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‘Oumuamua, Thin Films and Lightsails

centauri-dreams.org

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Re: ‘Oumuamua, Thin Films and Lightsails

#81

Post by gwern »

empath75 wrote: post #61
gwern wrote: post #46

Earlier quoted context omitted.

Fermi's paradox demonstrates it's almost certainly not a light sail. For it to be a light sail which was observed by chance by our totally unprepared observatories after a window of less than a century but also consistent with all our observations of the universe, we would need to hypothesize that we got extraordinarily lucky to observe a super-rare artifact, or that countless (or one vast) interstellar, pan-galactic…

> even atmosphere composition tweaks visible on exoplanet spectrographs I'm fairly certain we can't detect that yet even if they had.

Exoplanet atmospheres can be studied by the transit spectroscopy method. This is how water has been detected, for example. Still no oxygen or any other signatures of life. Lots of hostile atmospheres, though: https://en.wikipedia.org/wiki/Extraterrestrial_atmosphere#Ex...

Re: ‘Oumuamua, Thin Films and Lightsails

#82

Post by empath75 »

gwern wrote: post #81
empath75 wrote: post #61

Earlier quoted context omitted.

> even atmosphere composition tweaks visible on exoplanet spectrographs I'm fairly certain we can't detect that yet even if they had.

Exoplanet atmospheres can be studied by the transit spectroscopy method. This is how water has been detected, for example. Still no oxygen or any other signatures of life. Lots of hostile atmospheres, though: https://en.wikipedia.org/wiki/Extraterrestrial_atmosphere#Ex...

I don’t think we could see a rocky planet like earth though.

Re: ‘Oumuamua, Thin Films and Lightsails

#83

Post by flukus »

lallysingh wrote: post #68
howard941 wrote: post #22

But if it was, is it friendly, or is this place a Dark Forest? https://en.wikipedia.org/wiki/The_Dark_Forest

Dark forests wouldn't waste a round-trip. They'd shoot first. This probe isn't aimed at Earth directly.

They have to know where to shoot, the dark forest theory doesn't seem to account for the ability to send probes.

Re: ‘Oumuamua, Thin Films and Lightsails

#84

Post by undersuit »

Chris_Jay wrote: post #48
stephengillie wrote: post #10

If we send a Voyager-sized probe to Alpha/Beta Centauri, could we use a similar gravity assist to slingshot around one of the stars? How good is our aim across 4.4 light years?

Wouldn't we have a robot steer the light sail as it got closer? Genuine question, this is well outside my wheelhouse.

I think that's the right answer, as it got closer the exact parameters for the slingshot could be refined with images of the system taken a few lightdays out with a strong camera. So we just need that robot really.

Re: ‘Oumuamua, Thin Films and Lightsails

#85

Post by yeswecould »

savrajsingh wrote: post #80
stupidcar wrote: post #76

Given how weird, and apparently unexplainable, various aspects of this object are, shouldn't we be moving heaven and earth to investigate the possibility of some kind of mission to it? From what I've read, there are ideas at least for how we might launch a spacecraft capable of catching up with it. Given the potential of what we could learn, wouldn't that be a better way to spend a few billion dollars than a return t…

We can’t catch it, but we’re on the lookout for the next one

We could catch it with a bigger, faster lightsail

Re: ‘Oumuamua, Thin Films and Lightsails

#86

Post by yeswecould »

skykooler wrote: post #50
gwern wrote: post #46

Earlier quoted context omitted.

Fermi's paradox demonstrates it's almost certainly not a light sail. For it to be a light sail which was observed by chance by our totally unprepared observatories after a window of less than a century but also consistent with all our observations of the universe, we would need to hypothesize that we got extraordinarily lucky to observe a super-rare artifact, or that countless (or one vast) interstellar, pan-galactic…

Or that this was a relatively nearby civilization, and the light sail was intentionally headed toward our solar system (like a few of our proposed interstellar missions to Alpha Centauri).

It could be a weapon, but they missed

Re: ‘Oumuamua, Thin Films and Lightsails

#87

Post by andrewflnr »

gwern wrote: post #46
rossdavidh wrote: post #19

While I find it highly unlikely, it does raise an interesting point about Fermi's Paradox, which is that even if there were enough alien life out there for its discarded light sails to go hurtling through our solar system every once in a while, we might not get any more evidence of it than this article demonstrates. So, it's almost certainly not a light sail, but even if it were, we would never know.

Fermi's paradox demonstrates it's almost certainly not a light sail. For it to be a light sail which was observed by chance by our totally unprepared observatories after a window of less than a century but also consistent with all our observations of the universe, we would need to hypothesize that we got extraordinarily lucky to observe a super-rare artifact, or that countless (or one vast) interstellar, pan-galactic…

Or it's a small piece of a larger, rarer piece of equipment that broke up. Or something we don't really have the imagination for. It's far too early to make absolute statements about what is and isn't possible wrt ETI.

Re: ‘Oumuamua, Thin Films and Lightsails

#89

Post by mrfusion »

It makes sense you would jettison your light sail before starting deceleration approaching earth. That means the things they jettison would pass by us first while the actual spaceship is still slowing down.

Perhaps the main ship is on the way!

Re: ‘Oumuamua, Thin Films and Lightsails

#90

Post by trhway »

StreamBright wrote: post #26

If I were a funny alien civilization and had some time to kill I would totally play skimming stones involving solar systems and Oumuamua like objects.

in a short time, may be even in our lifetime, we'll probably be able to set up manufacturing and sending out of the light sails like this just as a task performed 24x7 by several weaving/printing machines planted on some asteroid having needed raw materials. Given even today's technology something like on scale of hundreds of thousands of such sails can be produced yearly. We just have to get up there.
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