A ground-launched Orion could be built now, but it'd make a mess when it launches, and it'd probably be much too small for a useful interstellar mission anyway, because of that scaling problem I mentioned. The stresses are just too high, and it's pointless because you don't need a ship that rugged in space, only for transiting planetary atmospheres.
I don't think we have the capability now to build a sufficiently large ship on the ground anyway, even if we decided to say "screw it, we don't care if it's wasteful to massively overbuild this thing"; our materials science probably isn't up to the task. So we need to learn to build things in space anyway.
No, we don't really have this capability right now. But we need to assume we'll have it when we need it, and we need to work towards it, and not try any kind of missions requiring it until we do. Thinking about interstellar missions right now is really putting the cart before the horse; we haven't even gotten manned missions beyond the Moon, and even those were pretty simple (walk around, hit some golf balls, drive a rover around), not anything involving real work such as building a habitat or serious excavation or mining.
This is why I think all this talk about going to Mars is silly too; we need to be concentrating on closer things, like near-Earth asteroid retrieval and prospecting, and building a Moon base, and figuring out how to mine materials and build larger ships offworld. We need a bigger ship to go to Mars, not some little tin can that you can stick on top of a rocket; something the size of the ISS would be good, because the crew will have to be trapped in it for months, and they need stuff for landing on the surface and doing real work there. You can't do all that with something the size of the lunar modules we launched on the Saturn V.
I don't think we have the capability now to build a sufficiently large ship on the ground anyway, even if we decided to say "screw it, we don't care if it's wasteful to massively overbuild this thing"; our materials science probably isn't up to the task. So we need to learn to build things in space anyway.
No, we don't really have this capability right now. But we need to assume we'll have it when we need it, and we need to work towards it, and not try any kind of missions requiring it until we do. Thinking about interstellar missions right now is really putting the cart before the horse; we haven't even gotten manned missions beyond the Moon, and even those were pretty simple (walk around, hit some golf balls, drive a rover around), not anything involving real work such as building a habitat or serious excavation or mining.
This is why I think all this talk about going to Mars is silly too; we need to be concentrating on closer things, like near-Earth asteroid retrieval and prospecting, and building a Moon base, and figuring out how to mine materials and build larger ships offworld. We need a bigger ship to go to Mars, not some little tin can that you can stick on top of a rocket; something the size of the ISS would be good, because the crew will have to be trapped in it for months, and they need stuff for landing on the surface and doing real work there. You can't do all that with something the size of the lunar modules we launched on the Saturn V.