B How Sensitive Must SETI Arrays Be to Detect Extraterrestrial Signals?

  • B
  • Thread starter Thread starter Canada Bob
  • Start date Start date
AI Thread Summary
The discussion centers on the sensitivity of SETI arrays and the power required for extraterrestrial signals to be detected from within our galaxy. It raises questions about whether the lack of communication from advanced civilizations is due to insufficient signal strength or inadequate receiver sensitivity. The potential for focused signals, such as laser transmissions, is highlighted as a method to enhance detection chances, especially from nearby stars. The conversation also notes the challenges of targeting specific systems and the need for dedicated observatories to intercept these signals effectively. Overall, the interplay between signal strength and receiver capability is crucial in the search for extraterrestrial communication.
Canada Bob
Messages
20
Reaction score
2
TL;DR Summary
SETI
Fermi asks "why don't we hear from them" could that be because they don't "shout" loud enough or maybe our ears are sensitive enough to pick up a signal emitted by advanced ET's within just our own backyard.

Is it down to the sensitivity of the SETI arrays, or the strength of a signal from within our own galaxy to be picked up by the SETI or any other array on Earth ?

How "loud" would a signal have to be to travel from the further reaches of our own galaxy to be picked up by SETI, how much power would that transmission need ? is it possible to transmit such a powerful signal ?

Yea, I know, it's 6 of one and half a dozen of the other, hopefully there's an overlap as to how strong a signal could be and how sensitive a receiver could be ?

Bob.
 
Astronomy news on Phys.org
Canada Bob said:
Summary:: SETI

How "loud" would a signal have to be to travel from the further reaches of our own galaxy to be picked up by SETI, how much power would that transmission need ? is it possible to transmit such a powerful signal ?
That's not answerable without knowing how directional and focused the signal is. Think of an old fashioned lighthouse with only a flame as a light source. Ships 20 or more miles out to sea can see the flash of light.

But even with a highly focused beam, I think the only chance is from nearby stars.
 
  • Like
Likes FactChecker
IIRC, this is why there's now efforts to search for laser-borne signals.

One 'gotcha' on collimation etc is to use system star as Einsteinian lens.
IIRC, our 'focus' at ~550 AU, ~3 light-days, would give 'a few metres' resolution imaging of stars and planets out to 50-some light-years, 'kilometres' to thrice that.

Snag is each target system would probably need its own observatory and out-riders.

Conversely, the same 'lensing' could be used to practicably transmit towards those systems without requiring 'absurd' beam energies...

Down-side is improbability of intercepting such unless aimed our way...

Could be said that getting out to 'focus' represents a major 'filter'...
 
According to Seth Shostak, SETI searches aren't really looking for radio: they are looking for radar, presumably as part of a meteor early warning system. There is incentive to make the beam as powerful as you can and as directional as you can ( @anorlunda's point).
 
This thread is dedicated to the beauty and awesomeness of our Universe. If you feel like it, please share video clips and photos (or nice animations) of space and objects in space in this thread. Your posts, clips and photos may by all means include scientific information; that does not make it less beautiful to me (n.b. the posts must of course comply with the PF guidelines, i.e. regarding science, only mainstream science is allowed, fringe/pseudoscience is not allowed). n.b. I start this...
Asteroid, Data - 1.2% risk of an impact on December 22, 2032. The estimated diameter is 55 m and an impact would likely release an energy of 8 megatons of TNT equivalent, although these numbers have a large uncertainty - it could also be 1 or 100 megatons. Currently the object has level 3 on the Torino scale, the second-highest ever (after Apophis) and only the third object to exceed level 1. Most likely it will miss, and if it hits then most likely it'll hit an ocean and be harmless, but...
Back
Top