

I thought about that too, since it has been demonstrated on this forum in multiple threads that ITS could do a landing and return from the Moon using tankers.  Ultimately, it comes down to effeciancy versus use; How many times will it be used, and how?

It would require R&D and useage of this vehicle to cost less than just using ITS and tankers.  I think areas where a small dedicated lander could shine are tip-of-the-spear sortie type missions, areas an ITS couldn't practically go, or even to setup a landing pad for an ITS.

But there is no guarantee the economics work out.  Using an entire ITS is less efficient, but might prove cheaper if launch costs get low enough.  It's still too early to tell, imho, so I like seeing multiple approaches being considered.

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