Artemis 2

Sarkus said:
Sure. But this is somewhat of a false narrative, isn't it? That aim ignores a huge baseline shift in technology, industry, and economics. Heck, a VHS player when it first came out was a month's wage. If someone told you now that they could give me a really good VHS player for only half a week's wage, and that you should consider this an achievement, you'd look at them as if they were a bit weird, right? We have far better tech at far lower prices. If we're ostensibly just repeating what we did 60 years ago, I'd damn well hope it was significantly cheaper. Wouldn't you?? Basically, we're not starting from scratch here. We're not reinventing everything. We've been doing major launches for the best part of 60 years.
So, no, I don't buy that economics/efficiency argument as being particularly strong. ;)
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The technology increase has had little effect on the main hurdle to sending men to the Moon, and that's the rockets. The SLS is only moderately better that the Saturn V, that is because, at their heart, rocket's are pretty simple machines, and there just wasn't that much room for improvement in them from those used by Apollo. This is a matter of physics. You need considerable thrust to get a rocket off the ground and into orbit. There are two ways to get more thrust: Use a bigger engine ( which adds weight to the rocket) or increase the speed of the exhaust. If you were able to double the exhaust velocity, you'd be able to double the thrust. The kicker here is that in order to double the velocity you need 4 times the energy, and there are limits as to how much energy you can get from chemical fuels. And we are stuck with using chemical rockets for this job, as they are the only ones available that have a sufficient thrust to weight ratio. That's not to say that increases in technology haven't had an effect, but it has mostly been in being able to squeeze more into smaller packages, and thus increasing the capabilities of the probes we send out without increasing their mass. However, when comes to sending people, there isn't much that you can do about reducing payload, as they, and their life-support systems are going to mass a good amount no matter what.
 
billvon said:
I think if the goal was cost effectiveness and sustainability, they would have gone with an existing reusable launch vehicle (namely Falcon 9 Heavy) and done a combination EOR/LOR mission.

It's great what they have done with the SLS, but at the end of the day it's a very, very expensive expendable launch system.
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At present, the Falcon heavy has a payload of 25,000 kg. The Orion capsule/SM package by itself masses 26,520 kg, and that doesn't include the additional stage needed to get into a full translunar trajectory. The ICSP used by Artemis II masses over 32,000 kg by itself, and the Centaur V slated for used in future missions comes in at 53,000 kg. Would a system that involved separate reusable vehicles for Surface to orbit, orbit to Lunar orbit, Lunar orbit to Moon surface be preferable, sure, but considering that they already scrapped funding for the gateway lunar station, I don't see this happening soon. Maybe after an established presence on the Moon has shown its worth, they might invest in this type of infrastructure.
 
Janus58 said:
The technology increase has had little effect on the main hurdle to sending men to the Moon, and that's the rockets. The SLS is only moderately better that the Saturn V, that is because, at their heart, rocket's are pretty simple machines, and there just wasn't that much room for improvement in them from those used by Apollo. This is a matter of physics. You need considerable thrust to get a rocket off the ground and into orbit. There are two ways to get more thrust: Use a bigger engine ( which adds weight to the rocket) or increase the speed of the exhaust. If you were able to double the exhaust velocity, you'd be able to double the thrust. The kicker here is that in order to double the velocity you need 4 times the energy, and there are limits as to how much energy you can get from chemical fuels. And we are stuck with using chemical rockets for this job, as they are the only ones available that have a sufficient thrust to weight ratio. That's not to say that increases in technology haven't had an effect, but it has mostly been in being able to squeeze more into smaller packages, and thus increasing the capabilities of the probes we send out without increasing their mass. However, when comes to sending people, there isn't much that you can do about reducing payload, as they, and their life-support systems are going to mass a good amount no matter what.
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Your previous comment, and my reply, was never about the main hurdle, but about the economics of it. And the economics have massively improved, not because of anything NASA have particularly done, but because industry, technology, and our expertise are 60 years better than where they were. As exampled, if it still cost the same to produce a VHS player as it did when they first came out, you'd be laughing your way out of the store and buying yourself a far more capable 4K player at a fraction of the cost from somewhere else. This was never about demonstrating the efficiency, or the cost-effectiveness, or sustainability. It was all about setting the stage for the good stuff that's to come.
 
Janus58 said:
At present, the Falcon heavy has a payload of 25,000 kg. The Orion capsule/SM package by itself masses 26,520 kg, and that doesn't include the additional stage needed to get into a full translunar trajectory.
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Right. The reference mission I saw uses three launches - a Falcon Heavy with an extended second stage, a Falcon Heavy with a lunar lander, and a standard Falcon with an extended-duration Dragon. (This was a SpaceX proposal so it used all SpaceX components.) They rendezvous in LEO, use the extended second stage to put them into TLI and make both Lunar orbit burns, then use an (expendable) two stage lander to perform the mission. That way they can reuse most of the booster stages, and thus most of the engines. They can also trade off expendability vs payload, and 'sacrifice' booster stages to perform higher-payload missions.

You could use a Falcon Heavy to launch an Orion if you prefer. The Heavy has a payload of 50K kg to orbit in its fully reusable configuration.
 
exchemist said:
What that article fails to point out is the technology-driven aspect of this phenomenon. The algorithms of social media are designed to promote shocking or contentious content, because it provokes responses, and to keep people on-line as long as possible by feeding more and more of the type of content they have once chosen to view.

Thus the algorithms by design amplify the spread of misinformation.
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They should just refer to that as the "Quora" effect.
 
Janus58 said:
The technology increase has had little effect on the main hurdle to sending men to the Moon, and that's the rockets. The SLS is only moderately better that the Saturn V, that is because, at their heart, rocket's are pretty simple machines, and there just wasn't that much room for improvement in them from those used by Apollo. This is a matter of physics.
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That sort of tells me, we will not get too much further beyond Mars. Unless some entirely new physics is discovered. Like "manufactured" spacetime bubble warpage? Or the discovery of wormholes? ( While so far never been observed, is still a solution of GR) Or solar sails? Or probably the most realistic at this time, generation type space ships.
 
Roosters for ever said:
That sort of tells me, we will not get too much further beyond Mars. Unless some entirely new physics is discovered.
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The trick may be to get infrastructure out there. If we get a permanent industry on some moon or 'roid then it will serve as a stepping stone to the rest of the system.

Not out of system, but at least the Outer solar system.
 
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Roosters for ever said:
That sort of tells me, we will not get too much further beyond Mars. Unless some entirely new physics is discovered.
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No need for new physics. We already have ion engines for slow (cargo) flights, and VASIMR (plasma) and NERVA (nuclear thermal) engines for manned flights. NERVA has been tested extensively, and VASIMR has had some ground testing.

Both VASIMR and NERVA engines are aimed at use on a "cycler" - a deep-space craft that never lands, just shuttles astronauts, landers and cargo between destinations. NERVA requires more political than scientific work at this point, but can get you to Mars in 90 days with existing designs.

Beyond that, there are the DFD (direct fusion drives) that create both electrical power and propulsion with insanely high specific impulses. Still in the planning phase, it may get us to 10,000 seconds Isp, which means you could accelerate and decelerate the entire way, albeit at low accelerations (.05G or so.) That gets you there in well under 90 days.

In terms of physics, if we can get high enough specific-impulse engines to accelerate and decelerate at .33G, then times become:

Mars 6.5 days
Venus 5 days
Saturn 15 days

This also has the huge advantage of providing some "gravity" for the crew during the trip.
 
Lifting from massive gravity wells with rockets is so...20th century. Graphene space elevators are the future.

In 2019, the International Academy of Astronautics published "Road to the Space Elevator Era",[42] a study report summarizing the assessment of the space elevator as of summer 2018. The essence is that a broad group of space professionals gathered and assessed the status of the space elevator development, each contributing their expertise and coming to similar conclusions: that Earth space elevators seem feasible, reinforcing the IAA 2013 study conclusion, and that space elevator development initiation is nearer than most think. This last conclusion is based on a potential process for manufacturing macro-scale single crystal graphene[43] with higher specific strength than carbon nanotubes.
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en.wikipedia.org

Space elevator - Wikipedia

en.wikipedia.org en.wikipedia.org
 
Sarkus said:
Your previous comment, and my reply, was never about the main hurdle, but about the economics of it. And the economics have massively improved, not because of anything NASA have particularly done, but because industry, technology, and our expertise are 60 years better than where they were. As exampled, if it still cost the same to produce a VHS player as it did when they first came out, you'd be laughing your way out of the store and buying yourself a far more capable 4K player at a fraction of the cost from somewhere else. This was never about demonstrating the efficiency, or the cost-effectiveness, or sustainability. It was all about setting the stage for the good stuff that's to come.
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You can't apply consumer electronics economics to the production of launch platforms. I can offer the counter example of automobiles. They too have become more sophisticated with time, and the price has done nothing but go up.
 
TheVat said:
Lifting from massive gravity wells with rockets is so...20th century. Graphene space elevators are the future.
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Alas, space elevators (AKA Magic Bean Stalks) have been "the future" since I had a full head of hair. Still nothing.
 
Janus58 said:
You can't apply consumer electronics economics to the production of launch platforms. I can offer the counter example of automobiles. They too have become more sophisticated with time, and the price has done nothing but go up.
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They're hardly like for like, though. As you yourself have argued, the main hurdles of space travel remain unchanged. Cars are hardly a comparable like-for-like, with the tech and capability far in advance of what they were. That's why I referred to producing a VHS player now - something of comparable capability to the VHS player of yesteryear. If you mass-produced a car of the same spec, quality, etc as one from the 60s, it would almost certainly cost far less to build than it did then (inflation adjusted).
 
billvon said:
And in 50 years we may even have a mass driver on the Moon or a Skyhook on Earth.
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Skyhook Equator. Orbiting Rotating Launcher Animator-Calculator.

Skyhook Equator Skyhook space megastructures for launching from equatorial skies to Earth orbits. Orbiting Rotating Launcher Animator-Calculator. Skyhook (structure) – Wikipedia I was inspired to author my “Skyhook Equator” animator-calculator webpage by NASA’s Artemis II mission around the...
www.sciforums.com www.sciforums.com
 
Sarkus said:
you mass-produced a car of the same spec, quality, etc as one from the 60s, it would almost certainly cost far less to build than it did then (inflation adjusted).
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I was recently thinking about what if you could buy a new car that was as absolutely no-frills as say a 1965 Dodge Dart. We had a popular radio show stateside where a couple of car experts (Tom and Ray) offered advice, and I recall them humorously describing the Dodge Dart as a car "with eleven moving parts." Anyone who has recently had to replace airbags or the cat converter or ECU or injectors or any number of other post-60s tech in their car knows how expensive all such amenities are. I found myself kind of longing for a new/old car, with almost none of that - something like a 65 Beetle (my first car), with a small enough engine to pass most emissions tests, and be air cooled, suitable for local trips. (I wouldn't venture onto a US highway without airbags, however)

I could literally drop my little Bug engine out of the back and do most any repair with a few hand tools. Like Tom and Ray's Dodge Dart, it had about eleven moving parts. You could fix the carb with a paper clip. Such a car, if mfd now, could probably be mass produced for < $3000. They might want to upgrade airflow around the engine, though, and maybe a bit more shock-absorbent bumpers.
 
TheVat said:
I was recently thinking about what if you could buy a new car that was as absolutely no-frills as say a 1965 Dodge Dart. We had a popular radio show stateside where a couple of car experts (Tom and Ray) offered advice, and I recall them humorously describing the Dodge Dart as a car "with eleven moving parts." Anyone who has recently had to replace airbags or the cat converter or ECU or injectors or any number of other post-60s tech in their car knows how expensive all such amenities are. I found myself kind of longing for a new/old car, with almost none of that - something like a 65 Beetle (my first car), with a small enough engine to pass most emissions tests, and be air cooled, suitable for local trips. (I wouldn't venture onto a US highway without airbags, however)

I could literally drop my little Bug engine out of the back and do most any repair with a few hand tools. Like Tom and Ray's Dodge Dart, it had about eleven moving parts. You could fix the carb with a paper clip. Such a car, if mfd now, could probably be mass produced for < $3000. They might want to upgrade airflow around the engine, though, and maybe a bit more shock-absorbent bumpers.
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My first car was like that: a 1961 Morris Minor with a 948cc BMC A-series engine and an SU carburettor. I changed the big end bearings on that car without even taking out the engine. But now I think it would do my back in, bending over the engine bay.

Maybe we will find electric cars can be made equally simple though. In principle there is not much to them, after all. I am actually looking for one at the moment and trying to find one without a sodding computer screen on the dashboard. Maybe a Mini, if there is one with a big enough battery….
 
exchemist said:
My first car was like that: a 1961 Morris Minor with a 948cc BMC A-series engine and an SU carburettor. I changed the big end bearings on that car without even taking out the engine. But now I think it would do my back in, bending over the engine bay.

Maybe we will find electric cars can be made equally simple though. In principle there is not much to them, after all. I am actually looking for one at the moment and trying to find one without a sodding computer screen on the dashboard. Maybe a Mini, if there is one with a big enough battery….
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Oh those SU carbs were elegant things - variable venturi throat. LOL running a Mini on a big LA battery - we heard stories about stranded Beetles which played off that idea....engine was dead, so guy just kept turning the starter motor, flat terrain, he limps to the next town on his battery. Good luck finding any factory EV without the screen. Some of the first generation ones, like a Nissan Leaf, are a more stripped-down car, relatively. (If you go that route, you can upgrade to a newer battery pack, iirc)
 
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