[extropy-chat] Space colony behind the moon?

Robert Bradbury robert.bradbury at gmail.com
Wed Oct 18 19:12:05 UTC 2006

On 10/18/06, John B <discwuzit at yahoo.com> wrote:

> How hard is it to see a 300 Kelvin object against a 2
> Kelvin background? And that's assuming only
> shirtsleeve conditions - no motors or other
> 'hotspots'...

It would be more like a 20-40K background within the solar system and its
not hard at all.  The detectors in any IR telescope could manage it.  Our
mid-to-far IR technology isn't great (it isn't at the level of a 10
megapixel visible light camera for example) but that is because the market
for such sensors isn't as large not because we can't really figure out how
to do it.

The real question isn't what temperature is it at as much as it is how much
power is it radiating on an areal basis?  If its only radiating
0.00001W/m^2 [1] its going to be hard to detect no matter *what*
wavelengths the
photons have.


1. Thats an arbitrary number.  The better way to look at it is whether its
radiator size and our detector size are sufficiently matched that we can
count photons at specific frequencies at levels significantly greater than
the equipment or background noise.
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