Space Launch System Program is Finally Slowly Dying

NASA has switched to the SpaceX Falcon Heavy to launch the first two pieces of the Gateway lunar outpost in 2024. This will be a $331 million contract and will use a modified version of the Falcon Heavy. NASA is finally on the path to getting rid of the launch system waste of over 10% of its budget. NASA is still ramping up to waste money on an expensive and mostly useless International Space Station (ISS) in high lunar orbit.

The SLS launch system is the third iteration of efforts to convert and reconfigure the 1980s Space Shuttle components into an Apollo rocket stack. The previous version of the program (called Constellation) had one launch with a lot of problems. The new program had a one-minute hold-down test instead of an eight-minute test. Over $20 billion has been spent on SLS and over $10 billion was spent on the Constellation program. They are now spending $3 billion per year and the first launch and one of only three launches might start next year. This would be over 6 years later than the original plan.

If there are three launches with SLS, then the contractors will need to get paid until 2025 and receive another $10 billion. This will mean SLS will have been paid over $10 billion per launch. This would be over forty times the cost of the modified SpaceX Falcon Heavy. There is a non-zero chance that the first test launch does not happen. There is also even higher likelihood that the SLS program loses the two Artemis missions as well. If SpaceX gets to orbit with the Super Heavy Starship in 2022, then SLS could lose its final two Artemis missions.

The SLS program should have been canceled years ago when the SpaceX Falcon Heavy successfully flew. SLS should be canceled now. If it were canceled we could speed up the SpaceX Super Heavy Starship program and get dozens of SpaceX Falcon Heavy missions.

Older Wikipedia entry for Space Launch System expected eight Artemis launches using SLS in the 2020s and the Deep Space Habitat and many deep space missions. There were about two dozen missions planned and over a dozen were pretty solid. In 2019, there were four planned launches for the SLS system. This has now been updated to three launches.

The Deep Space Habitat became the Lunar Gateway Program. The Lunar Gateway is a program to use mostly the same contractors who built the International Space Station for $150 billion. They want about a dozen pieces to be built in a highly elliptical seven-day near-rectilinear halo orbit (NRHO) around the Moon, which would bring the station within 3,000 km (1,900 mi) of the lunar north pole at the closest approach and as far away as 70,000 km (43,000 mi) over the lunar south pole.

The Lunar Gateway is putting a needless detour from missions to the moon. The ISS budget was originally justified for NASA to learn how to send missions to the moon. Missions to the moon ended up not using ISS as a staging point. The Lunar Gateway will also not be useful for progressing manned space missions. The Lunar Gateway program is like building an airport in Antarctica and having flights from North America land in Antarctica before going to Australia.

SOURCES- Wikipedia, SpaceX, Space Flight Now
Written by Brian Wang,

71 thoughts on “Space Launch System Program is Finally Slowly Dying”

  1. The important bit to remember is "energy storage" at MWh levels, a means to store it and a means to get it out at MW power levels. All preconditions to select a high thrust propulsion system of choice are met. All of that technology exists today, enables fast crewed transits … and you still don't need nuclear.

    The smallsat example is only relevant as to show that a similar combination of technologies is already being explored and used. With that same tech tree you can go to higher thrust and higher ISP as desired because larger storage devices are being developed for terrestrial AND space applications. Can you store heat or energy that long? Besides the fact that you can, you also don't have too, in the extreme example you have 100W available, which, over months of coasting, is enough to store MWh's of energy.

    It is always a good idea not to waste time developing things you don't need. Nuclear fission isn't the devil, the devil is 'wasting time and money' on things you don't need because alternatives already exist, are cheaper, are available and are commercially attractive.

    KRUSTY surface power = useful, nuclear fission propulsion = not as good as claimed.

  2. The tech in your link is great for certain situations.

    It looks better than anything else for small satellites.

    It's good if what you are doing doesn't need extremely high ISP, steam at 1000 to 2000 K is in the ISP range of chemical propellant. Some chemical rockets will beat that, but can't be scaled down as far as this tech.

    It's not evident that this backs up your claim that we don't need nuclear for outer solar system probes. The article talks about storing solar heat to run the thrusters, but they are not talking about storing it for the many years it would take to get from LEO to the outer solar system.

    Your claim sounds more like something from an adherent of the 'nuclear is of the devil' religion, than from a serious examination of the merits of various energy sources under different situations

  3. No, I am not going to provide the links and I already gave you the names of relevant coordinated research efforts.

    But. Here is a newish system, already in the public eye, which combines similar ideas, similar storage media, and are a variation on the same theme at the lower end of the scale in terms of thrust, ISP and capabilities. The technology scales well in all dimensions of Thrust, Power to weight and capabilities.

  4. The energy storage systems & the 'high thrust' electric drives you talk about are new technology to me.
    Please provide links to information about them.

  5. Blue Origin – that hobby rocket that Bezos has been playing with. Don't think he was ever really serious about it – and now even if he does decide to get serious Musk has a big head start.

  6. The advantage of systems similar to what I propose is that no new technology needs to be developed and it avoids all nuclear related politics, changes of heart, red tape and the usual nuclear accidents. Nuclear needs to start from scratch again (the 70-ies tech and infrastructure is no longer available) which will result in a 20 year development cycle. I would advise to invest in a product, not a prototype, that is 3 years out from flying.

    High power bursts of 10minutes and more is plenty, even when trying to get into challenging orbits. It still allows for fast transits, avoiding the down side of high efficiency propulsion.

  7. Do your own reading.
    A nuclear propulsion system (not only the engine) realistically weighs : 10mton-20mton. Are there cheaper ways to heat hydrogen with that mass budget?

    Inverse square law gets you 100W from a solar panel array which is plenty. At Pluto it delivers 0.878W/m² compared to 1366.1W/m² in Earth orbit. Which implies that a 200m² solar panel is sufficient at BOL and 300m² with lots of degradation to charge the batteries or heat your thermal storage. This array (DSS Solarosa), at this size, together with e-storage or thermal storage and fast discharge caps is lighter than a nuclear reactor used for propulsion together with its radiators + shielding. Engine <100kg

    Supercaps are at 85+ Wh/l, 5.000 cycles, 97% ret. And no, you cannot buy them off the shelf, they remain in limited series manual lab production, recent example:
    High thrust is >50N/engine. But if acceleration is high and relevant for rapid transits depends more on thrust-to-vehicle-weight ratio. E-storage and T-storage can give you 1MW of power for ten mins or more. Long term thermal storage is at 2Kwh/liter and more at 2500kg/m³ with 70-80% eff. conversion to effective e-thrust and 20% thermal. You can optimize for thermal.
    Thermionic convertors can deliver 50Kw/m² so you get the electricity out fast (AMADEUS project). Combination with supercaps gets to a MW of power for ten minutes easy, which you combine in spaced bursts to enter orbits.

  8. As I recall Lockheed figured that out when looking to make the SR-71 – hydrogen fuel simply wasn't 'dense' enough. To get enough range the aircraft would have needed to be very large, with associated drag, which would have massively reduced its speed. Add in the need to refuel (and retrofit KC-135's to handle liquid hydrogen, and establish liquid hydrogen 'depots' where needed, which would have been a joy in and amongst itself) it's no surprise they went with JP-7.

    As you said – LH is only marginally better – the extra weight of larger tanks and insulation cancels the gain in ISP. Musk went the right way with methane, while NASA stuck with LH for way too long…

  9. ( I think I went beyond the number of characters allowed in a comment)
    Whether you are using solar or nuclear in space you just run your electric drive & radio at the power level you have available rather than add lots of massive batteries to do things in high power bursts.

  10. There is a lot in your comments that sounds implausible to me, & I would want links to some reliable source to back up the claims.

    The inverse square law is a problem for solar as you move farther from the sun. Twice the distance means 4x the area of collector for the same power.

    The Juno probe at Jupiter had to get by on piddling amounts of power from enormous solar collectors because NASA was short on PU238 for RTGs & the kilopower reactor wasn't yet developed.

    I could *maybe* see major improvements in the power per weight of solar far from the sun by having large curved mirrors of aluminized plastic concentrating sunlight onto PV panels to get about as much sunlight per m^2 of panel as you get without such mirrors at 1 AU. Perhaps difficulties with keeping things pointed right has prevented that from being done so far. Is something like that what you are talking about for solar in the outer solar system?

    When you write of 'high thrust' electric propulsion how high do you mean? IINM the highest used so far gives accelerations on the order of mm/s^2. For interplanetary travel that is plenty, you just keep up that acceleration for months. You only need higher acceleration for getting off a body with significant gravity.

    What are these marvelous batteries & capacitor banks? The energy per unit mass of such things is still low.

  11. Note that the NASA forum you cite is referencing a wiki article on THERMAL ROCKETS, which heat the reaction mass with an external power supply e.g. nuclear. In that case, hydrogen is a no-brainer but it doesn't translate to superiority in a chemical rocket.

  12. This is only true if you are regarding methane and hydrogen simply as reaction mass and adding fixed amounts of heat to them. In fact, in a chemical rocket your reaction mass is the reaction product of the fuel and the oxidant, i.e pure water for hydrogen-oxygen and water-plus CO2 for methane-oxygen. Hydrogen still wins out on paper for chemical rockets, but it's only marginally better and its low density requires larger tanks and more insulation, removing the advantage completely.

  13. NASA didn't lose the Saturn V plans. They lost the Saturn V parts suppliers when they stopped building Saturn V rockets. Not many of those components had other uses, so the suppliers shut down. Plans without a source for the parts aren't very useful.

  14. Brian's article quoted $10 billion per launch, but he was including all the development cost in that calculation and amortizing over only 4 launches, I believe. However, I've seen other articles that quoted between $1 billion and $2 billion per launch when considering only the operational costs. That is still a LOT more than Starship's projected cost per launch.

  15. Bezos just needs to give Gary Hudson his checkbook and walk away.

    Or maybe fund Skylon…a different direction.

    I wish Musk would use landing jets with small kerotanks for Earth landing s, maybe Dragon in the nose as an escape pod until things are dialed in. SLS and Super-Heavy are easier. Starship is really another Shuttle orbiter. That’s really going to be hard.

    Maybe Super-Heavy can be a Saturn IB design with landing legs between the tanks…

  16. SLS doesn’t need landing gear or a heat shield. Even if it cost 3 billion, an SLS tank station/wet workshop would have more floor space than the 100 bil ISS. A wet workshop is simpler than Starship.

    We had two EELVs, we can have two HLLVs, in case of problems

  17. The real interesting point will be if Orion is seriously proposed to fly on Falcon Heavy for an Artemis mission, as that will put the stake through SLS's heart. It appears to have been somewhat seriously proposed already, but there are a lot of hiccups to get there. We'll probably see Vulcan/Orion before FH/Orion.

  18. Indeed! But the Moon base is only for science/prospecting and support of robot mining. There is nothing to do on the Moon that does not have to be. Orbit is much closer, safer and easier than planet, Moon, surface.

  19. The Moon is a great place to mine stuff. Especially lunar basalt, which can be melted and extruded into fiber with way less energy cost than making steel, and also has a much better strength/weight ratio.

    Build a lunar basalt mine and a mass driver to shoot gravel into orbit, use mylar space mirrors to melt it, and you can build a huge O'Neill colony on the cheap. We probably need a Moon base to do all that.

  20. That sounds great in theory but per wikipedia here are the actual ISPs:

    Starship: 330 seconds at sea level, 380 in vacuum

    SLS main engines: 363 seconds at sea level, 452 in vacuum

    SLS booster rockets: 269 seconds

    Note the SLS booster rockets provide a total of about 30,000 kN thrust, while the first stage core provides only 7500 kN. So the overall ISP of the SLS first stage may well be less than Starship's.

    Second stage gives more advantage to SLS in theory, but that's somewhat offset by the larger fuel tank you need. Plus there's orbital refueling for Starship.

  21. It's too bad NASA lost the Saturn V plans. It had about as much payload as SLS and cost less per launch, after inflation.

  22. You don't need it for those missions either. Everything in space up to the Kuiper Belt does not require nuclear propulsion, nor nuclear RTG's. The reason being that a combination of batteries, solar panels, and capacitor banks are now lightweight enough, and reliable enough, to store the amount of energy, in the form of electricity, required to power a typical high thrust burn for a typical length of time.

    Because you have a lot of time between these burns (or intense periods of data collection and transmission) this means that a 100W equivalent solar panel can charge these 100KWh or MWh+ capacity batteries up to ranges well within the Kuyper belt. Even if the solar array required becomes very big at those distances, the system level mass is STILL lighter than the combined mass of the equivalent NTR system.

    The weight of KRUSTY means that it is not useful as a substitute for solar electric. There is only a very limited amount of very expensive missions you would use a Krusty for that it makes more business sense to develop alternative systems.

    But yes, I would like to have a KRUSTY module for surface power. 10-100Kw would be great to have. More would be even better if you produce Methalox locally and rapidly. Together with cheap heat storage in insulated basalt or sand, which is being demoed here on Earth in commercial plants, you have all season storage (this combo is useable on Luna and Mars in most adverse scenario's). We all have our favorites.

  23. "Pure electric propulsion does not have this problem and is now available at high thrust too, without needing nuclear."
    But if you want to do anything much farther from the sun than Mars you want nuclear to power that pure electric propulsion. The kilopower reactor or something similar is what we want for that.

  24. NTR is a dead end technology because it has too many parasitic mass that makes the system akin to a glowing white elephant on a skateboard being dragged forward by a very fast mouse. Unfortunately, because there is a relationship of mutual need, the mouse needs the entire elephant to go anywhere. This slows the system down in comparison to systems using normal chemical propulsion at lower ISP. Pure electric propulsion does not have this problem and is now available at high thrust too, without needing nuclear.

    The non-fission-nuclear alternatives (including solar thermal) are better in thrust, ISP and system level mass efficiency, the latter being the one that stops space cadets from paying any attention to NTR but remains seemingly always overlooked by NTR proponents. And because it will not be allowed to fly anywhere near earth, due to legitimate international concerns (warranted or not does not matter) its economical raison d'être is rather limited.

    The positive note here is that you can do all the exploration you like, cheaper, faster, with a commercial business case behind it, up to ceres, with alternative approaches.

  25. This is misguided thinking. We should never think of monopolies as an easy solution. If one company is performing much stronger than others the thinking should go on how to maximize generating business to the others. The Musk as shown himself many times in the past as cutting corners and not in the best interest of the public. I am not convinced that he will not behave like a monopoly if he is allowed to become, for whatever reason he has in mind. The price of SpaceX launches has not gone down for awhile although the costs for sure did.

  26. O'Neill's whole idea was to avoid launch as much as possible by starting to use lunar resources first, thus making Space profitable from the start. Space Solar. Our current Moon rover plans are what he recommended in the 70s, good idea, no? What is NOT an alternative at this time, and NEVER WAS is waiting until we launch stuff that works anything like ISM/ISRU will. Particularly, trying to live in a gravity prison. Dead end, 40 plus years already wasted. Have you read O'Neill?

  27. The SLS was never designed to put people in space, but rather to put money in pockets. A few years back they had an impressive achievement in creating some machine that would make large diameter rocket body components. I don't even think that stands up anymore in the real world.
    Today there's nothing technologically impressive about SLS. It's a rehash of the Space Shuttle rehashing Apollo. Apollo with the Saturn 5 was amazing, but really NASA has built no new impressive launch vehicles in over 50 years.

    Blue Origin still has a couple impressive technological achievements, mostly in rocket engines and take off/landing procedures. But let's get real. We're all still waiting for BO to get in the game for realsies. Bezos had the money to build an expensive toy, so he did.
    Elon is actually changing the tech curve.
    I don't expect anything exciting from BO. It's too late. They missed the window.

  28. The only thing worse than a corporate monopoly is a government-run monopoly.
    SpaceX is moving mountains, and the SLS is studying mole hills.
    It's worthless.

    Might as well advocate for the government independently rewriting Microsoft Windows to prevent their monopoly. I mean yeah we all want real choice, but a government-run monopoly is zero choice.

    Leave SpaceX alone. If Elon dies or goes senile, then let's worry about monopolies.

  29. A station in lunar orbit, or a LaGrange point is not needed for lunar exploration, but one is needed for lunar industrialization. Lunar material launched from the surface must be marshalled, and refined somewhere.

  30. I think the production starship is expected to be able make LEO by itself, but with no payload. Presumably that includes fuel for a landing.

  31. O’Neill’s whole idea was based on cheap reusable rockets to move lot’s of mass into orbit. Making humanity spacefaring, making space profitable and easily accessible came first. It was early in the Shuttle era and it was thought to be a path to that. It didn’t happen.

    Starship is about trying for that again and doing it better. For quite a long time “planet chauvinism” is required, at least until access to space is so routine and inexpensive that building large comfortable space habitats with lunar and terrestrial materials comes about organically. It’s NOT an alternative at this stage. That’s like Columbus deciding to skip Caravels and wait to build 100,000 ton cruise ships and container ships.

  32. We need to learn to live, work and mfg in Space, where there is energy, material and room. Science will be easy if we are doing things in orbit and mining surface. Halo will allow rego experiments, still have the required 0 g for high tech. More of a shipping and processing place than L5 or such. No need to learn 1/6 g crane operations.

  33. Gateway Halo has twice the radiation of Mars or Moon surface. Only LEO and thus ELEO(higher) have protection, other than Earth surface. Having to live on a gravity prison is a huge price to pay to use it as 1/2 of your radiation shield, or having to tunnel. A bag around an asteroid, with a smaller inflated bag inside, is a radiation shield, easy to make in 0 g.

    O'Neill settlements have better energy avail, 0 g for work and play, high g w/o load bearings for mfg and sep, 1 g if needed too, but not trapped by it. Mfg in 0 g is a huge deal, I'm sure you will agree.

    The task of moving material from the mine is just the start of the mfg process. Why don't we build factories in the bottom of the mine pits on Earth? A mass driver is small effort compared to working mfg in g. Or, grab the NEO that is going to smack Earth before it does. Stuff is there. Many things we have yet to discover will only be produced in 0 g, as some already are. Big $$$.

    For any population x, the ELEO and beyond rotating settlements are ALWAYS easier than Moon, certainly Mars. Partial g problems alone make the decision obvious.

  34. $10 billion a launch for SLS, disgusting. Imagine how much moon infrastructure for building truly massive and energetic spaceships could be built for $40 billion using SpaceX Starships? Orion drive and Zubrin salt water rocket designs could be built, tested and finalized?
    I have heard of people worried about a SpaceX monopoly, which doesn't make any sense to me. It may be my military training though, where they train us to reinforce success not failure. Reinforcing failure is a really good way to waste resources and lives without accomplishing the mission.
    We are no longer the sole superpower, we now have very potent competition. If we keep sticking our heads in our tighty whities through arrogance driven inertia then in 50 years the US will be a footnote in history instead of a shining city on the hill. Not even first among equals, just a toothless declining power.
    If we truly believe we are the greatest country in the world, we have already lost. This is something we need to develop an inferiority complex about, expand our capabilities ruthlessly, and prove every single day. Other countries are strong, smart, driven and will eat our lunch if we rest for too long on our laurels. SpaceX Starship is a good first step to accomplishing that, leaving our competitors in our rear view. As for loser companies and designs like SLS, good riddance, that's progress.

  35. Unlike the ISS, the Lunar Gateway is going to be outside the protection of Earth's magnetosphere. I can see it being useful for learning to live in that radiation environment, anyway.

    The problem with saying that our future home is inevitably in space colonies, not on the surface of planets or moons, is that it's only really true in the very long term.

    The one really big advantage space habitats have over planetary surfaces, is that planets are REALLY inefficient in their use of mass. Like, Earth uses 26 Billion kg per square meter to provide gravity. Compared to, what, a few tons for an O'Neill colony? So in the very long run, you could see almost all of humanity living in free floating colonies.

    The really big shorter term advantage of the surfaces of bodies like the Moon or Mars is that there's stuff there already. You kind of need stuff in order to live, and if you're in an empty orbit you have to import it.

    So, free floating colonies may be the inevitably long term winner. That doesn't mean they're obviously the best short to mid term solution. And you have to live through the short and mid term to reach the long term.

  36. Lunar or Mars base will give much higher scientific, technological returns than another ISS style station. And to know how to build a permanent base on another moon, planet and getting experience with that is also much more useful.

  37. For that money which was wasted on SLS we could have so much more – launched on Falcon Heavy.

    Lunar gateway is so so. We already build ISS and Moon is close to Earth, so it makes even less sense. A lot of science and experiements were already done on ISS,….

    And again Earth is so close that that even a rescue mission or resupply could arrive very soon. PORK for Boeing and some others.

    If they really "have to" they could build some small skeleton of a station, for possible modular upgrades and keep it small and cheap, just to try some concepts for Mars orbital station.

    They should focus on lunar and later mars base.

  38. I've been waiting for this zombie to be taken apart and mailed to the four corners of the planet so that it can never be resurrected. It's always felt, to me, like the government's last ditch effort to be the ones who control space travel [from the U.S.].

  39. I believe that, on Mars, Starship is SSTO. Actually SST Earth, isn't it?

    We tend to not realize that Earth is a particularly hard planet for rocketry. If the planet were 50% heavier, it would be nuclear or nothing.

  40. Yes, why not a tiny, mini NTR drive running on dissociated CH4 to supply the delta v once free from the gravity wells of planets and moons.
    Then it can use the same fuel infrastructure everywhere.

  41. At this point SpaceX is mostly about just getting things from ground to orbit. While there are technologies that might be better at that than rockets, we're not near the traffic level that would support them.

    But SpaceX's cash flow will increase drastically if Starship works out as planned, and at that point they might see it as worthwhile experimenting with something like rotovators, that would work well with rockets and their existing expertise in precision maneuvering them.

  42. VASIMR is hamstrung by being attached to NASA. NASA isn't in a hurry to put up the engine on ISS for station keeping and VASIMR has been reduced to making PPTs for solar electric tugs to take cargo from LEO to LLO.

    Engine itself is actually pretty good.

  43. NASA being a gatekeeper for humans in LEO was a monopoly
    ULA access to space was a monopoly
    SLS would have been a monopoly

    But all of a sudden SLS has serious competition from SpaceX and people are suddenly worried about monopolies. Anyhow BO will keep SpaceX honest.

  44. NASA won't ever make a habitat- they don't see pork river taking them in that direction. Nothing NASA does is geared towards colonization of space.

  45. hi Jean! you are correct… -the TLR of this is probably pretty low… I posted this just to state that SpaceX "should be" doing research into other means of propulsion than chem rockets to make the transition from Earth to Mars (or back) orbit… -VASIMIR is another good alternative tech to that (and probably much further along towards a high TLR level than this one (posted))…

  46. "The Lunar Gateway is putting a needless detour from missions to the moon." is planet chauvinism. O'Neill points out that exactly such places as the halo orbit are our future home. Use the Moon for material. It is not a place to live. Or work. Get used to this fact!

  47. I hate monopolies too.

    But what I hate are their perverse effects: price regulation, poor quality, exclusion of competitors by unfair practices, calcification of a market by bribing law makers.

    None of these behaviors have been shown by SpaceX (but they have been shown by their competitors. For decades).

    You can't stop them with the excuse they are too good and the rest will be left in the dust. Poor ULA and BO.

  48. Despite being a problematic program, it should not be used as an excuse by the blind programmable followers of anyone to constantly advocate him becoming a monopoly.

  49. What's the TLR level of this? because SpaceX is into investing in currently working technologies, not in those very early in their development or just in the conceptual phase.

    I know F. Chang Diaz's company has been building VASIMR for quite some time now, and while they have advanced a lot, the road there hasn't been all rosy. Or short.

    Nowadays the only existing, working alternatives to chemical rockets are ion thrusters, which are already made in sizable numbers for satellites.

    Don't get me wrong: I'll encourage anyone to keep investing in new rocket science. Every bit of new tech and knowledge can be useful. But as I said, SpaceX while being a company with the eyes in the future, works with the things and tech of the now, and it's doubtful they will invest in such new out-there concepts.

  50. You don't need SLS for anything.

    One refueling from your reusable starship negates the ISP bonus of the unreusable Hydrogen SLS stack.

    Its like saying you need a Hybrid car to go on a road trip because it is more efficient and you have to throw the car away when you are done so you need the most efficient car possible.

    There is NO reason why SpaceX couldn't make a NTR payload and attach it to rear of a Starship.

  51. use the Starship and Heavy booster for getting cargo/humans from planet surface to the orbital station and back….

  52. i.e., invest in this tech for doing Earth<->Mars transit and build two orbital stations (one orbiting Earth and one orbiting Mars) for doing transfer of humans/supplies between the planet, the station, and spacecraft equipped with these kinds of Fusion drives…

  53. Not so fast:
    "The reason they use hydrogen instead of methane is that specific impulse for a thermal rocket is inversely proportional to the square root of the molecular mass. CH4 is eight times as massive as H2, so you'd only get 35% of the ISP with methane as with hydrogen. If you can heat the hydrogen enough to make it dissociate, you can gain another factor of 1.4, or 4 times the ISP of using methane."

    That is why you need SLS–NTRs

    "What I can say now is that the Space Launch System is farther along than the Starship or any other commercial [project] with respect to a super heavy-lift capability that’s purpose-built for human spaceflight missions."

    Had SLS been used for Clipper, there would be no Cassini-type Earth fly-by that had the anti-nukes up in arms

  54. It has been slowly dying for some time now. Problem is that it has never been alive and it is hard to kill things that were never alive.

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