Author Topic: Hyperbolic Hyperbole or Interstellar Interloper? ('Oumuamua)  (Read 72249 times)

Online RonM

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #220 on: 11/23/2017 01:02 PM »
So what gravity is generated at the poles of the object given its length and spin rate?

Using SpinCalc with 200 meter radius and one rotation every 7.3 hours yields about 0.0000012 g.

Need to spin it up to about 2 rpm to get 1 g.

http://www.artificial-gravity.com/sw/SpinCalc/SpinCalc.htm

Offline Star One

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #221 on: 11/23/2017 05:13 PM »
New article by Jason Wright.

Is 1I/’Oumuamua an Alien Spacecraft?

Quote
No, I don’t think there’s any reason to think it is, but there’s lots of chatter on Twitter that suggest astronomers think it could be:

Quote
That said, I’m glad that astronomers are, on the informal forum of Twitter anyway, having a SETI discussion about the prospect of discovering interstellar probes passing through the Solar System.  It’s a neat topic, and once worth thinking about.  I hope ‘Oumuamua inspires more real work on it in the peer-reviewed literature, including concrete suggestions of what to look for when future interstellar objects are discovered passing through.

http://sites.psu.edu/astrowright/2017/11/22/is-1ioumuamua-an-alien-spacecraft/

The first comment under the article is definitely worth a read.
« Last Edit: 11/23/2017 05:52 PM by Star One »

Offline hop

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #222 on: 11/23/2017 06:51 PM »
Really, I was just playing around with ideas on how you could get very extended objects with enough tensile strength to spin in 8hrs (especially given the high density numbers from Bannister et al - 5.9g/cm^3 from memory).
As I understand it, the densities discussed in these papers is the density required for it to hold together by self gravity alone, without any strength. From Bannister et al
Quote
Such an ellipsoid spinning in P = 8.1 hours with a/b = 5.3 (Fig. 2) would require a density at least P = (a/b)2(3π)/(GP2) = 5.9 g.cm-3 to prevent it from shedding regolith, consistent with the observed absence of coma. If it is instead a contact binary of two prolate components, each with axes ratio 0.5(a/b) (to produce the same Δm) a similar density of 5.9 g.cm-3 is required to hold the components in mutual orbit. As these densities are unreasonably higher than those of likely compositions of silicate or icy materials, it requires that 1I/‘Oumuamua has internal strength.

If it has any strength, we know nothing of the density, and it doesn't actually need much cohesion to hold together, it just needs to be >0:
So what gravity is generated at the poles of the object given its length and spin rate?

Using SpinCalc with 200 meter radius and one rotation every 7.3 hours yields about 0.0000012 g.

Offline hop

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #223 on: 11/23/2017 10:05 PM »
Nice article touching on the "aliens" question from Corey S. Powell
http://blogs.discovermagazine.com/outthere/2017/11/23/interstellar-asteroid-mystery/

It points to this reference for past spectral identification of artificial objects

Observations of J002E3: Possible Discovery of an Apollo Rocket Body
Quote
In early September 2002, spectral and photometric observations of J002E3 were made at IRTF and Mt. Biglow in an effort to determine whether the object was an asteroid or a human-made. Early observations yielded a possible spin-rate and orientation. Additional spectral observations were completed in May 2003 at the Air Force Maui Optical Supercomputing (AMOS) site. Through the modeling of common spacecraft materials, the observations of J002E3 show a strong correlation of absorption features to a combination of human-made materials including white paint, black paint, and aluminum. Absorption features in the near IR show a strong correlation with paint containing a titanium-oxide semiconductor. Using the material model and the orbital information, it was concluded that J002E3 is a human-made object from an Apollo rocket upperstage, most likely Apollo 12. In addition, the J002E3 observations were compared to spectral observations of other rocket bodies launched during a similar time and the results agree well. Results from the observations and modeling will be presented. This work has been a collaboration of governmental agencies, education institutions, and amateur astronomers. Funding agencies include National Research Council, NASA JSC, MIT, University of Arizona, and JPL.

Offline ChrisWilson68

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #224 on: 11/24/2017 08:37 AM »
Nice article touching on the "aliens" question from Corey S. Powell
http://blogs.discovermagazine.com/outthere/2017/11/23/interstellar-asteroid-mystery/

It points to this reference for past spectral identification of artificial objects

Observations of J002E3: Possible Discovery of an Apollo Rocket Body
Quote
In early September 2002, spectral and photometric observations of J002E3 were made at IRTF and Mt. Biglow in an effort to determine whether the object was an asteroid or a human-made. Early observations yielded a possible spin-rate and orientation. Additional spectral observations were completed in May 2003 at the Air Force Maui Optical Supercomputing (AMOS) site. Through the modeling of common spacecraft materials, the observations of J002E3 show a strong correlation of absorption features to a combination of human-made materials including white paint, black paint, and aluminum. Absorption features in the near IR show a strong correlation with paint containing a titanium-oxide semiconductor. Using the material model and the orbital information, it was concluded that J002E3 is a human-made object from an Apollo rocket upperstage, most likely Apollo 12. In addition, the J002E3 observations were compared to spectral observations of other rocket bodies launched during a similar time and the results agree well. Results from the observations and modeling will be presented. This work has been a collaboration of governmental agencies, education institutions, and amateur astronomers. Funding agencies include National Research Council, NASA JSC, MIT, University of Arizona, and JPL.

It's considerably easier to distinguish human-made artificial from natural objects than it is to distinguish alien-made artificial from natural objects, because we know exactly how we made the artificial objects we have launched.

Offline RotoSequence

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #225 on: 11/24/2017 08:53 AM »
It's considerably easier to distinguish human-made artificial from natural objects than it is to distinguish alien-made artificial from natural objects, because we know exactly how we made the artificial objects we have launched.

The hypothesis that it's artificial in nature doesn't have a lot to go by, aside from a very strange aspect ratio and a lot of wishful thinking.

Offline ChrisWilson68

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #226 on: 11/24/2017 09:21 AM »
It's considerably easier to distinguish human-made artificial from natural objects than it is to distinguish alien-made artificial from natural objects, because we know exactly how we made the artificial objects we have launched.

The hypothesis that it's artificial in nature doesn't have a lot to go by, aside from a very strange aspect ratio and a lot of wishful thinking.

Of course.  But that's irrelevant to my point.

Someone gave one particular reason to think it's natural.  I was pointing out that that one reason wasn't very compelling.  It doesn't mean there aren't other reasons that are compelling.

Even if you agree with a conclusion, it's only right to point out when one of the arguments is flawed.

Offline Star One

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #227 on: 11/24/2017 09:35 AM »
Nice article touching on the "aliens" question from Corey S. Powell
http://blogs.discovermagazine.com/outthere/2017/11/23/interstellar-asteroid-mystery/

It points to this reference for past spectral identification of artificial objects

Observations of J002E3: Possible Discovery of an Apollo Rocket Body
Quote
In early September 2002, spectral and photometric observations of J002E3 were made at IRTF and Mt. Biglow in an effort to determine whether the object was an asteroid or a human-made. Early observations yielded a possible spin-rate and orientation. Additional spectral observations were completed in May 2003 at the Air Force Maui Optical Supercomputing (AMOS) site. Through the modeling of common spacecraft materials, the observations of J002E3 show a strong correlation of absorption features to a combination of human-made materials including white paint, black paint, and aluminum. Absorption features in the near IR show a strong correlation with paint containing a titanium-oxide semiconductor. Using the material model and the orbital information, it was concluded that J002E3 is a human-made object from an Apollo rocket upperstage, most likely Apollo 12. In addition, the J002E3 observations were compared to spectral observations of other rocket bodies launched during a similar time and the results agree well. Results from the observations and modeling will be presented. This work has been a collaboration of governmental agencies, education institutions, and amateur astronomers. Funding agencies include National Research Council, NASA JSC, MIT, University of Arizona, and JPL.

It's considerably easier to distinguish human-made artificial from natural objects than it is to distinguish alien-made artificial from natural objects, because we know exactly how we made the artificial objects we have launched.

Well said. Using human made objects as a baseline in this case seems a complete waste of time.

Offline RotoSequence

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #228 on: 11/24/2017 09:45 AM »
It's considerably easier to distinguish human-made artificial from natural objects than it is to distinguish alien-made artificial from natural objects, because we know exactly how we made the artificial objects we have launched.

The hypothesis that it's artificial in nature doesn't have a lot to go by, aside from a very strange aspect ratio and a lot of wishful thinking.

Of course.  But that's irrelevant to my point.

Someone gave one particular reason to think it's natural.  I was pointing out that that one reason wasn't very compelling.  It doesn't mean there aren't other reasons that are compelling.

Even if you agree with a conclusion, it's only right to point out when one of the arguments is flawed.

I must disagree to some extent. The argument "if they're aliens, we can't know what we're looking for" ascribes gaps in information or other missing pieces to a higher power (sufficiently advanced space-magic), which is a logical fallacy.

Still, I like entertaining the notion of aliens.  ;D

If the asteroid is in fact a ship, the detection of neutral coloration, similar to tholins, suggests active camouflage efforts or a buildup of interstellar debris over an extraordinary period of time. The former cannot be proven without active maneuvers or sending a probe to Oumuamua, while the latter needs a mathematical model to describe how tholins become tightly bound to the body of a ship, unperturbed by close passes to our sun. In addition, it would need to be determined if tholin buildup on a regular asteroid could be distinguished from tholin buildup on an artificial structure.

As an aside, the extraordinary shape of this object fits strangely with how utterly average its spectrum is for objects in the outer solar system; I would have expected its spectrum to reflect the processes that formed such an unusual shape to some extent.
« Last Edit: 11/24/2017 10:03 AM by RotoSequence »

Offline M.E.T.

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #229 on: 11/24/2017 11:04 AM »
It seems a bit strange that the aliens would go to the effort of covering the surface of the ship to resemble an asteroid, and yet retain a very "un-asteroid" like shape, which is what drew our comparatively primitive species' attention in the first place, despite us having very limited ability to track and observe their interloper.

One would think that with only a little extra effort, they could have modified the shape to be nondescript as well.
« Last Edit: 11/24/2017 11:04 AM by M.E.T. »

Offline Star One

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #230 on: 11/24/2017 11:38 AM »
It seems a bit strange that the aliens would go to the effort of covering the surface of the ship to resemble an asteroid, and yet retain a very "un-asteroid" like shape, which is what drew our comparatively primitive species' attention in the first place, despite us having very limited ability to track and observe their interloper.

One would think that with only a little extra effort, they could have modified the shape to be nondescript as well.

How do you know that in their solar system that isn’t a normal shape for asteroids. They might have converted an existing natural object.

Offline eeergo

Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #231 on: 11/24/2017 11:51 AM »
It seems a bit strange that the aliens would go to the effort of covering the surface of the ship to resemble an asteroid, and yet retain a very "un-asteroid" like shape, which is what drew our comparatively primitive species' attention in the first place, despite us having very limited ability to track and observe their interloper.

One would think that with only a little extra effort, they could have modified the shape to be nondescript as well.

How do you know that in their solar system that isn’t a normal shape for asteroids. They might have converted an existing natural object.

Occam's razor would suggest that, if that's a typical natural object in another system, it would be much more likely to have visited us as a natural phenomenon.

There's something that has always bugged me about this being an alien ship: why would they prefer a long shape over any other for a non-atmospheric ship? Ok, I get the O'Neill cylinder concept, but there are countless others with many morphologies... these "elongated shape = spaceship" are too (childishly, IMO) influenced by popular science fiction, and lack imagination -- when their proponents make it seem as if they are the one entertaining imaginative out-of-the-box ideas.
-DaviD-

Offline Bynaus

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #232 on: 11/24/2017 12:19 PM »
There's something that has always bugged me about this being an alien ship: why would they prefer a long shape over any other for a non-atmospheric ship? Ok, I get the O'Neill cylinder concept, but there are countless others with many morphologies... these "elongated shape = spaceship" are too (childishly, IMO) influenced by popular science fiction, and lack imagination -- when their proponents make it seem as if they are the one entertaining imaginative out-of-the-box ideas.

Well, it makes sense for a fast interstellar ship to expose only a small cross-section towards the direction of flight. I guess the best shape would be an elongated ellipsoid with an axis ratio proportional to the relativistic dilatation factor it can reach (so that the ship is an effective sphere at cruising speed). A 10:1 ratio would then correspond to a top velocity of 99.5% c. :)
« Last Edit: 11/24/2017 12:21 PM by Bynaus »
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Offline JasonAW3

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #233 on: 11/24/2017 01:51 PM »
Here's an ejection scenario that MIGHT explain the rather odd shape of this asteroid;

      The asteroid is the remnant of a rocky planet destroyed in a supernova.

      It occurs to me that many have described what would happen to a rocky planet hit by a suprnova's plasma wave front as being much like "a ice ball hit with a blow torch".

      Essentially; the planet is shattered and melted like being in a blast furnace.  As this would produce streamers and huge "droplets" of surface and subsurface materials, the object would likely take on an elongated form as it cooled, especially if it had a slow speed spin applied early on after the initial explosion.  Much like warm taffy being stretched as it cools.

      I would not be altogether surprised if we find that this asteroid has a higher density towards the ends of the object, rather than in the middle.

      Assuming that it is highly metallic as well, filaments of metal would also be stretched out through the structure of the asteroid, both keeping the asteroid from flying apart, as well as keeping it from collapsing into a more rounded shape.

      The tholins on the surface could have been generated by the mixed plasma in the supernova wave front.

      A nova, COULD produce similar effects, assuming the rocky planet in question is in fairly close orbit around its' primary star.

      Just a thought, but I suspect that this would be a good possibility.
My God!  It's full of universes!

Offline Lumina

Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #234 on: 11/24/2017 02:27 PM »
It might've lost its volatiles billions of years ago before it was ejected from its (now long gone) binary star system of origin.

jebbo:
I think the point is that Jupiter couldn't have done it (alone) because they never get close.

Three unusual attributes of this space rock. Elongated, ejected from its home system and free of volatiles.

It's worth considering whether a single cause could explain all three.

For example, a small rocky exoplanet had a near-miss with a Jupiter-sized planet, then another near-miss with its home star, breaking up into splinters, one of which was sent our way. Small differences in direction and velocity at the point of origin would mean that this is all we'd get to see from such an event.

Offline KelvinZero

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #235 on: 11/24/2017 03:14 PM »
I think we will find this shape is fairly common for asteroids that have just formed, and it is asteroids that are not ejected from their solar system that tend to get worn down into something more spherical over time.

https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA20280
https://www.space.com/5587-strange-asteroid-shapes-explained.html

On the subject of aliens, I think what you do the usual scientific process of competing theories. Initially you are just looking for something which is unusual, which is actually discarding all the common natural phenomena candidates. If it looks common without an anomaly, sure it could still be aliens in disguise but you can't do much with that.

Once you have found something really anomalous you are still faced with the situation "Unspecified natural hypothesis beats unspecified alien hypothesis." IMO this means that to progress further you have to look at the anomaly and brainstorm an actual deeper explanation for it, with predictions that can be tested.

The anomaly might a lot of plutonium or other short lived element for example. It is not just that it is anomalous and that we have difficulty imagining the natural process that would gather plutonium, it is also that we can imagine uses for plutonium, such as a powerplant. Then you could strengthen that powerplant theory by finding products of fast fission instead of natural decay (or something like that, Im hazy on the specific products)

Online Mongo62

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #236 on: 11/24/2017 04:06 PM »
I think that there has been a lot of unsupported speculation on this thread. What do we know for a fact about this object?

1. Definitely interstellar in origin, moving at close to the general velocity of gravitationally unbound objects in this part of the Galaxy.

2. There has been no obvious originating exoplanetary system found so far. There are a few possibilities, but all of them appear to have a low probability of being the originating system.

3. The reddish color slope of the object is consistent with an outer solar system object, either asteroidal or cometary. Its color is consistent with a variety of compositions, and in fact is exactly what would be expected for a dormant comet nucleus.

4. The shape derived from its light curve is highly unusual (but not unheard of) for a rocky asteroidal object, but comet nuclei have been found to frequently be quite elongated, although not as elongated as this object appears to be. A small sample size warning for comet nuclei, though.

5. Part of the light curve variations might be due to compositional differences, bringing its shape into the normal range.

6. Its rotation period of around 8 hours is not unusual, and is well over the limit for "rubble piles" of its size.

Conclusion: what we know of this object is consistent with a natural origin in the outer portions of an unidentified exoplanetary system.
« Last Edit: 11/24/2017 04:10 PM by Mongo62 »

Offline Star One

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #237 on: 11/24/2017 04:52 PM »
As this article points out Oumuamua might be a rare type of interstellar natural visitor to our solar system. Perhaps all the more reason to chase after it with a probe.

https://www.centauri-dreams.org/?p=38854
« Last Edit: 11/24/2017 04:53 PM by Star One »

Offline hop

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #238 on: 11/24/2017 07:11 PM »
It's considerably easier to distinguish human-made artificial from natural objects than it is to distinguish alien-made artificial from natural objects, because we know exactly how we made the artificial objects we have launched.
The point of the J002E3 reference isn't that we could recognize all artificial objects spectroscopically, it's that "things that look like asteroids" are a narrow subset of possible compositions, and we have the capability to recognize things that are wildly different.

Even if we had never built a Saturn V, we would have recognized J002E3 as weird. We certainly shouldn't assume that aliens would use titanium dioxide paint (though if they need white, it's a pretty good choice...) but unless deliberate camouflage is involved, using something that was a dead ringer for natural solar system objects would be quite a coincidence.

Offline ChrisWilson68

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Re: Hyperbolic Hyperbole or Interstellar Interloper?
« Reply #239 on: 11/24/2017 07:29 PM »
It's considerably easier to distinguish human-made artificial from natural objects than it is to distinguish alien-made artificial from natural objects, because we know exactly how we made the artificial objects we have launched.

The hypothesis that it's artificial in nature doesn't have a lot to go by, aside from a very strange aspect ratio and a lot of wishful thinking.

Of course.  But that's irrelevant to my point.

Someone gave one particular reason to think it's natural.  I was pointing out that that one reason wasn't very compelling.  It doesn't mean there aren't other reasons that are compelling.

Even if you agree with a conclusion, it's only right to point out when one of the arguments is flawed.

I must disagree to some extent. The argument "if they're aliens, we can't know what we're looking for" ascribes gaps in information or other missing pieces to a higher power (sufficiently advanced space-magic), which is a logical fallacy.

That's not in any way the argument I, or anyone else on this thread, made.

What I'm saying is that if we're considering an artificial object made by aliens, the range of things we need to consider is significantly broader than the range of things we need to consider if we're considering an artificial object made by humans.

It's not that we can't know anything about what we're looking for -- it's that we know less than if we're looking for something we ourselves made.

Still, I like entertaining the notion of aliens.  ;D

If the asteroid is in fact a ship, the detection of neutral coloration, similar to tholins, suggests active camouflage efforts or a buildup of interstellar debris over an extraordinary period of time.

That's only one possible explanation.

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