SPS in the Van Allens

There are some of us that don’t see the business case as stated (millions of tons per year) for the SpaceX Starship. The size of the vehicle has led to a number of problem with permitting, ground support equipment, and complexity of the largest spaceflight vehicle to date. Short version is that development is longer, riskier, and more expensive than with a smaller vehicle using similar technology. It is well oversized for the missions claimed for Starlink as simple math gives under 800 total flights for the heavyweight Starlink2 constellation. Mars colonization doesn’t seem to have a visible investment strategy other than Elon impoverishing himself along with everything he can obtain from government and investors. The known Artemis and other missions are well under the capabilities claimed for Starship. The thousands of annual flights at 100-200 tons per flight need another market. Otherwise a much smaller, simpler vehicle with less development investment and risk could do the known projects, and could have been in revenue service years ago.

Assuming that there is an unstated market for the projected capabilities of the Starship/Superheavy combo that is being kept on the down low for the moment, what could it be? Orbital tourism will very likely expand considerably over the next decades. Many of us think it possible that the ramp up will be slow enough and safety/regulatory concerns high enough to extend that market beyond the nearer term profits necessary to get an appropriate ROI.

A recent discussion brought up another possibility that may fit the hardware development scenario currently unfolding. That is Solar Power Satellites in an orbit low enough to vastly reduce the financial barriers to entry compared to SPS in GEO. The orbit also needs to be high enough to avoid most of the orbital debris and working satellites in LEO. That orbit appears to be in the lower Van Allen belts. About 80% sunlight in most of these orbits of interest. Somewhere around 3,000-4,000 kilometers up, the radiation deters most responsible satellite operators in addition to the extra distance from the surface. The orbit being higher also degrades surface imaging to some degree. A bit of extra latency for communications is also unwanted.

If an SPS can operate at those altitudes, it has a serious effect on the assumptions normally associated with the concept. The primary effect is that beaming power from a maximum of 15% of the distance to GEO reduces minimum antenna and rectenna sizes to 2.25% (15%^2=2.25%) of the area of those in GEO. Minimum size of beaming antenna 100 meters diameter and minimum rectenna being under a kilometer in diameter. Also by being in a relatively low orbit suggests that components can be carried up from Earth without first building a Lunar and orbital industry.

There are serious objections to the concept starting with the radiation environment. There were two suggestions concerning this. One was that the units take the mass hit to be radiation hardened since Starship is going to carry hundreds of tons per flight for costs lower that of the Falcon9 or any other rocket in the world. The other suggestion was that Tethers Unlimited had a viable concept for draining the radiation from the Van Allen belts. In either case, the mass lift capabilities of the Starship come into play.

Second objection was that the solar collectors and beams would be moving all over the sky with variable distances and angles to the rectennas on the ground. Electronic steering of radar and communications antennas has apparently taken care of that issue. Starlink being quoted as case in point. Various satellites would shift beams during the orbit such that they always had a receiver available. For the limited time they didn’t, and the limited times that the rectennas weren’t receiving, there is the battery tech from Tesla.

Third was the millions of tons of CO2 produced by tens of thousands of annual launches by this huge system. The counter to that is that the clean electricity delivered would more than offset the launch CO2 in the near term and almost eliminate fossil fuel pollution in the long term.

Fourth was that this was a high risk vehicle for the foreseeable future. As in Starlink, mass produced components should be inexpensive enough to risk the occasional bad day. The SPS could create the demand for launch after Starlink2 is up and running in profitable service.

My reservations about Starship haven’t gone away. This is just trying to see what reasonable justification there could be for a launcher to be built by the thousands and each vehicle launching daily with a hundred or more tons of payload. This post is speculation. It is based on skepticism about the purported markets and an expectation that there is a rational reason for going this big this fast.

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I do construction for a living and aerospace as an occasional hobby. I am an inventor and a bit of an entrepreneur. I've been self employed since the 1980s and working in concrete since the 1970s. When I grow up, I want to work with rockets and spacecraft. I did a stupid rocket trick a few decades back and decided not to try another hot fire without adult supervision. Haven't located much of that as we are all big kids when working with our passions.

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About johnhare

I do construction for a living and aerospace as an occasional hobby. I am an inventor and a bit of an entrepreneur. I've been self employed since the 1980s and working in concrete since the 1970s. When I grow up, I want to work with rockets and spacecraft. I did a stupid rocket trick a few decades back and decided not to try another hot fire without adult supervision. Haven't located much of that as we are all big kids when working with our passions.
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31 Responses to SPS in the Van Allens

  1. M. Melcon says:

    Possible fifth objection. If the SPS beam shifts from the receiving antenna to a city, is it a non-event, or an attack? I have seen estimates of power density up to 230W/m^2, about a quarter of sunlight, and 20 time human exposure standards.

  2. gbaikie says:

    “There are some of us that don’t see the business case as stated (millions of tons per year) for the SpaceX Starship.”
    Well a problem I have with millions of tons per year for me, is that enough of market to support having mass drivers on Earth.

    But in terms Musk’s plan, something like 7/8th of the millions of tons would be rocket fuel- and it seems Musk is in a hurry to have city on Mars. And I doubt one build such mass drivers very quickly- like, say, in less than 10 years.
    It seems the biggest advantage of Starship is it’s fast way to have crew exploration of Mars. Or it seems the only way to do Mars crew Mars mission within 2 decades- or the most payload NASA can land on Mars surface is 1 ton. Or they like a robotic rover which weighed 5 tons to explore Mars, but they can’t do it. And for crewed mission it seems one needs +50 tons.
    And I have no faith in making Nuclear rockets to get crew to Mars- and probably something I don’t want, even if NASA could build them, cheaply, and do it in less then 2 decades. But even if you had nuclear rockets, it still not clear to me how you land 50 tons of payload on the Mars surface.

    Now, I think a lot depends on whether the lunar polar region has mineable water.
    And in terms settlements on Mars, whether Mars has mineable water- water priced at $1 per kg {or less}.
    The other thing is if going have more than say 200 Starship launches, it seems have launch them from ocean. Which Musk has said will be, a some point necessary.
    And also by thousandth launch {or less} of Starship, the boilerplate Starship will be transformed into nothing like the current Starship.
    Obviously the Starship might be, say 4 times it’s size. But it “could” go in opposite direction, half the payload of boilerplate Starship.
    The main thing is can the existing Starship, re-entry from Earth orbit. And if can do that, can something larger or smaller re-enter from Earth orbit.
    And if Starship do something return to Earth from Moon and get to Earth orbit and/or Earth surface. If can that one has market of returning stuff to Earth from the Moon.
    And as far as market, if one re-enter from Earth orbit, then can do sub-orbital travel on Earth- and cheaper than airlines can travel.

  3. johnhare johnhare says:

    M. Melcon,
    I don’t see how you get from a quarter of sunlight to 20 times a lifetime exposure, especially for a temporary beam shift.

    Mass drivers on Earth have extreme issues that mitigate against them ever being built here. On the moon and other airless bodies it is different. This concept, if feasible, doesn’t require industrialization of the moon even to the extent of mining water. Also, it is quite difficult to take the massive Mars colonization seriously absent a compelling financial reason to go. This about a possible market that makes sense for thousand of annual heavy lift launches launches.

  4. gbaikie says:

    You don’t like space elevators, and I don’t either.

    And Spinlaunch may only work on the Moon, rather than Earth:
    What about, space guns:
    But I would tend to go with something like Hyperloop, but going vertical- and you probably prefer, I keep that to myself.
    I think tend think a space elevator like thing would work with the Moon- but it’s about bringing mass to the Moon rather using having things leave the Moon.
    But as broad matter, what meant would related what NASA doing quite few years ago, with Mag Lev as assisted launch system, but going more vertical. Though one probably would start with testing it, going less vertical.
    As far as Mars colonization {or Mars settlements} I think you need find a place on Mars where is get a lot water and at cheap cost, and that involve drilling water well, and pumping billions of tons of water per year- like they do in the Sahara desert.
    Or only way I can see of getting water to $1000 per ton {or less}.
    And you would have lakes on Mars- and in terms real estate, people would prefer to live on, in, or near the lakes.
    But in terms big things, I think living in Venus orbit and mining space rocks by bringing to Venus. But I see this as related to Mars {and the Moon}. Mars because using Venus orbit shorten the launch window, from 2.1 years to about 1 year,
    And Mars using mass drivers {or Moon using mass drivers} could ship water to orbit of Venus- and it has a lot sunlight.

  5. johnhare johnhare says:

    This post was about a rational market for the projected capabilities of Starship. The stated markets not matching the projected capabilities.

  6. gbaikie says:

    Well in terms market, the suborbital commercial and military demand could be huge.

  7. johnhare johnhare says:

    That is far out in the future. Suborbital is point to point which has serious credibility problems. Starting with permitting close enough to population centers to make it worthwhile. Booms are entertaining once in a while, but seriously annoying on a regular basis. Most especially to those not interested in the flights.

    Military should be very limited. Assuming there was a military demand for hundreds of Starship missions, that would indicate a serious failure in logistics planning as almost any conventional shipping method will be far more economical.

  8. gbaikie says:

    I would say it’s a regulation problem, rather a technical issue.
    In terms of a regulation problem it might be something in the distant future.
    It seems to me, we might already have ocean rocket launches if not for regulation issues.
    Ocean launches answers some of your issues regarding suborbital launches.

    So as timeline, one might ask when will SpaceX and/or Blue Origin and some other rocket business launch from the ocean in an efficient manner.
    It seems SpaceX might start doing this within a couple years- but regulation could delay it beyond 5 years.

  9. Ken Brown says:

    The guesses that Starship will cost less per unit mass for launches includes the assumption that one is using the entire payload capability (either mass or volume) of the vehicle. It also won’t come close if the mission means needing 6-8 refueling flights for Starship to get to its destination (a technology still not worked out).

  10. johnhare john hare says:

    There are so many claims by fans of Starship that I find fantastic that I don’t know where I should start. It’s not hard to find claims of $10.00 a pound to orbit or a Starship flying to Mars for less than $10M. This post was about a possible market as seen by the company that might justify development of such a large ship with such a high projected flight rate.

    Somehow I think refueling will turn out to be one of those “If we’d known it would work like this we would have done it decades ago” type things.

  11. gbaikie says:

    I think it’s better to think of price rather than costs. When will LOX or rocket fuel price in LEO is $1000 per kg or 1 million dollar per ton?
    And same applies to lunar surface when will price be $1000 per kg for lunar LOX at lunar surface.
    If and when the the price of LOX in LEO or lunar surface can be bought for $1000 per kg, one could expect the price will lower over time, and amount of time to drop by a significant would 5 or 10 year period.

    One also ask when will sold at some other price, like $2000 or $3000 per kg and would any buy it at $3000 per kg. If someone could sell Musk 1000 tons of rocket fuel in LEO, how much he pay? If all he has to do is show up with Starship, pay some money and he gets full tank.
    I don’t think he would pay $1000 kg but might pay $500 per kg. Others might pay more than $2000 per kg. Bezos needs less rocket fuel to complete his NASA contract, he might pay $2000 per kg. Musk could use falcon heavy to lift the rocket fuel and make money at $2000 or even $1000 per kg.
    So, if starship works better the falcon heavy, it’s not unlikely rocket fuel could be sold at $1000 per kg within 10 years. And question is how much more demand per year is it, and competing others, do you get if you sell at $500 per kg.
    Or Musk might offer it first at $500 per kg, to reduce competition and get more demand.
    It might cost him $600 per kg, but sell it at $500- because he got plan to reduce his cost to $400 per kg within a year. Or he ran Starlink at a loss, and he might be making a profit on it, now.
    And whether there is any demand for rocket fuel in LEO, could depend on whether the Moon has mineable water.
    Does Moon have mineable water? Is NASA going land humans on Moon anytime, soon and then explore Mars, any time soon?

  12. johnhare john hare says:

    I’m confused as to any relevance you see of the price of water to the possible SPS market in the Van Allens.

  13. gbaikie says:

    Price of lunar water at $1000 per kg, will cause or will occur with, lower earth launch costs. Lunar water at $1000 per mean somehow their has to enough demand for rocket fuel on the Moon.
    If NASA charges $1000 per kg, it’s not related to market, and so it doesn’t matter. A thing which in terms of NASA minning lunar water is how water are they making per year. If it’s over 1000 tons of water being mine per year, it matters in terms of market. But I doubt Congress will fund NASA enough to make that much water per year. Just as Congress would fund 100 rocket launches like SpaceX falcon per year.
    One could easily argue if NASA mined 1000 tons of lunar per year and sold it at 1 million dollars per ton this 1 billion dollar “business” in interfering with the private sector and/or is pork for anyone in the world. And pork is for congressional districts.

  14. johnhare johnhare says:

    And if launch from Earth to LEO comes down below $50 kg as some project, your whole concept is busted. Besides water having nothing to do with this subject, you have been posting about Lunar water for so many years that anyone that is going to “get it” has already got it.

  15. gbaikie says:

    My whole concept is related to what NASA should do- explore the lunar polar region to look for mineable water, but NASA should not attempt to mine lunar water, mining is what the private sector does.
    NASA should have not delayed exploring the Moon, and they should be in a big hurry to finish the lunar crew mission, and quickly start with the Mars crewed mission.
    What is need for Mars crewed mission is an understanding of how artificial gravity effects humans. NASA is late this game, also. So they should have already have done, since for decades they have saying to going to do Mars crew mission without doing a lunar crewed mission. So in addition to doing crewed lunar mission, they need to do artificial station {which they are doing, but again it should a pretty big priority to do, so they can quickly do the Mars crewed mission.
    Also I discussed Venus, which also related to Mars crew mission.
    Human settlements on Mars {private sector not NASA} will need to use Venus orbit.

  16. Jeffrey says:

    it is good to consider possible / profitable markets for Starship. we hope it will be an urgent concern soon.

  17. Jim Davis says:

    Musk himself has always been skeptical about SPS. The quote “SPS produces electricity where it is expensive and tries to sell it where it is cheap” is attributed to him.

    I think much the same objection can be raised about Mars (and other space) settlement projects. Space settlement proponents are trying to get people to move to where the cost of living is extremely expensive and the sources of income extremely limited.

  18. johnhare johnhare says:

    Good evening Jim,
    I won’t argue that this is the plan and it will work. I’m arguing that the suggested flight rate doesn’t match any market that I am aware of. This was a though about a possible market assuming all kinds of things going right. At least until tourism becomes a thing, and I don’t see that coming for several years.

  19. gbaikie says:

    “Musk himself has always been skeptical about SPS. The quote “SPS produces electricity where it is expensive and tries to sell it where it is cheap” is attributed to him.”
    His Starlink satellite are making most amount solar power in space, and at the lowest cost.
    SPS advocates have said launch to LEO has to reach $100 per kg to LEO, before one can do SPS. And I would say that’s in ballpark where, in some way, it “might” be done.
    Musk also says solar panels on Earth work {but doesn’t mention the cost}.
    I wonder what Musk thinks about SPS for Mars surface.
    Problem with solar panels on Earth is you only get about 6 hours of 24 hours of usable sunlight. With Mars surface you get 12 hours of the 24 hours. And with terrain advantage
    you can get more than 12 hours usable sunlight, on average. Plus Mars is smaller, and it’s shorter distance between time zones.
    The polar regions on Earth, suck for solar energy, but they the best places on Moon and Mars- because low angle sunlight has about same power as sunlight at zenith {which at when at zenith on Earth at sea level is about 1050 watts per square meter plus 70 watts of indirect sunlight- totaling 1120 watts per square meter of direct and indirect sunlight}.
    Anyhow on Earth you have peak solar hours and on Moon and Mars all sunlight is “peak solar hours”. And in polar region on Moon one has much shorter distant to next time zone and topography is everything. Mars similar but less extreme.

  20. Paul D. says:

    One possible justification is a part of a space arms race.

    Suppose China develops a similar launcher. Then, arguably there could be a race for placement of weapons in orbit. The side that launches the most mass would be at an advantage. This race could lead to arbitrarily large amounts of mass placed in high orbit. No external justification would be needed, any more than in previous arms races (battleships, ICBMs).

  21. DougSpace says:

    Curious. You don’t see the “business case” for Starship and yet you haven’t stated Elon’s business case. He has stated it from the beginning (Guadalajara) and all along. The business case is as follows:
    – Starship development from investors, NASA HLS, and SpaceX revenue.
    – Revenue from Artemis missions
    – Revenue from Starlink ($20-30B/yr) for Mars infrastructure development.
    – Revenue from military Starlink.
    – The intersection of those who want to go and those who can afford to go. e.g. there are 60,000,000 millionaires in the world. It doesn’t take but a small percent of those to fill the 1,000 Starships each launch window to 2050. DevelopSpace.info/venn
    – Full and rapid reusability to reduce the cost and expand the number (of countries and individuals) who can afford to go.
    – Then there’s point-to-point but I’m skeptical about that one.

    Elon specifically does not include SPS in the business plan and neither do I. I find the above list of revenue sources sufficient.

  22. DougSpace says:

    Oh, and a large lunar base as well,

  23. Jim Davis says:

    “ there are 60,000,000 millionaires in the world. It doesn’t take but a small percent of those to fill the 1,000 Starships each launch window to 2050.”

    Doug, this is a really poor argument. You cannot assume that millionaires, or even a small percentage of them, are going to spend their money in ways that you arbitrarily desire. You might as well claim that if only one in a thousand millionaires gives you a $100 you’ll have $6 million. The math works but the business case is absurd.

    But Merry Christmas to all.

  24. gbaikie says:

    “Doug, this is a really poor argument. You cannot assume that millionaires, or even a small percentage of them, are going to spend their money in ways that you arbitrarily desire. ”
    Well 60 million and increasing and getting older. A millionaire could give some 16 year old, enough money to go to Mars.
    What important is whether living on Mars, makes any sense.
    Is Mars actually a habitable planet. And/or is Mars an interesting enough planet to explore- so go to Mars to explore Mars, more. Or staying for few years, rather having family, a raising children and making a Mars civilization- rather than an outpost.
    So to be habitable, and the Moon is not habitable in comparison.
    The Moon is not habitable because, it doesn’t have enough water, and it’s 1/6th gravity
    may not allow it. And Mars 1/3rd gravity may also be a problem. Perhaps Moon could be made habitable, ie, it could import billions tons of water per year at low cost. And import food at low cost. And maybe 1/6th gravity is not a biological problem.
    But assumption is that Mars could be the most habitable place other than Earth- it has lots of water, it has enough CO2 to grow plants, and has enough Nitrogen.
    Mars crew exploration, will probably mine Mars sky, and Mars settlements will have to mine the Mars sky in order to grow food- the Mars sky is major part of why Mars is regarded as most habitable. And one could even get billions of tons of water from Mars sky, but it’s 210 ppm, and pretty expensive way to get enough water.
    Anyhow, Mars has to be explored to determine whether Mars is actually the most habitable place, other than Earth {or orbits of Earth and elsewhere}. And one aspect is how cheap can Mars water, cost. Or can mine millions of tons of water per year, at a low cost [and within decade or two, billions of tons of water per year].

  25. Ken Brown says:


    It’s not just the SpaceX fans that are quoting absurd prices/costs, it’s Gwynne and Elon as well. I can’t see how even their most conservative quotes are possible since the development costs of Starship seem to be accelerating with little to show for it, so by the time the system can launch commercial payloads, the company might be in the hole another several billion dollars they’ll need to recoup. That’s a problem with many large projects. The recurring/operational costs could be reasonable, but the costs to get to that point might make it unfeasible to pursue.


    I agree that NASA and/or other national space programs are the best suited for taking the lead on the science of Luna, but private entities should be the ones to do any development projects. I’d like to see NASA get a small lunar base established to do science leading to commercial investment to expand it to the point where NASA and other national programs wind up leasing space instead of the ones being responsible for the infrastructure outside of standards and design approvals/consulting. I’d like to see this happen before any serious money is spent on a crewed mission to Mars. While the moon is airless, Mars isn’t that far behind and getting a bunch of experience working with abrasive fines and the sorts of issues that will crop up is better than sacrificing a crew due to an unrealized assumptions.


    Elon is well known for overestimating revenue/timelines and grossly underestimating dev costs and times. I haven’t seen any real top level projections that put Starlink at anywhere near a $30BN/year revenue. Some don’t project any profit at all other than what could be brought in by selling it piecemeal to a whole bunch of people that can’t do math (IP). The military already operate their own satellites and aren’t going to use an insecure third party for anything sensitive. At the most, they might contract with Starlink so soldiers can communicate with friends and family when deployed, but there’s still the question of opsec on a system such as that. The revenue from HLS is already completely eaten by development costs. Space tourism fascinates plenty of people, but those that can afford it are often limited by age/health and it’s always going to be a big risk. I can’t even imagine having a spare $30mn to spend on a vacation, but I have a long list of all sorts of other things I could spend that much money on that would take years and years to use up.

  26. gbaikie says:


    I agree that NASA and/or other national space programs are the best suited for taking the lead on the science of Luna, but private entities should be the ones to do any development projects. I’d like to see NASA get a small lunar base established to do science leading to commercial investment to expand it to the point where NASA and other national programs wind up leasing space instead of the ones being responsible for the infrastructure outside of standards and design approvals/consulting.—

    My problem with this, is NASA is ordered to explore the Moon and then explore Mars.
    And at this point, I am not sure development of the Moon is a good idea.
    I don’t think “forcing” development is good idea, though blocking it, is a lot dumber.
    I view exploring the Moon by NASA has limited goals, and also think NASA has limited goals in regard to exploring Mars, that limited role is, the question, is Mars a habitable planet. With the Moon, it’s, does lunar polar region have mineable water.
    And part of whether Mars is habitable or not, is where does Mars have the most mineable water. Or simply, mineable water. Mineable water on Mars I would peg at water which can sold at $1000 per ton or 1 billion dollar for a million tons of Mars water. Mars requires a lot more mineable water than the Moon, and lunar water starting price is somewhere around, $500,000 per ton. And unlike Mars, the Moon doesn’t need as much water. Or just 1 million tons of lunar water, might be mineable. And Mars “needs” billions of tons of mineable water to be a habitable planet. Also if NASA find alien life on Mars, that in near term, puts the brakes on the question of whether Mars is habitable for humans.
    Say, NASA finds alien life on Mars, it then it should perhaps, turn around and focus on making lunar base as step to enable less of threat alien life on Mars to life on planet Earth.
    So explore moon, determine how well the orbital data fits what is found on the lunar surface, then quickly push towards exploring Mars {getting bases on Mars} if
    if life, and there is some threat of this life. Pack up your bases, and delay Mars exploration until this risk can assess. And having lunar base could be part of this assessment process {or you still exploring Mars, but have detour to do first} though assumes there mineable water on the Moon OR launch cost from Earth have fallen so low, that mineable lunar water is not required to have bases on the Moon.
    Of course if US congress will hand over lots cash, then US congress can get lunar bases and Mars exploration occurring at same time.
    But NASA plan, should sending less than about dozen lunar crewed landing, and then, explore Mars. And if Congress throws money them for lunar bases, of course, then, do it.

  27. Jeff Wright says:

    SPS in the Van Allens needs to have a working fluid and sterling engines—rad proof mostly I would think…

  28. DougSpace says:

    @KenBrown – “I haven’t seen any real top level projections that put Starlink at anywhere near a $30BN/year revenue”.

    “Starlink could eventually reach revenues of $30 billion a year”.


    In January 2017, SpaceX expected annual revenue from Starlink to reach $12 billion by 2022[11] and exceed $30 billion by 2025.[12] Revenues from Starlink in 2022 were reportedly $1.4 billion accompanied by a net loss, with a small profit being reported by Musk starting in 2023.

    11. Bajwa, Arsheeya (13 September 2023). “SpaceX’s Starlink falls short of growth expectations despite revenue surge – WSJ”. Reuters. Archived from the original on 7 November 2023. Retrieved 19 November 2023.
    12. Winkler, Rolfe; Pasztor, Andy (13 January 2017). “Exclusive Peek at SpaceX Data Shows Loss in 2015, Heavy Expectations for Nascent Internet Service”. The Wall Street Journal. Archived from the original on 17 November 2020. Retrieved 9 February 2018.

  29. DougSpace says:


    SpaceX is building a Starship Factory. The US government is going to find itself facing an interesting situation. Come up with a plan to take full advantage of the Starship Fleet or stand by while others take the lead. If there’s one thing that drives space leaders in Congress and the Administration, it’s to ensure that the US government stays in the lead in space. The Starship fleet doesn’t want to build a small government base, it wants to build a large and growing International Lunar Base. And that base will serve as the forcing function to quickly develop the surface technologies needed. And those technologies are exactly what private settlement needs. As flight rates go up, the per-seat price will go down thereby making private settlement more feasible.

  30. gbaikie says:

    Why stop at Starship?
    Build larger rockets.
    Government should provide a region in which larger rockets can be built and tested.

    Musk wants to launch a lot Starships per week. And he has mentioned he needs to launch them from the ocean.
    And it’s hard to imagine us being a spacefaring civilization without launching a lot stuff from Earth’s ocean.
    It seems US government should have some plans of how this is going to happen.
    Or governments makes laws and can have regulations which will enable such things happening, sooner, rather doing nothing and then trying to catch up to whatever other governments in world might do.
    Of course if other other governments don’t do this, it’s not a good excuse, not to do this.

  31. gbaikie says:

    In regards to Starship and governments, one thing could be exploring the atmosphere of Venus- have crewed mission to Venus.
    I think the orbit of Venus is quite important, in term humans becoming spacefaring civilization. And tend to regard going to planet of Venus as not very important, but it appears to me, due to governments not testing artificial gravity, it leaves Venus as only place in space {other than Earth} with natural gravity similar to Earth. So with Venus crew exploration, crew spend some time in microgravity of Venus orbit, and most of their time in natural gravity of Venus.
    And it’s seems the problem with going to planet Venus is similar exploring planet like Earth, or it hard to leave Earth and hard to leave Venus. So a focus of crewed mission to Venus is making enough rocket fuel to leave Venus, but it’s not that much of problem if crew have to stay in the Venus atmosphere for many years- though one would have to keep them resupplied. Starship resupplies Venus orbit, and from Venus orbit one would send balloon type vehicles get stuff to Venus atmosphere.
    If made enough rocket fuel in Venus atmosphere, you could have a Starship go Venus atmosphere from low orbit, refuel, and leave. But before that, crew could use smaller rockets to leave Venus and to transfer to Starship in the Venus orbit, and then return to Earth.
    Or in beginning not considering Starships {though could be variants} getting crew from Venus atmosphere back to Venus orbit. And have consider what kind of rocket could do this. Perhaps you would want to use mothership which boosts a crewed rocket.
    And Mothership could use CO and O2 for rocket fuel.
    So, very roughly speaking you could have something like Virgin Galactic Mothership and it’s rocket to carry crew to orbit. And you could just sub-orbital and catch crew rocket in low Venus orbit. Or crew rocket gets to orbit, and docks with a space vehicle.
    Let’s say could have something exactly like Virgin Galactic Mothership. It burns kerosene and air intake is enriched with oxygen. Exactly like it, other you have carry the oxygen {added mass} and kerosene, then how high {and fast] could it fly?
    Venus has slightly lower gravity and you are starting at 50 km elevation {and slighter lower for being at 50 km] On Earth flies to 50,000 feet [15 km]. So on Venus can fly to 65 km? Could mothership be launched at 60 km, and just mostly gain some speed?
    So, fall, add speed and rise higher than fell, and one going faster when launch the rocket.
    Wiki, Venus: 60 km: −10 C 0.235 7 atm
    0.2357 times 14.7 = 3.46 psi
    On Earth at 50,000 feet: 1.61 psi and air density: 0.113 kg/cubic meter
    Obviously things float better at 50 km in Venus: 50 km: 75 C 1.066 atm
    Due to higher density of CO2 atmosphere. But for living you want to live higher.
    So might store massive stuff at lower elevation where get more lift, live higher up, and launch higher than you live at.
    In terms near term missions, you send crew, and have way of getting them back, and each exploratory mission, or adding infrastructure, and getting to point where one can make a lot rocket fuel in the Venus atmosphere. But first going and getting crew back to Earth.

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