The new Orion spacecraft — Cadillac or Edsel?
Throwing a wrench into NASA’s engine of progress may not have been the intent of Vice President Pence’s first meeting of the National Space Council with his announcement that a human return to the lunar surface is the new direction for America’s human spaceflight program. But a wrench it was and will remain until pieces of the formerly touted “Journey to Mars” – the heavy lift SLS launch vehicle, the Orion spacecraft, and a relatively recent addition, the Deep Space Gateway (DSG, a small human-tended space station in a distant orbit around the Moon) – are reimagined and torqued into the new strategic direction.
Much venom has been hurled at the SLS launch vehicle, largely on the grounds of its alleged cost and its origins as a “government rocket” (i.e., “pork”). But heavy lift launch capability is extremely useful for the emplacement of a substantial cislunar infrastructure. Heavy lift permits the launch of large and/or multiple vehicles and facilities all at one time, and that makes the coordination of their arrival and assembly at a selected trans-LEO destination easier. The core SLS vehicle delivers 70-80 metric tones to LEO, more than enough to put about 10 tones on the lunar surface, or 15-20 tones into low lunar orbit. In addition, a large rocket also offers a large shroud diameter; volume can actually be more critical than throw mass for large architecture pieces like big landers and habitat elements. Technically, the SLS is a good fit for any future lunar return architecture.
The main argument against the SLS is its cost, but current estimates of $1-2 billion per launch are based primarily on the low projected flight rate planned by the previous program of record, which called for very few missions. A faster pace of a lunar surface return could bring these costs down, although they would still be in the range of multi-hundreds of millions of dollars per flight. If the long-promised and long-awaited commercial heavy lift vehicle eventually emerges, this estimate of cost – and the choice of a heavy lift launch vehicle – should be re-evaluated (but not until then).
The Deep Space Gateway (DSG) is an idea that comes from a variety of architectural studies that looked at the use of a staging node placed beyond LEO – well outside of Earth’s gravity well, for a human Mars mission. Initially focused on the Earth-Moon Lagrange Points, subsequent studies converged on something called a Near Rectilinear Halo Orbit, a complex path around the Moon that is relatively stable (requiring little orbital maintenance propulsion). The orbit selected for initial study is quite far from the Moon, up to 70,000 km distant. While this distance may make a good staging orbit for a departing Mars mission, it cannot easily support missions to low lunar orbit or to the lunar surface – the new strategic direction (delta-v to the surface from this orbit is near lunar escape velocity, ~2400 m/s).
In our published architectures (Spudis-Lavoie – Using the resources of the Moon to create a permanent, cislunar space faring system (2011) and Lavoie-Spudis – The Purpose of Human Spaceflight and a Lunar Architecture to Explore the Potential of Resource Utilization (2016), a propellant depot/transfer node is placed in low lunar orbit to keep the lunar lander transport a single-stage-to-orbit (SSTO) vehicle, making the lander completely reusable. Moving the node point to the Earth-Moon L-1 point costs roughly an extra 800 m/s in delta-v. Our lander design is already challenged with the requirement of re-usability (mostly propulsion system concerns: multi-start use lifetime, with little to no maintenance) and by having an engine-out capability to provide reasonable abort scenarios. Other design considerations include extreme temperature variations (thermal cycles) and parts fatigue, which results in higher subsystem mass than a single-use lander. All of these factors lead us to place the depot/node at the lowest reasonable point in orbit around the Moon, ~100 km circular. Orbital maintenance is on the order of 500 m/s/yr, which is achievable for the depot. After initial operations, the depot/node can change its orbit to a more advantageous one should future lander designs prove more capable.
Properly reconfigured, the DSG could serve as a low lunar orbit habitat-depot-node. This would require re-thinking its mission (fuel depot in addition to habitat) and its thermal design, because low lunar orbit can be quite warm on the daytime side of the Moon. The “lumpiness” of the uneven lunar gravity field (mascons) makes low orbits unstable and considerable propulsion is necessary to maintain it. However, we now have lunar gravity maps of extraordinary quality that reveal “frozen orbits” – ones where virtually no orbital maintenance is required (the currently operating LRO spacecraft is in such a frozen orbit). Use of these orbits would need to be traded against accessibility and lander energy cost, but in any event, a propellant depot would possess more than adequate propulsion for orbital maintenance. Finally, and most importantly, a station in low lunar orbit is well placed to support operations in space and on the lunar surface.
If both the SLS and the DSG could be adapted to the requirements of lunar surface return, what about Orion? Consider this: Orion was originally conceived as a component of the Constellation spaceflight system; it was designed to transport people to and from the Moon in a manner similar to the Apollo spacecraft. In short, this was a mission launched “all up” from Earth, with pieces discarded after use along the way. In the case of Constellation, two vehicles, Ares I and V, would launch the Orion and the Altair and transfer stage, respectively. The two vehicles would dock in low Earth orbit and depart for the Moon. Burning into lunar orbit, the crew would transfer to the Altair lunar lander and descend and land on the Moon for a period of a couple of weeks. After exploration of the landing site, the crew would ascend to the orbiting Orion and transfer into it for their journey home. The Orion spacecraft would discard its service module and re-enter the atmosphere at near-escape velocity, splashing down in the ocean for recovery. At each step in the above mission sequence, parts are discarded and not reused, requiring high levels of funding and leaving little, if any, hardware in space as legacy infrastructure.
When the Constellation program was cancelled in 2010, Orion was the only piece preserved, largely because at the time, it was the only spacecraft capable of sending American astronauts into space. However, without its Altair lander, Orion was no longer a lunar spacecraft system. It instead became a vehicle whose only purpose is to send crew into trans-LEO space and allow them to return to Earth with aero-thermal entry. It can support a crew of four, for periods of a couple of weeks, but cannot last much longer. It is for this reason that the ill-conceived Asteroid Retrieval Mission (ARM) concept was born – designed to give Orion someplace to go and something to do. Despite the fact that the ARM was nearly worthless scientifically and operationally, it was a mission configured to the capabilities of the Orion spacecraft. To support this scaled back mission profile, the current edition of the Service Module for the Orion (built by the Europeans) is smaller than the previous edition under Constellation. Unfortunately, that also means that the Orion can get into (but cannot then get out of) low lunar orbit, taking from Orion what little value it had for a possible lunar mission.
Where does that leave things as NASA contemplates lunar return? We currently have three pieces of space hardware, each configured to support a vaguely defined series of missions to deep cislunar space. The SLS can be adapted to transport all the pieces we need to establish and operate an outpost on the Moon. The Deep Space Gateway can be modified to operate in low lunar orbit, making it a possible staging node for trips to and from the Moon’s surface. But that still leaves us with Orion. True enough, crew members leaving the Moon will need a way to return to Earth, but if a permanent outpost is established there, we need to develop a reusable system that transports crew and cargo to and from low Earth orbit on a recurring basis (a reusable cislunar transfer stage). Such a vehicle would fire a rocket to accelerate out of LEO into a translunar trajectory. Approaching the Moon, it could burn into and out of low lunar orbit, delivering crew and supplies to be transferred into the lunar lander vehicle. On the way home, rather than direct entry and landing on Earth, it would aerobrake (i.e., use Earth’s atmosphere to slow the vehicle from escape velocity to orbital velocity) into Earth orbit and rendezvous with a transfer node in LEO. Here the crew would transfer to a commercial vehicle for return to Earth. All of these systems have been envisioned, at least conceptually, by a variety of published architectures over the last decade.
But can Orion be repurposed? In contrast to most informed opinion, I believe that of the three major human spaceflight pieces described here, Orion is the one that is the least useful and most likely to vanish. This should not be too surprising, considering that it is an orphaned, smaller piece of a larger system designed to return people to the Moon. Yet work continues on Orion, heedless of any possible change in mission – and has done so throughout the last 8 years as its mission gradually morphed from Moon-Mars spacecraft, to an asteroid spacecraft, to a “Space Station in Deep Space” spacecraft. This bureaucratic resilience suggests that setting Orion aside is a nonstarter – contractors and Congressional advocates may insist on its continuation, in a manner similar to the SLS “lobby,” which assured continuity of that development program.
Ideally, one would design a return to the Moon using a clean sheet, focusing on early robotic presence and a series of newly imagined, modular, reusable space-based human assets. However, we do not live in that world. So the question is how to “MacGyver” what we have to get what we need. Listed in order of decreasing usefulness, SLS, DSG and Orion can all be used in a lunar return. The SLS provides us a way to get large, heavy payloads to the Moon. The DSG, while not currently configured to support lunar surface activities, could be modified to do so without too much re-design. The Orion could be used for early human flights to the DSG – establishing a human presence near the Moon, while robots would do much of the early resource prospecting and processing work on the surface. After human return to the lunar surface, Orion could be docked at the DSG and serve as a “lifeboat” vehicle in the event that emergency circumstances require the outpost crew return quickly to Earth.
From Super-Apollo to crew assured-return vehicle – a diminished ending to a once-noble vehicle development? Possibly. It depends on your point of view. As it currently exists, Orion is not a particularly useful spacecraft. But if we use it to help establish a permanent human presence on the Moon, it will have served a noble purpose indeed.
One point on Orion. It’s life support and crew interface/accommodations systems work is all being done to BEO requirements and should be readily adaptable to both the proposed orbit to orbit and lunar landing vehicles.
The contracts would need to be set up to allow such synergistic use as that could save considerable time, risk, money and effort.
Good points — thanks.
The salient feature of any discussion concerning a lunar return is a lander isn’t it? Nothing can really be done with a way down to and back up from the lunar surface. Robot first, and then human-rated later. It is all about a big powerful lander that can bring up water from the poles. The power section of the New Shepard seems to be the hardware most likely to go on the SLS to the Moon.
In my view that lander with devices to render ice into water and propellant are the critical enablers that need to be talked about. In this respect the Orion is indeed a turkey right now. Until we have shielded habitats out there for people it is not necessary.
Launched from Earth an expendable XEUS will be able to land about 12 tonnes on the Moon. Where as a reusable XEUS operating from a lunar spacestation should be able to land about 25 tonnes. Since that is about the mass of a Bigelow spacestation it should be possible to devise a modern command module.
The command module will need full life support, docking port, air lock for Moon walks, limited cooking cleaning & hygiene facilities. storage space, sleeping area, internal cargo area, external cargo space and controls. The XEUS will provide the propulsion and possibly the navigation.
I’m already a huge fan of Lockheed Martin’s reusable single stage landing vehicle (MADV) concept that could land crews on the Moon or Mars. And since it has a delta-v capability of up to 6 km/s, it could easily be used for round trips between EML1 and the lunar surface on single tank of propellant (LOX/LH2). Since the MADV concept uses propellant producing water depots, it could easily be used to shuttle astronauts from LEO and EML1 or to Low Lunar Orbit.
http://www.lockheedmartin.com/content/dam/lockheed/data/space/photo/mbc/MBC_Updates_IAC_2017.pdf
Even though I’ve been a harsh critic of the Orion, Lockheed Martin could make the Orion commercially viable, IMO, if they utilized it within their own proposed propellant depot architecture. If fact, the ULA proposed mating the Orion capsule with an ACES 41 a few years ago.
Since it looks like the ULA is going to be using a standard LOX/LH2 ACES 68, that would be even better. An Orion/ACES-68 could easily shuttle astronauts between LEO and EML1 or Low Lunar Orbit if propellant producing water depots were located in those orbital regions.
Marcel
Can this be true? In nearly 40 years of talking about going back to the Moon, establishing infrastructure there and within the Earth-Moon system, no one, not one, in our government, Russians, Europeans, Japanese, (Chinese?) has ever taken a “clean sheet of paper” approach (other than yourself and Lavoie) to do this? I recall studies from Boeing, Lockheed, Mitsubishi Heavy Industries with these grand plans, and nothing has ever taken off. I’m old now, and all those youthful dreams have come to naught. What is wrong with the human race that we have lost our dreams and the will to make them reality? Keep pushing Paul. Perhaps “When the student is ready, the teacher will appear.”
In my view long duration missions are the key to success in establishing a human presence Beyond Earth Orbit. Long duration missions of a year and longer require 3 things:
1. Cosmic radiation shielding (which must be massive to avoid secondary radiation).
2. Artificial gravity (generated with a tether system)
3. Enough living space to meet the psychological needs of a worthwhile crew complement.
These three things will necessarily require 3 more things:
4. A state-sponsored program of Super Heavy Lift Vehicle launches.
5. A wet workshop designed as a lunar water shielded crew compartment.
6. A robot lunar lander able to harvest ice and shuttle hundreds of tons of water at a time to Low Lunar Orbit workshops.
The seventh requirement is of course vast amounts of money and the only activity in space that can provide such funding are the around 200 billion dollar a year GEO telecom satellite revenues.
So…transiting these shielded platforms back across the cislunar sea into GEO to replace the present satellite junkyard with human-crewed telecommunication space stations will provide revenue for continued expansion of LLO operations into a spaceship construction pipeline.
These spaceships would necessarily be nuclear propelled, which I have previously commented about on this blog. As the regulars here are aware I could comment further on the military and scientific uses of such a fleet.
Couldn’t a lander-ferry, refueled on the Moon using lunar polar ice, ascent to LLO or EML1, and directly dock with a vehicle coming from the Earth where they could exchange a cargo or crew module directly with the ferry which then returns to the lunar surface. What is the need for a middleman station at LLO or EML1 when the vehicles could interact with each other directly?
There are many advantages to having a depot/hab as an intermediate step in the journey between LEO and the lunar surface. A hab allows the crew to remain in place until orbital phasing allows minimum energy passages. It also allows us to collect propellant harvested from lunar polar ice in space in the form of water and electrolysize and store it there. It also serves as a relief valve for excess product from the Moon as we begin to produce more than we consume. Remember, our goal is not simply to go to the lunar surface, but everywhere in cislunar space. A staging node near the Moon acts as a clearing station for such missions.
There is a good argument for a depot. (And I am convinced that one is going to happen.)
It’s harder to see the argument for anything human beings need to use. Unless you want a lifeboat option. All that’s really needed is a simple insulated fuel tank you can transfer LOX to and from. And possibly some modest power and maneuvering bus (esp. if you stick it in LLO where mascons must be dealt with). Any crew capsule will have adequate life support to wait for any orbital phasing anyway.
To say that venom has been thrown at the SLS seems an understatement!
Good to see that most of the elements for a lunar return already are in development. Seems if we also get a new lunar lander, then we’re more or less in business.
As for Orion, I recall an idea of using the planned ACES by ULA as a service module, which would have extra section for life support and communications. Thoughts?
As for Orion, I recall an idea of using the planned ACES by ULA as a service module, which would have extra section for life support and communications. Thoughts?
As the service module is designed to be discarded after a single use, I doubt that there’s any real advantage to trying to adapt an ACES as a SM (which is really overkill) than simply building a new SM with the proper margins for consumables and propellant. Both are likely to be equally expensive. In any event, we need to transition from Orion (launched from Earth every time) to space-based, reusable assets.
Any interest in lunar cyclers Dr. Spudis?
If Orion was used to just dock with a cycler on the way to a lunar space station and then again for the way back then nothing in LEO would be needed and the capsule could be configured to carry more people- perhaps 6 or even 8 astronauts. The math in this paper I googled is way over my head.
http://cbboff.org/UCBoulderCourse/documents/LunarCyclerPaper.pdf
I sort of had in mind what ULA was planning with their lunar architecture, using just the Atlas and Delta rockets.
I imagine using the SLS, just a modification would be good enough?
Is it possible for Orion to be a reusable asset? I.E, resupply the thing, rather than return it to Earth each time?
LEO to GEO to Low Lunar Orbit and then back to a GEO space station seems like a possible useful role for future evolved reusable versions of the International Orion.
Orion’s evolved service module should be larger with options for twice as much delta-v capability, but essentially it could mainly fly docked to much larger robotic cargo or tanker spacecraft and serve to transport people from GEO to Low Lunar Orbit and back to GEO.
If, or when, a problem occurs with the propulsion system of the much larger robotic spacecraft, folks would still have the means for a quick ride back to a space station in Low Lunar Orbit or GEO or LEO or sometimes, if need be, to the Earth’s surface.
Minimizing human spaceflight risk is going to remain the critical issue even in the age of reduced mission costs due to abundant Lunar derived propellant in Cislunar Space.
Eventually, the military will want to be able to fly international missions in Cislunar Space and an evolved reusable Orion spacecraft based at a space station in GEO would likely have a role in those missions.
The ACES 68 can be reusable. And the ULA’s ACES based Xeus lunar lander should also be capable of transporting astronauts between LEO and EML1 or low lunar orbit as long as propellant depots are located at each destination for the return trip.
http://www.ulalaunch.com/uploads/docs/Published_Papers/Commercial_Space/2016_Cislunar.pdf
So I would agree with you that there are plenty of better alternatives to the Orion.
Marcel
“Technically, the SLS is a good fit for any future lunar return architecture.”
The SLS is THE Moon rocket….and without it we are not going anywhere for a very long time. This program is the single most critical component in any plan hoping to expand the human presence into the solar system.
That the NewSpace mob has waged a propaganda war against the SLS ever since the program began is so completely despicable it cannot be adequately expressed without resorting to foul language. The reason the SLS is so hated is of course because it is in competition with the flagship company for funding. And this is one of the main reasons I repeatedly state:
NewSpace is the worst thing that has ever happened to space exploration.
“If the long-promised and long-awaited commercial heavy lift vehicle eventually emerges, this estimate of cost – and the choice of a heavy lift launch vehicle – should be re-evaluated (but not until then).”
As I have commented upon for several years, the missing piece of the puzzle is the pressure-fed-ocean-recovered booster originally specified for the shuttle program. Musk and Bezos both failed the genius test by not going straight to the 1972 TRW study as a model for their hobby projects. “Commercial Heavy Lift” is not going to happen for the simple reason nobody is going to blow billions on a SHLV that generates zero profit. Neil DeGrasse Tyson saw through the facade years ago and exposed it. Really. The hype is there but it is a transparent enough scam. The players just want to garner support for their pursuit of tax dollars or misuse of company assets and promising the Moon furthers that agenda. Just like the always ten years away Mars fantasy. Nobody is going to live on Mars. It is a flim flam targeting emoting clueless sci-fi fans.
The pressure-fed booster and the wet workshop are what NASA should be pursuing and robot landers are what the “entrepreneurs” should be going full throttle on. But, for various reasons, that is not happening. For various reasons a long list of programs with worthwhile goals should have been funded over the last thirty years. The people protecting their own little rackets all made sure those worthy goals were kept out of the public eye and killed on sight by various means.
A series of wrong turns were made over the last half a century and getting the space program back on the right path is a hugely difficult challenge. It was and is easy enough to effect incredible misdirection, waste, obfuscation, and obstruction- when the citizenry is distracted by consumerism and manipulated by spin-master minions in the employ of industry. In the final analysis greed is the problem. The profit motive does not exist to advance and safeguard civilization- it exists simply to make more money. There is no cheap.
“Nobody is going to live on Mars. It is a flim flam targeting emoting clueless sci-fi fans.”
Eventually, someone *is* going to live on Mars.
I tend to agree Mars is not as promising for human colonization as some think (even with full terraforming that we are not capable of, we still don’t know how humans can live and reproduce in .38G – maybe it’s doable, but we simply do not know yet). But the interest *is* clearly there. Some hardy souls are going to try it; if not Elon Musk, someone else will try it by the next century.
And if that certain someone is willing to pay for it – let ’em try. Something will be learned in the process even if it doesn’t succeed very well.
But NASA is not going to colonize anything, on Mars, on the Moon, or in orbit, or deep space. That’s not in their statutory mission. Nor their budget. Tech research and radar mapping the surface of Europa is the sort of thing that’s really their forte. Colonization will require some other yet-to-exist entity, public, private, or a combination of both.
“But NASA is not going to colonize anything, on Mars, on the Moon, or in orbit, or deep space. That’s not in their statutory mission. Nor their budget.”
NASA can take on new missions and discard others like any agency. And their budget can go up. And they can be pointed at colonization. Saying that is not going to happen and then in the same comment saying “someone” is going to live on Mars is bizarre and makes little sense.
There is no reason to go to Mars. It is a scam.
The Moon is the place where the resources are close and in a shallow gravity well. The Moon is where colonization can begin as a public works project- as Gerard K. O’Neill envisioned.
Mars, like LEO, is a dead end.
The delta-v needed to keep a spacestation in lunar orbit is 0-0.4 km/s. This should be within the range of ion thrusters providing they are burning most of the year.
Adding a depot module to the DSG will increase its costs. I suspect it could not go with an Orion so either the full payload of an SLS or pushed out by a second propulsion module.
If you reduce the DSG to *just* a depot, you can offset that through a) elimination/reduction of extraneous habitation modules and b) commercial partners operating the actual depot tanks. Just keep it simple.
At most, you need only a power module and perhaps just a simple universal hab adapter for transfer to a lander (or use as emergency lifeboat). Anything beyond that should be offered to commercial operators if they want to add on to it through spare ports, to be launched on commercial launchers.
I think NASA can afford a lunar surface station, or a DSG – but not both. A simple depot might be a possibility in combination with the (presumably ISRU capable) lunar surface base. But that’s it. The money is just not there otherwise. And if I can only have one or the other, I would rather have the surface base.
A reusable manned lander will have to live somewhere, the obvious alternative is a Moon base. Constructing a lunar base able to refuel and mainataine the lander will take at least 10 years.
If managed properly the DSG habitat module will be the flight test prototype for the life support systems of the lunar base.
1. On the Deep Space Gateway, I might go further: It’s *only* as a fueling depot for reusable landers (or other craft) that it makes any sense at all. There’s no compelling reason for a scaled down ISS in lunar orbit. And for a fuel depot, you don’t need all of what is being proposed for the DSG.
2. Regarding SLS’s costs: “A faster pace of a lunar surface return could bring these costs down, although they would still be in the range of multi-hundreds of millions of dollars per flight.”
But that raises the question of how you pay for it.
Simply splashing or turning over ISS alone won’t cut it.
SLS right now is planned for a flight every other year, then rising to once a year or so by the mid-2020’s. If you want to increase the rate of fabrication of cores at Michoud, it will require (according to Charles Bolden) just about doubling the workforce, and other plant modifications. So there’ s a major capital investment up front, and that is going to offset a certain amount of economy of scale advantage.
And then, well, you need to come up with the money to pay for actual payloads for all these flights. Right now, SLS doesn’t have any payloads even for the few flights it *can* manage. And now we learn that NASA might be forced to build a new launch tower, since the cost of modifying what they have to accommodate the EUS may well be more trouble than it’s worth.
The concern about SLS is that it’s not affordable at *any* tempo.
That 8.4m fairing is nice. But it shouldn’t be a non-negotiable for payloads. ULA offers a 7.2m fairing for Atlas V; Blue Origin has just announced a 7m fairing for New Glenn; and SpaceX is apparently open to wider fairings for Falcon Heavy (now rated at 64mT to LEO in expendable profile). Given the vast differential in cost for these launchers versus SLS, it’s hard to say the modest increase SLS offers can justify using it over the alternatives now or soon to be available domestically.
There’s only so much money available for a lunar program (which I think we all want). So it’s a question of how to get the most out of what limited funds are going to be made available by Washington.
The SLS and its large Solid Rocket Boosters has dual NASA and military roles that shouldn’t be minimized in their importance.
Solid rocket motors power our nuclear delivery systems.
Solid rocket motors power our anti-missile systems.
Solid rocket motors power our air to air missiles.
Solid rocket motors power our air to ground missiles.
Solid rocket motors may eventually power our anti-NEO missiles.
The only real way to carefully maintain that large capability to produce solid rocket motors, test, and significantly improve its technological base is to actually be using that capability to routinely evolve, build, and fly various types and sizes of solid rocket motors.
The evolving SLS and its evolving, powerful, and efficient solid rocket motors also peacefully and yet effectively and consistently demonstrate the diverse and high technology military and space capabilities of America and thus serve as a useful deterrent to large wars.
The military folks like to keep a sharp edge on their swords and other weapons because they know a dull edge won’t cut much of anything in a war and won’t do much to help deter a potential large war or win a small war.
Evolving and maintaining a sharp edge to our extensive solid rocket production capability through actively using it for peaceful and trust building international space missions while it also directly makes an extremely valuable contribution to deterring large wars and winning small wars also means it should not be thrown away or diminished with a narrow and dangerous ‘penny wise and dollar foolish’ mentality.
“Simply splashing or turning over ISS alone won’t cut it.” – Richard Malcolm
Right! So we keep it and learn new ways to use it.
The International Space Station can be extensively modified, enlarged, and improved.
Old modules can be de-orbited.
Keeping the ISS permanently for research, testing of new space technologies, training of international Lunar crews, storing supplies and propellant, Earth and space monitoring, building and maintaining spacecraft, and the stacking or staging of missions to the Moon, asteroids, and Mars in the nearby and relatively safe harbor and significantly radiation reduced environment of LEO is a wise choice.
The ISS was built in large measure because of the real opportunities it offered to teach a diversity of humans and nations how to peacefully and productively work and live together in LEO and on the Home Planet while learning, testing, and evolving the many skills and technologies needed to explore space.
The political, diplomatic, economic development, and modernizing cultural usefulness and influence of the ISS are far from being fully exploited.
Many commercial modules could eventually be attached to the evolved and much larger ISS.
The SLS and other large launchers can be used to launch the needed new and much larger modules and other structures.
The ISS in LEO is useful, will remain useful, and has evolving and potential capabilities that should not be thrown away.