“No,” he said. “The possibility of being able to send people, particularly a large number of people, to settle another planet orbiting another star seems extremely small.”
I never cease to be amazed me at the lack of imagination among scientists and engineers. Of course this is matched by the bizarro flights of fancy of the artistic types at the other pole. In the middle are those few who have a knack for matching the elements that work.
If we can freeze people we effectively slow time down in much the same manner as time dilation does close to the speed of light. The most powerful device ever created by humankind, the H-bomb, gives us the ability to push a spaceship to a small percentage of the speed of light. Actually, it is more likely the bombs would slow down a spaceship arriving at another star after a centuries long voyage. A space solar power infrastructure powering a beam propulsion system would accelerate the starship on it’s way.
As I have stated for several years, freezing people has ramifications far beyond simply being able to travel to other stars. It would be the most disruptive and fantastic event in the history of the human race. Nobody would allow their loved ones to die when they could be saved and later cured- freezing would be a basic human right. Everything would change.
Yet we do nothing. We may be too stupid to survive. That is why it is so quiet out there.
“In 1966 Gemini 11 did a tether-generated artificial gravity experiment. A several thousand foot long tether system with equal masses on either end generating one gravity is the solution that people have been doing calculations for since the 1930’s (it was not known if humans would remain conscious without gravity so the tether was a solution to this possibility even then). No extensive testing is needed. We just need to build it and use it as it is pretty straightforward.
The ice on the Moon is the source for shielding. 15 feet and several hundreds tons of water for a small capsule. Well over a thousand tons for the very minimal crew space needed on a long duration mission. This is also pretty straightforward as well as how to push such a shield around the solar system- there is only one practical system. All the work to conclusively prove this concept was done in the 60’s and includes over 1000 live tests of the required devices.
And as for “living off the land” on Mars, what started the space colonization movement of the 70’s was the singular conclusion that one gravity was a prerequisite to any permanent colony. The less gravity the easier it is to build centrifugal “sleep train” facilities for small crews on small icy moons but for large populations miles in diameter artificial spinning hollow moons constructed of lunar material has always been, and will remain, the best plan.
It goes without saying (but I will say it anyway) that such a public works mega-project is the anti-thesis of the NewSpace scam (retire on Mars!) presently being endlessly hyped to the public.”
I responded to someone who had posted some interesting artificial gravity numbers on a forum. Unfortunately I cannot post those figures here because the moderator of that site has repeatedly banned me and warned me about using any material posted on his blog- or rather, news site, since he does not like it to be called a blog.
To generate one gravity on the inner surface of a sphere about 6000 feet in diameter the sphere would spin a little over 200 miles per hour and complete one revolution in a minute or so. A person living in such a sphere would take about an hour to walk the circumference and arrive back at the starting point.
It is a good example to explain what a Bernal Sphere would be like.
Unfortunately Dr. Spudis closed his discussion board down before I could respond to these replies and comments. So I am going to respond in italics here:
“A reusable Extraterrestrial landing vehicle could operate between the Earth-Moon Lagrange points and LEO and between the Lagrange points and the lunar surface using propellant derived from lunar water. A super heavy lift vehicle is great for deploying heavy cargo within cis-lunar space but its an inefficient crew launch vehicle since it throws away all of its components– every launch. This makes it necessary for the lander to dive 20,000 miles from GEO into LEO to pick up human beings and then boost out of LEO- presumably with propellants taken on at a fuel depot. What a mess. The Super Heavy Lift has to “throw away it’s components” but it can reuse them. And all the humans are on Earth right now so…..
Chemical rockets operating between the Earth-Moon Lagrange points and high Mars orbit would be much more efficient than nuclear rockets operating between LEO and high Mars orbit– because of the substantially lower delta-v requirements when launch vehicles from the Lagrange points. Plus the delta-v requirements to supply water and propellant for interplanetary vehicles launched from the Lagrange points is substantially lower than trying to supply fuel and water from the Earth’s deep gravity well. Nuclear rockets would never be allowed to operate in the magnetosphere, let alone in LEO or GEO.
IVF technology being developed by the ULA will enable us to utilize hydrogen and oxygen very efficiently. That piston engine is no miracle solution and while it might work well maintaining oxygen for an extended mission, hydrogen is a whole different set of problems.
Commercial crew vehicles will been in operation long before the SLS is launching humans into space. Perhaps, but it is meaningless since they are not going anywhere except LEO and that is nowhere.
The economics of propellant depots. Depots do not care where the propellant comes from. But even with the cheapest envisioned LV possibly to exist in the next 20 years the BFR/MCT cost of propellant at L2 would be $1,600/kg. BTW the cost of the reusable booster version of the FH for prop delivered to L2 would be greater than $3,200/kg. Now if a Lunar infrastructure for delivery of propellant to L2 to was put in at ~$60-80B development and initial setup with an annual operating cost of $10B that can deliver 17,500mt of prop to L2 a year over the lifetime of all the elements of the system, it can deliver to L2 propellant for $800/kg.
Conclusion is that it will be more than 20 years and probably even a decade after that that a system that can deliver prop to L2 from Earth to do so at the same cost as a Lunar system. But when evaluating LEO that is not the same story. The cost of delivery of prop from Earth by the FHR would be $1,600/kg equal to the same as it would cost to deliver prop from the Moon. The two systems would be direct competitors fro LEO prop sales and it would be available volume that would determine who the front runner supplier would be. BTW the max amount of prop that the before mentioned Lunar system could deliver per year to LEO would be 8,750mt. But that is also equivalent to over 200 FHR flights in one year. A flight rate not likely to be achievable in the next 10 or 15 years but such a delivery amount from Lunar prop could reach such levels in 15 years without much transfer tug hardware.” This kind of confabulation has been used by NewSpace fans for years to fill up the page and is devoid of any real facts.
“We sent animals into orbit, because we were uncertain that humans could live for relatively short periods in orbit.
We currently know that humans can live in orbit for more than a year, but we also know that the human body adapts to micro-gravity and this has various health consequences which begin immediately once in micro-gravity and over months of time, it worsen and have longer effects.
We can assume that in low gravity- the Moon or Mars, the human body will also adapt to this low gravity and have similar
effects as occurs in micro-gravity but we can also assume that differences between micro-gravity and say 1/3 of earth’s gravity are also quite different.
For instance fire is quite different in micro-gravity, whereas fire on Mars would behave fairly similar to how it behaves on Earth.
Or a toilet in micro-gravity has to be different than a toilet in micro-gravity, whereas a toilet on Mars could very similar to a toilet used on Earth. And living areas of enclosed environment like a submarine on Earth are similar to living areas on Mars- this is not the case when in micro-gravity.
A reason for exploration is to discover these types of differences, people once thought humans could not go faster than about 20 mph, and now human can travel at hundreds of mph, but there consequence of traveling at over 20 mph- ie, a collision at over 20 mph can be lethal. And we could not possible know about all the consequences of going over 20 mph, without actually going at speeds faster than 20 mph and learn ways of dealing with traveling at these higher speeds.
I would say making a top down type decision of assuming human can only survive in a 1 gee environment, is a policy decision which is criminal or at least, stupid. You would say that but Gerard K. O’Neill said basically the opposite and I will go with him, thanks.
One could decide that you don’t want to go more than 20 mph or that you don’t want to live in environment greater or less than 1 gee, but such personal choices are quite different a public policy type decisions.-particularly when it’s not based upon any information. Oh, but it is based on information- decades of space station debilitation.
One aspect is the need to explore Space, another aspect of this, is lower the cost to get into space. No….there is no cheap.
In my opinion NASA needs to explore space in such manner that it’s related to how one can lower the costs to get into space. So in terms of priority of exploration, NASA’s top priority should exploration that could lead to lower the costs of going into space.
If there was commercial lunar water mining this would lower the costs of getting into space. NASA mining lunar water wouldn’t lower the cost of getting into space. So NASA should explore the Moon to determine if and where there could be minable water on the Moon. That NASA has failed to do this over the last 10 years or so, is failure of the agency, whereas not sending crew to Mars, has not been a failure of the agency- rather than desire of doing this first, is the policy failure. That NASA is proposing a useless mission to Mars is the failure.
And that it took until 1998 to determine that there could water in the Moon, is another failure of this agency over the many decades, it’s existed. No argument there.
And that NASA do not have system that can refuel rockets in LEO, is another long term failure of the agency and general NASA focus upon having a earth launch owned and operated by the agency as been a failed policy over the decades- it’s the wrong focus of the limited resources NASA is provided to explore Space.” Mars and fuel depots are both completely wrong goals. The need to “refuel rockets in LEO” is a farce invented by the NewSpace mob to justify building hobby rockets.
“The more ambitious your space aspirations become, the more it makes sense to look carefully at using space resources. To me, this gets to the real debate behind the debate. Arguments over whether to use lunar resources or not really break down into one’s long-term desires for space—permanence versus transience, space-based versus Earth-based, pioneering and residence versus junketing and “just visiting,” opening up space for all versus exclusivity and restricted access.” Excerpt from Paul Spudis’ lunar resource blog.
What “we” as a nation aspire to accomplish in space is what continues to condemn Human Space Flight to the role of a political football. “We” want something for nothing but there is no free lunch; there is no cheap. Any large public works project is roundly damned by that increasingly manic tea party fraction of the population that considers government the great satan. There are NO such projects in existence except military programs. The last notable program was the Texas supercollider. https://en.wikipedia.org/wiki/Superconducting_Super_Collider
Instead of unlocking the mysteries of physics we bought the space station to nowhere.
It is true that politicians support projects that bring jobs to their constituents or money to their re-election campaigns. It is also true the captains of industry pursue projects that yield the highest profits for shareholders and this is how they keep their jobs. Politicians are theoretically public servants while the public in reality serves industry. Picking out the two salient parties in this arrangement we find the public is made up of the many citizens and shareholders count as the far fewer wealthy elite. The “permanence” and “pioneering” is to be found with the many and the “exclusivity and restricted access” is to be found with the few.
In regards to space the last great prophet of the many was Gerard K. O’Neill, who initiated the space colonization movement in the 1970’s. The prophet of the few is that person who need not be named whose enthusiastic followers currently dominate the discussion about space exploration. Most of those who read my short explanation of reality have found themselves automatically lining up their opinions to the right or the left. “We” have been conditioned to do this and it must be understood that leanings in either direction have little or nothing to do with space exploration except as to how this bias is exploited by those with an agenda. Follow the money.
The first card that is always played in such discussions is to brand the person speaking about “the collective” a communist or socialist or bleeding heart liberal or something equivalent. The second card is the tea party “scream cheap” declaration that any collective action is simple theft from the individual and criminal taxation. The third card is the cult of personality that calls on everyone to just trust that entrepreneur who has taken on the world and is a gifted genius beyond our understanding.
Take those three cards off the table and let “the real debate” begin.
“-specifically on refining and smelting metals on the Moon.” Excerpt from Paul Spudis’ Lunar Resources blog.
Fabricating multi-thousand ton alloy discs hundreds of feet across on the Moon would be the beginning of a golden age of space exploration. The larger the “engine” in a pulse propulsion system (it is actually just a big dumb piece of metal) the more efficient it becomes. Isp’s soar into the tens of thousands as the discs approach a thousand feet in diameter. The reason is simple; a hydrogen bomb is simply a fission bomb of a certain size with deuterium and tritium added. A few teaspoonfuls of these elements and the power of the bomb doubles and triples.
A half a century after Freeman Dyson and Ted Taylor studied the concept of these real life flying saucers it is still largely unknown to the public. Due to the counter-intuitive aspects of using nuclear weapons to push a spaceship through space it is usually overlooked in any survey of propulsion systems. This is the very definition of ironic as it is the only practical off-the-shelf means of interplanetary travel for the foreseeable future. It could be used to lift truly immense payloads off the surface of the Moon.
Inside the magnetosphere however the rocket equation still is king though.
In my view there are three likely avenues of approaching lunar resource utilization.
The first is to use robots as companies like Moon Express are exploring. It is possible that semi-expendable robot landers will be able to ferry water up to empty upper stages in lunar polar frozen orbits. If this proves practical then a thriving industry in cislunar space can be established without even landing humans on the Moon again.
The second is to find super large lava tubes theorized to exist in certain areas. These tubes may be very large- so large that small cities can fit inside them. This would allow humans to move right in with inflatable structures but would require human-rated landers. Because these tubes are not likely to exist near any of the polar ice deposits then a way to transport water from these polar regions to the tube sites will also be required.
The third avenue was proposed by Gerard K. O’Neill and had a minimal human presence on the lunar surface using electromagnetic rails guns to launch vast amounts of building materials into cislunar space for constructing artificial spinning hollow moons. The ice on the Moon may make this even easier by using Jules Verne gas guns to fire large payloads of ore and water towards space factories.
Ideally all three avenues will be exploited and support each other. Eventually beam propulsion would be used for travel in the vicinity of the Moon and finally to enable millions to migrate to space colonies from Earth. The SLS is the first step and succeeding iterations of Super Heavy Lift Vehicles will eventually generate thrusts triple and quadruple that of the original.
“Do we intend to operate in the current mode of custom-built, one-off missions or should we instead develop a robust, continuing space-based transportation system, one that can be used to accomplish a wide variety of missions and activities?” Excerpt from Paul Spudis’ article in Air and Space Magazine.
Dr. Spudis mentioned “one piece of an overall space strategy that is currently in complete disarray”, and that “one piece” that has always really bugged me.
If the private space god had started with something larger than the maritime equivalent of a canoe I would probably be a true believer. But…..the reality is the building block of this NewSpace “revolution” is a very low-powered mediocre engine that severely limited anything that could be accomplished from the start. We can see the consequences of this in a vehicle that violates the KISS principle 27 times over. I would add the miracle of propellant crossfeed is the guarantor of the optimistic payload and that feature does not appear to be forthcoming.
When I was 11 years old NASA studied that one piece of an overall strategy that I believe is critical to any effort to expand humankind into the solar system. The present 5 segment SRB at 3.6 million pounds of thrust is the most powerful booster on Earth- but a reusable booster surpassing this awesome device with a much higher thrust and Isp is what is needed.
I call it “the methane monster.”
“-the skills and technologies needed to acquire and use off-planet resources-“to launch tons of water from Earth is to completely miss the point of attempting it—we are learning how to “cut the umbilical cord”- Excerpts from Paul Spudis’ article in Air and Space Magazine.
Any dialogue with the NewSpace sycophants presently hijacking the discussion about space exploration inevitably devolves into their screaming cheap. When presented with any plan that requires government resources or things outside the capability of billionaire hobbyists the NewSpace mob wails and gnashes their teeth, crying out it is just too expensive and a waste of tax dollars.
This mantra is incredibly frustrating because these creatures claim to be all about space exploration but in reality are anti-space and have an agenda that goes nowhere but LEO- which is not really space at all. They will make noise about Mars and making us a “multi-planet species” yet when it is actually shoved in their face and they can’t avoid addressing the hard questions they default to snarky veiled insults and complaining on libertarian principles. A shaky facade as their flagship company is the poster child for corporate welfare.
The best example is of course the SLS; it is obligatory for the private enterprise fanatics to always make a Carthago delenda est statement about how the SLS should be canceled. I respond with my own version naming the space station to nowhere and the hobby rocket as items that must be done away with. The SLS is presently the only vehicle specifically designed to carry humans Beyond Earth Orbit and calls for its cancellation are for that reason. Going directly to the Moon dumps the NewSpace LEO business plan in the trashcan.
“When it comes to human interplanetary missions (as it inevitably does), we require hundreds of tons of material, all delivered to some marshalling area in space (e.g., LEO, GEO, Lagranians, or some other departure point).”- Excerpts from Paul Spudis’ article in Air and Space Magazine.
Any long duration missions into deep space will require massive shielding and artificial gravity. This is the dirty secret NASA does not want to talk about. No matter how willing to permanently damage their bodies astronauts are the decision is not going to be theirs- and nobody is going to sign off on profoundly debilitating and dosing human beings just for a T-shirt. The damage is certain and so is that damage being a showstopper.
Sending humans on multi-year deep space missions automatically means true spaceships with well over a thousand tons of water as a cosmic ray shield and an artificial gravity system. This automatically makes chemical propulsion useless for human interplanetary missions- only nuclear energy will work. And it may as well be stated in no uncertain terms- only one form of propulsion is viable- nuclear pulse propulsion. This means hydrogen bombs and those cannot be used inside the Earth’s magnetosphere, which extends almost to the Moon.
It is not that “space is hard”, it is that the truth about space is hard. The most basic truths about space exploration the public must come to understand is that LEO is not space and there is no other place to go to acquire shielding, assemble, test, and launch nuclear missions but the Moon. LEO is the worst possible place to put together spaceships and the smaller-cheaper-better hobby rocket scam makes the “flexible path” an unworkable mess.
“The proposed Falcon Heavy (if it works and costs as advertised) would emplace even more mass (about 22,000 tons for the same amount of money).”- Excerpts from Paul Spudis’ article in Air and Space Magazine.
Falcon light blew up as I recall on its 19th flight while ULA just went one hundred in a row- without blowing up. You get what you pay for. The cheaper-is-better crowd continues to proclaim a new age of cheap lift and just don’t get it: when the space station to nowhere closes shop, NewSpace is over. Low Earth Orbit (LEO) is not space. The mob of Ayn Rand worshipers who are anti-space, anti-NASA, anti-government, while posing as good ole boys waving the flag, have done more damage to space exploration than both shuttle disasters.
As the ISS deteriorates it costs more and more per year and very soon there will be a call to pour extra billions into this hole in LEO. Lashing together 3 hobby rockets to carry more junk up there to go in circles- going nowhere- is just more corporate welfare. The ideological war between those scamming taxpayers to continue this sham and those supporting Beyond Earth Orbit (BEO) operations with the Space Launch System (SLS) is real. The ice on the Moon and the Space Launch System to reach it should be the central focus of all true space advocacy.
NewSpace is the enemy. I have said it for years and have been banned from almost all the popular space forums for saying so. The time is coming when that sordid mess also known as “private space” and “commercial space” will either be exposed and rejected or finally and completely ruin any near term possibility of human beings again traveling in space. Abandoning LEO and funding more tooling and workers for SLS cores at Michoud is the only hope. A public works project to establish a permanent base on the Moon is the worthy goal- not LEO tourist stations and boot prints on Mars.
“For better or worse, the Apollo and shuttle days are gone, forever. But that is not a bad thing. We now have private enterprise taking over. There is now big money in space, in the form of minerals, energy, and microgravity-made products, to name just a few. Today, with the shuttle out of the way, private launch companies are moving into the fold, with much lower launch costs. That allows other interests, such as energy, asteroid mining, and space tourism, to take advantage of this new opportunity. The time for the space entrepreneur has arrived-”
Unbelievable. And I am banned from saying anything on this site also.
It is so sad. I may have to give up on ever seeing humankind leave Earth.
The naysaying that is thrown at any comments on the internet made about using lunar resources (ISRU) is quite amazing. Figure 10 in the recent paper on lunar resources is one simple way to slap such foolishness down.
Triton is my favorite moon and it is so far out there I always think about how long it would take to get there.
Earth escape velocity: 11.2 km/s
If each H-bomb can impart 100 mph then 1000 bombs can provide 100,000 mph. Using this figure for travels to icy bodies in the outer system a rough one way travel time can be estimated.
Launch point outside of Earth’s magnetosphere- lunar orbit
1. Moon 2.380 km/s =4.70 times less escape velocity than Earth
Asteroid belt
2. Ceres 0.510 km/s approximate travel time 120 days/4 months
Jupiter system 200 days/ 7 months
3. Ganymede 2.741 km/s
4. Europa 2.025 km/s
5. Callisto 2.440 km/s (outside of Jupiter’s radiation belts)
credit unknown- please leave comment and I will accredit
Gary Michael Church
The dirigible airship, the Zeppelin, may well spell the end of the satellite industry within a decade or two. Using new technology to make safe (with a double hull nitrogen ignition barrier), manipulate, and utilize the hydrogen lifting gas, these airships are the ultimate telecommunications platforms. The superiority of these stationary platforms hovering at 100,000 feet for months on end to the proposed networks of thousands of tiny satellites is obvious. When these airships reach a critical number and provide global relay capability even the geosynchronous satellites will suddenly be completely and hopelessly obsolete. With no satellites to launch the satellite launch industry will die. One factor driving this coming disruption is anti-satellite brinksmanship and the accompanying space debris issue. Concerns that global telecommunications could suffer an overnight catastrophe can be addressed with a relatively cheap and easy to replace/repair/upgrade airship fleet.
The satellite launch industry is headed for collapse and because airships can be constructed so quickly and are such a low risk technology the rapidity of the satellite industry collapse will be…..astounding.
The present network communications satellites can and should be replaced by high altitude dirigibles. A fleet of dirigibles hovering in the 100,000 feet altitude range and relaying information to each other from horizon to horizon across the globe. These different national fleets would essentially replace all satellites currently in use for telecommunications, navigation, and earth observation and provide much more effective cell phone and internet services due to being stationary and only 20 miles in altitude.
1. A double hull with a thin outer hull filled with nitrogen would provide an ignition barrier against any Hindenburg-type catastrophe. These dirigibles become more efficient the larger they become and in sizes comparable to the U.S. Navy Airships Macon and Akron have payloads of over one hundred tons. That payload using 1920’s technology can now be traded off by lifting less mass for very high altitude performance. If desired, dirigibles could be semi-autonomous and also accommodate small crews in pressurized cabins for specialized missions. These crew cabins could shuttle to these dirigibles in the air by capturing an arresting wire and detaching from a carrier aircraft or detaching from the dirigible and using a ram-air wing to descend and land.
2. Manipulation of hydrocarbon fuels and water as a hydrogen source and utilizing the hydrogen in reversible fuel cells, along with solar cells operating above the clouds at altitude, would provide months-long endurance. The large hydrogen filled structure could be utilized to protect electronics from any conceivable disrupting effects- even a Carrington-level- event might be survivable.
3. The airships have a service life as long as satellites, and can be brought down periodically for maintenance, upgrade, and repairs, and sent back up. They can also be moved several thousand miles to disaster zones, and be air-refueled when needed in winter-dark latitudes. Considering the cost of a satellite, the cost of rocket launch for the satellite, and rate of failures, the cost of a relatively simple metal and fabric frame and associated systems for the same price equates to Macon/Akron size dirigibles with a much lower initial cost. Since airspeed would not be the primary need these dirigibles would more likely be circular in design, even a fat-torus (doughnut) shape may suit some radar configurations.
Revolutionary concept application: Eventually, these dirigible hulls could be structurally connected to form an airborne-very-large-rectenna (cloud city!) for microwave power transmission from Space Solar Power satellites. The energy could then be concentrated into a tighter beam, with a much smaller danger zone incurred for transmission of energy to the surface of Earth.
In my view Paul Spudis has the correct solution; he has on several occasions written about a “Space Navy” as a separate agency. Having been in on the birth of the Department of Homeland Security I know this is not impossible. The DHS was brought into existence and I was made a part of it in a jiffy. The question is how to justify such a Human Space Flight-Beyond Earth Orbit organization? There are three reasons;
1. The nuclear deterrent is deteriorating and all three main players in the game, America/Russia/China have it in their best interest to not have weapons on hair trigger alert minutes away from their targets. I described moving the weapons into deep space in “Seven Steps to Space Travel” on this blog.
2. Planetary protection- Chicxulub/Tunguska/Chelyabinsk events are a good enough reason by themselves and all three nuclear nuclear powers can task their spaceships to intercept impact threats.
3. Survival colonies. Since it will take lunar resources to build a fleet of nuclear propelled and armed spaceships it only makes sense to have lunar colonies with women and sperm banks (Amazon women on the Moon) in case a global pandemic wipes out the human race. It sounds crazy but….yes, I am talking about all of them being young women. It only makes sense.
The Warrior
And of course these spaceships can do some exploring. If you have such Amazon-crewed space battleships out there the astro-cosmo-taiko-femnauts might as well go somewhere and Mars is actually a poor destination if you have the capability to take some mini-subs to the ocean moons of the gas giants.
oldAtlas_Eguy 
Ice on the Moon 
“A reusable Extraterrestrial landing vehicle could operate between the Earth-Moon Lagrange points and LEO and between the Lagrange points and the lunar surface using propellant derived from lunar water. A super heavy lift vehicle is great for deploying heavy cargo within cis-lunar space but its an inefficient crew launch vehicle since it throws away all of its components– every launch. This makes it necessary for the lander to dive 20,000 miles from GEO into LEO to pick up human beings and then boost out of LEO- presumably with propellants taken on at a fuel depot. What a mess. The Super Heavy Lift has to “throw away it’s components” but it can reuse them. And all the humans are on Earth right now so…..
Chemical rockets operating between the Earth-Moon Lagrange points and high Mars orbit would be much more efficient than nuclear rockets operating between LEO and high Mars orbit– because of the substantially lower delta-v requirements when launch vehicles from the Lagrange points. Plus the delta-v requirements to supply water and propellant for interplanetary vehicles launched from the Lagrange points is substantially lower than trying to supply fuel and water from the Earth’s deep gravity well. Nuclear rockets would never be allowed to operate in the magnetosphere, let alone in LEO or GEO.
IVF technology being developed by the ULA will enable us to utilize hydrogen and oxygen very efficiently. That piston engine is no miracle solution and while it might work well maintaining oxygen for an extended mission, hydrogen is a whole different set of problems.
Commercial crew vehicles will been in operation long before the SLS is launching humans into space. Perhaps, but it is meaningless since they are not going anywhere except LEO and that is nowhere.
Marcel