Rhys Taylor - On a related note, what do you think about the proposed lunar space station? I think assembling it in lunar orbit is going to be a real challenge. Especially since we don't have a lunar base.
David Lazarus Docking (perhaps berthing is more correct) modules together is something well practiced during ISS construction. Berthing couplings can involve auto-engage connectors for power, telemetry, gas and fluids transfer as well. So, construction is not so involved as process as it sounds.
William Black - It's still going to be a challenge being that it will be ~200,000 miles away and I'm sure things will go wrong if left unchecked. They are not g to have it populated all the time. So, it will also be sitting dormant for long stretches. More chances for things to go wrong. I'm not saying not to do it. I'm just saying that there are going to be plenty of challenges.
David Lazarus Telemetry systems in common use on modern spacecraft transmit on the order 200,000 channels of data -- so I don't know where you get the idea of things being "unchecked." I am somewhat knowledgeable on the subject -- present plans involve berthing modules together, that is the extent of the construction process. It's sort of pointless to argue about this, really.
William Black - I'm not arguing about the method. Even assuming we get a steady stream of telemetry data, can we not still agree that there will be challenges to building this space station? OK. Let's move on.
Rhys Taylor At present the plan is to use SLS -- which is problematic for many of us. NASA, for entirely arbitrary reasons, wants to use monolithic modules to give SLS something to launch. The reasonable question many of us ask is -- why spend 1.5 to 2 billion dollars per SLS launch when private launch providers like SpaceX can launch the necessary payloads for 180 million per launch. Right now the only module that exists even on paper is the power and propulsion module. Additional modules, which would be a common docking node and a small hab/lab module don't even exist as technical studies yet -- so there is no reason for NASA's insistence on monolithic modules.
David Lazarus I am only responding to your comments. I cannot read your mind, I do not understand what "challenges" you imagine there are to docking a few modules together. I don't know why you think we would need a moon base in order to dock a few modules together. As someone versed in the technical details I am doing my best to answer your questions.
William Black - You are right. I was not specific. However, I tho the challenges would be obvious. Rhys Taylor certainly touched on one and I agreed. Also, I did not say that we would need a moon base. However, you'd have to admit that it would be easier with one. I also agree with your suggested use of private launch providers. What do you mean by monolithic modules? The only references to monolithic design that I can readily find are for that of early space stations like Salyut 1 and SkyLab.
Another challenge, though we certainly did it before (over 40 years ago), would be getting people to the proximity of the moon. Also, with the moon being ~200,000 miles away, it doesn't leave much room for error. Rescue missions would likely take at least two days to reach the moon and would likely be mute. Especially if docking failed for some reason or if the hull of a module is breached. Again, I'm not saying not to do it. Obviously, the astronauts would have to accept the risk. In my opinion, that sort of thing comes with the territory. If you truly want to explore space, you have to accept the risk that you might die in doing so. In my opinion, that sort of death in the name of science is far more noble than dying in a manufactured war.
David Lazarus I cannot imagine any reason a base on the lunar surface would make docking a few modules together in lunar orbit easier. There would be literally nothing that astronauts stationed on the lunar surface could do to make the docking process easier. In fact there would be absolutely nothing for such astronauts on the lunar surface to do at all in regards to such a docking procedure.
Rendezvous and docking are not a challenge. It doesn't really matter if you are talking about 200,000 miles or 2 billion miles, the distance has nothing whatsoever to do with it. We have been performing rendezvous and docking every couple of months for the past 18 years -- every time we send crew or supplies to the ISS. It is not a challenge.
Skylab was much larger than the station that is being proposed, but it is a good example of monolithic. Monolithic just means big and heavy and all one piece -- this is the term NASA is using at the moment.
William Black - There is more to building a space station than docking. I can see where launching from the moon, assuming we had such capability, would be beneficial. For one, much less fuel would be needed. Also, with manufacturing facilities right on the moon, it could cost less to build.
David Lazarus We are talking in context of the present proposal for a lunar orbit gateway station -- as described here https://www.nasa.gov/feature/nasa-s-lunar-outpost-will-extend-human-presence-in-deep-space -- none of the ideas you mention have anything to do with the proposal and in fact go far beyond the scope of what what is presently on the table. NASA is not presently suggesting the extensive lunar surface facilities (costing trillions of dollars) it would take to manufacture space station modules on the lunar surface.
I skimmed through the conversation, so forgive me if I misunderstand something.
Docking in space is proven, even autonomously. There's still plenty of in-space assembly tasks that we rely on EVA to do, but it's fairly easy to imagine some Dextre-like robots doing more diverse types of assembly.
In cis-lunar space, I think the telemetry concern is one of time-delay (light-lag) rather than bandwidth. If we're talking about orbiting the Moon, then there's also the challenge of getting telemetry around the Moon with relays.
The time delays can cause some problems for a human operator (see Pilot-Induced Oscillation), or think of an international telephone call with a small delay that makes you step on the other person over and over. It's really frustrating, inefficient, and prone to problems.
I think the solution to the telemetry/telecommand lag problem is improved automation or autonomy. The human operator on Earth might be more of a supervisor, pointing and clicking, while the robot does more of the inner-loop dexterity sorts of control.
I don't see how having a base on the lunar surface helps the operation at all. The comms links would be shorter, so the lags would be less, but that hardly seems worth the high cost of setting up a base on the Moon.
Monolithic to me just means "one piece". Monolithic objects have advantages compared to equivalent objects made of smaller modules. For example, you might spend a lot of mass on fasteners and mating hardware to join smaller pieces. Sometimes you can get performance benefits from large, seamless part. No one races the Tour de France on a foldable bicycle.
Maybe a good down-to-Earth analogy is large wind turbines. You want to build them in remote locations, so small pieces would be much easier to transport on regular trucks, rather than big pieces on expensive customized transporters. But longer blades on a few huge turbines are more efficient than a lot of small turbines.
But cutting up a aerodynamically-optimized blade into small sections, and assembling them again in the field is also expensive. And you might take a big performance hit in efficiency of the turbine. And that performance hit is going to persist for the whole life of the turbine, not just the short-term installation process.
So, what do we get? Highly specialized transporters moving monolithic blades. asset.dr.dk
Nelson Brown Sure, but when you look at the Boeing Single Module space station from NASA TM X-53973 Space Flight Evolution the habitat decks are really four individual pressure hulls berthed and wrapped in an outer shell. That was a June 1970 study, three stations to be deployed in LEO, GEO, and low lunar polar orbit (which phases nicely with 14 to 21 day lunar surface stays and permits far side access). Lofted by INT-21 Saturn V and transported by the RNS (Reusable Nuclear Shuttle).
On the contrary side, smaller modules with common interfaces can possibly give you a lot of adaptability and opportunities for re-use (what can't you build with Legos?)
Mining on the Moon is going to take a lot of development. I think extracting and refining useful building materials, fuels, etc. is going to be very hard, but it's well outside of my knowledge (and anyone's knowledge?)
If the cis-lunar fuel-depot concepts of operations really are useful, I think we're going to be using mostly Earth-sourced materials for quite a long time, and get to Moon-sourced mass much later on. But that's a pretty feeble hunch on my part.
William Black - I'm not involved in Lunar Gateway at all, and I haven't been following it closely.
The first type of structure that comes to mind when I think of monolithic is a tank. If you want to minimize mass of the shell and maximize volume, you're going to want big, monolithic spheres.
Nelson Brown and William Black - Thanks for continuing the conversation. Though it's somewhat of a shame, I'll have to agree with the lunar mining analysis. If we halved the defense budget and spent half of that on space exploration and the other half on renewable energy, we could get much further along much faster. Not to mention that we've had certain technologies for decades now that are not in use because of Big Oil, but that's another bag of worms altogether. Right now, I'd be elated if we refined and greatly expanded wind and solar technology.
A friend not on G+ brought up another reason for monolithic structures. Failures tend to happen more often at joints. Monolithic structures tend to have better reliability.
It is irrational, in the course of discourse, to attempt to coerce every participant in the discussion to submit to the notion that what is involved is a undefined extreme risk, danger, and difficulty -- only referenced by a single, deliberately undefined, concept of "challenge."
The proposed lunar orbit "gateway" station does not fall into such a category.
Basic problems of orbital mechanics, to wit, navigating payloads from LEO to Lunar orbit -- this does not fall into a category I would call challenging. Not compared to our practical experience, skill set, and understanding of how to successfully perform such tasks.
The basic component of in space assembly of large structures is the practice of docking/berthing modules together.
Docking/berthing is proven. Even autonomously.
It should not have required more than six hours of discussion to establish these facts.
After this discussion Mr. Lazarus followed me on G+ and began posting similar Chinese finger-trap comments on my posts. I immediately blocked him -- I do not have the time, energy, or inclination to do six hour circular debates with this individual everyday on every topic I post and comment I make.
Rhys Taylor - Thanks for being a good sport in the other thread. It is pretty ridiculous, but I tried to get him to understand. If he continues to post nonsense, I'll definitely consider banning him. It's not something I like doing, but I guess it is warranted on occasion. I'll admit that I put forth some controversial ideas, but they are at least usually backed by people who are both somewhat knowledgeable and not total nut jobs.
William Black - Looking back over the thread, I missed some of your messages (I blame the G+ app for not updating all that well). I didn't mean to ignore you, sorry.
I think the trade studies regarding large parts vs. small could be really interesting. Certainly there's been a lot of success in docking/berthing since the 1970s, with ISS as the major example.
I'm not a fan of SLS, but I try to look for the silver linings. In another analogy, I think the 747 Dreamlifter. It's not intended to compete with the standard freighters, but it has a unique capability that is sometimes needed.
I don't know what the cost of Dreamlifter is vs. other freighters (development & operating), but I can easily see it being orders of magnitude more expensive.
Due to a small but consistent influx of spam, comments will now be checked before publishing. Only egregious spam/illegal/racist crap will be disapproved, everything else will be published.
"Mannequin Skywalker" groan.
ReplyDeleteAlso, if I'm reading the article correctly, 99.39 was in December. It looks like this flight was 106 km, above the Karman Line for bragging rights.
Corrected. That's what I get for posting when I'm half asleep. :P
ReplyDeleteApparently, Blue Origin has turtles on their coat of arms. Also, apparently, they have a coat of arms.
ReplyDeletefsmedia.imgix.net
Rhys Taylor - On a related note, what do you think about the proposed lunar space station? I think assembling it in lunar orbit is going to be a real challenge. Especially since we don't have a lunar base.
ReplyDeleteDavid Lazarus Docking (perhaps berthing is more correct) modules together is something well practiced during ISS construction. Berthing couplings can involve auto-engage connectors for power, telemetry, gas and fluids transfer as well. So, construction is not so involved as process as it sounds.
ReplyDeleteWilliam Black - It's still going to be a challenge being that it will be ~200,000 miles away and I'm sure things will go wrong if left unchecked. They are not g to have it populated all the time. So, it will also be sitting dormant for long stretches. More chances for things to go wrong. I'm not saying not to do it. I'm just saying that there are going to be plenty of challenges.
ReplyDeleteDavid Lazarus Telemetry systems in common use on modern spacecraft transmit on the order 200,000 channels of data -- so I don't know where you get the idea of things being "unchecked." I am somewhat knowledgeable on the subject -- present plans involve berthing modules together, that is the extent of the construction process. It's sort of pointless to argue about this, really.
ReplyDeleteWilliam Black - I'm not arguing about the method. Even assuming we get a steady stream of telemetry data, can we not still agree that there will be challenges to building this space station? OK. Let's move on.
ReplyDeleteI don't know anything at all about a lunar space station. I naively imagine the greatest challenge would be launching that much mass into lunar orbit.
ReplyDeleteRhys Taylor - Yes, I imagine that is going to be a significant challenge even assuming relatively small modules.
ReplyDeleteRhys Taylor - https://www.nasa.gov/feature/nasa-s-lunar-outpost-will-extend-human-presence-in-deep-space
ReplyDeleteRhys Taylor At present the plan is to use SLS -- which is problematic for many of us. NASA, for entirely arbitrary reasons, wants to use monolithic modules to give SLS something to launch. The reasonable question many of us ask is -- why spend 1.5 to 2 billion dollars per SLS launch when private launch providers like SpaceX can launch the necessary payloads for 180 million per launch. Right now the only module that exists even on paper is the power and propulsion module. Additional modules, which would be a common docking node and a small hab/lab module don't even exist as technical studies yet -- so there is no reason for NASA's insistence on monolithic modules.
ReplyDeleteDavid Lazarus I am only responding to your comments. I cannot read your mind, I do not understand what "challenges" you imagine there are to docking a few modules together.
I don't know why you think we would need a moon base in order to dock a few modules together. As someone versed in the technical details I am doing my best to answer your questions.
William Black - You are right. I was not specific. However, I tho the challenges would be obvious. Rhys Taylor certainly touched on one and I agreed. Also, I did not say that we would need a moon base. However, you'd have to admit that it would be easier with one. I also agree with your suggested use of private launch providers. What do you mean by monolithic modules? The only references to monolithic design that I can readily find are for that of early space stations like Salyut 1 and SkyLab.
ReplyDeleteAnother challenge, though we certainly did it before (over 40 years ago), would be getting people to the proximity of the moon. Also, with the moon being ~200,000 miles away, it doesn't leave much room for error. Rescue missions would likely take at least two days to reach the moon and would likely be mute. Especially if docking failed for some reason or if the hull of a module is breached. Again, I'm not saying not to do it. Obviously, the astronauts would have to accept the risk. In my opinion, that sort of thing comes with the territory. If you truly want to explore space, you have to accept the risk that you might die in doing so. In my opinion, that sort of death in the name of science is far more noble than dying in a manufactured war.
David Lazarus I cannot imagine any reason a base on the lunar surface would make docking a few modules together in lunar orbit easier. There would be literally nothing that astronauts stationed on the lunar surface could do to make the docking process easier. In fact there would be absolutely nothing for such astronauts on the lunar surface to do at all in regards to such a docking procedure.
ReplyDeleteRendezvous and docking are not a challenge. It doesn't really matter if you are talking about 200,000 miles or 2 billion miles, the distance has nothing whatsoever to do with it. We have been performing rendezvous and docking every couple of months for the past 18 years -- every time we send crew or supplies to the ISS. It is not a challenge.
Skylab was much larger than the station that is being proposed, but it is a good example of monolithic. Monolithic just means big and heavy and all one piece -- this is the term NASA is using at the moment.
Perhaps Winchell Chung, James Garry, or Nelson Brown can help you understand.
ReplyDeleteWilliam Black - There is more to building a space station than docking. I can see where launching from the moon, assuming we had such capability, would be beneficial. For one, much less fuel would be needed. Also, with manufacturing facilities right on the moon, it could cost less to build.
ReplyDeleteDavid Lazarus We are talking in context of the present proposal for a lunar orbit gateway station -- as described here https://www.nasa.gov/feature/nasa-s-lunar-outpost-will-extend-human-presence-in-deep-space -- none of the ideas you mention have anything to do with the proposal and in fact go far beyond the scope of what what is presently on the table. NASA is not presently suggesting the extensive lunar surface facilities (costing trillions of dollars) it would take to manufacture space station modules on the lunar surface.
ReplyDeleteMaybe an easy way to get a feel for the relative complexity is to play Kerbal Space Program. 😜
ReplyDeleteWilliam Black - I was speaking hypothetically as if a moon base already existed.
ReplyDeleteI skimmed through the conversation, so forgive me if I misunderstand something.
ReplyDeleteDocking in space is proven, even autonomously. There's still plenty of in-space assembly tasks that we rely on EVA to do, but it's fairly easy to imagine some Dextre-like robots doing more diverse types of assembly.
In cis-lunar space, I think the telemetry concern is one of time-delay (light-lag) rather than bandwidth. If we're talking about orbiting the Moon, then there's also the challenge of getting telemetry around the Moon with relays.
ReplyDeleteThe time delays can cause some problems for a human operator (see Pilot-Induced Oscillation), or think of an international telephone call with a small delay that makes you step on the other person over and over. It's really frustrating, inefficient, and prone to problems.
I think the solution to the telemetry/telecommand lag problem is improved automation or autonomy. The human operator on Earth might be more of a supervisor, pointing and clicking, while the robot does more of the inner-loop dexterity sorts of control.
ReplyDeleteI don't see how having a base on the lunar surface helps the operation at all. The comms links would be shorter, so the lags would be less, but that hardly seems worth the high cost of setting up a base on the Moon.
ReplyDeleteNelson Brown - Thanks for mentioning some challenges as well as proposing possible solutions.
ReplyDeleteNelson Brown - This goes beyond the scope of a lunar space station, but wouldn't a moon base be useful for mining operations?
ReplyDeleteMonolithic to me just means "one piece". Monolithic objects have advantages compared to equivalent objects made of smaller modules. For example, you might spend a lot of mass on fasteners and mating hardware to join smaller pieces. Sometimes you can get performance benefits from large, seamless part. No one races the Tour de France on a foldable bicycle.
ReplyDeleteMaybe a good down-to-Earth analogy is large wind turbines. You want to build them in remote locations, so small pieces would be much easier to transport on regular trucks, rather than big pieces on expensive customized transporters. But longer blades on a few huge turbines are more efficient than a lot of small turbines.
ReplyDeleteBut cutting up a aerodynamically-optimized blade into small sections, and assembling them again in the field is also expensive. And you might take a big performance hit in efficiency of the turbine. And that performance hit is going to persist for the whole life of the turbine, not just the short-term installation process.
So, what do we get? Highly specialized transporters moving monolithic blades.
asset.dr.dk
Nelson Brown Sure, but when you look at the Boeing Single Module space station from NASA TM X-53973 Space Flight Evolution the habitat decks are really four individual pressure hulls berthed and wrapped in an outer shell. That was a June 1970 study, three stations to be deployed in LEO, GEO, and low lunar polar orbit (which phases nicely with 14 to 21 day lunar surface stays and permits far side access). Lofted by INT-21 Saturn V and transported by the RNS (Reusable Nuclear Shuttle).
ReplyDeleteOn the contrary side, smaller modules with common interfaces can possibly give you a lot of adaptability and opportunities for re-use (what can't you build with Legos?)
ReplyDeleteNelson Brown Yeah, I can see both sides of that, good example.
ReplyDeleteMining on the Moon is going to take a lot of development. I think extracting and refining useful building materials, fuels, etc. is going to be very hard, but it's well outside of my knowledge (and anyone's knowledge?)
ReplyDeleteIf the cis-lunar fuel-depot concepts of operations really are useful, I think we're going to be using mostly Earth-sourced materials for quite a long time, and get to Moon-sourced mass much later on. But that's a pretty feeble hunch on my part.
William Black - I'm not involved in Lunar Gateway at all, and I haven't been following it closely.
ReplyDeleteThe first type of structure that comes to mind when I think of monolithic is a tank. If you want to minimize mass of the shell and maximize volume, you're going to want big, monolithic spheres.
Fuel-depots are going to need tanks.
I think this problem might lend itself to some "easy" back-of-envelope math.
ReplyDeleteWell, maybe a spreadsheet.
ReplyDeleteWish I could crunch on this right now, but I have to go.
Nelson Brown and William Black - Thanks for continuing the conversation. Though it's somewhat of a shame, I'll have to agree with the lunar mining analysis. If we halved the defense budget and spent half of that on space exploration and the other half on renewable energy, we could get much further along much faster. Not to mention that we've had certain technologies for decades now that are not in use because of Big Oil, but that's another bag of worms altogether. Right now, I'd be elated if we refined and greatly expanded wind and solar technology.
ReplyDeleteA friend not on G+ brought up another reason for monolithic structures. Failures tend to happen more often at joints. Monolithic structures tend to have better reliability.
ReplyDeleteNelson Brown - That's very true.
ReplyDeleteIt is irrational, in the course of discourse, to attempt to coerce every participant in the discussion to submit to the notion that what is involved is a undefined extreme risk, danger, and difficulty -- only referenced by a single, deliberately undefined, concept of "challenge."
ReplyDeleteThe proposed lunar orbit "gateway" station does not fall into such a category.
Basic problems of orbital mechanics, to wit, navigating payloads from LEO to Lunar orbit -- this does not fall into a category I would call challenging. Not compared to our practical experience, skill set, and understanding of how to successfully perform such tasks.
The basic component of in space assembly of large structures is the practice of docking/berthing modules together.
Docking/berthing is proven. Even autonomously.
It should not have required more than six hours of discussion to establish these facts.
After this discussion Mr. Lazarus followed me on G+ and began posting similar Chinese finger-trap comments on my posts. I immediately blocked him -- I do not have the time, energy, or inclination to do six hour circular debates with this individual everyday on every topic I post and comment I make.
Rhys Taylor - Thanks for being a good sport in the other thread. It is pretty ridiculous, but I tried to get him to understand. If he continues to post nonsense, I'll definitely consider banning him. It's not something I like doing, but I guess it is warranted on occasion. I'll admit that I put forth some controversial ideas, but they are at least usually backed by people who are both somewhat knowledgeable and not total nut jobs.
ReplyDeleteWilliam Black - Looking back over the thread, I missed some of your messages (I blame the G+ app for not updating all that well). I didn't mean to ignore you, sorry.
ReplyDeleteI think the trade studies regarding large parts vs. small could be really interesting. Certainly there's been a lot of success in docking/berthing since the 1970s, with ISS as the major example.
I'm not a fan of SLS, but I try to look for the silver linings. In another analogy, I think the 747 Dreamlifter. It's not intended to compete with the standard freighters, but it has a unique capability that is sometimes needed.
I don't know what the cost of Dreamlifter is vs. other freighters (development & operating), but I can easily see it being orders of magnitude more expensive.
Nelson Brown No apologies necessary -- G+ is sort of infamous for not updating threads as people comment.
ReplyDeleteI wanted to thank you for stopping by -- I think the thread needed your insights.
I should look deeper into Dreamlifter -- I have not followed it closely.
If I remember correctly, Dreamlifter was a billion dollar program, for 4 airplanes.
ReplyDeleteNelson Brown - Ha! Not as costly as the B2 stealth bomber.
ReplyDeleteDavid Lazarus - B-2 specializes in surprise deliveries.
ReplyDeleteNelson Brown - "Strategic weapons are something we don't need."
ReplyDeleteCan you name the song and band without looking it up? :^D