Why Physics Favors a Mass Driver Over Heavy Lift Rockets 

The difference between this and the infrastructure projects you cite is that this doesn't do anything until its finished. Power grids and data cables have been built out by lots of different groups piece by piece. The demand for them is also enormous.

As a land surveyor i do stare out the window in awe of the scale of interstate infrastructure as a whole and in a localized manner

Thing I noticed was, there as no mention of the total size of this thing. Their website shows a model. It needs Google Earth to display it. It's a ring. One side is east of Lake Tahoe. The other side is west of … Brisbane. Australia. They want to build a continuous track that circles the whole Pacific Ocean. Kiiinda guessing maintenance inspections on that, probably going to cost more than the launches save.

Next video: Why 5-year VC horizons, 4-year election cycles, zoning laws and airspace management DO NOT favour a mass driver over heavy lift rockets

Planetary LEO is cursed. Should be LPO because LEO is specific to Earth.

This seemed to have skipped over quite a few significant engineering details. The usefulness of a mass driver depends on A) How much Δv you can get out of it. B) How much of a payload it can launch. Lets look at point A for a moment, due to the nature of how a mass driver works, the velocity of a payload exiting the driver is equal to the Δv the mass driver would provide, since a mass driver can't exert force on an object that's already been fired after all. It takes about 9km/s to get from the surface to LEO, some of that is lost to air resistance, but most of it goes towards actual orbital velocity. If we look at the Space X starship as an example, the lower stage has about 3.6km/s of Δv and the upper stage has about 6.5 km/s, if we assume the mass driver provides only the Δv of the first stage, that means the payload would have to be traveling at 3.6km/s (almost Mach 11) in 1 atm, whihlch would cause serious heating issues, and the payload would still need to have 6km/s on-board just to get to LEO, and increasing the Δv should only amplify the heating problem. Now, you mention building the driver at high altitudes in your lecture, which would reduce your atmospheric pressure, and therefor reduce heating concerns, but the highest point on earth, Mt.Everest still has about .35 atm and very little significant change to Δv required to get to orbit, and considering spacecraft have to deal with reentry heating at pressures significantly lower than that, it likely still won't be nearly enough, and you would have to build significantly higher before you can get any practical amount of Δv out of the mass driver without heating issues, but as you build higher and higher, you start to run into the same issues a space elevator would have with material science being unable to keep up. Along side this, you also need to consider the maximum size and weight a mass driver would be able to sling, if we assume the above problems are somehow solved and we theoretically have a mass driver that can give a 6km/s Δv boost to a payload with minimal interference from the atmosphere, that payload would then need about 3km/s of its own Δv to orbit, and another 4km/s if it wants to go *to* another body *with* aerobraking and no return trip. Just getting that much Δv into a payload small and light enough to fire out of a mass driver would be an undertaking in itself, even with these liberties, the mass driver would be extremely impractical for anything but small probes run on highly efficient engines. By the time we get to the point where we can get significant practical use out of a mass driver on an atmospheric body, we would probably already have better options anyway, and it would make far more sense to relegate mass drivers to non-atmospheric bodies like the moon.

I note a conspicuous absence of any cost estimates for the mass driver system itself. Yes, it might scale better, but what actually is the baseline cost? If it adds up to thousands of times more than a conventional rocket design, then that’s a huge up-front cost hurdle, which would only be economically viable if the system were used thousands of times. Doing only a few launches a year would obviously not satisfy that requirement. Therefore, the main thesis of this project - that of cost reduction - is untenable.

Inertially supported structures are ridiculous. The chance of the drive system failing and the whole thing collapsing makes it a risk no sane person would ever take. Even ignoring that, is the cost of generating that much inertia included in the estimate of the mass driver? Propelling a hose into upper earth atmosphere large enough to hold the screws and magnets needed would require a constant baseline supply of power onto which you would add the cost of launching each payload into space. For that matter, the variable pitch screw idea also seems ridiculous. There's only one animation of how it would work in the whole presentation. Going by that animation, the payload is supported by a series of small magnets on the ends of moveable arms that adjust the orientation of the magnets to match the pitch of the screw. The problem with this is that propelling an object forward to reach escape velocity requires very large forces, and assuming magnets strong enough to hold onto the screws are able to fit in such a small space, there would still be enough force on each arm to make robotics a struggle. Now consider the fact that to adjust to the pitch of the screw, the arms need to occasionally pick up their magnet and move it to the other side of the screw. To do this, the arm would need to be able to pull the magnet away from the screw it's holding on to, so the arm would be subjected to even more force! The design in the presentation at least is ridiculous. Maybe a completely different design could utilize a variable pitch screw, but not this one. Despite the exponential costs of sending rockets round-trip to mars and other places, I don't see any other method becoming viable in my lifetime. But please, do your best to prove me wrong.

Fascinating concept, I would love to see a full feasibility study on this concept given the amount of trouble military contractors have had trying to make pulsed magnet railguns work. Seems like this could be trialled first on the moon to get cargo back off of the lunar surface, all aspects on the moon are better - lower escape velocity, no environmental concerns in terms of affecting the environment or the environment damaging the equipment (severe storms, earthquakes etc), no atmospheric pressure to deal with so no tube needed etc. This concept also means not blasting hundreds of tons of nasty regolith off of the lunar surface to settle on other space infrastructure like habitats. Biggest issue I can foresee is the amount of electrical energy needed in a short time, that infrastructure doesn’t exist on the moon today. Minor concerns of asteroid impacts damaging the system, but that’s extremely unlikely. However, it’d definitely be more of a concern if it were the only way (single point of failure) to get humans off of the lunar surface.

Good luck pulling a vacuum in that tube and not having any issues when when the vehicle leaves the end of it

Re: Mass stream or dynamic support infrastructure; I have seen plenty of theoretical design work, but outside of (comparatively trivial) things like mass dampers for skyscraper stabilization I have not seen any real implementations of dynamic structural engineering. It would seem that smaller scale design implementations would be a necessary precursor to any practical space infrastructure. Are there any examples of such, planed or working, dynamic support engineering?

I always thought the "halfway there" quote was referring to technological challenges.

The different powers of the launch mass cost and velocity curve are great. I never saw that basic concept.

I must have missed something. What was the cost of the proposed mass driver? (then, of course, multiply that number by 50 to get the real "built" cost). And what is the proposed cargo capacity? (cost of the mass driver will increase by the cube for more mass) I believe you proposed only a few launches a year, shouldn't you include this "cost per flight" as part of the analysis?

I find it quite hard to believe that a mechanical system like screws would be better than plain ol linear motors - electronics is fast and cheap. Dynamic structures are all but a pipe dream for now - supporting launch tube using drones? Oh come on. Building it on the ground or side of a mountain - thats a more realistic proposition. I'd like to see a launch loop based system built someday.

This proposal is like a Hyper-Loop on steroids....X 1,000,000. So far...the people who have tried to build even a short length of tube...then evacuate it have found it to be VERY hard to do. The velocity proposed for this 'Mass Driver' is many times greater and would require a near perfect vacuum which achieving in such a long tube would be nearly impossible. It's great to dream of 'what if's'...but when they can't be built regardless of the cost....we're stuck with the old 'Rocket Equation' as our only way to space.

Any launch plan which involves lighting your rocket engine(s) while the vehicle is already airborne will suffer from one of the same big risks that plagues air-launch systems (where you drop a rocket from a high-flying aircraft). When launching from a fixed mount on the ground, if your engine (or _too many_ engines) fail to ignite, or any other problem occurs which would threaten the success of the launch, you can simply never release the clamps and shut down the engines, and either recycle for another attempt or scrub to investigate the problem, fix it, and try again another day. But if you're already (ahem) _rocketing_ through the sky, you lose that option. If anything but the most minor of problems occurs with the ignition of the engines, you can kiss that rocket goodbye, along with whatever it's carrying. Nobody (aside from Virgin I guess, but that's not orbital class anyway) will want to risk humans on such a system (air launch, rail launch, etc) unless the rocket can be shown to have a 100% success rate across dozens of missions at a minimum. (Multiple engine-out capability would be a big plus there.) And even for cargo or satellites, such systems would still face very stiff competition in the development of fully-reusable heavy launch vehicles and, in time, we'll build that needed off-Earth infrastructure to supply fuel for return trips.

I had never heard of a plasma window before this, incredible invention

I didn't follow entirely but costs need to be divided clearly into development, construction and operational cost. For a mass driver it's also a huge difference if its cargo/fuel only or man rated. As an amateur I believe first step is a hybrid cargo and fuel launcher. It will accelerate at lots of Gs, be only some kilometers long, fire through a simple membrane at modest altitude. Also the cost of delta V is different. Once in orbit ion thrusters or nuclear can be used. Only crew to orbit will need the conventional rockets but we do that already.

Good luck getting the funding. Truly.

As someone who lives in hawaii I guarantee no one here will ever let you build that.

A mass driver to LEO seems like it is a pie in the sky endeavor until we are already in the Star Trek future. But it seems like you need to factor in mass drivers or spin launch in semi-low earth orbit, on the surface of the moon, on the Mars surface, in Mars orbit, and high earth orbit into your round trip calculations of cost.

How about a mass driver on the moon 1/6th the gravity no Atmosphere Gerald bull left plans for one

I hear that films and tv shows have generated in the public a great deal of interest in superheroes. I think it's high time we start researching ways to give humans superpowers. We already let the Transformers hype die down without taking advantage of that opportunity to build giant robots. Let's not make that mistake again.

I’m not sure why my algorithm recommended this to me, but I am glad it did! I thought this would be talking about rail/coilguns vs rocket weaponry in a sci-fi universe, but it’s still very interesting!

I wonder how long the US electricity grid will be the biggest 'machine'? What about the European connected grid, or perhaps the Chinese grid?

The first stage of the Falcon 9 completely replaces such an accelerator and is completely reusable and much cheaper

Undersea cables were first laid in 1988? Huh? Surely they've been around since shortly after the first telegraph networks.

THIS is why fantasies SMOKES finances. Everyday.

I really liked the presentation. I'd also liked to have seen a cost comparison against what I guess is a reasonably close proxy (give something some inertia, get it high before lighting the rockets) which is Stratolauch.

Is there more details on the screw based propulsion? The paper is not open access and isn't on scihub.

Our company worked some of these issues, back around the 60's and 70's, along with people like Bull and the Harp program. Those were total and absolute failures. We shot "objects" into local atmosphere at speeds of over 60,000feet-per-second, and the result was that they burned up, just the damaged Space Shuttle coming down, in a matter of few hundreds of feet. UNLESS you can get past the simplistic thermodynamics of air drag, and thermal heating, and Max-Q where the vibrations will shatter you, you will simply burn up, or disintegrate. HARP addressed some of these issues early on, and now we have the California wet-dream of having a vacuum tubed passenger train, running between cities at 500+mph. SO, you could build a tube up, to about 1000,000-feet altitude, to get past Max-Q air buffeting. It would cost a lot. If California had any brains, they would point their tube-rail up into the sky, and launch all of their Wokies out into space. 45-degree angle would work great. Give them token parachutes in case they fall back to the ground.

Once again the sci-fi of my childhood may be a tangible dream. Why did it take 60 years from Fireball-XL5 for anyone to consider this concept?

"support it with drones" - hahahahahhahahahaa I almost sprayed my breakfast all over the screen

What's going to happen when that vehicle, traveling well over supersonic (hypersonic?) speeds through an evacuated tube, hits the air at the end of the tube? At close to 15 psi? The sudden pressure change alone would challenge the structure. The shock waves would add to that, trying to tear the craft and the end of the tube apart. Then add the g-forces from the sudden deceleration. Even if the craft made it through undamaged (which means it's probably too heavy to reach space economically), could any living being survive it? Unless you want to build that tube to extend into the upper atmosphere, I really don't think this has a chance. Much better to accelerate the air in the tube, then slowly taper sides of the tube wider, slowing down the air gradually until it hits the end at near zero velocity. The supersonic shock wave would be behind them in the tube, and you'd have to deal with more heat buildup, but it wouldn't be like hitting a brick wall at the end of the run. Because, chances are, it Would be the end.

The solution to the cheapest mechanism for space flight (not the quickest) is high altitude balloon followed by solar sail many many orbits increasing speed till orbit escape velocity is reached. Also, beyond the cheapest way, it’s also the safest which expensive satellite manufacturers might care about.

The motivation to spend the money to develop and build the mass driver...comes from the value it makes possible The biggest driver is VALUE CREATED by industry dependent on products, mining, and materials created in space

It seems like an AC linear induction motor would be way simpler as a non-pulsed power option to move a sled really fast along a kilometers long track, compared to variable pitch screws. Maglev trains push themselves along using linear electric motors, and the only difference between maglev trains and mass driver launchers is whether there's a ski jump at the end of the line.

This certainly has a lot of application once in outer space, as you can more or less slingshot supplies on somewhat regular-ish routes (within the bounds of how orbits work). It works on the Earth, too, but the atmosphere is the main obstacle and the power of acceleration the second. This is not just the physical forces, but the electromagnetic forces likely being used for the purpose. You're looking at field strengths to rival MRI equipment potentially needing to switch at microwave frequencies, creating all manner of interference and induction concerns. The system would almost certainly have to be cavitating in nature with a sacrificial leading edge, or the nature of launch could be shifted to be a ramjet sled which has a far better performance than a rocket and could be returned and reused following a suborbital skip. Ultimately, I think a series of solutions will develop over the coming years. A first stage magnetic power shot which primarily boosts a "plasma jet" (for lack of a better term) carrier into a suborbital trajectory where the jet is capable of using trace gasses for propulsion at much higher specific impulse ratings, which builds the speed for a suborbital hop into which a payload is placed. Of course, if we can do that, why not just fly up there in the first place as we are clearly able to generate large amounts of electricity in a mobile platform... So likely some kind of fusion power or outright magic. A modified 16" naval gun was able to send projectiles into a noteworthy suborbital trajectory, so the problems may not be as bad as some have suggested.

OR (and I always choose this one because it's fun and absurd) We drill a half kilometer deep hole a couple meters wide, line it with cement and steel and use about a quarter of the normal fuel for a similar rocket payload to turn it into a heaping great gun. After all, if you can sling a full payload into orbit every thirty minutes or so for near the cost of liquid natural gas and oxygen that's a lot of mass you don't have to stress about putting up there at launch.

Yeah, computer simulations are great, as long as you don't have them model reality. You accelerate a space cargo ship to near orbital speed flat on the ground and guess what! It has zero speed away from the earth. ALL its vertical acceleration happens at the curve up! So your frictionless system has to work with the rockets weight times hundreds of g force. The rocket and payload has to handle this. And you want a tube to be lifted into the air. That hast to resist 6 to 7 psi per square inch of crush force, that has to be perfectly held in place, at the side of a mountain and its weather! And it has to deal with the loads breach of the seal and the atmosphere rushing tons of air in at the speed of sound because you are not hanging a massive door that closes in a few millisecond on your suspended pipe. There so much more wrong with this

I don't see square or cube scaling for mass drivers. I see runs-into-a-wall scaling. That's because, if you're going fast enough, running into fifteen pounds of air for each square inch of cross-sectional area is indistinguishable from running into a wall. There's a big difference between a very curved pipe thrashing around up in the air and a very straight vacuum tube staying so perfectly still that a payload at orbital speed will absolutely never hit the wall of the tube and convert its kinetic energy into thermal energy quickly enough to convert both payload and tube into incandescent plasma. A mass driver on a launch loop or a space elevator is a really cool idea, but I'm not optimistic. ISRU seems much more promising.

I think fuel production on the moon is an easier way to reduce space travel costs beyond LEO. As for getting to LEO, orbital tethers.

How do you turn the screws?

Where is the cost/kg vs delta-v tool you showed at 13:27 ?

Could the track for such a mass driver be looped on itself to save on the amount of hardware needed? You would need some kind of mechanism to let the "payload" escape at the right time and place but then it's very similar to that SpinLaunch thingy from a few years back (without such crazy centripetal forces)!

Yup, the tube launcher came to me on my first visit to the Big Island35 years ago, before surfing with the sharks.

You'd be surprised what a mass driver can do in his straight piped honda civic

Lets start this with international transport and see how that all works out.

I want to see the break down on the numbers thats what matters.... Such a great Idea!!!!

Is the screw spinning or do the grapplers move?

I was skeptical about mass driver or similar linear accelerators but quick wiki read told me that they are a bit more advanced in research state that space tethers.

amazing

Seems like a lot of technology to develop the thermal protection for launch, and deal with the sudden shock loading of transfer from vacuum tube to atmosphere, when launch systems to LEO are getting more cost effective while avoiding those issues. Would there be advantage to using systems like this in LEO to accelerate the vehicle from orbital velocity to interplanetary speeds? What about mounting it on Luna instead? A ship mounted version for Mining would be incredibly useful in returning ores and ices to locations where those materials will be needed, could the same technology be used to receive and park those payloads? And if so, could it be done without needing the usual Transfer Windows for unmanned payloads?

I Love this Idea!!! When i was a Kid i thought why not use a rail gun to launch half way to space!? Much more sophisticated take. would love to hear Specs on this idea. G-forces, length of "run way" Limitations?........ I feel like ideas like this need to be taken serious

A new hypeloop?

I think the use demand isn't high enough yet for higher range flight and it is largely a feedback loop as lack of ways to get there is part of the low demand. Something like this may not gain any traction until rocket tech is able to test the feasibility of space bases creating the demand for space travel

Is the cost of the vaccum part of the deltaV^2 cost scaling estimate?

The best site for a mass driver is on the moon. You don't need to get up to altitude to get out of the atmosphere, so there is no need for a never before constructed drone/balloon/inertial support system, just a dust cover and micro-meteorite shielding. Being able to send stuff from the moon to LEO, to Lagrange points, and on interplanetary trajectories could be a huge benefit if we are doing moon industry. There is a lot of aluminum oxide on the moon, so we can process that into aluminum for construction, or aluminum and oxygen for rocket fuel, that is the overwhelming majority of the mass of any spacecraft. There is water on the moon too. A mission plan where the complicated spaceship launches from Earth on a rocket, then meets up with a huge aluminum/oxygen booster in LEO that was built on the moon and sent by mass driver, lock them together, and off you go to wherever you want could be the minimum viable mass driver.

you make a suggestion for a temporary support with either drones or balloons would it be worth considering to place the tube in the ocean for support?

Maybe someone already pointed this out, but LEO means Low Earth Orbit, thus it is not correct to talk about other planets LEO. Similar to apogee and perigee, these terms are exclusive to Earth. The correct terms in this case are LO, apoapsis and periapsis.

If a rocket like the SpaceX Superheavy could be mechanically boosted to 20mph as the engines took over, how much extra mass could make it to LEO given the same amount of fuel?

Ecuador's Mt Chimborazo. Virtually on the equator and an altitude of 6310 mts. That's 50% greater than Mauna Kea. I agree that ground based energy is terrific because it circumvents the rocket equation. This particular design sounds very promising indeed. At the end of the tube you might use a 'burst disk' something like those spin launch guys are doing. Obviously you need to replace it for each launch and to evacuate the tube again. The air lock idea sounds good but it will have to be able to work very quickly even if the vehicle isn't actually at orbital velocity. And that's another point, if the mass driver "only" accelerates the vehicle to 13,000kms/hr or even 10,000, it will still require so very little fuel and a single vacuum optimized engine. A little like a typical second stage only it will still have plenty of ΔV in the tanks.

While Mass Drivers are definitely feasible for bodies like the Moon or Mercury, I doubt that our modern technology and governments could make one sufficient enough to get to orbit, or even close. The niche that the mass driver fills, providing mass amounts of delta v for low cost, can probably be filled, in part, with current jet technology. Considering our fastest and highest flying jets are basically exclusively military, I wouldn't be shocked if it could be adapted to space travel. I mean we reached 35km in altitude in 1977 using a Mig-22. Obviously, that's an order of magnitude under the required altitude to reach the exosphere, but that's far cheaper velocity with easier to manufacture technology. As air gets thinner, jets produce less thrust, of course, but they're basically just rockets that don't carry their own fuel, so it's better than nothing.

Airlock... "with fast doors" Uh.... no. So many issues. This is one of the key parts that MUST be answered. I was hoping for some sort of interesting break away material that can hold against the vacume yet not cause impedance and damage to the vehicle. Benifit of a break away material would be that the vehical will not need to be in the vacume tube while drawing down the vacume. So the vehical and supplies and occupants would not need to be in the chamber for HOURS, at least, while you draw down the vacume. You also would be able to accelerate into the first barrier and the air rushing into the vacume behind the vehical would aid in acceleration.

If you can get to orbit, then you can refuel at a H2 and O2 fuel station in orbit. I believe the way to go is to launch water into orbit. Using fine tuned launch vehicles (for the world you're launching from). And to crack the water in orbit into fuel using electrolysis with power supplied by solar panels. As a commercial enterprise.

I love this explanation. If we use this to put fuel and needed mass for round trip. But use rocket to move humans orbit to load on round trip rocket for round trip. Do infrastructure all the way to Mars is fuel dumps and supplies all along the way and to the surface of mars by the velocity tube. Do this so the g-forces could be increased in launch tube portion. Also we must start taking advantage of the low earth orbit junk and natural mass to fabricate the large round trip ships?

Mass driver... as in Spin Launch (AKA Yeet Launch? 🤣

Can you point out the differences between this and SpinLaunch? Seems like SpinLaunch has a more realistic idea but is unable to support human launches. This provides, what, more horizontal velocity, a human survivable capsule? Also what is the price difference between this and refilling in LEO like SpaceX plans to do with Starship? Refilling outside of Earth is dismissed in the presentation for infrastructure reasons as you only considered refilling from celestial bodies.

How long is the tube? And you have to keep the whole thing as a vacuum? That alone seems like a difficult task.

This is kinda the idea that was used in the movie When Worlds' Collide.

Most of our early space exploration / habitat-building will be done by robots with AI, likely humanoid for mast of them. This might be the case for decades. You don’t have to retrieve them on any human time-scale, they can (probably) withstand higher g landings too, probably more radiation tolerant, and certainly don’t need as much of a life-support system.

6:06 I think you were close to choosing the absolute worst colour combination for the lines on that graph, both for accessibility and aesthetics. I had to really really strain to see that there was even another curve on that graph at all since i'm mild deuteranopic. Just throwing it out there, please pay more attention to your graphs. Also my biggest concern with all of this besides what other people have mentioned is the screws. Either those little arms on the side of the cargo have to rearrange themselves constantly to "pull" it along, or the screw, along its entire length, and along a curve, must rotate at an incredibly high speed with no vibration and be free of all imperfections.

But if you allow for multiple launches to combine the deltaV of several launches from earth, doesn't that result in linear cost scaling? Linear is a lot better than x^2 or x^3 I think that's what halfway to anywhere means.

Several kilometers of lightweight evacuated hollow tubing is basically impossible to build with modern technology, certainly not cheap.

0 gravity losses is kinda good

Cost of system? Or how much $$ in moon access demand is needed?

i thought about this when i was a kid but using the maglev idea.. its been 30 years when are they going to do this already!?

maglev + tunnel secondary = 289 mile to orbit for 138 billion 159 /kg launch cost @ 2 G

If I had to guess before watching this, physics favors a mass driver whereas economics favor heavy lift rockets. Maybe a mass driver is the most efficient way to escape a gravity well in theory, but in economics the most efficient thing doesn't equal the cheapest, and cheap launch is all that matters in the end. If something is less efficient physics-wise, but less of an upfront cost and less of a maintenance cost over time, than why would anyone go for the more efficient option? In economics, "good enough" is well, good enough. Perfect is the enemy of the good after all

Then there's the best idea, which is to forgo payload engineering entirely and just fire raw materials at the moon to seed a future habitation area. Probably the most efficient method as far as Delta-V is concerned, given there isn't any Delta-V (in the conventional sense). So the per-kg cost is entirely electricity and armatures. The biggest problems with space travel are humans and electronics. Take them both out of the equation and mass relocation gets a lot simpler. Might take a few years for all the lunar dust to settle, though.

Mass driver makes much more sense on the moon.... or just a space elevator. On earth... would it be cheaper to LEO than falcon 9 or starship? I'm talking leo because the pod would not have much fuel left after circularisation burn. Lack of infrastructure, yes, this is huge. Dedicated transfer stages and refueling stations would bring the cost down. Also economics of scale. Instead of making 1 or a few ships, make 1000... standardize everything. Cheaper per unit, easier maintenance.

Humans need to have a mother ship

when humans are upgraded with my cybernetics then humans will be able to live long term without health problems on space stations and space ships

Altitudes, Velocity (x,y) curves of Rockets matches what is doable. It's the opposite for Mass Drivers.

Why not have the tube submerged under water? Then you don't need a mountain, but just the coast

Have you calculated how long the tube has to be for an acceleration that a human being can withstand? between 4g and 9g. It is many hundreds kilometers. It will be very complicated to get land for a project of this size.

Faster to Mars to reduce the time in space radiation? ... On Mars you are also very much exposed to space radiation. There is no shielding on Mars if you send astronauts to Mars. You have the shielding on Mars that you have in your Mars lander crew module. That cannot be so much more than you have in the crew module that brings you to Mars. Where should it come from? Or who should build it / and when / who should finance it, when the budget is reduced every time they speak about space missions? Even the tiny sample return mission got canceled. Who would finance robots that dig holes or build radiation shielding houses on Mars? And who wants to live in a tin can for two and a half or three years? That's more extreme than anything during C times. This tin can might be buried in the Martian ground. Walking around on the surface of Mars is prohibitibely expensive. You cannot open a window to get fresh air like in Antarctica. We have not even made a closed cycle for plants that grow and produce oxygen that people can breath. Biosphere2 had to give up. Lucikly they were on Earth and had fresh air around them and could open the windows. Thats not on Moon and not on Mars, etc. On the ISS they live from supplies from Earth that come every few months. You can only bring supplies to Mars every 26 months, every 2 years... Yes, it's still possible, but it needs a giant budget. And faster travel to Mars does not help. There is no air to breath on Mars, no radiation shelter, not even a radiation sheltering atmosphere - just 1% air density on Mars than on Earth and only CO2, no free oxygen to breath, not even if you compress the Martian air. You need lots of power to do anything, to generate water or oxygen. That power device and other machinery is heavy... (don't speculate on diesel engines, you don't have diesel and don't have oxygen, you need oxygen to breath!) If you bring that there, make sure, it still works when the astronauts come there, make sure, they all land close together, not too far off or it's over. It's still possible, but very very very expensive. Maybe there's a budget if another country tries to plant a flag there... And there's another country that's trying to land on the south pole of the Moon first to plant a flag and say it's their land and not your land... And then they might try Mars...

A big issue is RETURNING TO EARTH. In order to return to Earth from Mars, for example, then all of the infrastructure needs to be already put in place and ready to go (tried, tested, reliable) BEFORE you ever land on Mars in the first place. Mars is just one example. But the same holds true if you intend to LAND on any extraterrestrial body. This has been done with our own moon, but everything beyond that requires much more infrastructure, and because of this is far, far more complicated and costly. Do note that with smaller bodies, it's comparatively not as complicated, because, just for example, it's relatively much easier to rocket away from an asteroid, even an asteroid as large as Ceres. Of course, there are other issues relevant to humans traveling through space for long periods of time, such as radiation, and the need to produce "artificial gravity" using some kind of system to produce centrifugal forces, as well as the supplies needed for water, air, and food. Even with submarines and space stations, which employ systems to greatly extend supplies of water (recycling) and air (using energy to produce air from water), the scale is months, not years. Astronauts engaged in interplanetary travel will require systems that provide water, air, and food for years at a time, with zero resupply from Earth. Now obviously, autonomous cargo resupply ships can be put in place at destination targets. But all of this, again, makes things more complicated and costly. As far as I'm aware, while there are all kinds of ideas about how to conduct such missions, there is, literally, nothing in place today that deals with all of these issues. THIS is why the moon base related projects are the best idea all the way around. Why? Because it's the best kind of "testing ground" for how to go through a sophisticated process of development - and, at the same time, have the ability to retrieve astronauts and return them to earth when inevitable failures occur during the development stages.

These people are just about an inch above the Flat Earth guys in intelligence...

Is there not an economy of scale? In other words, the more we (SpaceX) launch, the lower the cost.

Mass drivers would work fine if we had no atmosphere.

Current market situation prevents building of many nuclear power plants. Although they'd be HUGELY beneficial for the climate, very cost effective once in operation and are a proven technology that everybody knows it works. But financing just a couple of billions for a guaranteed revenue is enough to break the business concept. We are not even talking about purely hypothetical concepts of this variable pitch screw driving something to speeds ~km/s. And suspending vacuum launch tubes via "inertial support".

Well, it sure is fun to think about, but I think I need to call my boy @Thunderf00t in for a debunk. Nice idea, though. I'll pay it more attention once Elon has finally delivered Hyperloop. When that's economically viable and practicable to construct, /then/ we're "halfway" to mass drivers replacing rockets to space (on account of the whole evacuated tube engineering and the need for a looooooooooooooong run of it to be elevated to the stratosphere+. This is a space elevator; materials science says you can't make 'em, only imagine them. This idea is complete fantasy (certainly for any onward-traveling space vehicle of human proportions; but something tiny, like a 4" cube-sat or a rifle bullet, might just be feasible, if totally non-viable from an economic perspective). (Thunderf00t's already done a debunk video on a similar project, which was to use a mountainside evacuated centrifuge to "yeet" an object to orbital velocity.)

The cost for SpaceX per launch isn't 100m, 200m or 270m. SpaceX makes a large profit. The cost of a fully loaded Falcon 9 on the pad is 100 million, but factoring in 15 to 20 re-flights and it's cost to SpaceX is less than 1/8. Approaching 1/10th. Starship will not expend the upper stage and will drive costs even lower.

lunar aerobraking? I thought the moon was a pretty good vacuum?

Reason why it won't work: Atmosphere is pretty dense at sealevel.

Nope, perigee will be under the Earth. How do you circularize the orbit? You can't unless you have 2nd stage propulsion in the payload. And if you do and it's small enough to work then just use that propulsion to go into space instead as it must be magnificent for you to have any useable 2nd stage mass to payload ratio.

Starships future launch cost is around 10 million to LEO. If it takes 8 more launches to fully refuel in LEO, it will carry 100 tons to the moon. $80M for 100Tons. Thats $800 per kilo. I can afford to pay for my own trip to the moon🎉

Doubt