[Astronomy help] Likelihood of discovery?

[RyanW]

Originally Posted by KarlKost

I dont think a TL 9 civ would be able to have that many "probes" around it's own solar system as to be able to detect such an object actively trying to hide behind another celestial body. That would be more of a TL 10 civ thing to do.

There have been several probes in distant heliocentric orbits. Most of those were either specialized for solar observations (STEREO A and B), close research of NEOs (Hayabusa and OSIRIS-REx), or deep space observations (Spitzer Space Telescope).

There have been proposed missions for asteroid detection systems (which would be ideally equipped to detect spacecraft, as well) in exotic orbits. It's easiest to spot asteroids with your back to the sun, so the Sentinel mission was planned to be placed at Sun-Venus L3. If it hadn't been cancelled, there wouldn't be many places in the solar system that you could reliably hide. At TL 9, the only thing preventing a Sun-Venus L4/5 asteroid binoculars is political will to pay for it.

On the other hand, politicians spending money to avoid a planetary scale extinction is probably less believable than an invisibility cloak.

[fwcain]

As soon as your ship starts powering up its systems -- presuming it was mostly powered down for most of its trip here in the first place -- then your ship is going to be a very noticeable source of heat that infrared sensors will immediately pick up. The difficulty of hiding a powered device in near absolute zero space is quite difficult (read "darned near impossible, barring magic-tech that can violate the laws of thermodynamics"). This unfortunate side effect of real-world physics has been the source of more than one online discussion in some of the other newsgroups I've read.

Franklin

[fwcain]

Originally Posted by Anthony

...if the ship has internal heat sources (which it will because it has a power plant), any resulting thermal signature will not be affected by distance from the sun, so the ship is likely to be very visible in infrared. This wouldn't be too relevant to current-day sky search programs since such sensors won't work well through the atmosphere, but a mature TL 9 with significant space-based resources will probably be using space-based thermal scans.

We already are using IR detectors in space. The Webb telescope is one such example.

[Rupert]

However, if you're in the outer system, and know that all the sensors looking for you will be in the inner system, you can pump the heat to radiators that face way from the inner system. You'll be nice and cold in one direction, and very warm in the other. Too bad if you were wrong about the direction the sensors would be...

[RGTraynor]

A couple of thoughts.

First off, a major factor in the ship's ability to go stealth mode is this: (a) why would they want to?, (b) what reason do they have for thinking that there's a technological civilization based on Earth, which (c) they would perceive as being a threat to them?

Secondly, obviously -- as other posters have already established -- the technology to detect an object that size at that distance was present on Earth in late TL 6, never mind 9. It's not whether, but how quickly.

Think of present-day minor planetoid discoveries, where Michael Brown and his team has been the great stars of the 21st century. He's found asteroids smaller than this ship in the asteroid belt, and while sometimes it's taken the public beyond the IAU a while to give a damn, sooner or later it pays attention.

Now what happens, with tech a TL more advanced than ours, when a large object like that all of a sudden appears within the orbit of Saturn. Just like that. When damn near every object larger than a click within Neptune's orbit has been bagged, tagged and catalogued. Brown's grandchildren would find that sucker within days, it'd be confirmed within hours, the Solar Republic's Grand Council would be in emergency session a half day later, such space fleet as they had would be on high alert fifteen minutes later, and the boffins would be planning the probe.

[Anthony]

Originally Posted by fwcain

We already are using IR detectors in space. The Webb telescope is one such example.

We aren't using them for broad area surveys, though. We managed magnitude 19 surveys in the 90s, going beyond that leads us to things like Pan-STARRS (2010) and LSST (expected online 2024).

[David Johnston2]

Originally Posted by Anthony

For this, I would treat it as an asteroid.

A very hot asteroid. Given the parameters of this object what will give it away is the infra-red it will radiate unless it puts a large object between it and the infra-red telescopes a TL9 future civilization will have in space. It takes some pretty extreme super science to cancel out that.

[KarlKost]

Originally Posted by RyanW

There have been several probes in distant heliocentric orbits. Most of those were either specialized for solar observations (STEREO A and B), close research of NEOs (Hayabusa and OSIRIS-REx), or deep space observations (Spitzer Space Telescope).

There have been proposed missions for asteroid detection systems (which would be ideally equipped to detect spacecraft, as well) in exotic orbits. It's easiest to spot asteroids with your back to the sun, so the Sentinel mission was planned to be placed at Sun-Venus L3. If it hadn't been cancelled, there wouldn't be many places in the solar system that you could reliably hide. At TL 9, the only thing preventing a Sun-Venus L4/5 asteroid binoculars is political will to pay for it.

On the other hand, politicians spending money to avoid a planetary scale extinction is probably less believable than an invisibility cloak.

I never said we dont have "probes" around the Solar System. What I said is that we dont have enough to dected funny objects trying to hide from us.

What I mean is that, for that kind of "alarm system" we would need a sort of "satellite constelation" around our solar system of a kind similar to the satellite constellation that we have around Earth, and such endeavor would only be feasible for a TL10+ civilization

[KarlKost]

Originally Posted by RGTraynor

A couple of thoughts.

First off, a major factor in the ship's ability to go stealth mode is this: (a) why would they want to?, (b) what reason do they have for thinking that there's a technological civilization based on Earth, which (c) they would perceive as being a threat to them?

Yeah, it's more or less something I had adressed before with other words. All the talk about them actively hiding was if they care enough to do it. If they dont, it's a given that we would spot them.

Now, as to why would them give a damn, it could for example be a "Prime Directive" for instance. I hardly believe a TL11 civ would ever feel threatened by a TL 9 one. That would be like a nuclear submarine commander feeling threatened by a steam warship that doesnt have a sonar. It's absolutely nonsensical.

But a Prime Directive sort of thing could be possible. And as to why they would "know" that there's a TL 9 civ here, first they would know due to our radio transmissions and secondly even if they didnt know, this could just be a basic procedure when jumping into solar systems that hold planets on the... Sorry, I forgot the term in English, but planets in the line of orbit that allows for liquid water. So, common procedure, always hide from such kinds of worlds. That could be one explanation.

Most likely thou, those guys would probably not care, seeing the civilization bellow as "just a bunch of medieval barbarians".

[Taneli]

Does the FTL in your setting have any kind of signal upon exiting hyperspace? Could the local civilization detect it?

"Not moving", has the ship established an orbit around the local star or some planetary body, or is it in a free fall towards the local star, or is it on a hyperbolic trajectory that will take it out of the local star system? Or does it magic... ultra technically stay in place compared to the local star, and the other local bodies just approach it and then start moving away from it.

Even if the ultra tech drive has no signature, the latter one would be a pretty big discovery quite soon after a technical malfunction has been ruled out from any small body tracking telescopes.

Unless it has no signature, at which point it depends if it happens to block any star under a longer observation. Imagine that popping into our system and blocking Betelgeuse or some other often tracked star... Unless it's truly invisible, meaning that one can see through it, in which case we wouldn't be able to detect it at all.