Heat Signature Of Space Craft

[Moontanman]

How far away could a 500 mega watt reactor be detected by it's heat signature? If a nuclear powered space craft were "cruising" by and it had to obey the laws of thermodynamics it should have a significant heat signature. Since getting rid of waste heat in space would require large radiators shouldn't an infrared telescope be able to pick up such a space craft?

[CraigD]

If a nuclear powered space craft were "cruising" by and it had to obey the laws of thermodynamics it should have a significant heat signature. Since getting rid of waste heat in space would require large radiators shouldn't an infrared telescope be able to pick up such a space craft?

I’ve not tried calculating it, but given how sensitive modern infrared telescopes are, and how close the hypothetical spacecraft would be compared to their intended exoplanet targets, I’d guess yes, a present day space, aircraft, or ground-based infrared telescope could spot a spacecraft radiating lots of infrared in its direction.

 

It’s no great engineering feat, though, to control the direction you radiate your waste heat, and cool other parts of a spacecraft to cryogenic temperatures (that pretty much describes the design of the soon-to-be-flow Webb IR space telescope), so if the spacecraft didn’t want to be seen in IR, it would be no big deal to avoid detection.

[Moontanman]

 I’ve not tried calculating it, but given how sensitive modern infrared telescopes are, and how close the hypothetical spacecraft would be compared to their intended exoplanet targets, I’d guess yes, a present day space, aircraft, or ground-based infrared telescope could spot a spacecraft radiating lots of infrared in its direction.

 

It’s no great engineering feat, though, to control the direction you radiate your waste heat, and cool other parts of a spacecraft to cryogenic temperatures (that pretty much describes the design of the soon-to-be-flow Webb IR space telescope), so if the spacecraft didn’t want to be seen in IR, it would be no big deal to avoid detection.

Sneaky bastards aren't they!

 

I am trying to work out some rough speculations on my idea of the galaxy being colonised by beings that no longer use planets but build something similar to a Stanford torus and simply take home with them as they spread through the galaxy stopping near things like Kuiper objects to build new habitats, resupply lost volatiles and moving on. I can see the possibility of many different species exploiting various niches much like a planetary ecosystem..      

[CraigD]

I am trying to work out some rough speculations on my idea of the galaxy being colonised by beings that no longer use planets but build something similar to a Stanford torus and simply take home with them as they spread through the galaxy stopping near things like Kuiper objects to build new habitats, resupply lost volatiles and moving on.

If you’d asked me a year ago, I’d have said material-hunting space gypsies would have gone straight for inner planets where all the good stuff is concentrated in a small volume rather than bothering to gather it in the immense volume of the Kuiper belts, but since rock start astronomer Mike Brown and his young sidekick Konstantin Batygin announced their suspicions and planned hunt for a 10 Earth mass “planet 9” about 600 AUs out (vs Pluto’s 30 to 50, way past even Voyager at about 134), I think everybody that has ‘em needs to rethink their assumptions about solar systems.

 

If as Brown and Batygin pretty compellingly argue, there’s a giant planet lurking between the Kuiper belt and the Oort cloud, visitors seeking riches might not even bother crossing the Heliopause (at about 121 AU), but just set up shop around it.

 

The prospect of detecting anything less massive than a planet at 600 AUs seems pretty bleak to me, so if Planet 9 is swarming with space gypsies, unless they went out of their way to let us know they’re there, I doubt we would with our current technology. On the other hand, if their society includes curious explorer types, I expect they’d find expeditions Sunward irresistible.

 

Though it’s just wild speculation, the idea of Earth-pranking ETs based a mere 600 AUs (0.01 lightyears) away strikes me as much more plausible than ones commuting from other stars.

 

Brown and Batygin’s Planet 9, announced only a couple of months ago, is, I think, not yet appreciated as a source of inspiration for SF. Nifty! :)

[Moontanman]

If you’d asked me a year ago, I’d have said material-hunting space gypsies would have gone straight for inner planets where all the good stuff is concentrated in a small volume rather than bothering to gather it in the immense volume of the Kuiper belts, but since rock start astronomer Mike Brown and his young sidekick Konstantin Batygin announced their suspicions and planned hunt for a 10 Earth mass “planet 9” about 600 AUs out (vs Pluto’s 30 to 50, way past even Voyager at about 134), I think everybody that has ‘em needs to rethink their assumptions about solar systems.

 

If as Brown and Batygin pretty compellingly argue, there’s a giant planet lurking between the Kuiper belt and the Oort cloud, visitors seeking riches might not even bother crossing the Heliopause (at about 121 AU), but just set up shop around it.

 

The prospect of detecting anything less massive than a planet at 600 AUs seems pretty bleak to me, so if Planet 9 is swarming with space gypsies, unless they went out of their way to let us know they’re there, I doubt we would with our current technology. On the other hand, if their society includes curious explorer types, I expect they’d find expeditions Sunward irresistible.

 

Though it’s just wild speculation, the idea of Earth-pranking ETs based a mere 600 AUs (0.01 lightyears) away strikes me as much more plausible than ones commuting from other stars.

 

Brown and Batygin’s Planet 9, announced only a couple of months ago, is, I think, not yet appreciated as a source of inspiration for SF. Nifty! :)

 

 

Once you realize that metals are not necessary to build habitats it opens a whole new can of speculations. carbon in it's various forms could make up the lions share of a colony making metals only necessary in small amounts that would be available in places like the Kuiper belt and the Oort cloud.   In fact if Oort clouds are common around stars and they stretch halfway to the next star as is the current thinking interstellar travel might be more of a series of short hops instead of long journeys...