Step one, move past capitalism and profit based economics so we can focus on space exploration for the infinite abundance and it's own sake instead of short term profits and unintended (and unavoidable) long-term self destruction
Mass Drivers seem absurdly impractical on Earth, but I do believe they will be a staple of the Moon and Mars. Low gravity + zero/minimal atmosphere changes the equation significantly in favor of mass drivers.
I am sure numbers wise this works out, but frankly I don't think a single structural or aerospace engineer would be able to watch this presentation without fainting. Having launch infrastructure would definitely be a boon to expanding our space presence, but the scale of such a system is multiple orders of magnitude more intense in scale, complexity, and margins that building it would push our ability to build as a species to it's limit. It's hard enough to build and maintain a length of steel to be straight enough to run a train over it at 200 miles per hour. Maintaining an evacuated cylinder multiple miles in the sky, with the margins to maintain an object going possibly multiple thousands of miles per hour is a task straight out of the worst nightmares of engineers.
Humans cannot leave the earth for prolonged periods. So far, we know our blood cells die off faster than they can be replaced, and our kidneys also malfunction. They're probably related. There may be more issues.
Well, I haven’t read all of the 438 comments at the time of writing this, but I’ve read quite a few and have a very basic question to add. All (significant) technical challenges aside, a gun is pretty useless if you can’t aim it. How do you plan to aim yours?
While the general concept is sound, the things needed to create a functioning and cost-effective version (a huge vacuum tube, very regular launches, support systems, reliable accelerators, etc.) may mean it's something not really feasible at this moment in history - much like how Archimedes could quite easily have been able to calculate that a hundreds of meters long ship with a thick metal hull would indeed float, but such a design would've required tens or hundreds of years of work and the manufacturing power of the entire world at the time.
I'm not dismissing all the difficulties for reaching Mars - longer voyages mean more provisions are needed, more shielding. Shorter voyages mean more delta-V. But comparing current costs to Moon/Mars to current costs to LEO are misleading, we are at different stages. LEO/GEO are mature destinations, you can book transport to cargo from a bunch of proven commercial providers. Insurance is available and relatively affordable. The Moon has private companies which are offering transport, but none have done so successfully - yet. Even governments are struggling. Once we start launching to the Moon once a month or more, the cost to go there will plummet. Same for Mars. All destinations will become vastly cheaper when we get full reusability. And also - reentry craft have blunt forms to keep the compression wave away from the skin and reduce the heating. I'm not sure a vessel accelerating up to launch speeds would benefit from a sharp form - the dynamics there are much different from low speed craft.
Thank you for the insights into the complexities behind space exploration! Given the issues that the native people of Hawaii have with the observatories in Mauna Kea I would warmly suggest dropping that last bit though - it is a great piece of emotive storytelling in itself, but somewhat culturally insensitive…
good try mate, even if your entire concept is flawed from the ground up at least you came up with something. Keep studying so you can scratch bad ideas faster. I am sure you could still use your imagination to come up with cool new stuff but you need a better way to filter good ideas from the bad ones even before you work on a presentation and even present It. At least you got the experience tho! even if you failed this time you can get it on the next one. But make sure you have a good one!
Helpful infrastructure would truly be a game changer in lowering cost to deep space destinations. I don't think mass drivers are worth focusing on right now as propellant depots would be much more disruptive. We can already send payloads to LEO for relatively cheap, and if the promise of Starship pans out it'll be even cheaper. If you can refuel there, then going anywhere else only costs the fuel plus the propellant depot's profit margins. Once you can make propellant depots, you can also progressively add them in different orbits as you scale up and as the demand manifests. Not to mention, if you add some living space to your depot, it can become a destination in itself.
I would like to illustrate a couple engineering issues with this concept : 1. The largest vacuum chamber in the world right now is the Space Power Facility from NASA. This facility costs in the order of hundreds of millions of $ to be built and operate. The Space Power Facility is many orders of magnitude smaller as a vacuum chamber compared to any legitimate mass driver concept. Any mass driver that is kilometers to hundreds of kilometers long would be the equivalent of stacking SPF vacuum chambers on top of each other and a single SPF is only about as high as a couple dozens meters. At best, to reach a single kilometer would likely require a minimum of 20 SPF chamber equivalents. To even reach a single kilometer, let alone many, the costs would be in the order of billions to dozens of billions of dollars and that's not accounting for the thermodynamic inefficiencies of vacuum pumps. Vacuum pumps are extremely inefficient and the higher the volume, the worst the inefficiencies get due to higher potential for leaks scaling with the surface separating the vacuum and the pressurized portion. This is also not accounting for the acceleration systems, only the vaccum architecture. There is a reason why hyperloop concepts and such never go very far and are mostly vaporware, the vacuum alone is likely enough to kill any mass driver concept adopting it. 2. Acceleration and distance is also something that needs to be discussed. Let's say we build a mass driver that does not kill people and we give it an acceleration of 5G since 10G basically makes people faint or die. Through simple kinematics equations, we know that at 5 Gs of acceleration (a modestly uncomfortable ride), a mass driver getting a vehicle to 6km/s would be 370km long. That's the best case scenario for a mass driver with people on board. Reducing Gs will linearly increase time and the length varies by the square of time so we are looking at exponentially increasing length for any less than 5 Gs. On the other hand, increasing acceleration will be more and more uncomfortable for people and likely won't reduce the length enough to make it economical. As discussed above, if 1km costs in the order of even a single billion $ (which is extremely conservative), then hundreds of km would make this cost about as much as the GDP of Denmark before even launching a single vehicle or about 10x the budget of NASA. For every km built, between 5 and 20 launches will occur in terms of current launch cost, that means that to be economical, a 370km long mass driver would need to launch at least (extremely conservatively) 1850 vehicles at the same launch costs as current levels over 5 years with a launch every single day. Dividing launch costs by 2 would mean one launch per day for 10 years and launching once every 2 days at the same costs as today's launch market would also take 10 years to recuperate the investment. Long story short, any metric indicates that to make it more affordable than the current launch market or even equal to it would take an extreme level of use.
Mass drivers will not be practical on Earth until the sci fi future, at least not for the whole trip to LEO. A catapult assist a few miles long could cut a little bit of fuel, though, and make launches marginally cheaper. Then those cheaper launchers can be used to build a much more practical mass driver on the lunar surface, which would allow in-situ fuel production and launch to a LEO rendezvous. Combined, those would make missions beyond LEO wildly cheaper. But the concepts you discuss here are fiction for a long time. An evacuated tube that long is so prohibitively expensive and delicate that it defies comprehension.
This is pretty similar to an idea I was working on around 2005. I still think it is do-able, and worth doing. Video I produced around 2012 in the link. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-1EniBZQjRog.html
I have to absolutely reject the statement at 18:36 that the complexity of a dynamically suspended structure would be the same as that of undersea cables. You're talking about something with moving parts (and magnetically suspending those moving parts). Something with at least one vacuum tube (3 if you want separate ones for forward and reverse mass flow and the launch tube). That comes with much greater structural requirements and need to be vacuum-tight rather than water-tight (or "merely" gas-tight). And even worse, the moving parts are inside that vacuum chamber which you can't regularly open for maintenance, so the moving parts have to be designed to last with a guaranteed "virtually zero" failures until they are due for replacement. That's like saying that a highway is "not much more complicated" than a gravel foot path though the forest, since their cross sections look similar except for one or two layers more. Also I don't have the time stamp on where you said it but no, vacuum tubes wouldn't be comparatively light. If they were, we'd have vacuum balloons like the 1800s predicted. In reality, vacuum tubes are as heavier than airplane bodies. (They have to take 1 full atmosphere in the "made-the-titan-sub-implode" direction whereas airplane bodies have to take half an atmosphere in the "self-stabilizing" direction.)
You show the cubic and quadratic curves at 11:35 overlaid with several moon destinations' delta vees. That implies that you can go all the way to those destinations with mass drivers, which you can't. The mass driver can only ever do the "acceleration" portion of the trip: From earth surface to: A) LEO, B) transfer orbit to geostationary or other high orbits, C-E) a hyperbolic escape from earth's gravity directly into a Hohmann transfer orbit (sun-centered) that takes you into the Hilbert sphere of some planet/moon. But you still have to carry fuel (and pay the rocket equation it's dues for): A/B) orbit circularization C) deceleration into a capture by the planet/moon (90% of the full delta-vee if you can aerobrake? Not sure if that discount only applies if you can afford the time to make several passes in and out of the Hilbert sphere) D) deceleration from intercept orbit into a circular low planetary orbit (90% of the full delta-vee if you can aerobrake) E) active braking to get from there to a soft landing. Plus the whole return trip. If you look at the graph at 5:07, the end of the light pink bar is about where the mass driver can get you. The majority of the delta vee still has to come from rockets. Or in other words, the difference between going to LEO and going to Mars and back will still be a factor of 10000 times more expensive. And if you can cut the cost to LEO to 1% of it's current cost, then the cost to Mars and back will also be 1% of the 10 trillion it would cost today (100 billion). But that's still far far from economically viable.
Would the two worm gears be continuous along the entire length of the accelerator? If yes, then would you have to slow down their spin for each launch to accommodate each payload starting from a standstill at the west-most side? Or could a variable “thread pitch” that changes along the length of the accelerator to accommodate the payload being sped up solve this?
Mass drivers on Earth are so flawed in basic concept that I cannot believe you spent so much time on this subject. There are 2 insurmountable problems. First, the G forces. The linear acceleration of the payload in the time and barrel length is off the friggin' chart. There ain't many materials that can withstand that at all, and those that can are basically construction material, not the delicate circuitry of electronics, the carefully balanced shafts of turbopumps, fuel piping, etc. let alone squishy humans. This is only compounded if the barrel takes a turn up a mountainside like in your example, when the projectile is already nearing orbital speed. Now you have a HUGE lateral G, not just the aft G, and the lateral G is perhaps even more depending on the radius of the turn unless that radius approximates that of the Earth. The gun barrel itself probably can't be made strong enough to force the projectile into this turn without the projectile going straight ahead into the mountain. And don't get me started on the Gs the sled will experience making an even harder turn AND slowing down after releasing the payload. Second, EVEN IF you can somehow overcome the G issues, you are unleashing a projectile at near orbital velocity (if not somewhat faster) in the lower atmosphere. EVEN IF you can keep the projectile from instantly vaporizing upon sudden exposure to the relatively thick air, you are STILL going to create the mother of all sonic booms. This will likely cause extensive damage to everything for many miles around, like that meteor that exploded over Russia some years back. Now, put a mass driver on the Moon, where there is no atmosphere, and use it to shoot inert rocks which can maybe take the G forces with no meaningful damage, and you might have something workable. After all the velocities needed to enter LMO or even lunar escape velocity are considerably lower than the corresponding values for Earth. But those Moon rocks would still require a sufficient demand to make the whole project worth the cost. If you're building mass drivers on the Moon, you're past the point of needing rock samples to study back on Earth. So why would you need an interplanetary supply of Moon rocks in industrial quantities? Anyway, no matter how good the math looks in terms of cost, there are INSURMOUNTABLE physical obstacles to ALL pipe dreams about creating orbital-ish velocity projectiles on the Earth's surface as a way to escape the tyranny of the rocket equation by eliminating the rocket. Sure, you can make the economic argument in favor of such things, but you can't change the laws of physics, which say "nope".
10:26 The US power grid is smaller than the European power grid. Europe has 523000 kilometers of high-voltage (>110kV) AC lines, more than twice the 240000 kilometers of the US grid.
21:29 - your nod to the "adventurous Polynesians" might be appreciated, if it didn't fly in the face of what the indigenous peoples of Hawaiʻi actually want. Please go watch "astronomy has a colonialism problem" (v=R7hK5_Rj--8) from @dr.fatima, and consider revising your thinking in that regard.
While I do agree that mass drivers give some interesting options to potentially reduce launch costs, I do think you're taking the alternatives a bit to lightly in this video. For instance the Falcon 9 is certainly the cheapest option around right now, but it's also obviously being rapidly pushed into obsolescence by SpaceX plan with Starship. Specifically a lot of the current rocket costs aren't in their energy costs, but instead in their one time capital costs. This has an obvious major implication on the cost curves if it can be resolved as SpaceX intends. More specifically it could push prices down by one to two orders of magnitude. And where currently R&D costs for one off beyond Earth orbit missions dominate the costs for such missions, this could then via mass production be driven down far closer to the fuel costs. Of course a substantial capital cost would remain, but it would help reduce the steepness of the exponential curve a fair bit anyway. So if they do actually succeed at that architecture, the prices to beat with a mass driver concept would be far far lower at LEO, and still not all to excessive yet for The Moon and Mars. Beyond that it does seem like the exponential function would start to bite more again. But it would still make the economic case for a mass driver in the short term substantially more difficult as one would need a more mature and cost effective variant to beat the competition. Admittedly with prices dropping that much space activity would probably rise quite a bit and so in the mid term perhaps there would be more interest to explore alternative launch options as the renewable rocket solutions max out what they can do cost wise. Though I do think in the mid term this system will develop yet another challenger which will be a bit problematic. Which would be chemical systems becoming obsolete for in space propulsion. Even now the USA is already developing a nuclear thermal propulsion with twice the ISP that chemical can hope to reach, which would obviously impact the cost curve. But that's really just a side show, the bigger issue is that Fusion power increasingly looks like it is reaching a level where it might become good enough for space propulsion. For instance the CFS SPARC project which is already quite far along in construction is expecting first fusion around 2026 of a standard Tokomak ring design which they hope to get up to a power return eventually of 11. It's torus size is far smaller then for instance the Starship diameter, so in principle if they made it work eventually one could single launch the core of the system in to space in a singular launch. Fusion systems obviously give access to plasma at tens of millions of Kelvin, and thus even if one has to add a fair bit of mass to improve thrust to weight ratios to a reasonable degree would probably give access to very high ISP numbers. Probably starting at thousands and in later generations pushing in to the tens of thousands and maybe even an order of magnitude more. This would mean even early systems might make getting tens of km/s of delta-V far far more affordable then previously and later gens perhaps hundreds to thousands of km/s delta-V. I think it would be pretty hard to create a mass driver that could completely beat the economics of such Fusion rockets if they did come to reach such a level. Even if one built a ring around the Earth, the g limitations for launching objects would probably constrain one to below 100 km/s. Though perhaps this would still be some what competitive in reducing transit times to places like Mars, Venus, Mercury and Jupiter. Still this means that one instead might in the shorter to mid term become stuck trying to defeat the economics of chemical rockets to LEO. Which if they become fully reusable would be a fairly substantial challenge, as likely the Mass driver system might have to start pondering how to recover its launch vehicles as well then. Possible in principle of course, as Starship obviously could do it as well, but still it's a major extra complication to the system. Another issue is that fully reusable wouldn't be the final form of chemical launch systems, I can conceive of at least two further steps they can do to help reduce costs further yet. - One is introducing the recently maturing rotating detonation engine technology. These seem to promise a moderate ISP increase over current engines, I've found it hard to find an exact figure but am guessing for now it might be 10%. While 10% ISP isn't that large a gain of course, it might increase the mass fraction to orbit by a factor of two or so, helping half effective costs again. - The other is that an air breathing first stage should be technologically possible considering how hypersonic technologies are working out lately, especially as those apparently pair well with detonation engine technology which are said to greatly reduce the difficulties of engines able to work at such high speeds. The real gain here is of course that such air breathing engines would have substantially higher effective ISP, which would thus help improve the mass fraction and thus cost picture of the overall rocket. I'll admit I'm not sure how much so though, especially as developing a very large hypersonic air breathing stage would obviously be a very challenging and costly prospect. In any case, these various factors means the kind of numbers one might need to beat to become economic in the mid term might be much harsher then you projected in this video. It may well be possible as you can avoid needing to drag nearly as much fuel up, but there will probably be substantially less margin to work with then one would like.
The problem with that, is that it would be too ambiguous to judge. How does one measure technological progress? Intuitively our rate of technological progress is exponential, but it's not at all clear what the base of that exponent is. What would it mean to double our technological progress? And a halfway measurement requires a beginning point. Do we start at discovering fire or later?
Just wondering what is rhe peak acceleration of this system and would it be too much for folks to get inside that driver thingy and get blasted off into space? I have a bad back so i would probably prefer not to try it.
trying to re-invent the "hyper loop"? What happens when the vehicle bursts out of the vacuum tube and hits the atmosphere at escape velocity, when it would need heat shields for re-entry?
Your plan is to use a massive piece of infrastructure for a few weeks every 2 years? Sounds cost-effective... I'd be interested to see Starship on your cost/kg vs delta-v graph.
Starship is still subject to the rocket equation. At ISDC2023, I did talk about Starship versus Falcon 9 if you're interested in comparing Starship to Falcon 9. See: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-GvqAM9p4hss.html
Even the most advanced rockets available today are in essence no different than a steam engine. This being heat something up and squirt it out, this will never cut the mustard with regards to interstellar travel.
Awesome, as stupid as spin launch and as dangerous as Tesla's loop. Maybe you need to learn about how easily an implosion will destroy any tube, and please inform me about your magic plasma corks that can withstand a vacuum. You are embarrassing yourself with these mental masturbations.
Maybe a mountain sacred to an indigenous culture that is currently occupied by major institutions that don't care for the landscape causing friction with the indigenous community is not the best place to put that. Just a thought. Good talk otherwise.
