20 thoughts on “Developing Space”

  2. If using hohmann transfers, the shortest distance traveled to planet from Earth is Mercury- it takes about 105 days. The second shortest from Earth is Venus. And shortest distance between planets is Mercury to Venus- about 75 days.
    And one shorten the distance by using “not” simple hohmann transfers: hohmann + patched conic.

    A simple from Earth to Mars is 258 days [8.6 months]
    and with patched conic can land on Mars in about 7 months.
    With Starship Musk’s plan is to get to Mars in 6 months by using Mars atmosphere to slow down the Starship- a simple which go further out than Mars which intercepts Mars, and velocity the lost by using the Mars atmosphere.
    And the Starship could do the same thing with Venus,
    and thereby making the Planet Venus the shortest distance to Earth.
    And by using Earth atmosphere, the planets with shortest distance from Venus is Venus to Earth.
    Or could be less than Mercury to Venus simple of 75 days, but not less than Mercury to Venus using Venus atmosphere- not sure what that number is but probably less than 60 days, nor know number of Mercury distance to Venus with patched conic.

    Anyways with Starship from Earth could go to Venus, and use the atmosphere, and from Venus go to Mars
    and it’s atmosphere.
    And go the other way, Mars to Venus, and Venus to Earth and use both of their atmospheres.

    1. Using Starship, from Mars, Venus is the closest planet.
      And using Starship Venus become more of the hub of solar system.
      The Synodic Period between Mars and Venus is 0.9142 Years [333.683 days]: http://clowder.net/hop/railroad/VMa.htm
      Mars and Earth is Synodic Period is 2.1354 Years
      [779.421 days].

      If have artificial gravity station and fuel depot at Venus orbit you get from Earth to Mars [or Mars to Earth] with shorter launch window by having option of using Venus orbit, or rather than about 2.1 years, it can average to be about 1 year.
      There seems little doubt that Mars settlements will use Venus orbit.
      But first we have explore Mars, in terms crewed mission to Mars, NASA could plan to use Venus as way to to get back to Earth- without needing rocket fuel depot- but should NASA instead plan on making artificial gravity stations and depot in Venus orbit, first?
      It seems NASA would have to be crazy to do Mars crew exploration without first testing an artificial gravity station.
      They should have artificial gravity space station which can make Mars artificial gravity.
      And question is what is minimal radius needed for a Mars gravity station.
      They can also determine minimal radius of Lunar artificial gravity.
      What is minimal radius of lunar artificial gravity and what effect of this compared to microgravity and what is difference of Mars artificial gravity vs microgravity.
      And what is difference between Mars artificial gravity
      and Mars gravity.
      What seems to happen is that human adapt to microgravity.
      If human adapt to Mars artificial gravity, what difference is there in terms adaption between Mars gravity?

      1. SpaceX can use falcon-9 to test artificial gravity.
        Rather than payload launched from second stage.
        Extend second stage by 10 meter, and use it, as short radius artificial gravity station.
        Launch it to 28 inclination, and send another falcon-9 with dragon and crew to dock with it.
        This could cheaper than launch 2 dragons and using a rope. But you also keep the rope option, so one test larger radius than 10 meter.
        The added part to falcon-9 second stage [the artificial gravity station] could have say 4 floors [4 rooms] and a lower room can be launched as a solar flare shelter- which has water as shielding. But it doesn’t have much in terms life support systems.
        It brings a lot air- liquid air, and water.
        It’s mainly testing artificial gravity, though one could design it, later missions to it, can add stuff to improve it. So want crew there at beginning for say for weeks, or a month. And later crew could add stuff and as extended mission type thing, you even refuel the stage and leave LEO.
        But building up to 6 month crew stay which count as
        a completed mission, which could take 3 to 4 dragon crew visits.

  3. I think SpaceX screwed the pooch with Starship. Going from F9 to Starship size is not “iterative development”, it’s trying to take a leap that has a credibly high risk of bankrupting them.

    An intermediate size launcher anywhere between 30 to 60 tons, just pick a number, with higher energy upper stage would have worked far more reasonably and would probably be operational right now. Far more modest infrastructure needed, good shot at trying to get a reusable upper stage. More than enough capacity to make Starlink operationally sustainable.

    For the lunar and Mars fantasies, the smaller size makes no difference because they have orbital staging and refuelling already in the plan – just fly the tankers more often.

    People keep thinking that the physical scaling of mass ratios drives the economy, but i really doubt it does in reality. If it did, every airline would be flying Airbus A380s all day every day. They don’t, because operational concerns dictate economics.

      1. Well you all should like New Glenn rocket- methane first stage and LH2/LOX second stage.
        Of course Starship with LH2/LOX second stage would also be lighter.
        But I think Musk is doing boilerplate until works out
        the problems- and problem he wants to solve is having a big rocket to lower launch costs, so he can do his city on Mars.
        I tend to think if want a huge rocket, you have to launch from the ocean.
        I think US Space Force should focus on big rockets and launching from the ocean.
        Only aspect of land, is there is more land experience, and FAA is more experience with land launches. Or I could see them wanting to doing full scale environment review with ocean launches.
        So, from regulation aspect, small rockets from ocean, first. And/or Space Force does ocean launch related to national security issues- or Space Force might able to start with large rockets and ocean launches.

        1. I have two ideas about ocean launches, but could it’s just one idea. And call it a pipelauncher.
          A medium size pipelauncher is roughly Musk’s larger Starship: 20 meter diameter and +100 meter tall. It’s 20 meter pipe and +100 meter tall with 1 cap on end of it.

          So you put this in ocean, and open end fills with water, and eventually flips vertical. As ships do if broken in half.
          This also related a vertically floating “ship”:
          RP FLIP:
          https://en.wikipedia.org/wiki/RP_FLIP

          1. Second idea is cheap breakwater.
            20 meter diameter pipe and +100 meter long,
            two ends capped, and filled water freshwater at pressure of 10 psi [or more].
            The freshwater is less dense than sea water, so floats it [barely] in the ocean.
            So floats horizontally in the ocean about 1 meter above the water line. And 1 meter high wave will go over it, as will 10 meter high wave. And causes 1 or 10 meter high wave, to break. So other stopping wave, it make waves you surf on.
            So can have ocean settlements which have surfing areas.
            Or I call it, low income, beach property. It would have beaches behind the broken waves, also.
            I figure, if Musk makes Mars settlements, he will have to cause, ocean settlements. But you don’t need to wait for Mars settlements.
            I would start ocean settlements near coastal cities, and they also provide good surfing areas for the people living in the city.
            And so rather than breakwaters interfering with surfing waves, you make better surfing waves {safer surfing waves, also}.

        2. If Blue had a track record of accomplishment, I might or might not like the New Glenn. As it is, it’s irrelevant.

          1. Blue is connected to:

            –JUN 2023 Vulcan Flight 1
            Vulcan
            United Launch Alliance (ULA)
            SLC-41, Cape Canaveral SFS
            Florida, United States
            — with: 2x KuiperSat, Peregrine Lander
            Peregrine Lander | Astrobotic —

            Originally for May 4. Oh:
            May Vulcan Centaur • Peregrine
            Launch time: TBD
            Launch site: SLC-41, Cape Canaveral Space Force Station, Florida
            https://www.rocketlaunch.live/

            A United Launch Alliance Vulcan Centaur rocket will launch on its inaugural flight with the Peregrine commercial lunar lander for Astrobotic. The Peregrine robotic lander will carry multiple experiments, scientific instruments, and tech demo payloads for NASA and other customers. The mission will also launch two prototype satellites for Amazon’s Kuiper broadband constellation. The Vulcan Centaur rocket will fly in the VC2S configuration with two GEM-63XL solid rocket boosters, a short-length payload fairing, and two RL10 engines on the Centaur upper stage. Delayed from mid-2022 and late 2022. Delayed from 1st Quarter 2023 and May 4.
            Updated: April 24
            https://spaceflightnow.com/launch-schedule/

            So, if first is correct, delayed, if spaceflightnow
            is up to date, they still going for May 4- but if don’t hit narrow window, it has long delay.

            If successful will be test launch for upper stage
            LH2/LOX engine for New Glenn.

        3. I agree that a floating launch platform may end up being the answer, and was indeed part of the original plan. He needs to test a lot of other things first, though. And I guarantee that they learned a lot and will probably not have the same failure mode again.

          You could have an infinite number of intermediate sized rockets. Or, you could say Falcon 9 is itself the intermediate rocket between Falcon 1 and Starship. SpaceX would eventually need to do a full scale version anyway, so what’s the point of delaying by years and setting up yet another production line?

          SpaceX isn’t just making a bunch of rockets. They’re building a rocket factory. That’s a whole different animal. The basic design is probably not going to change much. All of that tooling and jigs and production workflow is eventually going to lead to automation.

          1. “””You could have an infinite number of intermediate sized rockets. Or, you could say Falcon 9 is itself the intermediate rocket between Falcon 1 and Starship. SpaceX would eventually need to do a full scale version anyway, so what’s the point of delaying by years and setting up yet another production line?”””

            It is not about an infinite series, but rather a rational learning curve. Boeing did not go from the B17 direct to the B52 with different engines, fuels, sizes, and layout.

            I don’t agree that there would be a delay of years building an intermediate vehicle as the engines and production methods would be the same in either case. It might even speed things up as testing could have been ongoing instead of stretched out as has been happening with the current size. If a 9 or so engine version was in revenue service right now, it seems likely that the larger version could be in service just as quickly as the current trajectory.

            And the need for this particular “full scale” version is not that clear to me. Rapid turnaround/high launch cadence is far more important. Also with the information gained from a simpler vehicle, the “full scale” version might be quite different. Falcon5 was skipped for good reason.

      2. That’s a good post, and the sheer size issues that you pointed at have only proven stronger with the destruction of the pad.

        I agree that the flight rate they are dreaming about simply won’t materialize. Meanwhile F9 will steadily keep throwing more tonnage in orbit than any other rocket ever has.

    2. Stralink is now cash-flow positive and has been for two quarters. Elon has the money he needs to finish.

    3. The best size for a vehicle is a function of many things, but route distance is certainly among the most determinative. The largest air and sea vehicles are used on the longest routes. The number of flights or voyages is then a function of vehicle size/capacity and market demand on said routes.

      Earthly routes have driven naval architects to design bigger and bigger ships that can carry cargoes with ton (or tonne) masses well into six figures. Future routes between paired destinations in space will dwarf those on Earth, of course, both in terms of actual distance and even of time taken to make a given traverse. If Starship is “too” anything, it is too small.

      But tankers, bulk dry cargo carriers and container ships didn’t grow from the size of Liberty and Victory ships to today’s monsters in a single leap either. Starship is a good next step. But it is hardly an ultimate vehicle and is most assuredly not “too big.”

  4. Elon talked about the size issue back when he announced the BFR/MCT. He claimed the issue is the physics of recovering the 2nd stage with its orbital velocity. A smaller 2nd stage is too dense to slow down in the upper. atmosphere, so it is exposed to more extreme heating in the lower atmosphere. The 2nd stage needs to be “fluffy”, both to slow down in the upper atmosphere and dissipate the resulting heat over a larger area, hence the ”belly flop”.
    Don’t forget that the Starship started as a scaled down ~1/2 dia version of MCT.

    1. I don’t understand the square cube law to act in that manner. I think that they had a good informative test flight. And that going gigantic to start with was a mistake. Not mutually exclusive.

      If Starship has high launch cadence within say two years, then I will have been proven wrong on some points. I doubt it will hit the launch cadence that many claim. I do believe a vehicle of more modest size with less unknowns could have been in profitable revenue service by now. And would retire many of the issues yet to be faced.

      1. What if Spacex launches 2 more Starship test launches this year?
        And second stage is recovered in some sense.

        Musk says going to launch a Starship in about 2 months and something like 3 more this year- and he tends to be optimistic.

        It seems Musk could have done the first test launch a lot more easily- say 1/2 fill the second stage and focus on landing the first stage.
        But he didn’t want the first stage as he had already made a better one.
        It seems one things he was testing was the zero stage, and if he had recovered the first stage, it would have been scrapped or like others kept in rocket garden.
        It seems when builds another launch mount it probably will be higher above the ground.
        And zero stage is most expensive thing he is making.

Comments are closed.