An ELEO Thought Experiment

Imagine that you could have 150,000 tons of cargo (or people) delivered to equatorial LEO annually, at $60/lbm. What would you do with it? What are the markets? We’re talking on the order of $5B/year.

[Update late afternoon]

Note that that’s less than a quarter of the NASA budget…

For that money, we could have 150,000 tons of material/people in orbit, or pay for another year of SLS/Orion.

[Friday-morning update]

Thanks to a comment, I went and rechecked, and found an error in the spreadsheet. The cost is more like $20/lbm.

63 thoughts on “An ELEO Thought Experiment”

  1. Grow food. Around the clock, no seasons to contend with, no droughts, no plant diseases, no bad weather. Need water and sunlight. Can get the water via heavy lift off the planet. Sunlight is unfailing and too cheap to meter.

    There is no reason anyone should be hungry on Earth. Ever. Again.

    1. Ooops and well, air. Air of some kind. Maybe not the kind that is pleasant for people. Rich in CO2 and very high humidity and hot. Like greenhouse hot.

    2. I don’t see how space-grown food can compete with terrestrial-grown food when the raw materials are $60/lbm. If it’s a space-manufactured product for export to Earth, it has to be high value per pound, like microchips. And the cost of bringing it back may be higher than the cost of getting it there, because it may not be able to return a hundred tons.

    3. Hunger today is not caused by lack of food. It’s purely political and growing more food will not solve this.

  2. Also really need soil and biotics living in the soil and you still have plant disease and it run rampant too complex on that scale. Want to say solar and water desalination, plus hydrogen production but don’t think the cost works out too well.

    1. You don’t need soil – hydroponics. And if there is disease, vent the compartment and start over.

  3. Solar thermal powersats in a “chain of pearls” constellation. Thermal inertia of the working fluid reservoir could be adjusted to avoid power drop off when the powersat is in the Earth’s shadow.

  4. Sorry Rand maybe most cost efficient go for bread and circus. Create a space sport send up a bigelow inflatable capsule to form an arena and have cameras and beam back to earth. It can be the 21 st century version of hockey .

      1. Sell tickets and concessions ? Though not quite sure about the hundred dollar hot dog and beer.

      2. You can min/max it but that requires knowledge that doesn’t exist. The more things done up there, the better but there should be margin left over for the unplanned.

  5. At $60/lbm, that is $120,000/short ton or $15.6 million to deliver a starship. But if the Starship is the cargo, it can deliver itself. The aspirational price is $2 million per mission and $5 million build cost per Starship to deliver itself + 100t of other cargo. That would be closer to $6/lbm or $21/lbm including build cost of the starship one way. I imagine the passenger version will cost closer to an A380 at $450 million, but there ought to be a happy medium. Delivering habitable volume–e.g. Mars Starships could be used as space hotels, space stations, tank farms, zero g industrial, etc. Visiting might cost $2 million per 100 passengers. Build a city out of them. 100 of them might cost $700 million delivered or $10.7B delivered if each of 10,000 people needed $1 million to fit out their own portion of the interior in style.

    1. That aspirational “price” is nothing but propellant costs. I’m being much more conservative in terms of other costs. And yes, I’m talking about cargo, not the Starship itself, which is assumed to return to Earth. That’s a separate application.

  6. As I’ve written for 25 years, now, the only thing that can be manufactured in space better than it can be on Earth is: spacecraft. You establish a warehouse for parts and a factory for custom assembly in LEO, then open it up to anyone with an idea for a spacecraft of any kind. Have a ground simulator facility where the manufacturing steps for a novel spacecraft can be developed, then upload the instructions to the robotic factory and voila! You have a new spacecraft in orbit! And it doesn’t have to go through, as an assembled system, the 12 minutes of torture that is launch.

    The rate of progress in space would be transformed. I advocated this when I was at DARPA, but it fell on deaf ears (for the most part). I even had a sort of a slogan for it. People at DARPA were always asking how long it would take for a particular spacecraft idea they had to make it into space. If the infrastructure I proposed were there, my answer would be: “It’s already there, it just hasn’t been put together yet.”

    1. I second that. Space docks to build out a solar transportation infrastructure. It would be like the railroads opening up the west.

      1. Then move the really massive projects out to the asteroid belts closer to the raw materials.

  7. –Imagine that you could have 150,000 tons of cargo (or people) delivered to equatorial LEO annually, at $60/lbm. What would you do with it?–
    It means lunar solar power could be sold for about $2 per kW hour, but lunar LOX might be only 1/5th the cost, or rather $1000 per kg, $200 per kg. As don’t know if lunar water is mineable. But seems a seat to Moon and back could be about $2 million dollars, as could seat price to Venus and back could cost about $2 million dollars.
    It seems we might know where to get 1 million tons of Mars water for about $1 per kg, or 1 billion dollar to buy 1 million tons of Mars water. Buy a cannon which put Mars water in high orbit and sell Mars water in high Mars orbit for $150 per kg or $150,000 per ton.
    1 million times 150,000 is gross of 150 billion dollars. Your long term business model is to sell food in Space. It seems cannon mass could be delivered mars surface with 1 or 2 starship trips.
    And if that could done, it seems one move water to Venus orbit and sell for 200 per kg.
    Making rocket fuel from Mars water in high orbit should be cheaper than making rocket fuel on Mars surface. Though shipping rocket fuel from Earth to Mars orbit would determines what can charge in Mars high orbit.
    So, if rocket fuel is at Venus, one sell tourist to venus orbit for 2 million per seat. But someone might paid say 4 million per seat to going there and back, quicker. And that would be 1/5th of what seats to ISS were paid for.
    It seems if someone would willing to pay 10 million per person to stay in hotel in skies of Venus. Then there would market for rocket fuel in skies of Venus. And seems one sell Venus sky rocket fuel for about same price [or cheaper] than Mars surface rocket fuel. Though person leaving Mars surface would use less rocket as compared to leaving the Venus sky. So going to leaving from Venus sky costs more than going to Mars surface and leaving, but per kg, Venus rocket fuel “might be” cheaper. Anyhow, Venus orbit seems more practical than Venus sky, but if Venus orbit is used, one will probably get hotel in Skies of Venus.
    Getting to Venus high orbit and leaving from Venus high orbit, should be cheaper and as compared to getting the Mars high orbit and leaving from Mars High orbit.
    And people as far as visiting, might want to go to Venus and Mars.

    Which is safer to go to from Earth, Venus orbit and Mars orbit.
    It’s quicker to get to Venus. And your orbital time is about 50% faster- or to change the orbit, one do it about 50% faster.
    It seems advantage is largely connected to cheaper seat tickets- and one will get a lot more Lunar exploration being done. Private/tourist exploration and governmental exploration.

  8. Build several Kalpana One space colonies. These have a mass of 8,500 tons. Have each one house 3,000 residents, and 2,000 tourist. The trip there would be $2,600.00 a seat, and staying there would be $7,000.00 a week. At first, the trip there would be $50,000.00, a seat, and $70,000.00 a week to stay there. Most hotel rooms would be in the zero G area. There would be 6 restaurants, 2 bars, one night club, one casino, and 6 churches.

    Also a movie studio. One with artificial gravity, and one in a zero G area.

    That’s what I would do. I would also mine the Moon, and near Earth asteroids.

      1. One of the benefits of ELEO is that if you aggregate most of your payloads in a single orbit, the relative velocities are low and you don’t have a debris problem. In this scenario, you’d put an upper limit on ELEO altitudes, and then require that anything in other planes must be above that altitude.

        1. There is an upper limit to usable ELEO, at least for human purposes. About 300 miles I believe. Thank you, Dr. Van Allen.

          1. I think they’re a little higher than that, but that’s plenty of altitude for the purpose; no need to be higher, other than drag and insolation.

        2. My sense is, the LEO constellations will be so valuable, no one will agree to your regulations. “What? Give up my broadband so you can use ELEO for something else? In your dreams, spaceboy!”

          1. I suspect the LEO constellations will dominate LEO, top to bottom, for the next two or three generations (so possibly the rest of this century), until superceded by a better technology. In any case, you’re much more likely to come up with an automatic space traffic control system technology than an international regulatory regieme that reserves the bottom half of LEO for an ELEO Economic Exclusion Zone. You want the UN saying who does what in LEO? Where does that end? In any case, the Starlinks already have krypton fuelled solar electric propulsion and an autonomous(ish) collision avoidance system that will only get better with time.

            And the Van Allens have an upper limit as well. There’s a lot more room up there for me to build my 5000 metric ton explorer ships without worrying about 200,000 comsats and a few orbiting rugby stadiums.

        3. In this scenario, you’d put an upper limit on ELEO altitudes, and then require that anything in other planes must be above that altitude.

          Satellite clusters like Starlink do pose some issues.

          Well the issue I see is that your ELEO altitudes are going to end up being very low, as equatorial plane crossings are occurring frequently now at altitudes ranging from 350km (217mi) to 550km (342mi) thanks to Starlink. Maybe you can convince Elon to raise the operational altitude to Starlink some. It is advantageous to them to have a higher ground footprint per bird which is what a higher orbit does, however the disadvantage is higher power consumption to communicate with the more distant ground stations. I think it would be preferable to keep satellite constellations as high as possible. The few hundreds of km’s needed wouldn’t be a big hit on performance or latency of the service. Or narrow their operational altitude band and allow nothing lower than 350mi which is not ascending/descending rapidly from their operational orbit. The density of something like Starlink probably should be restrictive on allowable altitudes.

          OTOH if put the satellite ‘band/cloud’ at very low altitudes instead, you sacrifice lifetime of an individual satellite for ‘clean space’ above. You still have the orbital insertion transit issue to deal with, but it’s not steady state once you get above the critical altitude. Maybe with some aerodynamic satellite design you can extend the life of a VLEO bird a bit?

          1. One more thought. With rollout of sat-to-sat communication in the newer Starlink birds, maybe it is possible to cluster the sats on-orbit a bit. So rather than a uniform distribution you have pair-wise clusters. Or some such. I’m sure there are many configurations one could conceive of. They can use sat-to-sat to relay when a ground station is out of range.The point being to create transit ‘gaps’ in the cluster. Avoid the ‘Doomsday Shroud’…. To borrow from some popular entertainment from the 60’s.

      2. To build Kalpana One, use large 3-D printers. Use some of the space for the building. But, at first you don’t build Kalpana One. Instead you build Mobile Work Cages. An MWC would be in the shape of a dome, or a sphere. When astronauts are working out side, they will be in a large cage. If something happens, and their line breaks, they won’t float very far. If they lose a tool, or a part, then that tool, or part will be in the cage, and won’t cause damage to other spacecraft, or satellites.

        Everything will stay in the cage. Later on, larger cages will be built around space stations. This will protect them from orbital debris. There would be an opening at each end. And at each opening, there would be a long tether. Spacecraft coming up from Earth, would attach themselves to the tether. This would allow the spacecraft to bring up more cargo..

        When mining the near Earth asteroids, cages would be built around them. This would prevent dirt, rocks, and metals from floating off. The openings would need to be very small. May also need to build a canopy over the mining site.

        Kalpana One would be placed about 360 miles above the Earth. They should be built in groups of 20. 20 towns would make 1 county. Each town would have 3,000 residents, and 2,000 tourist. This would give a county size of 60,000 people.

          1. I meant use some of the space debris for the building.

            I’d like to see some serious consideration of putting propulsion on the ISS and push it out to L4 or L5. A great place to salvage from… Plus with a little added sensing gear, we’d get long-term automated exploration of one of those orbits to see what might already be trapped there.

            But no, it seems the bureaucracy is dead set on a ‘controlled’ de-orbit before the end of this decade and hope there are no bad atmospheric interactions that lead to ground issues. Never underestimate the lack of bureaucratic imagination.

            OTOH maybe Elon will make them an offer and do it instead?

          2. I haven’t studied the issue, but if L4 or L5 could be reached via transit by raising the inclination a bit more, (its already pretty darned high at what 58deg?) it ought to be able to avoid the worst of the belts. And besides life support isn’t needed, just power and cooling for as long as it could last. Maybe in a drastically stripped down version (stripped in the operational not mass sense) that doesn’t require all that maintenance. The lack thereof in L4 or L5 would be the 2nd biggest issue (outside the propulsion module) and the one that would eventually shut it down. But you’d still have a lot of spare parts there…

          3. I’m not referring to transit through the belts; I’m referring to the radiation environment in cislunar space beyond them. And as William points out, it’s not designed for the thermal environment so far from earth, either.

          4. Refurbishing ISS and extending its useful life for another 20 years would be a useful exercise, if nothing else. Easy to replace the Russian segment (with a Gateway clone, or even Gateway itself, if…). Sans ROS, USOS will last until 2035, post IROSA. That said, it’s also not designed for the thermal environment outside LEO.

          5. And as William points out, it’s not designed for the thermal environment so far from earth, either.
            Again I’m not thinking of having anything *working* there, just raw material to salvage to help build something else.

            I think your *real* counter argument is that nobody will want parts off a Conestoga wagon when everyone is driving around in 1950’s era cars….

          6. Send the ISS to L1. Then build a cage around it. The cage would be in the shape of a sphere. Inside the cage, place old spacecraft, and satellites. This would be used as a museum. Need spacecraft, and satellites from different time periods. From the 1960s, to 2020s. Not every spacecraft, or satellite. If it is a spy satellite, then we need one from each decade. Same with communications satellites. About one, or two from each decade.

            Later on, build a pressurized ring around the cage. This is where tourist would go to observe the ISS, old spacecraft, and satellites. Hopefully, this museum will last for a thousand years, or more.

            People living hundreds of years from now, could see how we today travel to space. They will also see how we communicate.

          7. However the problem with anything not at L4 or L5 is that the other orbital positions are not stable and require propulsion to maintain station keeping. Not an issue at L4/L5, esp. handy when dealing with defunct hardware. But maybe because of that L4/L5 are too valuable to clutter up with a museum. Even a paying one….

          8. At the end of its lifetime, whenever that is, I’d like to see the USOS dismantled, loaded aboard Starships, returned to the ground, reassembled and mounted for display in the Udvar Hazy Center (probably in a new annex). Unlike ROS, USOS is not especially hazardous, so each module could be detached and stowed in a chomper Starship, probably 2 or 3 modules at a time. Maybe 5 flights total, depending on how many pieces of Truss you wanted (maybe toss the solar arrays?).

  9. “We’re talking on the order of $5B/year.”

    What I have been dreaming about is agnostic as to where things start. At ELEO, I’d put a station, or series of stations, to enable construction, research, tourism, and fuel. The first thing I’d request done is to put a constellation of satellites, built off of a standardized framework, around all the planets in the solar system, followed by more specialized orbiters and landers/rovers/other vehicles. I would also treat the asteroid belt as a planet in this scenario and send out satellites to map, prospect, and monitor it in real time. As novel asteroids were discovered, more specialized craft would be developed and launched to prospect them in detail. A similar approach would be taken to notable moonish and dwarfish planets.

    At $5 billion a year, this initial step would easily be completed but due to the nature of time and space, it would take some time for these initial constellations to be deployed around their destinations. While they are traveling, work would be conducted in the other areas. What would be required for follow up missions would change from theory to practicality.

    Research focus would be put on basic concepts of awareness, food, shelter, and water. The constellation missions build awareness. While we figure out what is going on out there, shelter is an immediate concern. First, safe habitats in ELEO, cislunar, and cismartian space. Second, whatever destinations humans will be visiting. Shelter and transportation are the important things here because food and water will be delivered from Earth initially.

    With less urgency but at the same time as the above takes place, research would look at what is needed to grow food. More specifically, how to build a web of food, nutrients, microbiome to support aquaculture and agriculture. A big part of this is learning how to process water from the Moon, Mars, and asteroids and what plants and aquatic species are best suited to those waters in order to reduce processing. I suspect that processing water for humans to drink will be a much easier problem to solve than what is needed for plants and aquatic animals, and likely solved by looking at the larger issue.

    The goal of this would be to better understand our surroundings and to then determine the best way to access resources, whether that is sending them someplace or going to them and using them in place. It would take into account the long time frames needed to reach plentiful resources and provide flexible activities in short and medium time frames.

    With modest investments of government money, and assuming we progress with a system similar to the commercial tract NASA is on now, fundamental questions would be answered and problems solved and while these answers present themselves, clever people and groups will discover markets and products that don’t currently exist and can’t be predicted. Allowing businesses to retain control over their products and to allow entrepreneurs access to infrastructure means that government need not plan everything and that the private sector will put in money, people, technology, and ideas that will enable both government and industry to do things we can’t imagine.

    I have to say, the question is a bit of a trap as there are so many unknowns and someone building a case to spend money needs to provide specific predictions. I think in a situation like that, prospecting the solar system provides results on varying timelines that constantly show something being done. Combine that with the current fad of going to the Moon and Mars and things could be exciting. To be responsible, we want to be looking at getting resources from the asteroid belt and the moons of Saturn but to do that, we need to start at the same time we do these other things because the timelines are so long.

    1. I think Starship might provide more launch capability than what is needed and this is great because it allows the free market to operate in the slack. It is a human tendency to plan everything out but you can’t. This is why successful organizations delegate responsibility and autonomy. Conceptualizing a system like this is difficult because the core of it are people and groups acting out specific objectives.

      Question: What are people going to do up there?

      Answer: I don’t know. Grow yeast from foot junk to make beer on Earth? Develop materials just strong enough not to break but spongy enough to keep those guys and gals living in tin cans on Enceladus entertained for a decade that will also be really really popular on Earth? Grow a truffle on Mars that all the restaurants on Earth will kill for?

      Then someone like me will be like, so what about that yeast you were talking about, where is that? Those sex robots gave everyone rashes! How do we get more of those truffles?

      How do you generate support for a system where the results are not only uncertain but have a guarantee of failure and while there will be success, it will range from the trivial to market shattering?

  10. The low-G muscle-powered flying area from Menace from Earth, but done as an cylindrical station instead. Spin gravity of somewhere around .1g, so less dizziness and such from a relatively small spin-gravity station. Trips to space (assuming 300 pounds consumables and 200 pounds of passenger) are about $30k, so you’d want multiple things to do other than watch the Earth spin by…

  11. A gateway station every quarter-degree or half-degree of longitude. We need between 1/2 to 1 earth gravity so long-term space life is practical. Make them visible to each other. Misery loves company. Equip each one with a space tug capable of feeding Buzz Aldrin’s lunar cycler. Start a Mars cycler. When the tug is not busy, use it to gather up all the unused big pieces of orbital junk; boosters, fairings, etc, and return them to their rightful owners. Or recyclers on the surface if they are of any value. Use some as bases to launch asteroid mining operations, others as fuel and repair shops, still others for manufacturing bases. Hydroponics will help with life support in terms of food and oxygen, use nuclear and solar for power. Make them family friendly and encourage people to live in orbit long term.

  12. The only thing available on LEO is vacuum, solar is intermittent. From ISS, we know that 0g is tolerable at around 6 months out of at least a couple of a years for middle aged astronauts. We don’t know if early 20’s would be more tolerant, less tolerant or the same. Space crew might look sort of like saturation divers, a fairly short working career before wear and tear make retirement advisable.

    The only thing it makes sense to put there is whatever will make it easier/cheaper to get someplace we actually want to be. I predict that place will be able to provide acceleration close to 1g most of the time or frequent crew changes.

    We’re not going to be producing food. Spending a fraction of the cost here on the ground would increase production by orders of magnitude. Microcircuits can’t be fabricated without gravity, a great deal of money is spent on vibration isolation as it is.

  13. ELEO might better be restricted to temporary assembly projects, for which it is ideal. Don’t want to clutter it up with giant space stations…

    What I’d do, in that vein, is build a fleet of interplanetary exploration and prospecting ships, based on a modernized and enlarged NautilusX design, with multiple rotating habs, nuclear electric propulsion, and a crew of 40 or so per ship, sent out two by two, with a focus on the NEO, Main Belt, and Jovian Trojan asteroids, Callisto, and the entire Saturn system. Known resources are water, CHON (petrochemicals), and the hydrocarbon riches of Titan. And whatever might turn up on Psyche. You’d refuel and resupply the ships by Starkicker cargo.

    When the Explorer Fleet was built, I’d switch to building dirigible rotating habitats that would basically be Kalpana One vehicles with nuclear electric propulsion. loaded with equipment and workers to exploit your finds. I might want to arm my ships against poachers.

    One resource that’s currently close to an unknown unknown is the availability of thorium and uranium off earth. Hopefully on Psyche. Probably on Mercury. Maybe on Venus. Almost out of reach. Be a shame if we wound up exporting plutonium from Earth.

    1. What I’d do, in that vein, is build a fleet of interplanetary exploration and prospecting ships, based on a modernized and enlarged NautilusX design,

      I’d love to see that too. Just not sure who is going to pay for it and why. Now if Cold Fusion had panned out and we’d rapidly discover there wasn’t enough palladium on the Earth and then by some sort of miracle, palladium in found to be in abundance in the asteroid belt, THEN I could see these being built by a government / commercial consortium. Some of the NautilusX progeny built for mining interests and some for scientific and other commercial exploration. A win/win. Whatever the commodity is, it needs to be consumable and in need of rapid replacement, otherwise you run into the ‘golden asteroid’ fallacy. i.e. the idea that asteroids of a once precious metal, like gold, once megatons and megatons of it are being brought back to Earth, remain valuable for long.

      So okay food for Earthlings grown in space bad idea. How about food for Martians? At least until it gets terra-formed? Still too expensive up and down? And not ELEO, ELMO maybe? You’d at least have a controlled environment to work with. You’d have to have that regardless. But maybe with solar available freely rather than lug in a nuclear reactor for feeding plants?

        1. If I were a Martian, I wouldn’t want to be dependent on earth for food.
          No, it’s a Martian orbiting platform growing food for Mars.
          Since the surface and atmosphere of Mars itself isn’t all the congenial for farming at least as we know it. ELMO.

          1. It shouldn’t be that hard to farm in greenhouses on Mars. It makes no more economic sense, even at $20/lbm, to grow food for Martians in LEO than it does for earthlings.

          2. It shouldn’t be that hard to farm in greenhouses on Mars.

            No it shouldn’t but a lot of the infrastructure you need to grow stuff on the surface of Mars is the same as you’d use to grow food in orbit over the Martian Equator. And instead of devoting a lot of your energy resources to growing food in a tough Mars environment, grow it where environmental control is easy and the energy is darned near free. But then there is the cost of up and down. And getting water from Mars to orbit, etc. etc. Nutrients and some of the pre-cursor chemicals for proto-soil or hydroponics would have to come from Earth anyway. Until it becomes self-sufficient. If your Martian nuke plant has plenty of capacity, you use that and grow on the surface. It takes a lot of energy, mostly for heat, the rest for light. But at least the crop is easy to tend to and unless you’re spinning the crop station, gravity is free, and as with people, for plants that might be important. I dunno. What does ISS agriculture say about that?

            Sorry I violated the terms of the OP moving from Equatorial Low Earth Orbit to Equatorial Low Martian Orbit. My bad.

      1. In my imagination, I’m only 35 and have just made a killing with my killer app, and now I have a hundred billion dollars to spend…

        One point I have made at every opportunity (beginning with my 1989 Ad Astra article “Harvesting the Near Earthers”) is, among the resources of near-earth space is tidally processed CHON, which I believe would be a useful substitute for petroleum, and we already have a well-developed petrochemical-based technology. People raise objections about importing such to Earth, always ignoring my point that it would be used in space. It probably will be more important than water in the long run, but there’s plenty of that, too. The point is to build a space-faring civilization, and doing it on purpose. The people of 15th century Europe didn’t quite realize they were building a seafaring civilizations, though I think Prince Henry may have guessed.

        1. The CHON must flow….

          -Indira Padiwan Monbiot Blepshod Princess of Tarpit*

          Home asteroid around the whipped-dessert planet 400PagesToGetToThePoint….

  14. What you can do is just about anything. I think the zero g sports thing would fly. I’ve long thought that Rugby would be vastly improved if the ball was eliminated and 3D would be great. Ender’s Game.
    Low g human powered flight, certainly.
    Orbital shipyard.
    Grow zero g pearls “Black Sky pearls”.
    Just get the capability and let the market decide.

  15. –[Friday-morning update]

    Thanks to a comment, I went and rechecked, and found an error in the spreadsheet. The cost is more like $20/lbm.–

    Hmm, well liquid Methane and LOX would be cheapest rocket fuel or is there a something cheaper.
    So it’s 3 to 1 and price liquid methane:
    ” Liquid methane costs about $1.35 per kilogram at the December 29 spot price. With the amazing recent drop in the price of oil, gasoline’s cost is about $0.73 per kilogram, so it’s not clear which fuel will be cheaper”
    Wiki starship first stage:
    3,400 ton propellent
    LOX: $100 per ton. $300 + $1350 = $1650 for 4 tons
    3,400 / 4 = 850 x 1650 = $1,402,500
    second stage: 1,200 tons rocket fuel / 4 = 300 times $1650 =
    $495,000 + 1,402,500 = $1,897,500 in rocket fuel costs
    Assuming multiple launches, costs building starport, rockets. launch control. ect, lowers. And airline operational cost are about 25% jet fuel. So guess 6 million / 100000 kg = 60 per kg
    6 million / 220462.26 lb = $27.22 per lb
    But in terms just rocket fuel
    2 million / 220462.26 lb = $9 rocket fuel cost per lb payload.
    $1650 / 4 = 412.5 per ton or 41.25 cents per kg
    With LH2 at $6 per kg and 6 LOX = $6.60 per 7 kg or
    94.28 cents per kg.
    And LH2 doesn’t work well for first stage and slapping on solids make rocket fuel price jump a lot higher.
    But with assist launch or launching from lower gravity worlds, which don’t require as much “horsepower” it seems LH2 & LOX rockets could work as well in terms rocket fuel costs.
    What is gravity loss for Falcon- 9 and Starship. I think Saturn V gravity loss was quite low, here:
    “Saturn V: Gravity Loss: 1534 m/s Drag Loss: 40 m/s ”
    So, can expect similar low atmospheric loss with the large Starship.
    I guess gravity loss depends number raptors used in the first stage.

    I wonder how much horsepower needed to leave LEO- second stage Starship seems like more than Saturn second stage and a lot more than the Saturn V third stage

    1. Part of the open question with regard to reusable ships and ISRU is where you’re at. Methane for Earth, Mars, Titan, and even Venus. Hydrogen for Luna, Callisto, and most other moons of Saturn. (I am accounting Mercury and the inner moons of Jupiter out of reach for now, along with Uranus and Neptune, things for the 22nd century to do.) Many asteroids, especially the Jovian Trojans, seem to have plenty of water and carbon. And Psyche may very well be an analog of Mercury (I hope so, anyway). If you wanted to, you could manufacture synthetic kerosene in situ wherever there was CHON. Or diesel, for that matter.

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