[cpncrunch]

This assumes that ETs are deliberately transmitting high power signals towards us (or into space in general), although I'm not sure that is a reasonable assumption. I think it would generally be unwise to loudly announce a civilization's presence.

According to chatgpt, our current earth-based radio telescopes would only be able to detect signals equivalent to radio leakage from earth at a distance of 1 light year.

[XorNot]

It's mostly not reasonable to try and ascribe human motivations to alien entities, particularly when we know some humans would definitely fire up the transmitter if they could.

The presence or current lack of alien signals at the very least bounds estimates of local population density and what energy scale they're operating on. Currently there's no nearby Type 1 Kardashev scale civilizations.

[cpncrunch]

Yes, there are arguments for and against sending out a strong deliberate "we're here" signal. But I guess you could also argue that the possible danger in announcing our presence is fairly well mitigated by the speed of light, as there are unlikely to be any other advanced civilizations within a few light years.

[socalgal2]

I heard this as well by scientists from JAXA. They gave a presentation on SETI.

When it came time for questions I asked. So, if we were at Alpha Centari could we detect signals from earth with the tech we currently have? They said "No". That was 2019. Maybe tech is better today?

[jacquesm]

But what did you think?

[cpncrunch]

What did I think about what?

[jondwillis]

ask chaptgpt about space telescopes

[adastra22]

There are no space-based radio telescopes.

(Well, none pointing at stars at least. There are some spy sats pointed down.)

[dylan604]

could you imagine something as big as Arecibo was or FAST is floating in space? That'd be impressive. Would a constellation set up more like VLA be possible? Keep increasing the size of it with Starlink like launches??

[NitpickLawyer]

There's a proposal for a large constellation of small, cheap-to-build radio sats. Heard about it on a Fraser Cain podcast. They plan to send them to one of the Lagrange points and spread them out in x KM cube pattern. They also want some of the sats to do some RF processing on-site, and beam just the "results" back.

[toxic72]

These aren't telescopes, but it is quite similar to what you're describing otherwise:

https://research.google/blog/exploring-a-space-based-scalabl...

[adastra22]

What's the point? The frequencies being listened to on these radio telescopes aren't affected by the atmosphere. Arecibo in space doesn't get you anything that Arecibo on the ground didn't (except hurricane resistance, I guess).

One exception is the far side of the moon to get away from radio noise. But other than that, there's no reason to put a radio telescope in space.

[defrost]

I'm a fan of ground based radio astronomy, however:

> there's no reason to put a radio telescope in space

sadly isn't as true as it once was ..

* https://www.aanda.org/articles/aa/full_html/2024/09/aa51856-...

Once that constellation is fully expanded as intended, the planned chinese constellation joins it, and other nations (India?, the EU?) pile on, things will get even noisier.

The dark side of the moon offers hope, but it's still a lot of addiional awkwardness and expense that could be avoided with better attention to "the commons".