11 ms·

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

by avian 9y ago

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.

InclinedPlane 9y ago
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.
- planteen 9y ago
  > 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.
  - InclinedPlane 9y ago
    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.
- TeMPOraL 9y ago
  > 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.
Avshalom 9y ago
Raman's always do thing in threes anyway so we'd have two more chances.
- trusche 9y ago
  Rendezvous with Rama was the very first thing that came to my mind when I first saw the news about this rock. Re-reading it now just for fun.
txmx2017 9y ago
I don’t understand this opinion. We know it’s trajectory.
- theandrewbailey 9y ago
  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.
  - txmx2017 9y ago
    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.
    - edejong 9y ago
      Hate to be grammar police, but 3x it’s -> its. Can read over it once, but the third time becomes annoying.
  - astrodust 9y ago
    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.
- rgbrenner 9y ago
  It's already on it's way out of the solar system: https://en.wikipedia.org/wiki/%CA%BBOumuamua#/media/File:Oumuamua_orbit_at_perihelion.png https://en.wikipedia.org/wiki/%CA%BBOumuamua#/media/File:Oum... Fastest object we've ever made was Juno, which went 25miles/sec (5 years to Jupiter)... this is traveling at ~30 miles/sec, and it's already getting pretty far from us: https://en.wikipedia.org/wiki/%CA%BBOumuamua#/media/File:Oumuamua-solar_system_2018.png https://en.wikipedia.org/wiki/%CA%BBOumuamua#/media/File:Oum...
nkrisc 9y ago
>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.
- ethbro 9y ago
  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?
  - DavidSJ 9y ago
    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.
johngalt 9y ago
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.
- inopinatus 9y ago
  You bring it back to your own system. And only then is the device programmed to activate.
- planteen 9y ago
  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.
  - 0xdada 9y ago
    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.
    - TeMPOraL 9y ago
      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.
  - codezero 9y ago
    For an analysis of possible launch dates / trajectories to intercept, check out this paper: https://arxiv.org/pdf/1711.03155.pdf 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.

by avian 9y ago

InclinedPlane 9y ago

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.

planteen 9y ago
> 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.
- InclinedPlane 9y ago
  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.
TeMPOraL 9y ago
> 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.

Avshalom 9y ago

Raman's always do thing in threes anyway so we'd have two more chances.

trusche 9y ago
Rendezvous with Rama was the very first thing that came to my mind when I first saw the news about this rock. Re-reading it now just for fun.

txmx2017 9y ago

I don’t understand this opinion. We know it’s trajectory.

theandrewbailey 9y ago
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.
- txmx2017 9y ago
  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.
  - edejong 9y ago
    Hate to be grammar police, but 3x it’s -> its. Can read over it once, but the third time becomes annoying.
- astrodust 9y ago
  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.
rgbrenner 9y ago
It's already on it's way out of the solar system: https://en.wikipedia.org/wiki/%CA%BBOumuamua#/media/File:Oumuamua_orbit_at_perihelion.png https://en.wikipedia.org/wiki/%CA%BBOumuamua#/media/File:Oum... Fastest object we've ever made was Juno, which went 25miles/sec (5 years to Jupiter)... this is traveling at ~30 miles/sec, and it's already getting pretty far from us: https://en.wikipedia.org/wiki/%CA%BBOumuamua#/media/File:Oumuamua-solar_system_2018.png https://en.wikipedia.org/wiki/%CA%BBOumuamua#/media/File:Oum...

nkrisc 9y ago

>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.

ethbro 9y ago
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?
- DavidSJ 9y ago
  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.

johngalt 9y ago

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.

inopinatus 9y ago
You bring it back to your own system. And only then is the device programmed to activate.
planteen 9y ago
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.
- 0xdada 9y ago
  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.
  - TeMPOraL 9y ago
    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.
- codezero 9y ago
  For an analysis of possible launch dates / trajectories to intercept, check out this paper: https://arxiv.org/pdf/1711.03155.pdf 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.