10 thoughts on “Raptor”

  1. I look forward to seeing weekly flights to the Moon. With propellant depots in orbit and on the Moon, like Moon Direct, it might be economical. I hope they can figure out how to make the business case close for a DC-9 level of payload capacity (9 tonnes) or bigger. 150 tonnes for Starship would be nice. It may have sufficient delta-V to go from Earth orbit to the Moon and back. I’m guessing if that’s true it only needs to stop in orbit on the way to the Moon and not on the way back. It’s not clear what the math is with regard to the capital utilization and development cost of a dedicated non-atmospheric vehicle. You certainly do not need to have the weight associated with reentry into atmosphere, but depending on the flight rate, one general vehicle may be better than two specialist vehicles. If flight rate is high enough, I’m guessing we’ll see systems with two or more sooner or later.

    1. Seguing just a bit, I’ve been seeing more chatter of late regarding the possibility of lunar depots. However, I’m concerned that the business model for them isn’t going to hold up.

      The whole reason behind making fuel on the moon (specifically for delivery and use elsewhere, as opposed to local lunar hops) was because a) the dV to LEO was lower, and b) because with low gravity and no atmosphere, tankers could be made light, cheap, and reusable.

      The same BFR that promises to make space travel affordable and frequent enough to make lunar fuel profitable, however, also promises to make it commercially obsolete. Why invest billions into starting up mining operations and a fuel plant on the moon, when you can make it “dirt” cheap in existing facilities on Earth and, by leveraging massively-reusable launch to LEO, deliver it there in hundred-ton lots for dollars on the pound? How can an untested lunar operation with zero existing infrastructure to lean on possibly improve on that cost structure, much less do so with a timeframe and certainty that would attract investors?

      Back to your point, I do agree that in the long run, using a dedicated cycler with shuttles optimized for local conditions based on each end makes the most sense for Mars; however, in order to prove that colonization is viable with any remotely realistic amount of free-market capital, Elon’s build-one-version-now-then-make-variants plan makes the most sense. I also suspect that a lot of this push is based around the unpublished requirements for earning the Dear Moon money.

      I assume that everybody here is aware of, if not already following, Scott Manley and Everyday Astronaut; if not, they’ve both recently posted very good videos on Elon’s latest series of tweetleaks.

      1. –The whole reason behind making fuel on the moon (specifically for delivery and use elsewhere, as opposed to local lunar hops) was because a) the dV to LEO was lower, and b) because with low gravity and no atmosphere, tankers could be made light, cheap, and reusable.–
        I would say whole reason is making rocket fuel in low lunar orbit cheaper.
        And rocket fuel in high earth orbit cheaper, and in Mars orbits cheaper.

        The main problem with making lunar rocket fuel is selling a lot of it, otherwise you just sell lunar rocket fuel at the lunar surface.
        So to sell more lunar rocket fuel, you sell it , at lunar low orbit.
        And it possible that you can only sell lunar LOX rocket fuel at lunar low orbit. Or might be able to buy Earth shipped LH2 at low lunar orbit cheaper than Lunar LH2 shipped to low lunar orbit.

        I say you have start with guessing what price of LOX on the lunar surface is worth. I would say LOX is lower price than LH2.
        On Earth LOX is far cheaper than LH2 per kg. LOX is about 10 cents per kg and LH2 is about $5 per kg.
        And rockets use 6 times more mass of LOX as compared to LH2.
        Or 7 kg of LOX/LH2 costs: 60 cents + $5
        Or per kg $5.60 / 7 = 80 cents per kg of rocket fuel.
        If shipping rocket fuel from Earth to LEO there will be less difference between the cost/price of LOX and LH2, but LH2 will be more expensive. As wild guess LH2 about 1.5 times the price, due to more tank weight per kg of LH2 which is delivered (not due to the $5 difference, unless launch cost to LEO is only about $10 per kg to LEO).

        With the Moon, it is cheaper to make LOX. It is easier to make into liquid- in terms of energy. And if making rocket fuel from water, you get 8 kg of LOX from 9 kg of water. So per 9 kg of water split, you two extra kg of LOX, in terms using it for rocket fuel. Plus in term of abundance, about 40% of mass of lunar surface is oxygen. Or if metals are made, a byproduct is oxygen.

        So if Lunar LOX is worth $1000 per kg, I would say Lunar LH2 is worth about $4000 per kg. And that makes lunar water worth about $500 per kg. And also lunar electrical power about $75 per kW hour.

        And rocket fuel at lunar low orbit about $4000 per kg with difference between LOX and LH2.
        Say LOX: +3000 , LH2: +4500 per kg.
        And water shipped from Earth about $3000 per kg at low lunar orbit.

        So if there was any need of water, that would cheaper to ship lunar water at lunar surface price of $500 per kg.

        Now let go with idea of very cheap earth launch cost.
        So let say cost to ship LOX from Earth to low lunar orbit was $500 per kg or less.
        That mean lunar water would have be less than $100 per kg. But it also mean lunar electrical cost would be lower.

        But with such low cost, one could (or should) have a different focus. One getting near the point of having space power satellites becoming close you being made. And might want to use Moon to make them. Or if can make electrical power cheap on Moon or anywhere else in space, SPS is trillion dollar market.

        Anyway, if launch cost are cheap, solar energy (or nuclear energy) is cheap on the Moon. With moon you don’t have energy storage problem you have on Earth. And as rough guide, once lunar electrical power is about 1$ per kW hour or less, Earth SPS should be close to being viable.

        1. Actually, SPS is going to have to spend the next couple decades competing (at least in the US) with turbines run on a glut of natural gas recovered as a byproduct of oil drilling. And after that, it may well have to compete with a new generation of small, mass-produced reactors.

          The point, though, is that there is less chance of a market in lunar fuel as a *leading* economic driver in space. Rather, lunar fuel only truly becomes worthwhile if, as you state, there is another economic incentive to large-scale operations on the moon. Otherwise, fuel is a *trailing* economic indicator, something that only becomes profitable once local demand has reached a certain level *for some other purpose or reason* (e.g., colonization because people “just want to live/vacation there”, or “we can build certain things better in zero-g”).

          But, SPS? Why not follow the idea to its logical conclusion? Wouldn’t it be cheaper still to build SPS on Earth, and ship the satellites into orbit on Starship/NG? Why do you need to invest billions into mining fuel on the moon, so that you can invest billions into making SPS sats from lunar materials, so you can make less money up front than if you had made the sats on Earth and shipped them to orbit in cheap reusable rockets? (And why *did* that old woman swallow the fly?)

          I don’t have a good answer for this. We need reasonably-priced infrastructure in order to support colonization, and a way for colonists to at least show the potential for eventual profit in order to encourage investment into that infrastructure. And right now, I’m not seeing anything that could induce anyone who doesn’t want to live off Earth to invest money in the hopes of making a profit. Elon plans to muscle through the first step essentially on the back of his own charity (from money he expects to make in LEO/MEO/GEO), but at some point, we either need a lot of wealthy people who want to retire off-planet, or some way for younger, less wealthy people to make a career, somehow.

          Anyways, this is starting to get a tad off-topic. Here’s hoping that the test-firing went well.

          1. –The point, though, is that there is less chance of a market in lunar fuel as a *leading* economic driver in space. Rather, lunar fuel only truly becomes worthwhile if, as you state, there is another economic incentive to large-scale operations on the moon. —

            The global satellite market which is about 300 billion dollars per year, is a much larger market than lunar water market, or lunar mining in general, and/or splitting lunar water to make rocket fuel.
            It would somewhat similar to oil business on Earth which is small fraction of GDP-unless a country is oppressed oil state. But like oil business, all business are dependant on oil energy (other oil products).
            So lunar rocket fuel business is small and HAS TO BE small in comparison to all the business dependent upon it.

            And one could say the lunar rocket fuel business has to start tiny and within decade become small, and lunar rocket fuel as compared rocket fuel made in this solar system, will never get much bigger than small.

            Or a significant aspect of lunar water mining and rocket fuel is adding another market to the existing space market rather than assuming it will or could equal the global satellite market (particularly if only concerned about next few decades).
            The other significant aspect is to be successful the lunar rocket fuel market has to somehow create or be involved with other lunar businesses (and possibly Mars businesses).

            In terms of ultimate type goals, the purpose of NASA exploring the Moon (to determine if and where there is mineable water) and in exploring Mars (to determine if and where there could be viable sites for human settlements) is to reach the distant future of having Earth SPS.
            If NASA get going and get lunar and Mars exploration finished within 3 decades, then we might get SPS within 6 decades from now.

  2. NASA and the Apollo cargo cultists in Congress are betraying their country by their continued support for the SLS and Orion. Especially with China looming in the background. They could easily have space superiority with both Space X and New Glenn Rockets, but apparently pork is more important than national advantage.

  3. I think it is quite surprising that SpaceX is the only contractor which did not get any funding in the EELV mk2 contract.

    Hopefully all these design changes mean that SpaceX can do the new space launch system with their own funds.

    1. I’ve heard speculation that it came with all kinds of strings attached, and Elon wasn’t willing to make commitments to keep a medium-lift, partially-disposable system running for a decade or more when he’s all in on fully-reusable heavy lift (and that’s before you look at the latest redesign, which would have driven government bean-counters nuts with the fundamental changes made on the fly, and apparently almost overnight after a new stainless alloy was publicly announced). Government wastes a lot of time and money in a desperate (and often unsuccessful) attempt to keep people from ripping it off, and they just can’t handle Elon’s level of project risk.

  4. In terms of NASA priorities.
    Explore Moon now, with robotic lunar landers.
    Have plan for ISS.
    NASA will not operate ISS, as it doing when NASA does Mars program. And NASA should not de orbit ISS.
    NASA needs to demonstrate an operational depot in orbit.
    NASA will use depots in Mars exploration.
    Commercial Lunar water mining requires the use of depots.
    Depots will probably be used by private rocket fuel supply for NASA Mars exploration.
    Finish Lunar program with crewed lunar missions.
    Then start Mars program.

    For crewed Mars missions get crew to Mars within travel time of 3 months and one can use chemical rockets, rather requiring nuclear and/or Ion (or etc).
    And departure from Earth to Mars, begins from high Earth orbit, rather than LEO.
    And will require a lot of chemical rocket fuel- it will be a spacecraft refueled at high earth orbit.
    And fast transit to Mars will be crew only, and they will dock with pre-positioned vehicles already at Mars orbit.

    (And from high Earth, one has departure burn near Earth and it would be getting the Oberth effect.)

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