Interstellar object ‘Oumuamua covered in 'thick crust of carbon-rich gunk'

A co-worker of mine, upon reading this, opined that my face was carbon-rich gunk. He's not wrong.

If it’s traveling too fast for us to intercept it, it’s location is irrelevant.

If our craft can accelerate fast enough to intercet it, it’s position is still irrelevant since we know it’s trajectory.

You can slingshot off of anything in any direction if you can compute your exit vector correctly. A couple of loops between the Earth and Moon and you could pick up enough speed to get anywhere you want.

The trouble is computing these trajectories is pretty tricky and if you get even one manouver wrong you crater or burn up in the atmosphere.

This paper explores the possibilities for such a mission. It’s not that far fetched technically. But realistically, I don’t think it would happen, even if the object looked more interesting than it currently does.

https://arxiv.org/abs/1711.03155

Wasn't there a practical design using atomic bombs to propel a spacecraft? Alien artifact would certainly justify the budget and risk. Though if a country determined it was alien, they'd probably not share it until their craft was well on the way.

In a slingshot maneuver, the vehicle approaches the planet from outside its sphere of influence on a hyperbolic trajectory, with the hyperbola’s eccentricity determining the angle between its incoming and outgoing velocity vector. From afar, it looks like it “bounced off” the planet, but it really just swung around it. Relative to the planet, energy remains constant — indeed the incoming and outgoing velocity will be the same — but relative to the Sun it will have changed a lot, because some of the planet’s kinetic energy gets transferred to the vehicle.

The downside is you can’t just park yourself around that planet waiting for the opportunity to do such a slingshot. Hyperbolic trajectories are inherently single-pass maneuvers, unlike bounded elliptical orbits. You could conceivably park in a high-energy, loosely-bound elliptical orbit, but to do this parking you still have to lose some of your energy relative to the planet in order to achieve orbital capture, and do a burn to regain that energy later. This is probably counterproductive if your ultimate goal is a solar escape trajectory.

That’s not even the most serious difficulty, though. Intercepting an extrasolar object (aside from a brief flyby, that is) requires not just achieving any solar escape trajectory, but specifically one in the same plane as the target. And even once that is achieved, an actual hyperbolic rendezvous is an extremely difficult maneuver, not to mention time-consuming: with the delta-V budget available to chemical rockets, I’d guess (without having done any calculations) that you’re looking at many decades or even centuries to complete the rendezvous.

Due to the constraints of physics and chemical rockets, spacecraft trajectories are hyper-optimized based on knowledge of the exact mission plan. I don’t think a general-purpose vehicle stationed in the outer solar system would be suitable here.

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

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.

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.

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.

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

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.

We're talking about 200 years before the thing is even 1000 AU away. Even 100 years from now it will probably be comparatively trivial to send out a probe to visit the asteroid, let alone 200. Also, interstellar asteroids might be comparatively more common than we've seen so far, but given the basic factors of how widely separated stellar systems are it's quite likely that they are still very rare. So even if we have discovered many more interstellar objects traipsing through our Solar System over the next many decades I highly doubt we'll have so many that we wouldn't want to visit all of them.

Nonsense. Nickel-iron asteroids are called "metallic," because they're largely made out of, well, metal. Stony asteroids are called "carbonaceous" because they've got a lot of carbon. They're very definitely not called "metal". And astronomers believe that the core of Jupiter is both hydrogen and metallic -- hydrogen compressed to the point where it acquires the property of a metal.

So: there are many things that are neither hydrogen nor helium nor metal, and a few things which are both hydrogen and metal.