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#51 2020-01-04 16:27:07

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,248
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Re: Constructing a human mission, a tonne at a time

Trying to inject some reality here. 

Kbd512 is quite right:  Spacex is busy enough just trying to fly some prototypes while fulfilling existing contracts for cargo delivery,  launch services,  and crew capsule development. 

Musk may want to bring everything to Mars for building a colony in the first several landings,  but his own people know better than that.  That is way,  way to hell-and-gone,  beyond them.  And most of them know it,  even if they cannot admit it without being fired.

There are no tested,  ready-to-use,  and full-scale machinery items yet available for making oxygen to breathe,  and water to drink,  for even a small group of people on Mars.  Much less the huge machinery needed to make a few thousand tons of liquified oxygen and liquified methane on Mars on a time scale of less than decades.  Or the ~100-1000 MW-scale electricity supplies needed to make any of this stuff work. (Mostly nuke,  because of those occasional pesky gigantic dust storms.)

Without those things,  Starship would be a one-way ticket to Mars for what amounts to a suicide mission,  something no sane government would ever allow.  And rightly so. 

As Kbd512 said,  it will be many years,  at least a decade or two,  before those things are ready to use.  No one is currently funding those developments.  I'm sorry,  but a lab bench-top demonstration device operating under benign conditions here on Earth,  is NOT (I repeat NOT!!!!!) the ready-to-use,  large-scale machinery we need. That difference spans a decade or 2 of development and demonstration work.  Always has,  always will. 

You wanna see a self-sustaining colony on Mars?  Then vote out the fools we have in Congress and the Executive,  and vote in somebody else who might actually address this infrastructure requirement.  (And I do mean ALL of them!) 

Problem is,  I cannot name a single name in either party,  or among the independents,  who would do such. Neither can anyone else,  or we might have seen some credible names here on these forums. We have not.

Musk may well get Starship to fly well enough to serve as a transport to LEO.  He might even get one to the moon and back, sometime in the next few-to-several years.  Remember,  he usually does what he promises,  but it also usually takes 2-3 times as long as he first thinks. 

Given a big transport like Starship to Mars,  and enough support to stomach a few fatal crashes getting there (big damned "if",  that one!!!),  there is a way to set up a small base supplied 100% from Earth,  that can be occupied for a while,  but it will NOT be cheap or easy. 

It takes about 1200 tons of LOX LCH4 propellants to get a Starship from Mars back to Earth,  and at reduced payload.  That would be the small crew plus their life support returning on their rotation back to Earth.

Assuming each Starship can hold 200 tons of propellant-as-payload to Mars (for 6),  and assuming one more ship can make up evaporative losses over a 13 month stay,  you could send the return propellant from Earth to Mars in 7 cargo Starships. 

One or two more could bring the supplies and equipment to set up a small base for a couple of years,  if need be.  Yet one more brings the crew and some more supplies and equipment.

That's 10 starships to Mars,  to get about a dozen or two folks to Mars, with enough to live for 2 years on stored oxygen,  stored water,  and stored food, all sent from Earth. 

10 Starships assuming 100% success getting them down on Mars without mishap,  and close enough to each other to be useful.  The odds of that happening are virtually nil. Sorry.  Nil!

Early on,  I'd guess more than half,  maybe 2/3,  of these vehicles will be lost in crashes or by landing too far away.  So you are really looking at 20-30 Starship launches from LEO, to put a couple of dozen people on Mars, for maybe 2 years.  Each one of those needs 6 tankers to fuel up for the trip from LEO to Mars. 

So,  the utter minimum number of launches required is (10-to-Mars)*6 tankers + 10-to-Mars = 70 ships launched from Earth. The more realistic figure is (20-to-30-to-Mars)*6 tankers + 20-to-30-to-Mars = 140 to 210 ships launched from Earth. 

Cost per launch of Starship is still unknown.  I do NOT believe $2M per launch!  I do NOT believe $20M per launch!  I might believe $200M per launch. 200 launches at $200M/launch ~ $40B. With several lost ships and a dead crew or two. Ain't gonna happen that way,  guys!

Whatever site we choose,  there needs to be a precursor mission that verifies resources of the type,  quality,  and quantity that can be used to provide water,  oxygen to breathe,  and to make 1000's of tons of propellant,  on (only!!!) a 2 year time scale. 

Some of that can be done with a very small crew,  and then left running,  with beacons in place on the ground,  and navigation satellites left in orbit,  for a much smaller swarm of Starship-sized transports later.  You have to do that, to verify the adequacy of all that infrastructure equipment in-situ,  and get the ground truth on your resources, before you risk a bunch of lives.

Anything else is unethical in the extreme. 

Then all you have to ship is the food,  until somebody can figure out what is really needed to grow it locally. I've seen lots of speculations about food production on these forums,  but the point is,  WE DON'T REALLY KNOW,  and we won't know,  until people have been there a while. 

That's the plain truth of it,  guys!

GW

Last edited by GW Johnson (2020-01-04 16:34:52)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#52 2020-01-04 16:52:09

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,310

Re: Constructing a human mission, a tonne at a time

One of the reallities as well for the Dragon and Falcon heavy is that even the moon missions are off which is also a precusor testing of ability for man even if its on a smaller time scale as all of the hardware to go, land and return are tested. Even Nasa took trial runs before going for all of those steps.
So if we can not go with what we have we need to change it for the better and not for just because we can build it big as that solves very little.

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#53 2020-01-04 17:25:35

louis
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From: UK
Registered: 2008-03-24
Posts: 5,969

Re: Constructing a human mission, a tonne at a time

Space X will be experienced in human flights within a couple of years. But there is a hell of a lot they can gain from the literature, from autobiographical publications, interviews with astronauts and so on, even before they attempt to put anyone in space.

SpaceNut wrote:

One of the reallities as well for the Dragon and Falcon heavy is that even the moon missions are off which is also a precusor testing of ability for man even if its on a smaller time scale as all of the hardware to go, land and return are tested. Even Nasa took trial runs before going for all of those steps.
So if we can not go with what we have we need to change it for the better and not for just because we can build it big as that solves very little.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#54 2020-01-04 17:31:53

kbd512
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Registered: 2015-01-02
Posts: 4,030

Re: Constructing a human mission, a tonne at a time

Louis,

I've asked you repeatedly to provide any kind of evidence (research papers on experiments conducted, patent applications, press releases, etc) that demonstrate that SpaceX has or is working on a MW-class Sabatier reactor and autonomous ice mining equipment.  Thus far, you've been unable to provide any (by "any", I mean anything beyond a statement made by Elon Musk) such evidence.  I have a pretty good idea of why that is.  There's no such equipment in existence and there never has been.  To my knowledge, only NASA and JPL have done any serious work on such devices (going from basic concepts to functional hardware that, at the very least, works in some kind of lab environment), but thus far their experiments haven't progressed to provide the capabilities required for SpaceX to do anything once they send their magical 500 tons of cargo to Mars.  I can only surmise that that's because it's nowhere near as simple or as easy as you think it should be.

You asserted that Lockheed-Martin's proposal is unrealistic and discounted it out of hand, whereas you assert that SpaceX has the only realistic program in place.  I'm not sure what you base your assertions on, so I have no idea why you think what you think.  If SpaceX's mission plan fails because their ideas are half-baked or otherwise unworkable, do you still want humanity to go to Mars?  You seem to hold this myopic idea that only SpaceX can do something worthwhile, despite the fact that their accomplishment list is rather short compared to NASA and their other contractors.  They're really good at launching rockets with small capsules or satellites and recovering the boosters for reuse.  That's quite laudable in and of itself, but a human space exploration program encompasses vastly more technology than that.  I can only speak for myself when I say that I'd rather attempt multiple approaches to empirically determine what works and what doesn't, because I'm more interested in sending humans to Mars than worrying about who gets their first or what technologies happen to work or fail.

In my alternative proposals regarding how this could potentially work, we try multiple approaches because that reduces the risk of failure.  If SpaceX's approach happens to work best, so be it.  I really don't care.  I'd be just as happy if SpaceX conducted a successful mission as NASA, ESA, ROSCOSMOS, or anyone else.  To me, this is about human advancement- leaving the cradle of life to explore parts unknown.  What I truly don't understand is the religious experience some people have when they listen to Elon Musk talk.  I value action more than speeches.

While you may not see any value to the multiple approaches taken by America's human space flight program, some of the rest of us think that's the best way to assure that missions are successfully executed.  I, for example, see real wisdom in having 3 different vehicles (Dragon 2, Starliner, Dream Chaser) perched atop different rockets (Falcon 9, Atlas V, New Glenn) because it assures access to space.  If a vehicle has a problem, reason unimportant when lives are at stake, we have a Plan B and Plan C ready and waiting to become the new Plan A.

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#55 2020-01-04 17:42:05

kbd512
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Registered: 2015-01-02
Posts: 4,030

Re: Constructing a human mission, a tonne at a time

Louis,

Reading about space flight does not make one experienced in executing successful space flight operations.  Sometimes you can figure out what failed and why it failed by reading, but most of the time actual hands-on experience is required.  I haven't seen any of the other contractor's space capsules explode on a test stand, which should be a relatively clear indicator that reading alone doesn't impart any practical knowledge.  Thus far, SpaceX doesn't have any human space flight experience whatsoever, even though NASA is hoping to change that in 2020.

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#56 2020-01-04 18:50:18

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,969

Re: Constructing a human mission, a tonne at a time

I think your approach underestimates Musk's resourcefulness.

Of course, I have no evidence that Space are working on a MW-class system for manufacturing methane. It would just seem odd if he wasn't since it is an absolutely vital keystone in the architecture of Mission One.

What we do have evidence for is (a) Space X's stated overview plan for Mission One, which does involve manufacturing methane and separating out oxygen on Mars and (b) we know they have been researching landing sites with JPL-NASA around the Arcadia Planitia/Amazonis Planitia boundary.

We also have plenty of evidence to suggest Musk is deadly serious in attempting to reach Mars as soon as possible.

Autonomous mining equipment is common in the mining industry. Use of hammers, diggers and buckets is common in mining and construction. We know NASA are far advanced with pressurised rovers. We know Musk has referenced the possibility of a pressurised version of the Cybertruck being used on Mars (the vehicle does seem suspiciously robust, it has to be said, for purposes on Earth).
It may well be that planning is more advanced than we think.

That's just a commonsense observation I would say. People were surprised when Musk started building Starships. I was surprised to see that recent photo of three domes for the SuperHeavy being prepared. 

I don't think I said Lockheed-Martin's plans were unrealistic, in the sense of being infeasible. I said they were "nonsense", by which I mean they make no sense to me. To put in all that huge effort (and money) into design of various modules that have in essence only one purpose - getting to Mars - is a foolish way to proceed. The genius of Musk's Starship proposal is that it can (potentially) work for: ISS supply,  satellite placement in Earth orbit, orbital tourism, lunar orbital and surface tourism, lunar exploration, Earth-to-Earth transportation, Mars exploration, Mars settlement and even outer solar system exploration. The multi-purpose character of the Starship means that development costs can be spread across a range of activities. Moreover the large payload capacity of around 100 tons sets it in a class of its own, enabling it put in place significant infrastructure in one go. It makes possible not simply Mars exploration but Mars settlement.

I am currently reading a book - Apollo 11: The Inside Story - which actually has a lot about the Space Race between the US and USSR. What strikes me is the pace of development. It seems to me that Musk is working much more at the pace of the Soviets and Americans in that era and also maintaining a real focus on the task (not doing what contemporay NASA does, which is diffuse its focus in several directions). Whole new approaches to space vehicles and exploration would be formulated and engineered in weeks and months not years and decades.

I am a cheerleader for Space X for two reasons: (a) because I think they have "the right stuff" to do it, and do it quickly and (b) because I think they are the best hope for humanity on Mars - establishing a stong, free society on the planet before the party-poopers arrive.














kbd512 wrote:

Louis,

I've asked you repeatedly to provide any kind of evidence (research papers on experiments conducted, patent applications, press releases, etc) that demonstrate that SpaceX has or is working on a MW-class Sabatier reactor and autonomous ice mining equipment.  Thus far, you've been unable to provide any (by "any", I mean anything beyond a statement made by Elon Musk) such evidence.  I have a pretty good idea of why that is.  There's no such equipment in existence and there never has been.  To my knowledge, only NASA and JPL have done any serious work on such devices (going from basic concepts to functional hardware that, at the very least, works in some kind of lab environment), but thus far their experiments haven't progressed to provide the capabilities required for SpaceX to do anything once they send their magical 500 tons of cargo to Mars.  I can only surmise that that's because it's nowhere near as simple or as easy as you think it should be.

You asserted that Lockheed-Martin's proposal is unrealistic and discounted it out of hand, whereas you assert that SpaceX has the only realistic program in place.  I'm not sure what you base your assertions on, so I have no idea why you think what you think.  If SpaceX's mission plan fails because their ideas are half-baked or otherwise unworkable, do you still want humanity to go to Mars?  You seem to hold this myopic idea that only SpaceX can do something worthwhile, despite the fact that their accomplishment list is rather short compared to NASA and their other contractors.  They're really good at launching rockets with small capsules or satellites and recovering the boosters for reuse.  That's quite laudable in and of itself, but a human space exploration program encompasses vastly more technology than that.  I can only speak for myself when I say that I'd rather attempt multiple approaches to empirically determine what works and what doesn't, because I'm more interested in sending humans to Mars than worrying about who gets their first or what technologies happen to work or fail.

In my alternative proposals regarding how this could potentially work, we try multiple approaches because that reduces the risk of failure.  If SpaceX's approach happens to work best, so be it.  I really don't care.  I'd be just as happy if SpaceX conducted a successful mission as NASA, ESA, ROSCOSMOS, or anyone else.  To me, this is about human advancement- leaving the cradle of life to explore parts unknown.  What I truly don't understand is the religious experience some people have when they listen to Elon Musk talk.  I value action more than speeches.

While you may not see any value to the multiple approaches taken by America's human space flight program, some of the rest of us think that's the best way to assure that missions are successfully executed.  I, for example, see real wisdom in having 3 different vehicles (Dragon 2, Starliner, Dream Chaser) perched atop different rockets (Falcon 9, Atlas V, New Glenn) because it assures access to space.  If a vehicle has a problem, reason unimportant when lives are at stake, we have a Plan B and Plan C ready and waiting to become the new Plan A.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#57 2020-01-04 18:53:20

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,969

Re: Constructing a human mission, a tonne at a time

Of course, but reading about the Apollo Mission and the Space Race (see my previous post) is a reminder that Korolev and Von Braun were having to invent things from scratch.  Space X can draw on a wealth of experience when it comes to designing for human flight and also for providing for life support over a long duration (thanks to the ISS).  That is a leg-up...they are not having to work things out from the ground up.

kbd512 wrote:

Louis,

Reading about space flight does not make one experienced in executing successful space flight operations.  Sometimes you can figure out what failed and why it failed by reading, but most of the time actual hands-on experience is required.  I haven't seen any of the other contractor's space capsules explode on a test stand, which should be a relatively clear indicator that reading alone doesn't impart any practical knowledge.  Thus far, SpaceX doesn't have any human space flight experience whatsoever, even though NASA is hoping to change that in 2020.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#58 2020-01-04 19:20:43

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,969

Re: Constructing a human mission, a tonne at a time

GW,  the average person drinks something like 2.5 kgs of fluids and takes in about 1.5 kgs of food per day.  Assuming I've remembered that right, that's 4 kgs per day. For a 200 day flight to Mars that would be for a 3 person crew (I'm assuming two Starships, each with a 3 person crew) 12 kgs x 200 = 2.4 tons. That's out of a payload of 100 tons. You could multiply that by 10 times to provide enough food and fluid for 2000 days and you're still at only 24 tons for 3 persons or 48 tons for the full  6 person mission. That's 48 tons out of a total mission tonnage of 500 tons.

I am surprised people don't see what a game changer it is having all that tonnage available. You can have your Mars mission with absolutely no water recycling if you like. Of course, I think they will provide for water recycling. I presume they will buy in the ISS technology but also have some back up technology in terms of simpler recycling techniques.

The methane-oxygen manufacture process is certainly one of the top three challenges along with the landing/ascent protocol and human health. It could be cracked within six months I would say. We're not trying to overcome any fundamentals here, we're simply trying to scale up lab-scale testing to something approaching an industrial facility. But there are analogues for all the steps in the process. It's simply a case of bringing together lab knowledge, similar industrial processes and Mars-proofing, after which you probably need another six months of rigorous testing.  I think as regards Mars-proofing, I see no reason why the facility needs to be placed in the near vaccuum on Mars. It can be housed in an appropriate hab with air locks.  You'd probably double or treble up the habs, to provide some failsafeness as well.

I think Space X's chief engineer has said they can do the Mars run on one launch plus five refuels launches. Space X's Mars Mission would require something like 36 launches...which could probably be accomplished with 12 Starships I would guess (there being multiple reuse).

You are in my view being incredibly pessimistic about methane-oxygen on Mars!

Water ice location, NASA tells us, will not be a problem, as long as you land where the ice is just below the surface. So it's really just an engineering challenge, and one that will have a lot of money thrown at it.

I bet you could solve the challenge if you got given $500 million GW!

As for shipping out food, I would think within 10 years there will be virtually no need to do that - food will be imported simply to provide the meat content and some variety. So within 10 years I am pretty sure Mars will be 80% self-sufficient.


GW Johnson wrote:

Trying to inject some reality here. 

Kbd512 is quite right:  Spacex is busy enough just trying to fly some prototypes while fulfilling existing contracts for cargo delivery,  launch services,  and crew capsule development. 

Musk may want to bring everything to Mars for building a colony in the first several landings,  but his own people know better than that.  That is way,  way to hell-and-gone,  beyond them.  And most of them know it,  even if they cannot admit it without being fired.

There are no tested,  ready-to-use,  and full-scale machinery items yet available for making oxygen to breathe,  and water to drink,  for even a small group of people on Mars.  Much less the huge machinery needed to make a few thousand tons of liquified oxygen and liquified methane on Mars on a time scale of less than decades.  Or the ~100-1000 MW-scale electricity supplies needed to make any of this stuff work. (Mostly nuke,  because of those occasional pesky gigantic dust storms.)

Without those things,  Starship would be a one-way ticket to Mars for what amounts to a suicide mission,  something no sane government would ever allow.  And rightly so. 

As Kbd512 said,  it will be many years,  at least a decade or two,  before those things are ready to use.  No one is currently funding those developments.  I'm sorry,  but a lab bench-top demonstration device operating under benign conditions here on Earth,  is NOT (I repeat NOT!!!!!) the ready-to-use,  large-scale machinery we need. That difference spans a decade or 2 of development and demonstration work.  Always has,  always will. 

You wanna see a self-sustaining colony on Mars?  Then vote out the fools we have in Congress and the Executive,  and vote in somebody else who might actually address this infrastructure requirement.  (And I do mean ALL of them!) 

Problem is,  I cannot name a single name in either party,  or among the independents,  who would do such. Neither can anyone else,  or we might have seen some credible names here on these forums. We have not.

Musk may well get Starship to fly well enough to serve as a transport to LEO.  He might even get one to the moon and back, sometime in the next few-to-several years.  Remember,  he usually does what he promises,  but it also usually takes 2-3 times as long as he first thinks. 

Given a big transport like Starship to Mars,  and enough support to stomach a few fatal crashes getting there (big damned "if",  that one!!!),  there is a way to set up a small base supplied 100% from Earth,  that can be occupied for a while,  but it will NOT be cheap or easy. 

It takes about 1200 tons of LOX LCH4 propellants to get a Starship from Mars back to Earth,  and at reduced payload.  That would be the small crew plus their life support returning on their rotation back to Earth.

Assuming each Starship can hold 200 tons of propellant-as-payload to Mars (for 6),  and assuming one more ship can make up evaporative losses over a 13 month stay,  you could send the return propellant from Earth to Mars in 7 cargo Starships. 

One or two more could bring the supplies and equipment to set up a small base for a couple of years,  if need be.  Yet one more brings the crew and some more supplies and equipment.

That's 10 starships to Mars,  to get about a dozen or two folks to Mars, with enough to live for 2 years on stored oxygen,  stored water,  and stored food, all sent from Earth. 

10 Starships assuming 100% success getting them down on Mars without mishap,  and close enough to each other to be useful.  The odds of that happening are virtually nil. Sorry.  Nil!

Early on,  I'd guess more than half,  maybe 2/3,  of these vehicles will be lost in crashes or by landing too far away.  So you are really looking at 20-30 Starship launches from LEO, to put a couple of dozen people on Mars, for maybe 2 years.  Each one of those needs 6 tankers to fuel up for the trip from LEO to Mars. 

So,  the utter minimum number of launches required is (10-to-Mars)*6 tankers + 10-to-Mars = 70 ships launched from Earth. The more realistic figure is (20-to-30-to-Mars)*6 tankers + 20-to-30-to-Mars = 140 to 210 ships launched from Earth. 

Cost per launch of Starship is still unknown.  I do NOT believe $2M per launch!  I do NOT believe $20M per launch!  I might believe $200M per launch. 200 launches at $200M/launch ~ $40B. With several lost ships and a dead crew or two. Ain't gonna happen that way,  guys!

Whatever site we choose,  there needs to be a precursor mission that verifies resources of the type,  quality,  and quantity that can be used to provide water,  oxygen to breathe,  and to make 1000's of tons of propellant,  on (only!!!) a 2 year time scale. 

Some of that can be done with a very small crew,  and then left running,  with beacons in place on the ground,  and navigation satellites left in orbit,  for a much smaller swarm of Starship-sized transports later.  You have to do that, to verify the adequacy of all that infrastructure equipment in-situ,  and get the ground truth on your resources, before you risk a bunch of lives.

Anything else is unethical in the extreme. 

Then all you have to ship is the food,  until somebody can figure out what is really needed to grow it locally. I've seen lots of speculations about food production on these forums,  but the point is,  WE DON'T REALLY KNOW,  and we won't know,  until people have been there a while. 

That's the plain truth of it,  guys!

GW


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#59 2020-01-04 19:49:31

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,310

Re: Constructing a human mission, a tonne at a time

The trouble is that you are not preparing the food to eat, that you have not considered the container that holds the water, the bulk waste of packaging that the food will come in. That you will need something to eat it with, that water is used to cleanup the eating and cooking utensils....then where is all the waste created collected

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#60 2020-01-04 20:18:49

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,969

Re: Constructing a human mission, a tonne at a time

Yes, all that needs to be taken into account. But I was giving some extreme figures there - 2000 days and taking all your food and water...and no dried food. The reality is there will be some water recycling, if only via dehumidifiers!

Yes, water is used not just for survival. However, in space moist wipes have been found v. useful for maintaining hygiene, so I expect that would be followed on a Mars Mission. Moist wipes for a the outward journey would be a trivial amount of tonnage...I am guessing just a few kgs.

As for washing up...well yes, I don't think they bother much with plates or cooking utensils on the ISS do they?  There will be packaging and so on, but I doubt that will add more than say 2 tons to the 48 ton total.


SpaceNut wrote:

The trouble is that you are not preparing the food to eat, that you have not considered the container that holds the water, the bulk waste of packaging that the food will come in. That you will need something to eat it with, that water is used to cleanup the eating and cooking utensils....then where is all the waste created collected


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#61 2020-01-04 20:23:59

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,310

Re: Constructing a human mission, a tonne at a time

"No dried food" means refridgeration and freezers that add to mass and energy as well heat removal infrastructure...It also means canned foods as not much stays fresh after a couple weeks.

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#62 2020-01-04 20:41:34

kbd512
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Registered: 2015-01-02
Posts: 4,030

Re: Constructing a human mission, a tonne at a time

Louis,

I don't think I'm under- or over-estimating anyone or anything.  What I have been doing for years now is looking, thus far in vain, for evidence that ANYONE is seriously working on the MW-class Sabatier reactor that would be required to make SpaceX's proposal work.  Whenever your plan dictates the use of a hydrocarbon fuel, the refinery is a mandatory piece of equipment, meaning not open for discussion or debate.  Playing silly word games with current technological reality won't change it.  My own "common sense observation" is that whenever someone makes a claim without a scintilla of supporting evidence, there's little reason to believe it, no matter who said it.  We humans also have these fairly well-established concepts we call marketing and propaganda, neither of which imbue a product with any demonstrated capability.  Elon Musk is a master of marketing, yet some of what he claims is clearly more marketing than demonstrated capability.  The employees of SpaceX are highly innovative engineers, but some of the ones working on critical systems such as the check-valves for hypergolic propellants, are also a little greener than you'd like to believe.  That's just an honest observation of what I've seen happen with their hardware, which takes nothing away from the truly excellent work that they've done.  As such, this mission simply won't happen in the claimed time frame.  The mid-2030's "first mission" was and is a pretty accurate launch date goal / target.

So, while SpaceX's plan absolutely could work, there's a mountain of development work to accomplish before it does work.  The only thing that was "surprising" to me about Starship is that they didn't first apply every concept they thought would be needed to make Starship work and incorporate it into a Falcon booster and upper stage.  If the LOX/LCH4 engines are all they're cracked up to be and on-orbit refueling is such a piece of cake to do, then fabricate a sub scale demonstrator in the form of a fully reusable Falcon booster / upper stage combination that uses the Raptor engines and demonstrate propellant transfer in orbit.  Until those technologies operate as reliably as a Singer sewing machine, fabricating larger and more expensive propellant tanks won't make any difference.

SLS was / is far more expensive than it needed to be precisely because NASA decided to alter every last part of their design, to include the engines, to the point that it shares virtually nothing in common with STS.  Their management has this weird character flaw whereby they constantly attempt to make something that's nearly or actually impossible work, such as the issue of sufficient thrust to achieve the delivered payload target using 4 instead of 5 RS-25 engines in the core stage.  Their design review committee knew from the word "go" that SLS wasn't going to lift 130t without 5 RS-25's, yet insisted on dragging out development with 4 RS-25's and future SRB development to "save development costs".  Naturally, nothing of the sort ever happened and what transpired wasn't the least bit surprising to me.

Regarding the approach SpaceX has taken, with respect to mission hardware development, I seem to recall that America was explored long before it was settled.  In the past, exploration was generally a mandatory activity to figure out where the resources to enable settlement were located.  I don't think sensor technology has fundamentally changed that requirement for colonization, apart from making locating the resources a bit faster and more efficient.  For SpaceX's plan to work at all, industrial scale technologies need to be applied to the processing of resources from another planet with unknown qualities from high-power / high-efficiency / highly-automated machinery that doesn't presently exist.  All of that would be much easier to accomplish after a single human exploration mission had confirmed the characteristics of the available resources.  If the required quantities of water were indeed available just 1 meter below the ground vs 1 kilometer below the ground, that's an entirely different problem to solve and solving the former is not necessarily any easier than the latter, which would be precisely why your first course of action should be determining what problems you have to solve (something you can only do through exploration and experimentation).

NASA doesn't have a mandate to colonize other planets.  Our space exploration agency does have a mandate to explore other planets, which transcends myopic Mars colonization efforts.  In that regard, development of purpose-built vehicles designed to facilitate exploration makes quite a bit of sense.  They don't have the same goal as SpaceX does because colonization was never part of their charter.

In any event, I'm a little bored with discussing what little SpaceX is actually doing.  Right now they're trying to meet the terms of their existing contracts while development of Starship and StarLink is ongoing.  Feel free to cheer-lead away for SpaceX, but try to understand that some of us don't share your level of enthusiasm without demonstrated results.

Incidentally, focusing development efforts on purpose-built hardware ensures that the result is optimized for operation in a specific environment.  A purpose-built, in-space-only interplanetary transport vehicle doesn't need reentry heat shields or massive chemical rocket engines.  That means it can be optimized to provide life support functions in a microgravity or artificial gravity environment.  Since at least 6 months of a 2 year mission are spent going to and from Mars, that's a pretty big deal.  If you can't land, reason unimportant, then the long term habitability of the vehicle is all that matters.  Starship is an all-or-nothing affair.  The launch / multiple on-orbit refueling operations / transit / reentry / landing is either perfect or you don't survive long enough to make anything else an issue.  The design requirements for those use cases are wildly divergent.  Furthermore, sending a Starship to Mars for 2 years instead of using it to continuously launch payloads from Earth makes very little economic sense for a company claiming to be concerned with the economic viability of Mars colonization, as Dr. Zubrin has already pointed out.

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#63 2020-01-04 21:01:56

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,310

Re: Constructing a human mission, a tonne at a time

I agree that the Falcon Heavy capable of launching to LEO 63mT of payload is plenty to build the refueling depot concepts.
Send up in the complete assembly with the solar panels on the sides, the radiator on the other, a tank of water, a tank filled with co2 and lets go..then fill a stage sent up empty to prove out what can be done....

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#64 2020-01-04 22:08:47

kbd512
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Registered: 2015-01-02
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Re: Constructing a human mission, a tonne at a time

SpaceNut,

A fully reusable Raptor-powered Falcon Heavy size booster and upper stage with on-orbit refueling would arguably be a greater mission enabler, for both exploration and colonization, than a brand new gigantic rocket that still has to refuel to go anywhere else but LEO.  Since empirical evidence indicates it's not possible to make a 747 cheaper to operate than a 737, I see no evidence that larger rockets will be cheaper to operate than smaller rockets.  It's not possible to make a 4-engined aircraft cheaper to operate than a 2-engined aircraft, which is why all the passenger service airlines have switched to twin engined aircraft.  The fuel costs have been steadily killing off jumbo jets while smaller but still highly capable aircraft have largely replaced them.  So...  Figure out how to operate a fleet of small rockets with daily launches and that will be the fastest way to reduce launch costs.  When there's enough demand to justify larger rockets, then and only then should larger rockets even be considered.

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#65 2020-01-04 22:39:40

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,310

Re: Constructing a human mission, a tonne at a time

Last I knew Musk said no to changing the falcon second stage from its current fuel and engine but that would make sense to do. He did tweet about a mini starship but there has not be anything but a full scale prototype work....

https://en.wikipedia.org/wiki/SpaceX_rocket_engines

https://www.teslarati.com/spacex-supera … elon-musk/

[SpaceX is using] SX 300 & soon SX 500. Kind of a modern version of Inconel superalloys. High strength at temperature, extreme oxidation resistance. Needed for ~800 atmosphere, hot, oxygen-rich turbopump on Raptor rocket engine.” – Elon Musk

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#66 2020-01-05 07:41:41

louis
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From: UK
Registered: 2008-03-24
Posts: 5,969

Re: Constructing a human mission, a tonne at a time

This is a good description of what is required:

https://www.thespacereview.com/article/3484/1

The Exytron approach at Augsburg might be relevant:

https://www.carboncommentary.com/blog/2 … -and-reuse

They do seem to have an installed pilot project:

https://exytron.online/en/news/

It would obviously need scaling up.

This Danish biogas planet has successfully experimented with a methanation plant...but again, looks like they need to scale that up.

https://www.lemvigbiogas.com/MeGa-stoREfinalreport.pdf

But this might be where Space X would go for manufacture or consultancy advice for their own manufacture.


kbd512 wrote:

Louis,

I don't think I'm under- or over-estimating anyone or anything.  What I have been doing for years now is looking, thus far in vain, for evidence that ANYONE is seriously working on the MW-class Sabatier reactor that would be required to make SpaceX's proposal work.  Whenever your plan dictates the use of a hydrocarbon fuel, the refinery is a mandatory piece of equipment, meaning not open for discussion or debate.  Playing silly word games with current technological reality won't change it.  My own "common sense observation" is that whenever someone makes a claim without a scintilla of supporting evidence, there's little reason to believe it, no matter who said it.  We humans also have these fairly well-established concepts we call marketing and propaganda, neither of which imbue a product with any demonstrated capability.  Elon Musk is a master of marketing, yet some of what he claims is clearly more marketing than demonstrated capability.  The employees of SpaceX are highly innovative engineers, but some of the ones working on critical systems such as the check-valves for hypergolic propellants, are also a little greener than you'd like to believe.  That's just an honest observation of what I've seen happen with their hardware, which takes nothing away from the truly excellent work that they've done.  As such, this mission simply won't happen in the claimed time frame.  The mid-2030's "first mission" was and is a pretty accurate launch date goal / target.

So, while SpaceX's plan absolutely could work, there's a mountain of development work to accomplish before it does work.  The only thing that was "surprising" to me about Starship is that they didn't first apply every concept they thought would be needed to make Starship work and incorporate it into a Falcon booster and upper stage.  If the LOX/LCH4 engines are all they're cracked up to be and on-orbit refueling is such a piece of cake to do, then fabricate a sub scale demonstrator in the form of a fully reusable Falcon booster / upper stage combination that uses the Raptor engines and demonstrate propellant transfer in orbit.  Until those technologies operate as reliably as a Singer sewing machine, fabricating larger and more expensive propellant tanks won't make any difference.

SLS was / is far more expensive than it needed to be precisely because NASA decided to alter every last part of their design, to include the engines, to the point that it shares virtually nothing in common with STS.  Their management has this weird character flaw whereby they constantly attempt to make something that's nearly or actually impossible work, such as the issue of sufficient thrust to achieve the delivered payload target using 4 instead of 5 RS-25 engines in the core stage.  Their design review committee knew from the word "go" that SLS wasn't going to lift 130t without 5 RS-25's, yet insisted on dragging out development with 4 RS-25's and future SRB development to "save development costs".  Naturally, nothing of the sort ever happened and what transpired wasn't the least bit surprising to me.

Regarding the approach SpaceX has taken, with respect to mission hardware development, I seem to recall that America was explored long before it was settled.  In the past, exploration was generally a mandatory activity to figure out where the resources to enable settlement were located.  I don't think sensor technology has fundamentally changed that requirement for colonization, apart from making locating the resources a bit faster and more efficient.  For SpaceX's plan to work at all, industrial scale technologies need to be applied to the processing of resources from another planet with unknown qualities from high-power / high-efficiency / highly-automated machinery that doesn't presently exist.  All of that would be much easier to accomplish after a single human exploration mission had confirmed the characteristics of the available resources.  If the required quantities of water were indeed available just 1 meter below the ground vs 1 kilometer below the ground, that's an entirely different problem to solve and solving the former is not necessarily any easier than the latter, which would be precisely why your first course of action should be determining what problems you have to solve (something you can only do through exploration and experimentation).

NASA doesn't have a mandate to colonize other planets.  Our space exploration agency does have a mandate to explore other planets, which transcends myopic Mars colonization efforts.  In that regard, development of purpose-built vehicles designed to facilitate exploration makes quite a bit of sense.  They don't have the same goal as SpaceX does because colonization was never part of their charter.

In any event, I'm a little bored with discussing what little SpaceX is actually doing.  Right now they're trying to meet the terms of their existing contracts while development of Starship and StarLink is ongoing.  Feel free to cheer-lead away for SpaceX, but try to understand that some of us don't share your level of enthusiasm without demonstrated results.

Incidentally, focusing development efforts on purpose-built hardware ensures that the result is optimized for operation in a specific environment.  A purpose-built, in-space-only interplanetary transport vehicle doesn't need reentry heat shields or massive chemical rocket engines.  That means it can be optimized to provide life support functions in a microgravity or artificial gravity environment.  Since at least 6 months of a 2 year mission are spent going to and from Mars, that's a pretty big deal.  If you can't land, reason unimportant, then the long term habitability of the vehicle is all that matters.  Starship is an all-or-nothing affair.  The launch / multiple on-orbit refueling operations / transit / reentry / landing is either perfect or you don't survive long enough to make anything else an issue.  The design requirements for those use cases are wildly divergent.  Furthermore, sending a Starship to Mars for 2 years instead of using it to continuously launch payloads from Earth makes very little economic sense for a company claiming to be concerned with the economic viability of Mars colonization, as Dr. Zubrin has already pointed out.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#67 2020-01-05 08:26:01

tahanson43206
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Registered: 2018-04-27
Posts: 5,120

Re: Constructing a human mission, a tonne at a time

For Louis re #65

Thank you for taking up the challenge from kbd512 ...

https://exytron.online/en/news/

This appears to be a full scale deployment of (almost) all of the techniques we've been discussing in recent months (if not years). 

What do you mean about "scale up" ???

I am curious about the claimed 87% efficiency, but I suppose if heat is counted for heating air and water for the homes that claim makes sense.

The 13% lost would presumably be whatever solar energy was NOT captured as useful heating.

In addition, if gas is used in traditional stoves, the CO2 generated would mix with the air in the home, which would then be exchanged with outside air to keep the needed balance between gases. 

The article did not say specifically that the output of furnaces is captured, or if it did I missed it.

The default would be to vent exhaust from high efficiency gas furnaces to the outdoors, and to take in other CO2 from the air at the methanization plant.

The entire set of concepts would appear (as I interpret it right now) to translate fairly well to Mars. 

A difference would be that ALL CO2 would need to be collected, so I would expect it would not be used for stove heating inside a habitat.

Pressure cookers are likely to be a popular category of cooking equipment on Mars.  An extension of that concept for Mars might be a pressurized oven, connected to the habitat space but separated from it by an air lock. 

Depending upon the results of a cooking session, a habitat occupant might decide to vent cooking gases to the outside rather than admit them to the habitat.

SpaceNut ... I'll bet that with the all-male engineering oriented nature of the forum membership the subject of cooking has not come up before.

Louis, if you have expertise in this area, this is a good time for you to start an exploration of concepts to go beyond the simple hydration process that is (apparently) the main food preparation method on the International Space Station.

(th)

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#68 2020-01-05 10:39:59

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,310

Re: Constructing a human mission, a tonne at a time

Climateworks is the other european company that is doing this same thing of co2 collection to fuel.

Chief cook and bottle washer for a family of 6 as wife could not standup to do so makes for some one that can do....
As for capability, microwaving is not cooking.
Most long term prepared foods are heavy with preservatives and they still will only last just so long.

These are all mass contributors for a mars mission.

We have yet to itemize them all as to what they are and the mass and energy that they all will require.

If the means to get mass to mars is in 1 ton increments as one of the variables we know then we need to focus on the list.

Next for the mass we need to know the volume that it will take as that container for mars can also only be that to which we can land with currently.

The next up is a trade table of mass for changes to what we can do for energy or equipment to save on cargo to mars.

This is how we would be able to preload a site for a manned mission.

I am currently working on the deliver vehicle numbers to see if we can get that mass for payload number to rise with what we currently have to land on mars in Red Dragon and the new Red Starliner as they are all that we have for capsule at this time.

Each has parts which make it work and that redesign would get more mass to mars for either in the end.

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#69 2020-01-05 11:28:57

tahanson43206
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Registered: 2018-04-27
Posts: 5,120

Re: Constructing a human mission, a tonne at a time

For SpaceNut re #68

There is some debate for your position on microwaving << grin >>

In recent months I've noticed packages coming on the market to take advantage of the (somewhat unique) properties of potatoes.

If the quality of the dish set before the family is the criterion, then I can confirm that the packages I have tried recently have proven quite acceptable.

Unfortunately, while the packages in question sold out, they have NOT been replaced.  The market in question is part of a chain, and purchases are made at regional headquarters, so I'm guessing the vendors are competing for shelf space.

I am less impressed by the competitive packages, which appear to require the "chef" to do more to prepare the dish for table.

The point here is that the ** real ** cooking is happening at the test kitchens of the vendors, where people with advanced degrees in related fields are going all out to find ways to solve the myriad challenges of delivering microwave heated products to the table.

***
Returning to Mars ... your point about mass for cooking (or other household activities) is a good one.  Mass was less of a concern when folks were moving their households from Europe to the Americas, although even then it WAS a concern.  At least a huge iron pot could be packed with something useful.

The solution in the case of the Americas was to learn how to make needed implements locally.

The same will most likely turn out to be true on Mars or other off-Earth locations.

***
I'd be interested in your evaluation of the oven-behind-an-airlock suggestion for the Mars habitat. 

Aromas of slow cooking may be inviting if care is taken in selection of ingredients and the pace of heating, but the lack of air circulation in a habitat may make what we take for granted in our homes on Earth less agreeable to all residents.

***
Taking the discussion of cooking a step further, and hoping for participation by ** real ** Texas barbecue aficionados, I'd like to offer my observation that despite some experience, I still manage to generate volumes of pungent smoke when I've allowed heat to build too rapidly, or made other mistakes which are the fate of the occasional grill operator.

It is possible [someone named Pete] will set up "Pete's Bar and Grill" in Sagan City (2018) [The ** real ** Sagan City], and management of the air in ** that ** facility will be interesting to study!

(th)

Last edited by tahanson43206 (2020-01-05 11:34:16)

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#70 2020-01-05 12:03:24

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,310

Re: Constructing a human mission, a tonne at a time

Part of air cleaning for co2 is circulation and filtering so we will have a dehumidifier within the complete unit.
That item may be appealing as its fresh and refridgerated or frozen for the microwave cooking. The waste stream of packaging is mass that we must launch and it adds up for disposal process. The energy for the microwave and refridgeration or freezing also adds up for the power source issues for each of the legs of a mars mission that follows. Now multiply that by 3 meals at minimum for each day to arrive at numbers....

Take a look at the best sold by date and then think about the journey legs of the mars mission as to how old on launch it will be. Outbound leg is 6-9 months long, if we leave food on orbit its going to be years old for a return trip, the time on planet would be approximate 500 days give or take 100 days, then trying to eat the food on the remaining 6-9 months before getting home.

edit:
Gourmet Cooking en route to Mars

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#71 2020-01-05 13:29:56

tahanson43206
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Registered: 2018-04-27
Posts: 5,120

Re: Constructing a human mission, a tonne at a time

For SpaceNut re #70

The time frame under discussion varies from forum member to forum member, and post to post.

I was thinking about underground habitats on Mars, well after the initial exploration phase. 

Your post appears to focus on travel to and from Mars.

I would like to point out that freezing food supplies makes ALL KINDS of sense, and there is NO reason why any energy has to be expended keeping frozen groceries well below 0 degrees Centigrade.  Unlike in the days of exploration of the Earth on sailing ships, when freezing was not an option, I can see no reason at all why a generous supply of every conceivable menu could not be packed up on the travel package.

The frozen groceries (as I am thinking of them) would NOT be part of the landing party supply.  They would (most likely) subsist on hydrated packages.  However, the main ship (which in my concept of the expedition) would remain safely in orbit, could continue to prepare nutritious and "fresh" meals three times a day.

As a side point .... planners for submarine deployments have to contend with all the issues this topic is addressing, and (from what little I am able to glean from what little is published), they are VERY successful, whether the cuisine is US, Russian, French, Chinese or other nations with undersea fleets.

The submarine model seems (to me at least) well worth study for those planning underground habitats on Mars, with the notable difference that on Mars, greenhouse facilities are not only desirable but obligatory.

Your concern about mass is understandable, but I hope that expedition planners will be provided sufficient financial resources to provide everything that is needed for the crew to travel safely and in some comfort.

(th)

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#72 2020-01-05 14:34:38

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,310

Re: Constructing a human mission, a tonne at a time

For SpaceNut re #70

The time frame under discussion varies from forum member to forum member, and post to post.

I was thinking about underground habitats on Mars, well after the initial exploration phase. 

Your post appears to focus on travel to and from Mars.

Yes food on mars refrigeration should be low energy as mars is quite cold so the energy is used to pump a working fluid that runs throw cooling tubes to the outside to the inside cold storage box. Heat exchanging coils are what we are doing with the working fluid that is pumped on request and blower fans are used to keep the exchange of cold air in the chamber for storeage happening.
So minimal controls and sensing as a normal refridgerator or freezer would have.

200910-omag-foods-in-freezer-949x1356.jpg

https://www.foodsafety.gov/food-safety- … age-charts

As you can see even a submarine with the fridge and freezer will work with this time table in these and so must any crew going and staying on mars.

https://www.foodsafety.gov/print/pdf/no … rage-table

https://www.fda.gov/media/74435/download


The main part of the topic is how do we get what we need to mars if all that we can land is in a 1 mT package.

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#73 2020-01-05 16:42:45

kbd512
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Registered: 2015-01-02
Posts: 4,030

Re: Constructing a human mission, a tonne at a time

Louis,

I couldn't help but notice that the target date Lemvig Biogas has set for a 25MW installation of their technology runs into 2035.  I can only presume that that's because this is an area of active development for the company.  Notice that just as NASA does when they develop a fundamentally new technology, Lemvig started with a lab scale demonstrator, progressed to a proof-of-concept installation, and the next item on the agenda is a sub-scale pilot plant to demonstrate commercial / industrial operation.  Additionally, note how the optimal conditions for CH4 production differed somewhat from what the literature stated about what was ideal.  That little bit of reality also flies in the face of the assertion that you can learn how to do something just from reading about it.  Even a "well understood" reaction such as the Sabatier reaction clearly doesn't blindly follow the "theory" of how it's supposed to work.  They still have no clue about how long the catalyst will last in their reactor, either.  They also have 2% CO2 in the CH4 output as well, which isn't going to work at all in a rocket when you already have at least that much unusable propellant left in the tanks (knocking 2% off your available fuel is meaningful, hence propellant densification here on Earth) and, you know, that tiny little problem with having chunks of frozen CO2 in your LCH4 tank.  All of that stuff is kinda important, even if all you have to do is guarantee a single return trip.

Could SpaceX develop their own Sabatier reactor in-house?

They certainly could, but along the way they're going to discover all these "gotchas" that dictate the actual rate of progress made in complex technology development programs.  Lemvig's program spans decades, for example.

Remember what GW said about practical implementations of a fundamentally new technology always being around 15 to 20 years down the road?

Yeah...  That.  Seems to apply equally to both Lemvig and NASA, despite wildly different technological paths, requirements, and budgets.

So...  When NASA says a crewed mission to Mars using ISRU / ISPP is destined for the mid-2030's, I think that figure is based upon TRL of required technologies under active development, not simply the agency dragging their feet.  Everything has to work well, failure modes have to be well characterized, and fixes have to be practical and comparatively easy / fast to accomplish.

Everyone,

I want everyone here to take a good look at Lemvig's 2.5MW biogas plant:

Lemvig 2.5MW Biogas Plant

Note that tiny looking big rig delivering manure for scale in the lower right hand corner of the picture labeled "Reception Hall".

I want one of our smart guys here tell me how much we have to scale this facility down to even fit inside a Starship, no matter what it weighs.  With that, maybe some of you who are not having religious experiences when incredulous plans are offered up as solutions can begin to understand the scale of the problem.  One of those steel cans labeled "primary digester" probably weighs more than a fully fueled Starship.  Lemvig's "little" facility produces ~2.5MW of power using ~362t of manure slurry and ~75t of compost material per day.  Over the course of a year it produces nearly 3,000t of biogas (CH4).

In terms of propellant, 1 Starship requires 1,100t of LOX/LCH4 to make 1 flight back to Earth.  Thankfully, only 240t is LCH4.  NASA's 1/36h scale propellant requirement demands 52kW of continuous input power, 17kW of which is devoted to regolith mining and drying.  In order to actually send all Starships back to Earth to continue generating revenue for SpaceX or sending people and equipment to Mars, we'd need to produce at least 1,200t of CH4 over the course of 2 years.  I suppose we might want to keep a spare Starship on Mars, provided we have the tools to use the parts to repair another Starship, but we're talking about constructing something with 1/6th of the production capacity of Lemvig, which remains one of the largest biogas plants in the world 30 years after it was built, for SpaceX to get all of their ships back.

Since we can't source hundred tons of manure everyday to feed into Lemvig's process to produce that methane, nor do we have the rocket technology to ship a 1/6th scale Lemvig to Mars even if we did, that means we'll need to scale the technology down to something that fits on a single Starship and virtually all of the input power and resources for the process must come from whatever technology we bring with us and whatever we can find on the surface of Mars.  Incidentally, Lemvig also operates 24/7, not just whenever the Sun is shining or the wind is blowing.

Lemvig Biogas Plant YouTube Video

Most of these biogas plants are at least the size of a city block.  The technology does work and it does produce useful if meager output, but the scale of the inputs required is staggering.  In Lemvig's case, that equates to 159,505t of waste products per year.

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#74 2020-01-05 16:57:04

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 21,310

Re: Constructing a human mission, a tonne at a time

The magical ingredient in a bio reactor is bacteria and these can get quite small but they do need heat and time to build up to the levels we need. The larger container not only means more wate but heat and bacteria as well to make it work.

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#75 2020-01-05 19:58:27

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,969

Re: Constructing a human mission, a tonne at a time

Yep, I noticed the 2035 thing.  I suspect that's more about their expectation of the cost profile. Cost profile is pretty irrelevant for a first mission to Mars, as it was for a first mission to the Moon. No one was bean counting back in 1969! But if you are running an energy plant on Earth, that is your major consideration. 

I fully accept the lab scale > proof-of-concept > sub-scale > full scale pattern but I don't accept the overlong timeline.

The Germans developed a jet engine in four years from first proposal. The A4/V2 rocket went from drawing board to effective weapon within 7 years. The Apollo mission to land a man on the Moon took about 7 years from the drawing board.  The Hovercraft went from design to commercial service in about 4 years. 

These things are really much more fluid than GW's dogmatic 15-20 years. The Sabatier reaction concept has been around for over 100 years. We knew how to build a Fax machine over 100 years ago but it took about 70 years before it came into general usage.

Mission One to Mars won't be governed by commercial considerations. It will be governed by the Mission aims and architecture: there will be plenty of funding available to get it right.

The main processes of the Lemvig project (biogas production) are irrelevant to Mission One on Mars so not sure why you spent so much time discussing them!  Rest assured, Space X won't be relying on manure to get to Mars!! 

I am happy to stick with an estimate of 1 MWe average continuous power to produce enough fuel-propellant to return one Starship to Earth. Space X are not proposing to return all 6 Starships to Earth - so your diversion there doesn't work.





kbd512 wrote:

Louis,

I couldn't help but notice that the target date Lemvig Biogas has set for a 25MW installation of their technology runs into 2035.  I can only presume that that's because this is an area of active development for the company.  Notice that just as NASA does when they develop a fundamentally new technology, Lemvig started with a lab scale demonstrator, progressed to a proof-of-concept installation, and the next item on the agenda is a sub-scale pilot plant to demonstrate commercial / industrial operation.  Additionally, note how the optimal conditions for CH4 production differed somewhat from what the literature stated about what was ideal.  That little bit of reality also flies in the face of the assertion that you can learn how to do something just from reading about it.  Even a "well understood" reaction such as the Sabatier reaction clearly doesn't blindly follow the "theory" of how it's supposed to work.  They still have no clue about how long the catalyst will last in their reactor, either.  They also have 2% CO2 in the CH4 output as well, which isn't going to work at all in a rocket when you already have at least that much unusable propellant left in the tanks (knocking 2% off your available fuel is meaningful, hence propellant densification here on Earth) and, you know, that tiny little problem with having chunks of frozen CO2 in your LCH4 tank.  All of that stuff is kinda important, even if all you have to do is guarantee a single return trip.

Could SpaceX develop their own Sabatier reactor in-house?

They certainly could, but along the way they're going to discover all these "gotchas" that dictate the actual rate of progress made in complex technology development programs.  Lemvig's program spans decades, for example.

Remember what GW said about practical implementations of a fundamentally new technology always being around 15 to 20 years down the road?

Yeah...  That.  Seems to apply equally to both Lemvig and NASA, despite wildly different technological paths, requirements, and budgets.

So...  When NASA says a crewed mission to Mars using ISRU / ISPP is destined for the mid-2030's, I think that figure is based upon TRL of required technologies under active development, not simply the agency dragging their feet.  Everything has to work well, failure modes have to be well characterized, and fixes have to be practical and comparatively easy / fast to accomplish.

Everyone,

I want everyone here to take a good look at Lemvig's 2.5MW biogas plant:

Lemvig 2.5MW Biogas Plant

Note that tiny looking big rig delivering manure for scale in the lower right hand corner of the picture labeled "Reception Hall".

I want one of our smart guys here tell me how much we have to scale this facility down to even fit inside a Starship, no matter what it weighs.  With that, maybe some of you who are not having religious experiences when incredulous plans are offered up as solutions can begin to understand the scale of the problem.  One of those steel cans labeled "primary digester" probably weighs more than a fully fueled Starship.  Lemvig's "little" facility produces ~2.5MW of power using ~362t of manure slurry and ~75t of compost material per day.  Over the course of a year it produces nearly 3,000t of biogas (CH4).

In terms of propellant, 1 Starship requires 1,100t of LOX/LCH4 to make 1 flight back to Earth.  Thankfully, only 240t is LCH4.  NASA's 1/36h scale propellant requirement demands 52kW of continuous input power, 17kW of which is devoted to regolith mining and drying.  In order to actually send all Starships back to Earth to continue generating revenue for SpaceX or sending people and equipment to Mars, we'd need to produce at least 1,200t of CH4 over the course of 2 years.  I suppose we might want to keep a spare Starship on Mars, provided we have the tools to use the parts to repair another Starship, but we're talking about constructing something with 1/6th of the production capacity of Lemvig, which remains one of the largest biogas plants in the world 30 years after it was built, for SpaceX to get all of their ships back.

Since we can't source hundred tons of manure everyday to feed into Lemvig's process to produce that methane, nor do we have the rocket technology to ship a 1/6th scale Lemvig to Mars even if we did, that means we'll need to scale the technology down to something that fits on a single Starship and virtually all of the input power and resources for the process must come from whatever technology we bring with us and whatever we can find on the surface of Mars.  Incidentally, Lemvig also operates 24/7, not just whenever the Sun is shining or the wind is blowing.

Lemvig Biogas Plant YouTube Video

Most of these biogas plants are at least the size of a city block.  The technology does work and it does produce useful if meager output, but the scale of the inputs required is staggering.  In Lemvig's case, that equates to 159,505t of waste products per year.


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