WI: Elon Musk pushes Launch Loop?

First, a quick forward: I wasn't sure whether to put this in FH or Post-1900, and settled on this forum because a) I am posing this happens prior to the present and b) I'm more interested in the impacts in our general time, rather than decades out from now. But I won't protested too loudly if a mod decides this is better placed in the FH subforum.

Anyway, the premise here is that Elon Musk (or Jeff Bezos, it really doesn't matter) falls in love with the idea of a Launch Loop, rather than reusable rockets. Advocates claim that one could be built in the ballpark of $10 billion. So, SpaceX becomes a company dedicated to the idea of building one of these massive machines. What happens?

Note that I'm not asking "What if Elon Musk builds a Launch Loop?" What I'm asking is "What if Elon Musk decides he wants to build a Launch Loop, instead of building reusable rockets?" In other words, the discussion is about the attempt to do so, and the consequences in the near term

Things to consider:
- He brings his celebrity to the idea
- Launch Loops need a lot of space on the ground (2000 km), who is going to humor him, if anyone?
- There's less of an opportunity to build on incremental improvements: either it works amazingly better than current tech, or not at all. No gradual transition from just launching rockets, to launching and recovering the first stages, to launching and recovering both first and second stages.
- How does this influence the rocket market? There's one less competitor, but there's still Blue Origin (or SpaceX, if we've swapped out Musk for Bezos)
- Would SpaceX be able to secure gov't contracts, as it has in reality? Would it starve for customers until it could (maybe) get the thing working? Or would NASA be pumped to see someone else throwing money on a grand project like this, and do what they could to support?
- How does this mesh with his HyperLoop idea?

Discuss amongst yourselves.
 
He brings government funding to whatever he does so that helps.

Getting the kind of space for that isn't too hard at all, really. Alaska or the Nevadan desert have more than enough space and nobody using it.
 
- Launch Loops need a lot of space on the ground (2000 km), who is going to humor him, if anyone?

Australia, Argentina, Canada, possibly the United States or even Russia? Although land rights will be a huge issue in any case, and you'd have a coalition of ranchers, environmentalist, and indigenous groups opposing the construction no matter where you build it. Australia is the best since it's closer to the equator.

Saudi Arabia might be a possibility too, but there's a higher potential of terrorism and the bad PR of working with the Saudis considering the human rights situation. Parts of it might need to be in nearby countries (Oman, Jordan) since it doesn't seem there's a 2,000 km stretch of land in Saudi Arabia. Still, the Saudis have a lot of oil money, and having a launch loop would ensure continued economic prosperity even after all the oil's gone/price of oil permanently collapses.

Alternatively, you could put the thing in Antarctica, after you've called a global conference to amend the Antarctic Treaty. This would increase the cost immensely, as well as increasing the launch costs since you need to ship whatever you're launching into space to Antarctica to begin with.
 
Antarctica is a bad idea due ethics, totally dire logistics and losing the velocity assist from Earth's rotation. Australian outback may be best compromise, provided you stay well clear of Ayers Rock aka Uluru and ask very, very nicely...
 
Just a reminder that you’ll want to build it as close to the equator as possible. Building over water is the most likely scenario, though you’ll still likely want to have it start on land, and face east. So, some equatorial east coast.

Maybe we should change this to Jeff Bezos, since Brazil’s equatorial coast happens to be where the Amazon empties out into the Atlantic.
 
Indeed! Building at the equator, launching at zero inclination, is the only way to put a continuous stream of penny packet payloads into a common orbit from which they could all be gradually gathered up to a single space station--though the volume of launch would be such that one would very quickly go over to having many stations, a half dozen or so.

At any other latitude, each separate launch, going into a fixed inclination (presumably due east so the inclination matches the latitude pretty closely) puts the payload into a different orbit--same inclination, but different nodes on the celestial equator; to move material from one of those to another is the same problem as changing inclination anyway. Only launching straight east from the equator puts all the payload into the same plane.

And of course the Pacific Ocean offers plenty of choices of ranges, well under the aegis of the USN, on the equator where a sea-based launcher could be located.

At other latitudes, every 12 hours a given orbit coincides, but the whole genius of something like a launch loop is that you launch a heck of a lot more often than every 12 hours, otherwise it is too expensive relative to payload throughput to be competitive.

Unfortunately the equator, especially in the mid-Pacific, is logistically expensive to reach from most industrial centers--this would give a strong preference to Australian and East Asian based industrial nations. The USA is sort of competitive but Europe is pretty well shut out.

And having reached an equatorial low orbit, with shepherd tugs or individual OMS on each payload packet bringing the loads to central processing at a station or six in a higher orbit, the stations are not in a convenient place for many purposes. Excellent for sending geosynch satellites on up, poor for any other purpose; visual coverage of the ground is poor, being restricted just to limited line of sight above the equator; the plane of Earth's equator is not ideal for launches to the Moon or most solar system objects beyond.

But considering the tremendous savings on the cost of mass to LEO versus using a rocket, we could then afford to be prodigal with things like inclination changes! The very worst case is to achieve a polar orbit. The rule is delta V =2 x Sin (Theta/2) * V-sub0, the latter term being the orbital speed at a given altitude. To turn 90 degrees then we need 2^1/2 * V-sub0, which is considerably more than a rocket launching into a polar orbit from the ground would cost. But don't give up yet; in LEO we can use a smaller and more efficient rocket than we might get away with for a ground launch where the name of the game is brute force at first. Say we had a 3 tonne satellite, and we want it in polar orbit. We could use a single RL-10 producing about 7 tonnes of thrust at Isp of about 450 sec. We would need as much as 62 tonnes of stage to put that little payload into polar orbit by sheer rocket thrust alone; this admittedly sucks. Still putting 65 tonnes of materials up to assemble such a "tug" would perhaps be a lot cheaper than launching 3 tonnes on a normal OTL EELV rocket directly into polar orbit.

We can do better. Imagine that instead of using rocket brute force alone, we could aerodynamically bank off of Earth's atmosphere. Supposing we can manage a lift/drag ratio at hypersonic speeds of 4, and that target orbital speed is about 7800 m/sec at roughly 100 NM circular altitude. First we must lower the orbit a bit so that at perigee the craft is in atmosphere thick enough for decent lift. Getting the necessary lift force will generate drag, which slows the craft down--we need to restore the lost speed for it to return to apogee. The same mission will require an order of magnitude less overall mass I believe; 6 or 7 tonnes ought to do it, and doing it twice (to return the shuttle vehicle to equatorial orbit) would require something like all up 14-15 tonnes, and we have a craft capable of the same mission many many times.

Thus, a single launch loop can shift all mass from Earth to LEO, where it is gathered up by patrolling tugs to a few stations in equatorial orbit, and from there dispatched, after being aggregated and assembled into whatever inclination we desire. For redundancy's sake we'll want several launch loops.

Sadly, the economics of this makes sense when one proposes really grandiose scales of spacecraft in orbit, but on a smaller scale it is said "there is no demand" for the capability. I think this a little bit fatuous in that in if someone does build it, the demand will emerge--but it is certainly true that convincing a board room of investors that this will happen before the fact will be a tough sell. No one invests therefore.

I think it is scandalous NASA has not at least pursued a few small scale projects, as a proof of concept and opportunity to work out anticipated bugs. But that isn't the most outrageous scandal of NASA management this past generation alas.
 
Hyperloop as it is hyped is already pie in the sky, and this is several orders of magnitude more difficult.

No one is talking about using magnetic suspension for Hyperloop, for speeds of (only!) .3 km/sec, and they acknowledge the difficulty of maintaining a near-vacuum over a few hundred km.

Thousands of kilometres of iron tube magnetically suspended in vacuum and moving at 14 km/sec? That's a lot of power going into something 5cm in diameter, with nowhere for the heat to go. At that speed, if the terminal loops are 200km radius, the cable is experiencing 100 g. What is the tensile strength of hot iron again?
 
For the record I don't see Musk doing this, because he is very much a means to an end guy. What he wants is to go to Mars and live there, and his projects are incremental steps toward that goal. If a launch loop system and still more evolutions from it existed, his goal would be far easier to reach, but the up front investment cost is always going to be too big a leap for him to make by himself. If the combination of his vision plus incremental launch cost reduction persuaded a lot of other people to adopt comparably grandiose visions, then together they might see a case to split the cost of developing a loop system. But he doesn't plan on such optimistic scenarioes; he plans on what is attainable by his own efforts and taking advantage of as much help as he can leverage. So if suddenly there was a huge "go to orbit" bandwagon, he'd trim his sails accordingly but barring that event, he'll stick to cheapening rocket launch, until the Mars colony he envisions is in reach, then go to Mars and I guess the rest of us are on our own after that. Presumably he'd keep his hand in by remote control and if his assets left over are enough to stay in the game SpaceX will plod on, and may get round to a launch loop eventually.

My personal bee in my bonnet is that there is a lot of enthusiasm for geosynchronous "sky stalk" type systems, and these bug me because I don't like how they preempt orbital space all the way up to geosynch and beyond; then too I dislike how long it takes to ride an elevator at reasonable rail speeds all the way up to geosynch, passing through the Van Allen belts slowly and being exposed to galactic cosmic rays all the way. This is why I prefer the idea of low Earth orbital belts, essentially more or less continuous rings under tension because of dynamic elements constrained electromagnetically into LEO sized circular paths, with the dynamic elements going faster than orbital speed. Such rings can drop elevator cables from them to bring material up above the atmosphere, and then ride on the ring in the same fashion as a launch loop to reach speeds in excess of escape velocity to be flung out on free trajectories on fast paths to the Moon or beyond. Rings tethered to Earth's surface will be automatically precessed by the tension to track the Earth's surface, so a ring set up at an inclination to the Equator would automatically be held on a great circle path over Earth's surface; they can double as a transit system above the atmosphere allowing transfer to distant points on Earth with good energy efficiency and very high average speeds. It would be a lot slower than suborbital transfer but also a lot more flexible.

I actually envision a dual system; an Earth anchored system would enable Earth point to point transport and serve as a means of transfer from Earth to space and back; this would channel through a dual equatorial system, the equator serving as a "bevel" as it were on which a second, farther out equatorial belt would ride coupled and stabilized, to enable a second system that does not turn with Earth but rather stays fixed in the plane of the ecliptic. I envision several loops in the outer system; the equator which is the contact with Earth that stabilizes it (a rigid ring centered on Earth's center is not stable; if it drifts it tends to fall down with the attraction on the part nearer Earth outweighing the weakened attraction on the part farther away--putting down several widely spaced tethers to the surface would stabilize it; this cannot be done for the outer set that is not precessing around as part of the rigid Earth's rotation so the equator is the only common point of contact, along with polar tethers at each pole) and serves as a transfer zone.

Such a system allows access to medium deep space somewhat faster than via a "Beanstalk" and does not clutter up most of space with fixed structures.

I am less sanguine than I used to be because I came to realize that in engineering terms the tension on the rings probably would be comparable to the beanstalk requirements and so require similar materials. We can lower the tension down to zero but the lighter the tension, the more mass we need to build into it to lift a similar load. One way or another the engineering task is of similar magnitude. I think we could get going on a Launch Loop today, pending necessary R&D to address some problems of stability foreseen--which is what NASA should have been doing this past generation; the launch loop idea has been floated widely at least since I was in high school if not longer. (That was the early 1980s). Some somewhat useful form of orbital loop is probably feasible at considerable cost today as well, if not already back in the '90s. But the really nifty extensive system I hope for would indeed be a project for a day when we could "just as well" build a Beanstalk.

We hates it, Precissious, yess we doess! Want pretty ringsses! No nassssty Ssstalkesses!

Any and all of these projects require huge investments up front as well as posing political issues so I don't have too much hope of seeing any of them happen and worry the whole world system may collapse us into Dark Ages before any are built as well. Too bad.
 
Hyperloop as it is hyped is already pie in the sky, and this is several orders of magnitude more difficult.

No one is talking about using magnetic suspension for Hyperloop, for speeds of (only!) .3 km/sec, and they acknowledge the difficulty of maintaining a near-vacuum over a few hundred km.

Thousands of kilometres of iron tube magnetically suspended in vacuum and moving at 14 km/sec? That's a lot of power going into something 5cm in diameter, with nowhere for the heat to go. At that speed, if the terminal loops are 200km radius, the cable is experiencing 100 g. What is the tensile strength of hot iron again?

I believe Loftstrom and others did the math on the thermal aspects, which are the major constraint on launch rates--which would still be orders of magnitude higher than conventional wisdom says is "demanded." Note that when the cable, or system of free-flying separate pellets in some concepts, is being turned around on the ground they are embedded in much more massive structures that take the G-load; the tension on the moving elements if any can be kept low there. There are other issues of dynamic stability that need to be addressed, per some critics anyway, but I think there is nothing like experimental efforts to make scale models to tackle those, and I'd think they could be licked with enough ingenuity.

The killer problem remains that no one with resources to spend on solving these problems and paying to build any kind of dynamic launch system is very keenly interested in doing so, not with real money.
 
I would like to remind everyone that my question was focused on the efforts to build a launch loop, rather than the ultimate results, which are better suited to the FH forum.
 
I would like to remind everyone that my question was focused on the efforts to build a launch loop, rather than the ultimate results, which are better suited to the FH forum.

Donald Trump calls Elon Musk "Loop Man" on Twitter or something for his two big ideas of hyperloops and launch loops. Or he becomes known as a "loopy" guy in comedy/pop culture.
 
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