[JohnStu]

Under surveillance by the government? Yes. I have my satellites looking at you right now. No, don't exit the room to look up, look for the missing dark pixel on your monitor, I have a camera there.

[Widdekind]

John Cuthber, on 12 February 2012 - 03:14 PM, said:

Indeed, so you just made the problem 20,000 to 1,000,000 times worse by using radio waves.

You now need a mirror 1,000,000,000,000 metres across to "see" the earth with a 1 m resolution from Pluto using 50cm radio waves...

Essentially the numbers get silly here because the resolution is comparable with the wavelength- so the size of the mirror has to be comparable with the distance.

What about synthetic aperture arrays, that can mimic ultra-long baselines (), for resolution (), at the cost of some sensitivity ?

[Xittenn]

So just for discussion purposes what about Gamma rays emitted by K-40 or even the highly improbable neutrino emission?

Gamma roughs to ~0.5 - 500m, I don't know what frequency of gamma. . . .

I would assume we are already using gamma telescopy to search for life . . . .

or have at least proposed it!

[JohnStu]

Xittenn, on 5 March 2012 - 01:37 AM, said:

So just for discussion purposes what about Gamma rays emitted by K-40 or even the highly improbable neutrino emission?

Gamma roughs to ~0.5 - 500m, I don't know what frequency of gamma. . . .

I would assume we are already using gamma telescopy to search for life . . . .

or have at least proposed it!

They aren't using any sensors to search for life directly, like seeing their "capital city". But rather searching for signs of life. They can tell some planets might have life by knowing that the outer layer atmosphere has high level of oxygen and ozone.

[Xittenn]

That was the idea yes. I was just thinking that it might be possible to resolve gamma emissions over a few elements known to be incorporated into our own biological systems near surface. I don't know how readily this could be done, but I would imagine being able to do so might actually gain us some insight into said capital city. I thought MILDI was orbit to surface gamma spectroscopy but apparently not. I suspect with a large enough array it might be possible to gain some intel. on far away planets, but then again maybe not, I know very little about this sort of thing.

[Schrödinger's hat]

Xitten:
Gamma rays can theoretically be resolved to a much better image, but the practicalities of building a telescope for them outweigh this.
You lose a large portion of your light, focusing it is hard and so on.
As far as I am aware we only use gamma telescopes for observing bright astronomical phenomena. They don't have a lens in the traditional sense, but work by having the light graze along the edge of a mirror.

Imatfaal and Klaynos:
Interferometry.
I know building things down to the wavelength at planetary distances may as well be considered impossible given our current technology, but then so is building a planet-sized individual telescope.
There's also exotic things like gravitational telescopes (use the field around a sun, neutron star, or black hole as your objective lens). I don't think they're ever any good for observing things smaller than a planet though. Something to do with the way the field bends light becoming a good approximation of a lens only at extremely long distances.

[Xittenn]

I was just thinking on the lines of signatures, the resolving matter was distinguishing the above surface from the surface and below. At any rate I'll take your word for it!

[imatfaal]

Schrödinger, on 6 March 2012 - 06:28 AM, said:

Xitten:
Gamma rays can theoretically be resolved to a much better image, but the practicalities of building a telescope for them outweigh this.
You lose a large portion of your light, focusing it is hard and so on.
As far as I am aware we only use gamma telescopes for observing bright astronomical phenomena. They don't have a lens in the traditional sense, but work by having the light graze along the edge of a mirror.

Imatfaal and Klaynos:
Interferometry.
I know building things down to the wavelength at planetary distances may as well be considered impossible given our current technology, but then so is building a planet-sized individual telescope.
There's also exotic things like gravitational telescopes (use the field around a sun, neutron star, or black hole as your objective lens). I don't think they're ever any good for observing things smaller than a planet though. Something to do with the way the field bends light becoming a good approximation of a lens only at extremely long distances.

Well we will soon hear if the square kilometre array will be built in Oz or Safrica - and that's gonna make a substantial leap forward. The Meerkat preliminary observatory (just built to show proof of ability/concept in Saf) has already gone on line and shown good results. I suppose we could envisage in the not too distant future a darkside of the moon array - shielded from all earth light, no atmospheric problems and just a minor logistical problem in getting there

[Ras72]

I'd say the most efficient way to conduct planetary exploration or surveillance would be through micro robots. The way to go would be through storms of more or less intelligent, cooperating, micro and nano bots.

Of course if aliens were studying us it is extremely likely that their technological level would be higher than ours. Once you assume that, then you have to admit they may have every kind of technology we consider remotely feasible and possibly beyond. In which case you can conclude that they could well be studying us right now by whatever means you can (not) imagine and we would have no way of finding out.
Go paranoia go!

[Airbrush]

Ras72, on 24 April 2012 - 03:32 PM, said:

I'd say the most efficient way to conduct planetary exploration or surveillance would be through micro robots. The way to go would be through storms of more or less intelligent, cooperating, micro and nano bots.

Of course if aliens were studying us it is extremely likely that their technological level would be higher than ours. Once you assume that, then you have to admit they may have every kind of technology we consider remotely feasible and possibly beyond. In which case you can conclude that they could well be studying us right now by whatever means you can (not) imagine and we would have no way of finding out.
Go paranoia go!

Yes, if they have been here for a while, they may know more about us than we know about ourselves! Maybe with their advanced technology they can learn more about us in a few years than we could learn about bacteria in centuries.

[space noob]

I'm thinking why would they? If earth found another planet with intelligent life then we would survey it just to weigh up possible risks, but it wouldn't take long to contact them, to beings in another system, earth would be facing towards the sun and have it's back to them so even finding earth would be hard when it's dark to them, possibly playing the Beatles out in to space may have attracted their attention though, I believe that at the point where humans are advanced like we are now is like going up on a chart, at the bottom you have your poop slinging monkeys, in the middle are your cave men and near the top is us, the very top of the graph would be a more advanced species, I don't think we can become highly advanced in a way that resembles sci fi super intelligence, so a species with the means to survey us seems unlikely to me, it could also drain a good bit of a planets resources to launch an operation of that extent, like I said at the beginning there isn't really a reason to, if they where wanting to attack earth from light years away and they had the technology to survey us like that then they could probably do it off their own planet