21 thoughts on “Elon’s New Rocket”

  1. I’ve written a piece on the same theme for the next issue of The New Atlantis.
    Looking forward to reading it.

    1. For a moment, Rand, you had me worried that you had published an article in The Atlantic.

      That takes 50 points of a person’s IQ, right there!

    2. BTW meant to write that I thoroughly enjoyed reading Zubrin’s piece as well. Thanks for the link.

  2. Great piece, and looking forward to yours Rand. I must pick a nit:

    [Artemis…SLS…Orion…Gateway] NASA may fly a few missions that way. But frankly, this is to avoid the embarrassment of having spent so much time and cash on systems that were never used.

    Really had to chuckle there. “Embarrassment”. I think most would agree that the whole concept of NASA experiencing embarrassment over spending gobs of money with little or no tangible results could be considered… the word that comes to my mind is “quaint”.

  3. One thing in the article caught my attention. Someone (and I think it might have been here on this blog) said that the fuel-delivery capability of Starship meant local fuel production on the lunar surface no longer made sense, at least in the short-term. But Zubrin calculated that such could reduce the number of Starship launches to the moon to 1/3. That’s got to have tremendous leverage.

    1. It only makes sense if you’re refueling Starships on the lunar surface. Otherwise you still have to lift the lunox to somewhere else, which negates a lot of the advantage. If you’re servicing a permanent moonbase, they yes, make lunox. Mars ISRU makes more sense because it’s so much farther away, with flight opportunities years vs. days apart.

  4. If we will having profound potential, how about an artificial gravity space station at Venus?
    ” NASA’s goal is to minimize the time the crew travels between Earth and Mars to as close to two years as is practical. ”
    I get a bit annoyed with idea trying to round trip to Mars as short as possible- I think should send crew to stay Mars for +3 years. But do like idea being able leave Mars and requiring the least amount time to Earth, but if had station with artificial gravity, it could return from Mars to Venus and/or Earth.
    And in terms of Mars having towns/settlements it seems one going to use Venus.
    So I think NASA should explore the Moon, to allow/determine whether one could have commercial lunar water mining. And if you can buy lunar fuel on Lunar surface, one could have all kinds of bases on the Moon. Many countries could have many bases on the Moon, and all kinds of stuff.
    And I think NASA should explore Mars to allow/determine whether Mars settlements would commercially viable. Or not really keen towns which quickly turn into ghosts towns on Mars. NASA should look for better places for towns on Mars.
    A problem with commercially mining lunar water, is someone finding a much better spot to mine lunar water. Same goes for Mars town, someone could find a better place to have a town- making your town a ghost town. Or in term of commercial anything, competition is what “kills you”. So uncertainty of whether you got a good site for mining or living, is an investment risk. Of course another risks is town site has political problems, like alien life discovered near it. Quarantine is not good for business.
    And I think if one somehow get Mars settlements, first that lead to lunar development, and/or getting lunar development happening sooner helps make Mars settlements more viable.
    So, if you have lots people living on Mars returning to Earth {or Venus} faster, becomes more important.
    So, of course a question is if going to have artificial gravity space station, why not have in Mars and/or Earth orbit, instead of Venus?
    I would not say should not have at Earth and/or Mars, rather saying maybe Venus first. Or Earth first and move it to Venus. But if NASA worried returning quickly in terms round trips to Mars for explorational purposes of Mars- why not space station at Venus?

    1. I don’t think everyone at NASA, or many other places, has realized what “propellant rich” means. One of the things it will mean is transits to Mars measured in weeks, rather than months. Musk is talking about staying on Mars for years, with quick crew transits on either end. A lot of people are still thinking of two-year round trips, with 30 days at Mars, tops.

      Which is not to say that large rotating space habitats won’t have a big part in the future to come (providing we don’t allow the religion of Marxism to destroy our civilization). I think it’ll be a while before we do anything with Venus, as I don’t have much faith in floating cloud cities. But the time will come when workers out among the moons of Saturn will need a place to live.

      1. Not that I am travelling there anytime soon, but what is the radiation environment of Saturn’s moons of interest?

        Yeah, yeah, I can look this up but Web sites disclose magnetospheres and radiation belts and plasmas blah, blah, but could humans live there and for how long?

        My understanding is that for Jupiter, Io is uninhabitable, but what about other moons?

      2. Even if one is “propellant rich” you still have launch windows- and Venus to Mars has twice the launch windows as Earth to Mars.
        So using both Venus and Earth, one gets roughly 2 to 3 times as many launch windows. Or analogies to Air travel, 2-3 times as departure and arrive times from New York to London.
        And using hohmann type transfer, you get to Venus in about 2 to 3 months, and from Venus to Mars in about 2 to 3 month. And of course faster if using non hohmann and more delta-v.
        And I would say it’s “more critical” for leaving Mars to get to Earth and/or Venus, than getting from Earth to Mars. Or when have Mars settlements, you will be using the Venus orbit.
        So in terms of NASA goal of enabling commercial lunar water mining and commercial human settlements AND to help with logistic of NASA Mars exploration Program. NASA should at least put depot in Venus orbit- but I think it should put artificial gravity space station. And artificial gravity could be Mars gravity .

        1. You could also send 6 crew to Venus, and from Venus orbit send 3 to Mars. So one can select from 6, 3 going to Mars when they are already at Venus orbit.
          Venus space station should have focus on medical infrastructure. And built up to handle any medical issues- including “Mars alien life” problems. And you have less of speed of light issues at Venus distance as compared to Mars distance. You could later have isolation infrastructure on the lunar surface- but the Moon has lower gravity.
          So, if become a issue, could also build up in Venus orbit and may be also build 1 earth gee or 1/2 earth gee space stations.

        2. Interesting. I’d never really considered Venus a potential way-point on the way to Mars. But it’s an interesting consideration of interplanetary infrastructure. Here’s a great area where I think NASA could also focus on for expanding beyond lunar space, since opportunities to fly-by Venus occur twice yearly. A fly-by mission perhaps to follow up with crewed orbital stays. Certainly a Venusian fly-by would not be much of a stretch for a Martian Starship. Heck with a little ingenuity it could probably be done with a Crew Dragon variant and Falcon Heavy now. A hand wave I know, but not a big one. There had been a proposal for an eye-balls out fly-by mission to Venus using Apollo hardware after-all.

          1. I really wish they’d done that (I was 18-25 during Apollo and was quite excited by everything AAP). The test flights described were really an unnecessary, once Skylab flew. Even if the wetlab didn’t work out well, they still had the CSM and mission module.

  5. This is kind of what I was talking about when I talked about not unstanding “propellant rich.” Launch windows are not just dependent on planetary alignments, they’re dependent on requiring miminum energy orbits. Being propellant rich means you can make faster transits at opposition and conjunction, *or* you can mak slower transits away from the so-called “windows.” In practical terms, crewed ships will make fast transits at particular times, while cargo-only ships will just fly when they are ready. For *inert* cargoes, the Pipeline Effect dominates. It doesn’t matter how long it takes lumps of ore to get from Hektor to Luna, for example. The speed of product in a pipeline is irrelevant, so long as it keeps coming out the spigot at the consumer end. Solar sails could do that job.

  6. Regarding radiation environments, Wendell Mendell did a book on this decades ago called “The Resources of Near-Earth Space.” Among Jupiters Galileian satellites, only Callisto is accessible to our current technology. Since it’s made out of water ice, I imagine it’ll be useful. By contrast, the entire Saturnian system is benign enough, other than being cold as frel. And, of course, Titan has lakes and seas of rocket fuel just waiting for us to pump it.

  7. Hop David’s, Cosmic Train Schedule:
    Which indicates past and future simple hohmann transfers
    to planets.
    So from above Earth to Mars:
    Starts in 2001 and goes to 2313 AD
    All the trajectories are the same and not meant to be exact.
    But the Synodic period always is same and is: 2.1354 years. Or 779.42 Earth days or 2 years and 49.42 days.
    And with simple hohmann {which is rarely used, as time to arrive shorten with change trajectory call patched conic- but to keep it simple, the time of simple hohmann is 0.7087 years. Or 0.7083 times 365 days is 258.5295 days and in terms 30 day months: 258.5 / 30 = 8.616 months.
    NASA routinely send robotic spacecraft to Mars surface which gets there is about 7 months. But if has large payload and wants to use least delta-v, the trip time will a bit more than 8 months. As with the Curiosity rover. Wiki:
    “Curiosity was launched from Cape Canaveral (CCAFS) on 26 November 2011, at 15:02:00 UTC and landed on Aeolis Palus inside Gale crater on Mars on 6 August 2012, 05:17:57 UTC” …”touchdown target after a 560 million km (350 million mi) journey”
    One make simple, by saying the longest distance traveled is the simple hohmann and requires least delta-v as it little change the vector of trajectory {or than minor course corrections]. And shorter travel are done traveling a shorter distance to Mars.
    A hohmann plus patched conic is hohmann type transfer which go further than Mars distance, and patched conic changes the vector so arrives at Mars distance, and arriving before Mars is at opposite of sun {from Earth}.
    “How long would a mission to Mars take?
    The cruise phase begins after the spacecraft separates from the rocket, soon after launch. The spacecraft departs Earth at a speed of about 24,600 mph (about 39,600 kph). The trip to Mars will take about seven months and about 300 million miles (480 million kilometers).”
    Or 7 month trip goes much shorter distance.
    Earth to Venus
    Synodic period: 1.5987 Years
    Trip Time: 0.3999 Years
    And Venus is closer to Sun, it opposite from Earth is a shorter distance.
    Parker solar probe {which want get very close to Sun} left Earth and when past Venus {and gravity assist using Venus] and it took about 52 days to reach Venus from Earth launch:
    August 12, 2018: Launch – 3:31 a.m. EDT (7:31 UTC)
    October 3, 2018: Venus Flyby #1 – 4:44 a.m. EDT (8:44 UTC)
    So it hohmann transfer going close the far side of sun, and change trajectory [with gravity assist} to get even closer to far side of sun.
    So in terms of Hohmann transfer around the fastest one get to Venus is about 50 days. So it was not hohmann to Venus, it hohmann to much closer orbit around the Sun, and traveled very short distance to get to Venus {and required huge amount delta-v to do this, and if wanted to stop at Venus, it again would require a huge amount of delta-v. {Using Venus atmosphere to stop is probably too hard to do. Though one might design spacecraft in the future which might be able to “fairly” safely, do it}
    Anyhow the Synodic period is fairly long with Earth to Venus {or is same with Venus to Earth}. Mars to Venus:
    Synodic Period: 0.9142 Years
    Trip Time 0.5954 Years

    A interest puzzle, is can get from Earth to Venus quicker than 50 days, using a non hohmann transfer? Or can go a shorter distance to Venus from Earth.

  8. Hollister “Hop” David is a wonderful resource and I’m glad I made his acquaintance. Still, talking abut Hohmann orbits illustrates the problem. Look at it in the simplest possible terms. Transfer between Earth and Mars is an elipse. As you go faster, the elipse gets taller, and the curve segment between Earth and Mars becomes a smaller portion of the whole elipse. If you go fast enough, the curve segment resembles a straight line (although it’ll be a while before we have spacecraft that can manage relativistic speeds!). I wrote an article for Ad Astra back in 1989 called “Havesting the Near-Earthers” that talked about some of this.

    While there’s a shortest orbital distance form Earth to Venus that can’t be transcended, the transit time is limited by technology only. With the rockets we have now, probably 25 days is the limit of what’s possible, and 80 days to Mars. The Mars transit in 39 days with VASIMR (or two weeks to Venus) requires a solar array the size of a mall parking lot (i.e., a mile wide) or a 600 ton fission reactor. So possible, but unlikely.

    1. “While there’s a shortest orbital distance form Earth to Venus that can’t be transcended, the transit time is limited by technology only. With the rockets we have now, probably 25 days is the limit of what’s possible, and 80 days to Mars”

      25 days from Venus to Earth or Venus to Mars? It seems with technological limitation it’s quicker to go to Mars from Venus than from Earth to Mars. And also quicker to go from Venus to Mars, than Venus to Earth. And this true with hohmann type transfer and non hohmann transfer. But not true with burn, burn, then turn around and brake- or not available technology.
      Ion would have advantages from Venus, and to anywhere, as compared to from Earth to anywhere.
      But not counting this more solar energy power advantage, is it faster to go to Mars from Venus and compared to go to Mars from Earth using the low thrust power as done with ion engines?
      Or using Ion engines is a non hohmann transfer**, and it’s non hohmann we have used. Or only other type of non hohmann we have done is in regards to many gravity assists we have used.
      ** If ion engine are only firing when at perigee {doing multiple orbits} and not spiraling out, then they are closer to a hohmann transfer. Or further one goes away from a instantaneous increase in velocity, the less of hohmann, it is.

  9. The Venus way-station idea won’t work for a number of reasons (besides that it depends on unnecessary low-energy orbits). The most important one is that it is functionally equivalent to an Aldrin Cycler, which was a parlor trick the “propellant rich” Starship paradigm renders obsolete.

    Look at it this way: suppose you wanted to build a rotating space station in LEO. Starship could have lifted ISS in 10 flights, at around $2mln per flight (so $20mln). Let’s say your AG stayion needs to be 10 times as large to be useful (remembering ISS hosts a crew of 7). So 100 flights for $200mln. Ignoring the cost of the station itself, a bargain. Now lets say you wanted one in orbit about Venus. Okay, now those 100 flights have to be supported by 600 tanker launches, for an added $1.6 billion. And, of course, that’s only launch costs. Now you have a space station in orbit around Venus and 100 Starships stranded with it. So now you have to fly tankers to Venus and launch other tankers to refuel the tankers… clearly this is not the way to go about it. So maybe you build the station in LEO, add a large ion drive and fly it to Venus in one lump. Great. And if you can fly it to Venus, then you can put in an orbit that intersects Earth and Mars at every synod. That would be an Aldrin Cycler.

    But let’s say you really want the Venus waytation. Now you have to supply and maintain the station orbiting Venus, and what’s it for, besides storing people on their way to Mars? As a fuel depot for Starships? What fuel? Shipped from Earth or Mars? Jonathan Goff did a piece on Venus ISRU back in 2013 that’s worth rereading (found at Selenian Boondocks). Basically, you can make methane and lox from the Venusian atmosphere, but then you’re talking an infrastructure that looks like cloud cities.

    In brief, there’s no infrastructure that beats launching tankers to LEO from the ground with readily anticipated technology. There are limited cicumstances where ISRU pays off (Moon, Mars, and Callisto). Even depots are part of an infrastructure buildup that’s going to take time.

    Not that I don’t support human Venus exploration, with a small space station in Venus orbit, and crewed LTAs descending to the 50km level at first, eventually maybe landing atop Skadi Mons in the Maxwell Montes once the technology is tested out.

  10. “But let’s say you really want the Venus waytation. Now you have to supply and maintain the station orbiting Venus, and what’s it for, besides storing people on their way to Mars? As a fuel depot for Starships? What fuel? Shipped from Earth or Mars? Jonathan Goff did a piece on Venus ISRU back in 2013 that’s worth rereading (found at Selenian Boondocks). Basically, you can make methane and lox from the Venusian atmosphere, but then you’re talking an infrastructure that looks like cloud cities.”

    No premise is based upon there being mineable lunar water, and you ship lunar water to Venus. If there isn’t minable lunar water, you have get rocket fuel from somewhere else in space. I wouldn’t get it from Mars, but “maybe” the moons of Mars.
    It seems to me if NASA doesn’t find mineable water on the Moon {and no one else can} I would still continue with idea of exploring Mars. And I certainly would not put a base on the Moon, I don’t think if NASA finds lunar water, NASA should get bogged down on lunar surface. Or determine if there is or is not lunar water, but don’t stop, immediate go into the Manned Mars program- get bases on Mars {not on Moon}. Once got crew on Mars, and Congress wants add enough for Lunar base, then NASA could do a lunar base. But there commerical lunar water mining “happening” I pick a station in Venus as higher priority than a lunar base {if Congress wants both- don’t argue, do both}.
    What is mineable lunar water, if can make 10,000 tons of rocket fuel in ten years and lunar water is around $500 per kg {or better if less] and LOX can sell for $1000 per kg {or less}.
    What is hard, is getting enough demand for 10,000 tons of lunar rocket within 10 years. Next turning 10,000 ton of lunar water into rocket fuel require a huge amount of electrical power available within say 5 years. You might start with 50 tons of rocket fuel in first year, double it each year giving the 10,000 ton total over first 10 years. Or you going to get better at making rocket fuel over time, and you “have to” get more demand for rocket fuel over time [within the first decade- your investment aspect is going to mostly about how you do in first 3 to 4 years {and what growth going to seem likely before the 10 years is done].
    And if ship LOX to low lunar orbit, that increasing the demand for lunar rocket fuel. So have ship LOX to Low lunar cheaper than LOX shipped from Earth, you don’t have beat LH2 or liquid methane shipped from Earth. And since lunar water is $500 per kg cheaper than Lunar LOX, Lunar water could be more profitable to ship to Low lunar orbit, than LOX. Or for Venus station which want lots of water, it’s going from lunar surface to Venus orbit, and most delta-v in getting it to lunar low orbit. Or ion rockets could work to get to Venus and return empty to Lunar orbit.
    Or said what hard, what not hard is making lot’s of lunar water, if you sell 10,000 of water for lunar surface rocket and sell another 10,000 tons lunar water shipped off the Moon, that will lower price of lunar water. Lower price is lunar water does not change price of rocket fuel very much, it’s the up front cost of electrical power generation which problem. Or shipping water to Venus and having Venus solar energy split water, is pathway to lower lunar rocket fuel costs.
    Before I considered the Venus station, another market for Lunar water [or LOX] is Mars orbit {or any high earth orbit}. And Venus orbit would be cheaper to ship to than Mars orbit. Or one consider it possible or likely that rocket fuel in Venus orbit, could be cheaper than Mars orbit- or even high Earth orbit.

  11. Here goes:
    Depot: Rocket fuel Tanks: 4 meter diameter tanks with both ends being 1/2 hemisphere caps. 20 meter long, ends 2 meter of this total length and 18 meter cylinder which are 4 meter diameter. Wall thickness 1 cm. Ends 2 cm thick. Steel with density of 8000 kg per cubic meter.
    4 meter = 157.48″ and 1 cm = 0.393701″ should able to safely have 140 psi pressure.
    Volume of 18 meter long and 4 meter diameter: 226.19 cubic meter. Outside surface area: 226.2 square meter. Total volume of steel: 2.261 cubic meter: 18,095.56 kg. Ends: .51 cubic meter, 4,080. Totals 22,175.56 kg
    Launch many of them, have designed so ends them can be connected. Starship can put 21 tons to GTO. The “shortness” of tanks was chosen so could fit in starship {hopefully}. It seems to me such tanks wouldn’t need a fairing, so something like Heavy Falcon could launch if were twice as tall.
    And tanks could made carbon fiber and/or light and strong metal alloys. Anyhow, starship could launch LEO, and assemble there, or something like a GTO, and assemble, or refuel and assemble in high Earth orbit. And final result is get say 8 of these tanks which made in long cylinder and be in elliptical orbit of Venus- say, zero inclination and 800 km by 60,000 km.
    And going to fill 2 of 8 with LOX and 6 with LH2. And end with LOX would be much more massive and tend to point at Venus {due to gravity gradient].
    If one filled with LOX the LOX mass would be about 258 tons. And one filled with LH2 would about 16 tons of rocket fuel.
    Full of rocket fuel, 516 tons of LOX and 96,356 kg of LH2. And total mass of tanks: 177,404.48 kg. And other stuff about another 10 tons. And some of that would be solar panel at bottom of LOX tank. With elliptical orbit most of time it should be more 10,000 km from Venus and at this time solar panels would be facing sun. And approaching or leaving perigee they more facing Venus, and at perigee facing Venus, and should able to get solar energy from the clouds reflecting sunlight. And heating of tall cylinder [160 meter tall} should mostly occur when approaching and leaving Perigee- or has larger cross section in sunlight, and at most time a small cross section. Or more than 80% of time only small portion of it is heated by sunlight.
    This would be about 1/2 mass ISS {without the delivered rocket fuel}.

    The AG station would also be a long cylinder, and is spinning and be able to control it’s spinning. And because it’s spinning, it’s rather
    complicated to try to point solar arrays. And in terms a random facing, panels only get about 25% solar power per total square meter of solar panel area. But since one can control of your orbit and spin, you could increase so it’s 30% or more rather than 25%. Or way designed it, if either of ends were always facing the sun, it would get far less than 25%.
    And due to relatively small portion solar panels of getting solar power and due to added mass, it didn’t look it would very efficient at splitting enough water to provide enough rocket fuel for other spacecraft.
    Anyhow, way it designed it’s not for a fulled fueled starships park at either end {or one end}. Or not design to spin as much a 1 million kg of mass at any significant amount gee {can’t do mars gravity or even 1/2 mars gravity].
    And would also less mass than ISS- and could make about 30 tons of rocket fuel per year.
    But something making rocket fuel from water should be more than 400 tons per year.
    So above depot would get rocket fuel from Earth or Moon. Might do depot first, or AG station first or at same time. And whatever going to make rocket fuel
    from Lunar water, would be commercial operation. But it should require less mass than the depot or AG station.
    AG station would have more than 100 tons of water for radiation shielding, and have at most around 12 crew. So most of time maybe 6 or less, and for months of time 12 or more. Also uses water to balance mass- by moving 10 tons of water from one end to other.

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