We didn't have the tech for nuclear bombs until we decided we wanted to blow up cities. We didn't have the technology to go to the moon until we decided we wanted to go there. A little more than ten years ago the Motorola Razr was the height of mobile phone design.

Stuff like NERVA or Project Orion stayed proposals not because they're impossible, but because there's nowhere we really need to get that fast to justify the risks/expense/fallout.

"We need to get to this interstellar starship" would change the cost/benefit ratio of developing the tech needed.

NERVA was actually prototyped in the 60s, right? Dirty, but something that was known to work.

Certainly it would be impossible for NASA in it's current state.

Don't underestimate the gap between a science/jobs program like NASA vs what happens where there is an acute national interest. A derelict alien spacecraft would present an objective that no world power could ignore. Nation states taking enormous risks and spending hundreds of billions would make our current space program look like hobbyist work. In that setting, I would hesitate to say what is impossible.

For an analysis of possible launch dates / trajectories to intercept, check out this paper: https://arxiv.org/pdf/1711.03155.pdf

In summary, you're pretty much right. If we could launch in 2017, we could have done it, but I don't think we have any spares of Rosetta or similar intercept missions sitting around.

Cool paper. I used to work in the space industry. When I said "We don't have the technology", I meant there is nothing at Technology Readiness Level (TRL) 6 using NASA's ratings. Current state of the art is TRL 1 or TRL 2.

https://www.nasa.gov/sites/default/files/trl.png

That image will prove valuable to me.

Now - whenever people accuse me of never finishing anything I shall respond that I'm actually achieving TRL2 across a broad front.

All we would need is to send a bunch of fuel in parts, dock all of them and fire the strongest engine we have. It _is_ rocket science, but I don't think it's far out of reach if we have the money to spend on resources.

That is indeed how you do things in Kerbal Space Program, but back on Earth, it would require at least a few procedural - if not technological - breakthroughs to pull it off.

Which is to say - I'm all for it! The sooner we make those breakthroughs, the better.

Where there is a will there is a way. Exciting prospect.

Small robotic probe accelerated by a few nukes (positioned along the way by conventional ships) hitting a blast shield?