Or maybe it is its skin, and we’re looking at the equivalent of a dead beached whale. One might imagine the funeral rite of interplanetary life forms would be to send their deceased on a deep space trajectory.
Personally, I'm strangely happy that this is turning out to be "just" an ordinary piece of space rock. Imagine if it looked more like a spent booster or a probe from remote observations. We would have no realistic way of intercepting it to learn more about it. It would forever remain an open question whether it was just a strange rock or a once-in-a-life-time missed opportunity to explore an artifact from an alien civilization.
>We would have no realistic way of intercepting it to learn more about it.
Currently.
Intercepting it and returning it from wherever it is 100 years from now could theoretically be easier than intercepting it from when it passed by in the present.
Or if not perhaps in 1,000 years retrieving it and studying it will be trivial; if it's still that interesting by then.
Relevant question: Given that most intercept courses for this purpose seemed to use planetary gravity assists, would it behoove us to park one or two intercept satellites in a high Jupiter / other multi-planet orbit, ready for tasking?
Is there even any such stable orbit? From which minor burns could easily set final, post-slingshot trajectory?
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.
I wouldn't even consider conventional chemical rockets for such a rendez-vous. There already are plenty of other options available: ion thrusters, or the new plasma thruster NASA is currently working on, which is very promising, or a laser sail... even that dubious emDrive if it proves working. The tricky part is really what to do on arrival if we don't want to just pass by it at an enormous speed.
If there was solid evidence that it was of alien manufacture, we would go get it. No question. Access to something like that triggers 'national security' type responses. Projects under that heading have bottomless budgets and high risk tolerances.
We don't have the technology. The fastest object we have ever made is Voyager 1 at 17 km/sec. It got its speed by flybys of Jupiter and Saturn. Oumuamua is going 26 km/sec.
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.
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.
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.
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.
People keep saying this, it's wrong. We absolutely, 100%, will flyby this object, and likely do a rendezvous mission as well.
It may be going fast, but partly that's because it sped up a lot through the inner solar system, as it climbs out of the Sun's gravity well it will slow down a great deal. And the solar system is big. It won't be light-years away in a few decades, of course, it's not going nearly that fast, it'll take nearly two centuries to get 1000 AU from the Sun. So we have all of that time to go out and do a flyby mission. We could put one together today that would reach the asteroid within the next 30-40 years if we really wanted to (at a modest cost of a few billion dollars). If we went wild and spent tens of billions on a mission we could do a rendezvous mission in 20 years. Meanwhile, launch systems are getting better and cheaper so almost certainly we'll get to a point where a realistic 10-20 year cruise timeframe mission is not just feasible but affordable, and then we'll go take a look at it.
> It may be going fast, but partly that's because it sped up a lot through the inner solar system, as it climbs out of the Sun's gravity well it will slow down a great deal.
It doesn't help us much, since we'll be going against gravity too. ∆v required to reach the object won't change significantly over time, and with present technology, it's the strongest factor which determines what we can or can't do in reasonable time right now.
> We absolutely, 100%, will flyby this object, and likely do a rendezvous mission as well
That's a lot of confidence. This is the first interstellar object passing through imaged. However, we believe several of these objects pass through the solar system per year. Why haven't they been detected until now? We didn't have sensitive telescopes doing whole sky surveys like Pan-STARRS until recently. As more projects like LSST come online, we will undoubtedly discover more interstellar objects. And we will learn a lot more about them from Earth-based observations. Perhaps we will get to the point with telescope sensitivity where we can detect them years away so they intercept is simpler. But I do not share your confidence that we will send our first probe to explore interstellar objects to Oumuamua just because it was the first one discovered.
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.
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.
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.
"Practical" in the sense of yes, the physics work, for the ones we know of. And assuming there was reason to quiet the Green crowd from freaking out about us launching nuclear bombs into orbit.
Knowing it's trajectory and throwing something at it fast enough are two very different things. There's no planets between here and there that we could sling-shot off of. Even if there were, we don't have anything to send out to it.
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.
Yes but in some cases, astronomy uses slightly different definitions of key scientific terms: "metal", for example, means anything other than hydrogen or helium.
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.
