Isn't that the shape of the Delta Flyer diving towards the camera?

A rocket engine is a pretty specialized piece of hardware, and without any major world wars going on, who's going to invest in advancing the technology for faster rockets? The airline industry is in dire straits as it is, it's not exactly going to be developing rocket jetliners anytime soon.

So I don't really see which of currently researched techs could make the rocket engine cheaper. I'd like to hear your thoughts on which of the technologies you mentioned (or any others) look likely to produce a better rocket engine?

What makes you assume such time will come without investing in it?

You're suggesting just sitting on our asses and hoping some magical tech will just materialize that will make everything just teddy bears and rainbows.

It proved it could be done. That's pretty meaningful.

Without Apollo, we'd still in 2009 be wondering if putting a man on the moon was even possible.

Now we *know* it's possible, it's just a matter of money.

That's a pretty damn meaningful difference.

Actually no, it's not. They both have the same delta-v requirement.

http://en.wikipedia.org/wiki/Delta-v_budget

From LEO to lunar orbit is 4.1 km/s.

From LEO to L4/5 is *also* 4.1 km/s.

I imagine it's actually cheaper to go to the L-point on the line between Earth and Moon but it's less interesting than 4-5 IMO.

Until someone can come up with that "something better" than ion/chemical rockets, this is the only road available to us.

Travel with us on it, or don't.

We fully understand how massive an operation manufacturing is. That's why we need to get started *now* so we can get something built someday.

We either do something with what we tangibly, actually have, or we sit down and dream about, "oh, we could do so much if only we had MacGuffin so-and-so".

However, propellants can be mined in space instead of exported from the very expensive Earth gravity well. Hence, a mining station. I know I said "smelting", but I didn't mean an exclusively metal processing yard. NEOs have volatiles too, and they can be mined and processed into fuel without needing to import volatiles from Earth. So, a station at L4 that mines both volatiles and metals, would be invaluable to space exploration.

Yeah, that's why we need to build bases at the LPs, so we can finally experiment and figure out if we can make artificial gravity work right to compensate for things like bone loss.

One of the possibilities for radiation shielding is picking an interesting NEO and burrowing inside it, letting its crust take care of the shielding. Or the moon. Either, really. A NEO would be easier to spin up for artificial gravity experiments, though.

I agree that flag-planting missions are pointless. Unless something permanent is built, one might as well not do it.

You are correct, though, when you say that an L4/NEO mining station would have bigger long-term delta-v costs than a moonbase mining station.

We got the Apollo modules to the moon and back. L4/5 are easier to get to than the moon. Ergo, there is no technical barrier preventing us from ferrying Apollo module sized chunks of ISS-A to L4 and leaving them there. Accumulate them over time and build.

You're absolutely correct that moving the ISS itself is unfeasible. I meant building a new ISS, call it ISS-A if you want.

Yes, it would require massive amounts of tonnage to be lifted from Earth, but at least it would be a long-term investment that won't fall out of the sky someday like ISS will. Build it slower than the ISS for all I care, but something permanent needs to be built in space, and unless you get it to a Lagrange Point, it will be a wasted effort.

The delta-v required once you've achieved Earth escape velocity, to the closest NEOs, is 0.8 km/s. That's *half* of what you need to get from lunar surface to lunar orbit, in other words the Apollo lander module's fuel supply would be enough for a trip to a NEO and back, once you've gotten out of Earth's gravity well.

Not really. It just hasn't been tried yet because NASA, for all its achievements, isn't exactly a daring and innovative agency.

There's no big technological barrier preventing us from an L4 - NEO - L4 trip. It's totally within the realm of possibility. It only needs to be done.

There were many other meaningful things to Apollo than just its newness. You may not believe space exploration to be inherently meaningful, but I for one do.

I agree that doing the same thing would be pointless. Instead of just going, planting a flag and coming back home, we should be building an infrastructure in space that will eventually facilitate staying there.

I'm inclined to agree, but I didn't say anything about further than the moon. There's plenty of infrastructure to build inside the moon's orbit. Like our first space shipyard at a Lagrange Point.

I don't really agree with that. Putting an ISS at a Lagrange Point would be far more stable and a 100x better long-term investment than putting an ISS in LEO.

Since an ISS at LEO will require *constant* re-boosting to keep its altitude (its orbit naturally decays about 20km lower every month and fuel needs to constantly be ferried up to keep it from falling down), but an ISS at a Lagrange Point would require trivial stationkeeping.

Therefore, an LP base makes more sense than a LEO base. Now, one could say that a Moon base makes more sense because it has raw materials available, but that is ignoring all the Near-Earth Asteroids, which could be reached from an LP at trivial fuel amounts. You can mine the NEOs just as well as you can mine the Moon, thus building a nifty base at an LP that would serve as a great staging ground for humans in space. No gravity well to descend into or try to get out of.

The #1 thing humanity should build is a mining/smelting/shipyard at a Lagrange Point. Before a moonbase, before anything else, really.

And Flexible Path accommodates those kinds of goals.

I don't concur with that. The Apollo program was implemented under chemical rockets.

Having said that, I fully agree that billions thrown in research for alternative propulsion methods would be spectacular.