Comments on: Will the next space disaster be a debris collision? And Kessler Blankets.

By: Greg Laden

Greg Laden — Fri, 26 Oct 2012 00:44:51 +0000

The thing is, I assume that “intelligent beings” that develolp space travel will almost always develop space junk, and eventually a Kessler blanket. So, although they may last only a few thousand years, they will be very common. Most “intelligent being’s” will wipe themselves out before they get Dyson spheres. It’s a numbers game. I’m betting on the idiots. Hard to lose that way!

By: Steven Earl Salmony

Steven Earl Salmony — Fri, 26 Oct 2012 00:24:09 +0000

http://www.chasingice.com/

By: travc

travc — Thu, 25 Oct 2012 10:07:54 +0000

The time window seems awfully small. Artifacts/features lasting only a few thousand years aren’t really very useful for ETI hunting.

I’m assuming that there is a relatively effective and efficient technology for dealing with orbiting junk which we haven’t yet come up with yet.

BTW: I also agree with an Asimov story (can’t remember which one) with respect to looking for radio transmissions. Pretty much pointless since the time between discovering radio and deciding that high-power omni-directional broadcasts are a stupid way of communicating is almost certainly quite short.
And I’m ignoring attenuation.

By: Birger Johansson

Birger Johansson — Thu, 25 Oct 2012 08:48:33 +0000

Stanislaw Lem’s satirical “The Star Diaries” mentiones that all systems with advanced civilizations will have suns with lots of cybernetic junk orbiting them after being dumped in graveyard orbits, loudly complaining about their plight in the radio band.

By: Michael Kelsey

Michael Kelsey — Thu, 25 Oct 2012 03:48:41 +0000

@Eric: Thank you! That’s why I’m not an astrophysicist 🙂 It makes good sense, and is a potentially measurable signal: different apparent diameters as a function of wavelength. It might even be something the EHT would (in principle) have the resolution to detect.

By: Eric Lund

Eric Lund — Wed, 24 Oct 2012 21:26:56 +0000

@Michael: Metallic debris would sporadically reflect radio waves in certain frequency ranges that a naturally occurring ionosphere would not. It’s the same physics that prevents wi-fi signals from propagating through metal walls. You’d need a very sensitive telescope covering a wide enough frequency range to see it (and I’m not sure any such telescope or suite of telescopes exists on Earth), but the net effect would be a certain fuzziness of the object in certain wavelength bands.

By: Michael Kelsey

Michael Kelsey — Wed, 24 Oct 2012 19:59:46 +0000

Look for Kessler Blankets, eh? Dyson spheres have a fairly clear observational signature: size of a red giant or supergiant, but a temperature in the infrared (several hundred K).

It’s not obvious (to me, a non-astro physicist) that a planet with a Kessler blanket has a clear signature at all. Maybe one of the astro’s can point out what I’m missing below 🙂

A populated small rocky planet (found via long-term transit observations) in its star’s habitable zone will have an IR temperature around 300 K, just like Earth (i.e. an atmosphere with a moderate enough greenhouse effect to support liquid water).

Add a thin blanket of metallic fragments and organic vapor, and what do you get? Maybe a marginal difference in [Fe/O] or far-IR rovibrational states from the rocket fuel. But will that difference be outside the normal statistical variation of our full sample of such planets? Will the [Fe/O] signal even be above instrumental noise?