mal comments on a post from last year:
Well, there’s nothing wrong with current Russian commercial space program such – they are launching OneWeb satellites now and there’s a Korean one thats supposed to go on Angara. SpaceX does have more launches but thats because they launch their own Starlink constellation and Russian Sphere is not there yet (Russia needs to invest more in Space Simulation chamber for payload testing and development, they are building 2500 m3 one which is better than current 1800 m3 or even European 2400 m3, but no match for destroyed USSR one at 8,000 m3 or American at 20,000 m3).
On market pricing, Russians still dominate. Proton market price is $65M/22 tons to LEO, or $2,950/kg. Reusable Falcon price is $50M/15 tons (due to fuel return requirements), or $3,330/kg. Russians are cheaper and more efficient due to more stages on Proton vs Falcon.
For space tourism, Soyuz is more reliable, has a kitchen and a toilet, and ticket price of probably $30M/seat ($80M NASA price). Russians were charging $20M per seat a decade or so ago, even with inflation and upgrades i don’t see Soyuz pricier than $30M. It is also good at orbital mechanics so its fast to ISS. Current NASA contract pays $100M/seat to SpaceX ($2.4 billion/6 launches/4 seats each). I’m sure it will be cheaper in the future, but I don’t see them beating Soyuz prices for a decade.
In the near future though, this is going to change. Starship is huge and will dominate cost per kg. At that scale, opportunity cost of return fuel will be minimized and reusability will finally make economic sense. With refueling capabilities, Starship will dominate local space, and Russia doesn’t really have anything comparable. The good news is Starship is a fairly simple construction (a flying steel grain silo) so Russia should be able to just copy it. No shame in that.
So to answer your question. Aside from marketing hype and propaganda, current Russian commercial space offerings are highly competitive with US. In the near future, when Starship will be able to deploy any satellite on any orbit in local space and keep deploying them by the 100’s and 1,000’s, Russia will not be competitive anymore. Starship is a game changer. In the far out worlds, asteroid belts etc., chemical gas burners such as Starship will hit the limits of physics and Russian nuclear electric plasma accelerators will dominate the deep space.
I like to say, this is the biggest irony on Earth. Elon Musk, electric car guy, invented the best gas burner. Russia, known as planetary gas station, invented the best electric space propulsion system.
He talked of more recent progress here.
At an international expo ‘Archimedes’ in Moscow Keldysh Center (Russian research institute) demonstrated experimental device for radiation of waste heat into space. Device is dedicated to thermal regulation of spacecraft. I’m not sure if it’s a panel or fiber based one, or maybe even a droplet (panel is worst, fiber is OK, droplet is the future).
And speaking of the devil, it looks like Russians solved the droplet dispersion problem back in 2017. This guy solved it, to be exact.
Topic starts at around 6:20. To recap for non Russian speakers. Any moron can build a nuclear reactor and launch it into space, its easy to do. So why then the largest single power unit in space is about 20 kW? Because while producing electricity in space is easy, dissipating waste heat is not. Space is like a giant thermos that insulates well. The only way to get rid of heat is through radiation. Conventional way is radiator panels, but it’s extremely inefficient as their size requirement grows two orders of magnitude faster with power level increase. Past few hundred kW, those panels will weigh more than all the rest of the spacecraft put together.
To improve heat radiation efficiency, we must move from 2D panel to 3D geometry. Hence the droplets, as small droplets maximize surface area to volume (mass) ratio. This will allow for orders of magnitude lighter cooling systems and therefore high power output (nuclear reactors are very light compared to the weight of the cooling system they require). The droplets are made as you pass diffusion pump oil through an atomizer basically.
However, there is a problem. Small droplets accumulate static charge by picking up free electrons from space. This causes them to repel from each other and that makes collecting them back after they cooled off very difficult, and this results in coolant mass loss. That was the problem with Kaplya-2 experiment on the International Space Station back in 2014. There were a number of proposals put forward (external electromagnetic fields, plasma feed to neutralize the droplets etc) but they are all cumbersome, unreliable, or require expendable materials which makes them unsuitable for years long operation.
A simple, robust, and permanent solution to the problem is to illuminate the droplets with UV light at around 140 nm wavelength. This will trigger photoelectric effect that will kick off the excess electrons from the droplet. Unlike external electric field, there is no danger of over-ionizing the droplets and stripping too many electrons which will cause the same repulsion problem. No complex control is needed. All it takes is about a dozen UV lamps and those will condition the droplets for easy collection and minimize coolant losses.
The rejoinder is that local space is commercially attractive (Starlink is the obvious one… perhaps passenger and cargo transport, if the more optimistic projections pan out).
The tons of money made from this can be recycled into more ambitious projects.
Can the same be said of deep space? Asteroid belt mining has been often speculated about. But most resources are very cheap – and have been becoming much cheaper relative to the size of the world economy.
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America can say “Russia and China are “militarizing” the space” (exactly what America is also trying to do) and then block even civilian and public exploitation of space resources from them. Or just default to the route of denying strategic resources up there for the tried excuses of “autocracies can’t manage anything and will threaten everyone else”. And even that failing, put some obstacles on their way.
The SpaceX mission Inspiration4 has a black lady “pilot.”
I thought they were spam in a can, but I’d be worried about her somehow turnimg the autopilot off in moment of pure sass.
Proton rocket as cool looking as it is uses highly toxic hypergolic fuel.Kazaks are unlikely to allow it to launch from Baikanour for much longer since the toxic first stage lands back on their territory.
In the near future (2-3 years) it will be Angara vs Starship the result of which aren’t looking too good for Russia in the commercial space launch market.
Perfect description. I think Russia should work for constructing another Angara launch-pad in Baikonur after completing the one placed in Vostochny. This would allow to increase the mass delivered by the Angara-5 to LEO from 24 tn to 25+ tn. AFAIK current Kazakh-Russian collaboration is restricted to use the Zenit pad to launch the perspective Fenix rocket (which is basically a Zenit without Ukrainian components and a slightly enlarged payload).
Proton-M is a cool looking 1960s style rocket, but it is too contaminant for current standards.
What about Amur? Isn’t it a gas burner? Or is it too little, too late to actually get built?
SpaceX have the Raptor working well now, I doubt its finished, they will be tweaking it for a while yet, but at this point Musk will already be think about the next big engine project, this might be some form of Nuclear propulsion, building a Methane powered engine was Robert Zubrins idea. Zubrin has another idea for a Nuclear Salt Water Rocket
Would be the obvious next step for SpaceX
Currently, i don’t see commercial projects in deep space being viable. BUT – it won’t always be this way.
First, i want those Zeuses/Nuklons going to the Jupiter moons and such. Russian nukes will melt the ice and drill deep down. With half a megawatt of electricity on tap the amount of science can be done is massive. It can revolutionize our knowledge of the Solar System.
Second, I’m not saying aliens, but… lol. Things like Oumuamua demonstrated that we can’t see a damn thing in space. We seriously need to consider planetary defense against various suspicious flying rocks. Even if they don’t hit Earth directly, we need to know they are coming and sample them whenever possible. Science gains are huge, and it may even save the planet. And again, those half MW units can power some insane observation capabilities.
Third, as weird as it sounds, but future of space is in biotech. There are some very interesting things happening tissue engineering and 3D printing cells already. Russians are planning to send their new space station to less protected polar orbit to study radiation resistance of living critters. I think its a correct move and we will be pleasantly surprised. Also, on Earth there are various ignorant calls to ban important biotech research. Automated deep space orbital science stations can be used to successfully run away from Earth based “bioethicists”. That research will be worth $trillions.
And finally, while resources are cheap now, this may change. As world GDP grows, Africans etc will richer. Once they get rich, they will start banning resource extraction on their lands. Nobody wants to live next to a cobalt mine. Environmental movements will flourish and extraction industries will get banned on Earth.
Jeff Bezos is correct – heavy industry will be forced off planet by the environmental movement. Asteroid mining will become viable then.
Amur is a nice little rocket, Soyuz replacement i believe, it will be used for some specialized orbits but it’s no heavy lift.
Russia is trying to avoid heavy lift route due to costs, it seems like. Angara 5V will do 37 tons which may or may not be sufficient. Keep in mind that ultimately, with nuclear tug, it becomes 37 tons to almost anywhere in the solar system direct which is insane.
Imagine a three stage orbital assembly – 37 tons for nuclear tug, 37 tons fuel, 37 tons payload.
With those 7,000 second ISP ion engines, your delta v budget will be like 28 km/s. By contrast, Starship, even fully fueled will be gimped by those 380 seconds ISP Raptors. 1320 tons full, 120 tons hull mass, and 100 ton payload only gives you 7 km/s delta v. You will be waiting forever for gravity assist launch window.
28 km/s is a lot better than 7 km/s. Even if Russian ISP will be lower than 7,000, say 4,000, you are still looking at 16 km/s. Plasma accelerators are the future. Starship Raptors are nice engines but they are outclassed.
Another curious thing about Starship. I see a lot of development of the freighter, but not a lot about payload. Maybe I missed something, but i haven’t heard anyone saying “Yay! We made a 100 ton Mars Bulldozer! Let’s test it!”.
There is no satellite or other space vehicle currently in development that can fill a Starship. Those vehicles take many years to develop and build, and yet no announcements have been made. They are rather expensive too.
So there is only one agency right now with money and secret payload development capability – Pentagon. So likely of Starship being a military bomber/killer robot delivery vehicle is high.
This only confirms what some have been saying: that SpaceX goal is not Mars, but fast military deployment within Earth. These monsters would fly a suborbital path and land anywhere in the world within minutes, to continue spreading democracy, diversity and human rights.
Starship seems to me as a retro-futuristic and Flash Gordon comic-style thing. I doubt about the ability of this strange “thing” to reach the space.
Agreed except this.
Historically, resources are #downonly. (Oil price / S&P 500).
https://i.imgur.com/Ix9EhBF.png
Some of the people who worked on the James Webb telescope are already thinking of something bigger, since they work for NASA, they will say the next big telescope will use the SLS, but like the Europa Clipper my guess is that they will use Starship. SLS delenda est
Anyone wanting to send probes to the outer Planets will want to use Starship
Most people with a serious interest in Space now assume that Starship will work, even Besos has come to that conclusion and is now working on his own smaller version called Jarvis, Besos won’t show us any concept art, apparently he’s worried competitors will steal his ideas, LOL
SLS delenda est
Na, the goal has always been Mars, but they have to make money to get there
I forget the wealth of information that can be mined in the open thread. I gotta manage my time better………
Maybe. We’ll see i guess.
Then where’s the hype over 100 ton Mars bulldozer or whatever? Where’s Martian payload development?
I mean, NASA has Perseverance rover on Mars. Its an amazing human achievement. It cost a ton of money, and mission was known years in advance, and launch windows established, and you could track them building and testing it.
And what’s that thing weigh? 2 tons? Now can you imagine 100 ton payload? It would be monumental human achievement. So where is the hype? Where is the mission development?
I don’t see it. I do see an obvious interest from US military though, and i know for a fact they have ready payload – Rods from God orbital bombs, and probably killer robots/drones too. So i make a rational conclusion that Starship is a military orbital freighter/bomber.
I’m sure it will work. Starship is a combination of Soviet N1 rocket with Soviet RD-270 full flow staged combustion engine, with vastly improved electronics and controls, and optimized for methane.
Its actually a very good, robust design. Kinda surprised Russians didn’t go for it first.
But i wouldn’t put all my eggs in one basket. SLS is a very powerful rocket with a very good upper stage (those RL-10’s are pretty awesome). And its already almost done. So i would keep some missions for it, just in case.
Most of the people that i talked to in the oil business were on the peak oil side. Exploration and extraction are getting costlier , and newly discovered proven reserves are shrinking every year. There’s always shale to maintain current production levels but most shale firms have never turned in a profit until now.
I realized I was wrong about peak oil when the US, a country with relatively scarce oil reserves (relative to ME and Russia, say), which had furthermore been exploiting those reserves most intensely and for the longest time, started to massively expand production in a near vertical upwards line, breaking all the nice “Hubbert’s Peak” projections, and eventually recovering its 1970 era peak and going well beyond that.
If you can do that in the US, then you can repeat it Russia, China, Middle East, etc. and at a much greater scale (if it becomes economic to do so).
Many people seem very excited about the potential of the Advanced Cryogenic Evolved Stage of the Vulcan to use Moon fuel and refill that way. But I really don’t know enough about it to say whether it hype or not.
From my perspective, the main potentiality of the moon is as a weapons base and all this other stuff is mainly about getting lesbo black women to the moon.
IMO, the energy requirements of mass lift could easily be put into advanced smokestacks and other pollution mitigation devices.
Whether space industry makes sense or not will have nothing to do with pollution and everything to do with whether space mining makes sense.
Many have criticized Bezos as his concept art looks more like Elysium (a place for the wealthy to escape the poor on Earth) than space factories.
It’s not so much the economics that I’m concerned about, but rather various permitting limitations for resource extraction and heavy industry.
Things can make economic sense, but if Scary Child Greta says you can’t build a mine, then you can’t build a mine.
I’m not concerned about Peak Oil, or peak cobalt, or peak copper or whatever. There is almost infinite amount stuff out there, but if suburban housewives build a school over it, you ain’t getting it. As world grows richer, number of suburban housewives will increase in places like China, Africa, etc. Places where we usually mine things and process things. And to be fair, the housewives do have a point. Then again, maybe pollution abatement technology will advance fast enough for us to co-exist peacefully.
From my personal experience in US chemical industry, we did have a boom, but please look where – South where permits are easier to get, so fracking could get developed. So we got polyethylene production boom basically, thanks to cheap petrochemical feedstock and energy. But there is more to industrial civilization than polyethylene, as important as it is. And even with fracking and polyethylene, New York Times was complaining about it non stop. So I don’t know if fracking boom can be replicated in the US as easy going pro-business Southern attitudes are replaced by more complaining from NYT elite opinion makers.
If New York Times thinking spreads to China and Africa, we may run into problems on Earth.
The problem with the SLS is the cost, why does it all cost so much, its a joke, its using engines developed in the 70s, only the solid boosters are upgraded, they have spent 20 billion so far, SpaceX have spent less on Starship. Starship beats SLS on every metric, and it looks like Starship will reach orbit first
SLS delenda est
Hydrogen tech costs more than methane tech. But it also delivers more (hydrogen is the best chemical fuel reasonably possible), so for national security and technical development reasons, I would recommend keeping SLS around.
Yes, RL-10’s are from 1970’s. And they are expensive. But they push up to 470 seconds ISP. While Musks’s Raptors are good, they only go to 380 seconds.
You really don’t want to lose the technology and know how for much higher performance engines. Some day there will be a mission for US that will require those extra 90 seconds, and it will be good to have that on tap.
The one thing that bugged me about this is Russians used heavy oil as their transfer medium. I personally ran a diffusion pump for like 3 years, as in, operated, took it apart, cleaned it, and I used phenyl silicone diffusion pump oil.
Phenyl silicone has higher refractive index (its shinier) relative to heavy oil, so if you want to maximize your quantum yield (how much heat you convert into light), you probably want to have shinier stuff.
Ironically, I used that same pump oil as refractive index tuner for data storage technology materials I was cooking at the same time.
Anyway, I understand why Russians use diffusion pump oil for this technology. I know how those pumps work, and yes, cooling something like a nuclear reactor in space is a perfect application of the technology.
But if Putler reads this blog, phenyl is the answer for quantum yield optimization in the organic liquids world. If you can handle solids, titanium is the answer, but this may not be feasible in space. But heavy oil is meh.
Over the course of a years-long mission, won’t most of the coolant be lost?
TL;DR – some criticism of starship + lots of discussion of nuclear propulsion that hasn’t feature systematically anywhere else to my knowledge
Starship is truly a game changer for low-Earth orbit operations (putting crude but cheap stuff into orbit to built large space stations, transport 100s of people, deploy 100s of satellites at the same time, etc.), but if you think about it, it’s rather extravagant as a transport vehicle for deep space.
Lunar flight will require anywhere between 4 and 16 refuelings per flight to delivery 50-100 tons of payload to Moon’s surface. The refueling operation will take between 8 and 32 weeks. During this time the ship in orbit will have to maintain its cryogenic methane storage for months, which is very difficult even on Earth . Flights to Mars and beyond will require similar amounts of fuel or more. That is, to make a 6 month journey to Mars you would have to park your spaceship in Earth orbit for 6 months to refuel. One round trip will take ~3 years total, not taking into account the “small problem” of producing fuel on Mars and 16 refuelings on low Mars orbit. Assuming 10 year realistic life span. Each “Starship” will be able to make 3 round trips to Mars max. Assuming 100 passengers per trip and a price tag of $500 million (very generous, in the long run assuming mass production $1 billion is more like it), you have 300 round trip passengers per starship, or $1.5-3 million per passenger, not even taking into account all other costs. In aviation the cost of the airframe itself is probably only 1/10 (maybe a bit more, I don’t remember) of the final flight ticket cost. That is, we easily get into >$50 million per passenger territory.
Flying to other planets on a “Starship” become downright silly. Going to outer planets is actually easier than going to Mars, since good departure windows occur nearly once a year, but the distances are so great that chemical rockets would take many years to get where they need. The difficulty with parking around Jupiter or Saturn is that you need extra fuel for maneuvers around different satellites, landing, etc, which “Starship” will never have – all methane will evaporate over 5-7 year journeys. The only feasible way for it to break upon arrival is by flying through planetary atmospheres to enter capture orbit.
Nuclear rockets though are total game changers in many domains, though maybe not in commercial space for now. Nuclear power in low earth orbit is extremely useful on low orbits for military applications. The current Russian plan is to have a 200 kW – 1MW radar system (or several of them) to radiate the entire planet, something ground based radar systems can’t do effectively (over-the-horizon ground radars can scan much of the planet but are limited to shortwave radio frequency, which makes it ineffective for precise targeting). Such radars make stealth aircraft pretty much useless + allow for advance targeting of incoming aircraft and missiles. In the future multi-MW space nuclear reactors will be able to fire short laser pulses over vast distances that pack as much energy as artillery shells, with no dissipation. Such laser canons are being developed by Russian scientists for military purposes and for laser-ablative nuclear propulsion (using the nuclear reactors to power lasers that would burn a polymer fuel pellet, thereby multiplying thrust by a factor of 5-10 relative to electric plasma propulsion. More Russian plans using radars – using sounding radars. Most powerful space sounding radars to date are in tens of Watts range, they are able to crudely probe surfaces of planets to depths of hundreds of meters. Nuclear power 500kW class sounding radar will be able to map the crust of the Moon, solar system planets and planetary moons more precisely to depths of many kilometers – unprecedented leap in geology. More will be learned about planetary sciences using these radars than in the past 1000 years.
Deep space flights only make sense using nuclear electric propulsion. American plans for nuclear thermal propulsion (heating hydrogen using nuclear rods or solar collectors) only make sense for Earth-Moon travel (2-4 week roundtrip max vs 5-7 months for nuclear electric), going anywhere beyond that only makes sense using nuclear electric. The “Zeus” spacecraft will be a 500 kWe nuclear rocket that will take 5 years to go from Earth to Moon to Venus to Jupiter to Callisto/Ganymede. I’ve heard in a presentation by Keldysh Center senior engineer that the plan is to develop 100 MWe nuclear rocket by 2050. It will have delta-V of ~200 km/s and enough thrust to go to Mars in 39 days, to Jupiter in 6 months, and to outer solar system in 2-3 years with a cargo of ~100 tons (comparable to Starship). That’s 10 round trips to Jupiter, 5 to Uranus and 3 to Neptune in 10 years. Mars will still be hard because of inconvenient launch windows, but better than Starship. The cost of construction will be modest. 100 MWe nuclear powerplants are routinely used in ocean vessels (though different designs). Liquid droplet radiators are 10-20x lighter than metal ones , so the mass of 100 MW rocket will be ~400-500 tons including 100 ton payload (lighter than fueled Starship, can be built in Earth orbit using 4-5 Starship launches). It has enough fuel for a round trip (unlike Starship) and can perform maneuvers in planetary systems to hop from one moon to the next. The projected cost of 500 kWe “Zeus” is 5 billion rubles, or ~$200 mil. PPP. Cost is not gonna rise linearly – probably as a square root, i.e. 100 mW will cost about as much as a nuclear ice breaker or an aircraft carrier, especially if large “gas torch” rockets are available and deployment is cheap + mass production will make all the difference. The price is, however, high enough that deep space mission will remain great power domain.
The limit of nuclear power in space is likely ~100 MWe, maybe you can push to 1GWe, but even droplet radiators increase such that the 1GW ship becomes so massive that there are no efficiency gains from increased electric power. The distant future of electric propulsion in space is still Fusion power. Fusion in space can theoretically be designed such that only 5% or less of fusion energy converts to thermal heating that needs to be removed using radiators. This allows scaling to many GWs or even TeraWatts in the future, allowing 1-2 week flight times to Jupiter and Brachistochrone trajectories (shortest time trajectory vs. currently used smallest fuel burn). Nothing is in the works in Russia r.n., but I know that this is a pet project of irrc chief plasma physicist in Kurchatov institute + Novosibirsk Academy of Science Physics institute converted their experimental magnetic mirror rig in a highly efficient plasma rocket engine. Who knows, maybe they will learn how to turn it into a fusion rocket.
Right now two institutes are working on nuclear rocket design in Russia – KB Arsenal and Keldysh Center. Literally the entire country is designing or testing parts for this device, almost 100% of the spacecraft is new. There has been a lot of lab work in the US on some components of nuclear rockets (VASIMR engine, radiators, less on reactors), but only this year the defense department realized the potential of nuclear reactors in space, so I’d say the US is currently 15-20 years behind, at best 10 years behind, at worst 30 (no major experience operating nuclear reactors in space, overall degradation of nuclear competence). China is more active. By my estimation based on papers that I’ve read at least 3 teams are working on each nuclear tug component (reactor, engine, radiators). The Chinese design is basically the same as the Russian design, though funnily their work is more transparent than Russian, they publish their research in major journals in English, Russian breakthrough work has no citations and is located in backwater Russia-language journals, often affiliated with parent Institutes. Very little published work since 2012, a lot of it is top secret.
I agree.
Private space companies can produce a hell of a result with chemical rockets (still to be seen with Blue Origin), but there are limits to what chemical rockets can do. And they can’t clear the regulatory hurdles for nuclear.
Our future as a species settling and colonizing space is dependent upon the free-energy powered FTL-starships, which means either highly efficient nuclear power or some great innovation that is either to be done or to be made public.
Russia is touching upon this and that is good. Fuel in space is a deadend and always was, for we must surpass our nearest islands for the great Ocean.
I think there is space for private companies in advanced Earth-Moon transportation. There is a startup that uses solar light collectors to heat-up hydrogen to achieve 3x the specific impulse of SpaceX Starship, combined with relatively high thrust. Such systems are really simple to make (few moving parts), cheap, and the result is similar or better than nuclear electric propulsion by almost every metric. A good candidate for Earth-Moon transportation is solar electric. Solar panels are cheap and can be made light, such that the performance is similar to nuclear electric for a fraction of a cost. Either way non-chemical propulsion will be slow, but you can imagine caravans of cheap solar-powered cargo vehicles transporting stuff to the moon. The main advantage of nuclear in Moon research is providing stable power for scientific payloads, such as radar.
It was generally believed that FTL requires exotic physics, such as negative energy – until 2020. Last year several papers in actual Physics journals came out about theoretical warp drives. The idea is to put the spaceship into a soliton – standing space-time wave/warp bubble. One paper shows a configuration of a positive-energy soliton that can exist at FTL speeds. Not everyone agrees – there is theorem in mathematical physics that says that FTL travel violates some conditions of general relativity. The author of FTL-soliton paper thinks that the theorem’s axioms are to restrictive, therefore it doesn’t apply to his warp drive. He says that he has ideas about how to reduce energy requirements for the soliton creation to Fusion-reactor levels of energy + some ideas about how to make this warp bubble in principle using plasma (very evocative of Star Trek). But still no one understands how to get the soliton up to FTL speeds though. Either way, seems like in the next few decades physicists may sort this problem out, which is very exciting. Here’s the video:
you might bet the “over” on any Elon Musk stated timeline but never bet against him accomplishing his stated goals. Many have and lost.
Solar panels don’t work well away from the Sun, so even by Jupiter performance will be meh.
That said, solar sails are definitely in the cards for future propulsion tech.
Imagine a nuclear electric tug launching a solar sail on a slingshot manuever around the Sun. Solar sails go wild near the Sun. Now that would be a ride of a lifetime.
True, but I meant that private companies might make solar electric for Earth-Moon missions, it could totally be feasible. Imagine ultra-light (say 0.1 kg per m^2) 5-10% efficiency square kilometer solar array with a plasma rocket engine – it could work as an Earth-Moon shuttle with week-long round trips at very high fuel efficiency, making Starship-like designs unnecessary. The trick is to bring the price of such arrays down to normal solar array levels + figure out how not to turn them into solar sails.
Solar sail slingshot around the sun would indeed be awesome, in fact at presently feasible technology level it’s probably the only way to get to a solar gravitational lens (to directly image surfaces of exoplanets with high resolution) within a human life time. Combining it with nuclear is a must, since you’d need a lot of power for such missions just to operate the telescope and provide communication.
Musk wants to launch Starship multiple times per day from more than one location, so refuelling a Starship won’t take weeks, it will be done in days
That’s what salesmen want you to believe. I do chemical transfers for a living, here on Earth, and if somebody tells me “days”, i know for a fact it will take weeks on the real world.
That said, its not really a show stopper with 2 year period between launch windows.
Chemical transfers you say, yeah I do a bit of that myself. I just transferred a can of Guinness into a pint glass, only took me a few seconds. I sorry but I just can’t see why transferring liquid Methane and Oxygen from one Starship to another takes weeks, so far you are the only one making this claim
Because to refuel a single Starship will require like a dozen docking manuevers for the tankers carrying 100 tons each.
Right now, the fastest and best space dockers in the world are Russians with 3 hours from launch to the ISS. It takes SpaceX like 2 days to do the same thing. And thats just travel. Fuel transfer is on top of that.
There is only one spaceport right now for Starship sized ships, in Boca Chika. So at least initially, you will have to launch sequentially. Even if all goes well in all the launches all the time (it won’t), you are looking at best case scenario of two day turnaround between refueling lanches.
So realistically, three weeks or so to refuel a single Starship.
To add to that, these three-hour transfers take months of painstaking preparation to execute, partly because there are humans on board, partly because margin of error is very low, unlike in 2-day ISS transfers. For the Russian lunar program in its early phase the plan is to do a 4-launch orbital assembly on LEO, and they dread the possibility of things going wrong enough that many would rather wait for a super heavy booster that will do the job in 1-2 launches.
What about the car-metro tunnels though?