LM Descent Stages Today?

[The Flying Kerbal]

Hi Guys,

I suspect this is a stupid question, but it's one I don't know the answer to and I've never found it on Google.

It's almost fifty years since Apollo 11 landed on the moon, and over the next few years a further five followed in its wake.  When it was time to leave, they used the descent stage as a platform from which to launch the ascent stage, and ever since the descent stages have been sitting on the lunar surface.  Over the years, would they have deteriorated in any way?  Obviously they wouldn't have rusted, but what about radiation, would that have affected them or turned them into radioactive deathtraps for any future visitor who comes across them?

And then there's the fuel.  I remember reading the chemicals used were so nasty they prevented the engines fitted into each lander from being test fired, apparently the engines would have been destroyed by the corrosive effects of the chemicals during the test, and made unusable.

Or maybe they would be as pristine today as when the Eagle and her sisters first set down back in the day?  Does anyone know?

Many thanks all!  

[Hannu2]

Rubber and plastic parts have become brittle due temperature cycling, residual fuels and oxygen may have corroded some parts, batteries have destroyed and maybe corroded their environment and so on. Modules are certainly in very weak condition, except the metal frame which is probably quite intact.

Cosmic radiation does not make materials significantly radioactive. Astronauts took rocks which had been billions of years on surface without any problems with radiation.

[kerbiloid]

ICBM using hypergolics stay fueled for decades. Imho, unlikely the tanks would be corroded.
Regolith is exposed under the same radiation for billions years, but is not radioactive.

I would presume that daily temperatures -100.+100°C and vacuum welding would do more.
Probably any organics (colors, rubber, plastic) has turned into powder, while metal parts are partially crashed by the temperatures, partially welded together by vacuum.

[Hannu2]

3 minutes ago, kerbiloid said:

ICBM using hypergolics stay fueled for decades. Imho, unlikely the tanks would be corroded.
Regolith is exposed under the same radiation for billions years, but is not radioactive.

I would presume that daily temperatures -100.+100°C and vacuum welding would do more.
Probably any organics (colors, rubber, plastic) has turned into powder, while metal parts are partially crashed by the temperatures, partially welded together by vacuum.

If I remember, propellants were in rubber balloon in metal tanks. I think there had no reason to specify it last decades. Mass budget of LM was extremely tight. Therefore they had to use lightest possible materials in engines instead of corrosion resistant materials, which are used for example in engines and RCMs of deep space probes, which use same hypergolic propellants and have to last decades.

[sevenperforce]

Mechanically, the later LM descent stage engines were crumpled on touchdown, because they had nozzle extensions that impacted the ground.

Don't underestimate the impact (no pun intended) of MMODs. Plus, the stages are on the surface, so you have spalling from impacts with the surrounding regolith.

[PB666]

8 hours ago, The Flying Kerbal said:

Hi Guys,

I suspect this is a stupid question, but it's one I don't know the answer to and I've never found it on Google.

It's almost fifty years since Apollo 11 landed on the moon, and over the next few years a further five followed in its wake.  When it was time to leave, they used the descent stage as a platform from which to launch the ascent stage, and ever since the descent stages have been sitting on the lunar surface.  Over the years, would they have deteriorated in any way?  Obviously they wouldn't have rusted, but what about radiation, would that have affected them or turned them into radioactive deathtraps for any future visitor who comes across them?

And then there's the fuel.  I remember reading the chemicals used were so nasty they prevented the engines fitted into each lander from being test fired, apparently the engines would have been destroyed by the corrosive effects of the chemicals during the test, and made unusable.

Or maybe they would be as pristine today as when the Eagle and her sisters first set down back in the day?  Does anyone know?

Many thanks all!  

The hydrogen from space tends to blacken the surface. micrometeorite impacts. Apollo 11's tanks were nearly expended, so not to much there. Chemicals are nasty to humans and the environment, metals, I don't think there is a problem.

[sevenperforce]

Don't want to hijack this thread, but when I saw the thread title it made me think -- what lunar descent stages would be available today?

[radonek]

One interresting trivia I read somewhere - flags that featured prominently in photos were not "space grade" so solar radiation likely  turned them plain white by now. Fitting I'd say.

[YNM]

I thought there were photographs off LRO that shows the descent modules still intact ?

[1101]

https://www.nasa.gov/mission_pages/LRO/news/apollo-sites.html

They are certainly there, but it's hard to state how intact they might be from a few pixels of image.

Even if propellant leaked from them, I wouldn't expect much damage to be visible at the scale we see here. 

http://www.spaceinminiature.com/ref/apollo/sim7_images/fig14.jpg

Obviously the image linked above hasn't had the ascent module take-off from it, so appearance may vary.

[sevenperforce]

21 hours ago, radonek said:

One interresting trivia I read somewhere - flags that featured prominently in photos were not "space grade" so solar radiation likely  turned them plain white by now. Fitting I'd say.

Obligatory:

Spoiler

If Congress decided to suddenly give NASA 100% of the budget it needed to do another flags-and-footprints mission to the moon, on the condition that it be done as fast as humanly possible, what descent and ascent stages would we use?

Edited February 1, 2018 by sevenperforce

[insert_name]

10 hours ago, 1101 said:

https://www.nasa.gov/mission_pages/LRO/news/apollo-sites.html

They are certainly there, but it's hard to state how intact they might be from a few pixels of image.

Even if propellant leaked from them, I wouldn't expect much damage to be visible at the scale we see here. 

http://www.spaceinminiature.com/ref/apollo/sim7_images/fig14.jpg

Obviously the image linked above hasn't had the ascent module take-off from it, so appearance may vary.

There appears to be some debris near the stage and the ground next to it(even on the other side of the shadow) is blackened, not sure if this is from the landing or not.

[Confused Scientist]

13 hours ago, PB666 said:

Chemicals are nasty to humans and the environment, metals, I don't think there is a problem.

The descent module's fuel tanks were designed to rupture within days of landing. This is because to pressurize the tanks and feedlines, NASA used a helium disc that would be opened when the LM descent motor ignited for the first time. The valve could not be closed, but this was not a problem because the engine would only be needed for a few hours. However, if the helium disc was allowed to continue venting into the tanks after touchdown, they would eventually rupture and damage the ascent stage. So, NASA decided that the tanks should rupture once they got above a certain pressure, which on Apollo 13 occurred while the LM was still docked to the CSM providing RCS and course corrections with its motors. Because of this, they had to plan to do all of their free-return maneuvers before the tanks ruptured.

[Nibb31]

They would be intact, but any propellant or hydraulics would have vaporized by now. Metal parts would probably be intact. Rubber seals, wiring insulation, or plastics will be brittle and cracked. I would think that the Kapton foil will have degraded to a point where it would crumble to dust if you touched it.

[sevenperforce]

You know, in his original 2011 unveiling of Falcon Heavy, Elon posited that two FH launches is all it would take to drop astronauts on the moon and bring them back.

[The Flying Kerbal]

As usual, terrific answers from everyone.  I remembered hearing about the fuel tanks exploding after so long because of the pressure buildup, but forgot about that.

2 hours ago, sevenperforce said:

You know, in his original 2011 unveiling of Falcon Heavy, Elon posited that two FH launches is all it would take to drop astronauts on the moon and bring them back.

I didn't know that.  No fault to Elon musk, and I admit he has some amazing technology going at the minute, but I don't always take everything the man takes too seriously.  Sometimes i think he genuinely get over enthusiastic about what capabilities he has at his disposal, and others might be just a little headline grabbing.

Thanks for all the answers guys, every one of 'em is appreciated. 

[magnemoe]

2 hours ago, sevenperforce said:

You know, in his original 2011 unveiling of Falcon Heavy, Elon posited that two FH launches is all it would take to drop astronauts on the moon and bring them back.

Two expendable falcon heavies would let you put 130 ton in orbit, this is in the ballpark of Saturn 5 to LEO, so it should work, downside is that you would need one more stage, say put one smaller stage with storeable fuel below the moon lander, second launch with dragon also has an stage but this with lox. You burn that stage for moon injection and follow up with the stage below the lunar lander you also use this to put you in orbit around moon. This stage can also be used as an crash stage for moon landing simply to give more margins. 

You land on Moon, top of lander goes back to dragon Apollo style, dragon has an small kick stage instead of trunk for the burn back to earth. Optionaly fuel tanks for the drako / super drako.
Storeable propellant in the moon lander stage not only because it will be used to get into moon orbit but also because the second launch can be delayed.   
Outside of the moon lander its not much new technology needed.
Still you need some the stages much be able to dock for one and this has to be integrated. 
Also not sure if falcon heavy upper stage can handle 65 ton payload, focus on current version is heavier satellites to LKO with first stage reuse. 

[sevenperforce]

31 minutes ago, The Flying Kerbal said:

I didn't know that.  No fault to Elon musk, and I admit he has some amazing technology going at the minute, but I don't always take everything the man takes too seriously.  Sometimes i think he genuinely get over enthusiastic about what capabilities he has at his disposal, and others might be just a little headline grabbing.

It's not actually false. Falcon Heavy can throw about 20 tonnes to TLI. The whole integrated Apollo stack, including CSM and LM, came in at 44 tonnes. 

3 minutes ago, magnemoe said:

Two expendable falcon heavies would let you put 130 ton in orbit, this is in the ballpark of Saturn 5 to LEO, so it should work, downside is that you would need one more stage, say put one smaller stage with storeable fuel below the moon lander, second launch with dragon also has an stage but this with lox. You burn that stage for moon injection and follow up with the stage below the lunar lander you also use this to put you in orbit around moon. This stage can also be used as an crash stage for moon landing simply to give more margins.

Storables would not be able to get as good of isp as the MVac, so if you're doing TLI it's far more efficient to go straight from the pad to TLI on the Falcon Heavy and simply use a smaller payload. Methalox or hydrolox would be better, of course, but then you have to deal with mounting a cryogenic fuel tank and engine on top of Falcon Heavy, which would be tough to do with the LM and impossible to do with the crew-carrying CSM.

Your first Falcon Heavy launch would send the lunar descent and ascent modules to TLI. Use the descent-module engine to brake into lunar orbit, like the plans for Altair. Once your lunar module is in orbit, send up a Falcon Heavy with Dragon 2, but put a few Dracos in the trunk along with a nice big fuel tank. That goes to TLI on the Falcon Heavy alone, after which the Dracos in the trunk perform the lunar orbit insertion.

Joint Lunar Orbit Rendezvous, flags and footprints, and you're done.

[Racescort666]

17 hours ago, sevenperforce said:

Storables would not be able to get as good of isp as the MVac, so if you're doing TLI it's far more efficient to go straight from the pad to TLI on the Falcon Heavy and simply use a smaller payload. Methalox or hydrolox would be better, of course, but then you have to deal with mounting a cryogenic fuel tank and engine on top of Falcon Heavy, which would be tough to do with the LM and impossible to do with the crew-carrying CSM.

I was like "oh, if real life were like KSP, you could just throw a Centaur and you'd have a solution." Then I ran the numbers, < 800 m/s, never mind... Good thing I'm a big enough nerd to run the numbers before making that suggestion. Also, Centaur is too long to fit in a Falcon payload fairing.

[magnemoe]

20 hours ago, sevenperforce said:

It's not actually false. Falcon Heavy can throw about 20 tonnes to TLI. The whole integrated Apollo stack, including CSM and LM, came in at 44 tonnes. 

Storables would not be able to get as good of isp as the MVac, so if you're doing TLI it's far more efficient to go straight from the pad to TLI on the Falcon Heavy and simply use a smaller payload. Methalox or hydrolox would be better, of course, but then you have to deal with mounting a cryogenic fuel tank and engine on top of Falcon Heavy, which would be tough to do with the LM and impossible to do with the crew-carrying CSM.

Your first Falcon Heavy launch would send the lunar descent and ascent modules to TLI. Use the descent-module engine to brake into lunar orbit, like the plans for Altair. Once your lunar module is in orbit, send up a Falcon Heavy with Dragon 2, but put a few Dracos in the trunk along with a nice big fuel tank. That goes to TLI on the Falcon Heavy alone, after which the Dracos in the trunk perform the lunar orbit insertion.

Joint Lunar Orbit Rendezvous, flags and footprints, and you're done.

Lunar Rendezvous makes far more sense I agree, you would need storables for the lunar orbital burn as you say. 
 

3 hours ago, Racescort666 said:

I was like "oh, if real life were like KSP, you could just throw a Centaur and you'd have a solution." Then I ran the numbers, < 800 m/s, never mind... Good thing I'm a big enough nerd to run the numbers before making that suggestion. Also, Centaur is too long to fit in a Falcon payload fairing.

Note that you would obviously need an larger fairing, you would probably need to reinforce the second stage on FH too. 
This require development and testing obviously however even an test launch would not scratch the SLS budget. 

[sevenperforce]

3 hours ago, Racescort666 said:

I was like "oh, if real life were like KSP, you could just throw a Centaur and you'd have a solution." Then I ran the numbers, < 800 m/s, never mind... Good thing I'm a big enough nerd to runn  the numbers before making that suggestion. Also, Centaur is too long to fit in a Falcon payload fairing.

From an Oberth/dV-efficiency standpoint, there are quite a few different options. The Merlin's lower isp and higher thrust is beast for getting off the ground and into orbit, but it's less useful for getting beyond LEO. However, when the alternative is a non-cryo hypergolic with even poorer isp, it's a good idea to make the most use of it, especially if you can do the TLI straight off the pad. 

Then again, one option would be to use an inverted version of the Earth-Lunar-Orbit Rendezvous planned with Constellation. Constellation had the man-rated Ares I lifting Orion into LEO, then using Ares V to lift Altair into LEO for a rendezvous. After docking, the Ares V upper stage would send the whole stack to a free-return, after which the Altair's descent engines would perform the lunar orbit insertion burn. Using the lander's engine for the insertion burn is slightly more efficient than going the Apollo route (using the CSM's engine), since you get to drop those tanks on your landing. 

The inverted version of the Constellation architecture would be to send a prop-heavy lander up to LEO on the first Falcon Heavy, then send up a Dragon 2 (with kick stage in the trunk) and dock to the lander in LEO, with the Falcon Heavy upper stage still attached to the Dragon 2. That stage then fires for the TLI, rather than the lander's terminal stage as in the Constellation plan. This allows the whole mission to make optimal use of the two equally-sized LVs rather than using one gigantic HLV and a smaller man-rated launcher.

I haven't crunched all the numbers, but one very interesting option would hinge on whether the Falcon 9 upper stage can be easily modified for extended-lifetime restarts. That's where things get really interesting, because you could dock both stacks in LEO, use the Dragon 2's ascent stage for the TLI, and then use the lander's ascent stage in cislunar orbit to perform the insertion burn. Dry mass does start to pile up a bit, in that scenario, but you make the best use of the MVac's higher isp relative to storables, and you have the smallest cislunar mission stack, which means less dev cost.

21 minutes ago, magnemoe said:

Lunar Rendezvous makes far more sense I agree, you would need storables for the lunar orbital burn as you say. 

JLOR is good, but it means your Dragon 2's kick stage needs to carry enough fuel for both lunar insertion and for the Earth return burn, and I'm not sure exactly how much dV you can realistically cram into that trunk.

[sevenperforce]

37 minutes ago, YNM said:

Probably not on-topic :

Who would a private human launch falls into jurisdiction-wise ?

I guess after Dragon sends people to ISS, maybe Musk can pull up a show or something.

Well, it's never been done.

[YNM]

7 minutes ago, sevenperforce said:

Well, it's never been done.

Given the nationality rule though, probably not much different than a govt-operated, publicly funded one.

[magnemoe]

4 hours ago, sevenperforce said:

From an Oberth/dV-efficiency standpoint, there are quite a few different options. The Merlin's lower isp and higher thrust is beast for getting off the ground and into orbit, but it's less useful for getting beyond LEO. However, when the alternative is a non-cryo hypergolic with even poorer isp, it's a good idea to make the most use of it, especially if you can do the TLI straight off the pad. 

Then again, one option would be to use an inverted version of the Earth-Lunar-Orbit Rendezvous planned with Constellation. Constellation had the man-rated Ares I lifting Orion into LEO, then using Ares V to lift Altair into LEO for a rendezvous. After docking, the Ares V upper stage would send the whole stack to a free-return, after which the Altair's descent engines would perform the lunar orbit insertion burn. Using the lander's engine for the insertion burn is slightly more efficient than going the Apollo route (using the CSM's engine), since you get to drop those tanks on your landing. 

The inverted version of the Constellation architecture would be to send a prop-heavy lander up to LEO on the first Falcon Heavy, then send up a Dragon 2 (with kick stage in the trunk) and dock to the lander in LEO, with the Falcon Heavy upper stage still attached to the Dragon 2. That stage then fires for the TLI, rather than the lander's terminal stage as in the Constellation plan. This allows the whole mission to make optimal use of the two equally-sized LVs rather than using one gigantic HLV and a smaller man-rated launcher.

I haven't crunched all the numbers, but one very interesting option would hinge on whether the Falcon 9 upper stage can be easily modified for extended-lifetime restarts. That's where things get really interesting, because you could dock both stacks in LEO, use the Dragon 2's ascent stage for the TLI, and then use the lander's ascent stage in cislunar orbit to perform the insertion burn. Dry mass does start to pile up a bit, in that scenario, but you make the best use of the MVac's higher isp relative to storables, and you have the smallest cislunar mission stack, which means less dev cost.

JLOR is good, but it means your Dragon 2's kick stage needs to carry enough fuel for both lunar insertion and for the Earth return burn, and I'm not sure exactly how much dV you can realistically cram into that trunk.

Current issue is battery life, it should be easy to fix, adding solar panels should work, don't think stage use much power then idle. having the stage drain power from dragon or lunar lander panels is another. 
Longer term its oxygen boil off,  might be other issues too. 

[sevenperforce]

36 minutes ago, magnemoe said:

Current issue is battery life, it should be easy to fix, adding solar panels should work, don't think stage use much power then idle. having the stage drain power from dragon or lunar lander panels is another. 
Longer term its oxygen boil off,  might be other issues too. 

Without a specific lander design, it's hard to do much math to determine the most efficient solution.