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'Oumuamua: Interstellar Object: Rendezvous With Rama?

Yes, 'sub-space' communications aren't a realistic concept. Perhaps a communication system that uses tiny wormholes would be effectively the same, though; a wormhole just big enough to allow the passage of an electromagnetic signal would be completely undetectable in use and would permit an unjammable signal. Other possibilities are neutrino beams or the use of quantum entanglement, both of which have their own theoretical problems.

But this is the problem any attempt at interstellar contact would face - if they are interested in making contact, or just interested in accurate observation of our system, they would be monitoring radio waves as well as a range of other forms of radiation. If we hit it with enough wavelengths and particle types it should detect something, if it is looking at all.
 
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blessmycottonsocks said:
Curious-looking object, very different in shape to most asteroids. Would like to know what natural processes would produce such an elongated cigar-shape.
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Oumuamua's aspect ratio (length to width) is estimated at 10:1.

Similarly elongated bodies are known from our own solar system, but none to date have been attributed this extreme an aspect ratio.

Bear in mind that the attributed shape and aspect ratio have been deduced from indirect evidence. If certain assumptions (e.g., about albedo) are wrong, the estimates may be 'off'.

The leading interpretation I've seen for Oumuamus's apparent shape and lack of any outgassing evidence is that it's a shard from some larger body that disintegrated or suffered a collision / impact.
 
eburacum said:
A very entertaining discussion at Centauri Dreams about this object here.
https://www.centauri-dreams.org/?p=38844
Two interesting points; James Benford (who is the brother of the Sci-Fi author Gregory Benford; both are physicists) points out that the object is roughly the same shape and size as the Shard, and also roughly the same shape and size as many recent concepts for interstellar spacecraft.

Secondly the object is tumbling in an uncontrolled fashion every seven hours or so - this is not optimal behaviour for any kind of interstellar craft. There's no point building a streamlined spacecraft to reduce the cross-sectional area in flight then set it tumbling at random. You couldn't even generate artificial gravity using this sort of Non-Principal Axis rotation; people would just be falling all over the place.
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When it began its journey, it was probably flying in a dead straight line. Billions of years later, it's most likely been hit by all kinds of debris, causing it to tumble. If it is a spaceship, it's not working well right now.
 
It was in the vicinity of Vega 300,000 years ago. It certainly could have hit something during that long journey. But if it has been tumbling for tens, or hundreds, of thousands of years, that sort of negates the idea that it was streamlined in order to avoid such collisions. The streamlining obviously didn't work.
 
Does the idea of streamlining even work in space? What force are you streamlining against?
 
hunck said:
Does the idea of streamlining even work in space? What force are you streamlining against?
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Streamlining in order to make it a smaller target.
 
I dunno, making it smaller one way makes it larger in another.
 
eburacum said:
It was in the vicinity of Vega 300,000 years ago. It certainly could have hit something during that long journey. But if it has been tumbling for tens, or hundreds, of thousands of years, that sort of negates the idea that it was streamlined in order to avoid such collisions. The streamlining obviously didn't work.
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Vicinity Vega? Wasn't he in Pulp Fiction?
 
I saw this on the news earlier today and had wondered if this would have been raised on these forums!

As mentioned, its very unlikely to be an artificial structure, but it's not beyond the realms of impossibility. I mean, why not give it a quick look? We'll find out tomorrow evening (GMT) anyway. Apparently it won't take long for the radio telescope to give it a once over.

It's a bit of a weird shape though, isn't it? Quite spectacular in my humble opinion.
 
hunck said:
Does the idea of streamlining even work in space? What force are you streamlining against?
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Interstellar space contains dust, and atomic and molecular hydrogen. Not much, but enough to make a difference. An interstellar spaceship carves out a long, thin, tunnel or tube through space - not very wide, but very, very long, and anything inside the volume of that tube will collide with the ship.

By presenting a small cross-sectional area in the direction of travel, a spaceship reduces the chances of hitting interstellar debris. This is particularly important if the ship is travelling very fast - at 0.1 c, a grain of dust hits like a bomb. The effects of impacts from the side would be negligible on comparison.

However this asteroid is not travelling at 0.1c or anything like as fast; 'Oumuamua is only travelling at 0.00029 of the speed of light, and there is not much benefit from streamlining such a slow object. The elongated shape does make me wonder if this object has slowed down from interstellar cruising speed somehow.
 
eburacum said:
... The elongated shape does make me wonder if this object has slowed down from interstellar cruising speed somehow.
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I'm not understanding you on this point ... What is it about the elongated shape that insinuates it's ever been traveling at a much higher speed and has now decelerated? :dunno:
 
There is little need for a spacecraft travelling at 0.00029c to be streamlined. That is about 86km per second; only a little faster than the top speed of the Juno probe, which is certainly not streamlined. You'd only need to streamline a spaceship if it were travelling about a hundred times faster than this.
 
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eburacum said:
There is little need for a spacecraft travelling at 0.00029c to be streamlined. That is about 86km per second; only a little faster than the top speed of the Juno probe, which is certainly not streamlined. You'd only need to streamline an spaceship if it were travelling about a hundred times faster than this.
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OK - thanks for the clarification. I thought that may have been the rationale, but I wasn't sure ...
 
Another reason for an interstellar spacecraft to be elongated is the desire to put distance between the radioactive emissions from the drive and the crew compartment. There have been a number of recent conferences on interstellar propulsion and spaceship design, and various kinds of drive have been considered, such as fission, fusion and antimatter; all of these are highly radioactive and give off neutrons or gamma rays in deadly quantities. So the designers usually put the drive system at the end of a long central column or spine, far away from the inhabited section.
Examples below,
trek_anti2

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eburacum said:
Another reason for an interstellar spacecraft to be elongated is the desire to put distance between the radioactive emissions from the drive and the crew compartment.
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As envisioned by Uncle Arthur in 2001 with the Discovery One.
 
Has anyone remarked on the similarity to Arthur C Clarke's classic first contact novel Rendezvous With Rama?

It features an elongated, cylindrical object, initially thought to be an asteroid, entering our solar system. After scans determine it to be of artificial origin, a manned mission is sent to explore. Then the fun begins.
 
blessmycottonsocks said:
Has anyone remarked on the similarity to Arthur C Clarke's classic first contact novel Rendezvous With Rama?

It features an elongated, cylindrical object, initially thought to be an asteroid, entering our solar system. After scans determine it to be of artificial origin, a manned mission is sent to explore. Then the fun begins.
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Yep ... 'Rendezvous With Rama?' was the title of the first thread dedicated to Oumuamua:

http://forum.forteantimes.com/index.php?threads/rendezvous-with-rama.63235/

... and 'Rama' was one of the suggestions promoted for naming it.
 
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When I clicked on the link they wanted money to read more than ~ a paragraph?
 
Yes, they do need to make money somehow.
 
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