Rakaydos

It only violates physics if it works in a true vacuum. If it works in a merely high vaccume enviroment like space (even at a lower efficency) it retains many of it's advantages without breaking physics.

Actually it's just the costs of flying the materials, rounded up multiple times to allow for other expenses. I couldnt find raw material prices for any of the candidate materials, but I'm assuming the materials costs are going to be lost in the launch costs... though I could be wrong. Labor and machinery I left off entirely- I have n idea where to begin for that kind of expense.

How heavy of a railgun? how many launches to assemble, what kind of lander are you using to put it on the moon? I'm trying to put a pessimistic price tag on assembling the elevator, so there's a good price comparison to other space efforts.

Of M5 fiber, with a constant-stress exponential taper? According to the PDF I linked (I assume they did the math correctly), a bit shy of 1,000 tons. It's on Page 15

I dont see a mars trip being launched straint into MTO, without a lengthy assembly period on earth orbit. We arnt taking about living in the transfer engine's fuel tank, just in the equivilant to the Shuttle's External tank boosted into orbit and modified into a livable pressre vessel.

A lunar space elevator is a proposed piece of infrastructure to make space exploitation easier. Unlike most plans, it has nothing to do with decreasing costs from earth's surface to low earth orbit. Instead, it reduces payload mass by making missions to the moon (and potentially beyond) easier and less Dv intensive. So how expensive would one be to create, with current technoligy? Based on this pdf (http://www.niac.usra.edu/files/studies/final_report/1032Pearson.pdf) building an elevator who's counterweight is entirely cable, assuming a constant-stress exponential taper (it gets wider closer to L1 because it's holding more weight), is on the order of 300,000 km. (edit: fixed an order of magnatude error) That is also the minimum mass that would need to be launched from earth to bring the system online. However, once the system is online, you can build a counterweight out of lunar rocks, reducing the amount of cable needed to keep the system functional. This lets you repurpse those strands to reinforce the main cable, allowing the tram to carry more mass to orbit on each trip. So the initial Tether needs only to have enough strength to bring the tram down with a small excavation bot and back up with a load of lunar rubble- it can be reinforced after construction. The existing math assumes modern high strength composits, such as Carbon Fiber, Kevlar, or M5 Fiber. Page 21 of the PDF posted earlier shows the densities of canidate materials, and their stress limit. I have not been able to find costs per KG for these materials, but we can estimate the mass of cable needed, and calculate the number of launches needed- however mind boggling 300 km of rope is, the launch vehicals are still probably going to be the majority of the price. On page 15 of the linked pdf there's an estimate of the mass of an entirely cable lift, presumably made from M5 Fiber, the selection that is givin the most weight in that paper, somewhat shy of 1,000,000 kg, or one thousand metric tons. (rounding up to include spools and such to manage the fibers) A Falcon Heavy has a promised price of $90mil for 6.4 tons to GTO. lets round that down to 5 tons to L1, so the elevator will need on the order of 200 Falcon Heavy (or equivilant) launches to build. That works out to 1.8 billion dollars to launch the elevator, plus bulk material costs. Of course, rockets get cheaper the more they're flown, and a lunar elevator would be buying launches in bulk. it's concevable that the effort to build a Lunar elevator would itself drive the launch prices down. And once it is in place, it would help stimulate demand for lunar missions, including surface mining, refining, and production of space-rated equiment that would be far cheaper to "launch" than anything bade earthside.

Wet labs would be an interesting way to supplement spaced based manufacturing. If every upper stage you launch has a functional airlock on the o2 tank and systems to bleed the excess pressure (once the liquid o2 becomes gas o2), then once in orbit you can 3d print basic habitation equipment inside the tank. Bonus points if the insulation on the tank is made of salvagable 3d printable materrial.

I'm sure any number of "space realists" would be happy to point out various sources saying it would never happen. but that's beside my point. My point is that the Fermi paradox presupposes an innate expansionistic attitude that I feel would never survive the alien equivilant of the Cold War- the very worldview that would drive a species to space would drive that group's subspecies to throw nukes at each other, ending the expansion before it begins. We have one of the best shots of overcoming it, and I weep inside each time we, too demonstrate that lack of will.

So, other than cuting into propellant load, what's the reason yo cant build a workshop into the tank walls before filling and launching the tank?

Which is why I say this is the answer to the Fermi paradox. It will never be economical to expand a species into space, and the most economical approach is also the one most likely to end the species.

Do you happen to know what the hazards of occupying a spent LOX stage might be?

All the particle accelerators in the world would take decades to produce even a single gram of antimatter, and our storage techniques cant handle containing antimater for that kind of delay. Not this century.

5 trips, and that's it. And that's from a small, marginably life-bearing world that has no less than 4 major nearby colonizable bodies (Moon, Mars, upper Venus atmosphere, and Calisto). Our solar system is practically made for beating the fermi paradox, and not even we can muster the economic willpower to take more than the first step. If we cant do it, why should any other species?

No because it's taken 50 years for Voyager to get to interstellar space, and I dont see us launching another expedition in the next 35 years.

That's not the hard part, the hard part is surviving it. The ability to wipe ourselves out is limited by the very restrictions we impose that keep us out of space.

The fact that space pessimists are mostly right is the ANSWER to the Fermi paradox. It is effectively impossible to both survive controlling the atom, and to cost effectively explore space. if you have one, the other will get you.

...And this is the answer to the Fermi Paradox.

Or buried in riots.

Lighter than a Saturn 5 stage, though... http://www.thespacereview.com/article/1045/1 Was never actually built, but still...

It's a symmatry thing. you can turn energy into momentum, but it has to balance out- a photon out the back to push the vessel foreward. EM drive is way more energy efficent than that, implying it's pushing off SOMETHING. It transferring momentum to the nearby not quite vaccume, hwever, is almost as good. you lose efficency the farther you get from an atmosphere/star/galaxy, but it would still be entirly electrically powered space drive, without breaking physics.

...or just catch it before it reaches the water. Seriously, this is a plan sponsored by ula of all people- its easy, simple, and conservitive, requiring very little engineering effort. SpaceX's plan works better for the boosters, getting 100% recovsry, but core stage recovrry with spacex cuts deep into mass to orbit. The ULA plan recovers 90% of the costs without the mass penalty for the core stage- or the extra mass of wings for yhe booster and horizontal bracing to land on its s ide.

A singularity is a mathematical concept. Dividing by 0 is a singularity, as it simotanously generates an answer of infinity and negative infinity. What happens to mass that is so dence it overcomes it;s own resistance to becoming denser is a singlarity. However, there's a few theories that present alternatives. For instance, the theory that quarks break down into their compoent strings (in string theory) and become a single string-ball.

Basically taking the entire second stage+ payoad, sticking a NERVA on it, and everything else is fuel tanks for the NERVA, (or scaffolding to mount fuel tanks for the nerva) to be filled in orbit by later flights. Once in orbit, that upper stage becomes the engine section of a vehical assembeled in orbit. As a functional upper stage, it can be larger/more massive than it could be if it was just a payload.

Did you include the payload mass as more fuel? because the point of the design is that you can build the payload bigger because it helps lift itself.

Here's an idea, design your NERVAs to replace the normal upperstage of a Falcon 9/Falconheavy, Vulcan, or other existing launch system. Instead of expending the stage, dock it, refuel it and use it to propel the mars mission. This way it's managing it's own mass and size, helping itself get to orbit, while retaining the utility of existing launch architecture for the lower stages.