If we'd had another habitable world in our system...

[Nerys Ghemor]

...how soon would we have been able to figure that out, BEFORE sending probes or manned missions assuming there were NO sentient lifeforms who might be sending signals, or building anything that might be visible to telescopes?

What technology would have had to be available, and what would we use as the criteria? About what time period in our history would we have expected this to happen? (I'm benchmarking this against our own technological development, not accounting for any acceleration of development that might occur if a potentially habitable world were suspected.)

 

[Christopher]

Actually it was kind of the other way around: we tended to assume that other worlds were habitable until we gained evidence to the contrary. We thought there were canals on Mars and jungles on Venus. So we always suspected that other worlds were habitable, and that's what prompted us to explore them in more depth and eventually discover that they were lifeless (though some are starting to call that a premature conclusion where Mars, Europa, etc. are concerned).

So the answer probably would've come around the same time, once our techniques developed to the point that we could identify the actual composition of a planet's surface or atmosphere or get detailed visuals. Maybe a positive confirmation would've come a little sooner than the negative conclusions we eventually reached, but probably not by much, since if we'd been able to tell the difference between a habitable world and an uninhabitable one earlier, we could've ruled out habitability earlier. Really, in hindsight it's surprising how little we knew about even our nearest planetary neighbors as recently as 50 years ago. So the timing probably wouldn't have changed much.

Unless, of course, that other habitable world had had its own natives and they'd come here first, or sent us radio messages.

 

[Candlelight]

Once we had telescopes we'd be able to spot the canals, thus allowing Orson Welles to really scare the shit out of us.

 

[Nerys Ghemor]

What technologies would be used to come to a positive conclusion (and determine which worlds in the system did not share those properties)? Such as, how would we determine temperature and atmosphere composition, or any other information that might let us know that we were indeed looking at a habitable world? And when were we able to get sufficient imagery from the surface of our world to tell that there were no forests on Venus, or water-filled canals on Mars?

 

[Silvercrest]

What are we counting as a habitable world? Among other things, lot of free oxygen? I thought it's been proven that a world without plant life won't have much free oxygen. If true, then if we spot a world with free oxygen, chances are pretty good it already does have life. Seems like that would be the simplest answer to your question.

And if we don't expect to find free oxygen, then what do we count as habitable? Just trying to define your benchmark a little here.

Am I correct about the oxygen thing?

 

[Nerys Ghemor]

I'm ruling out sentient life--however, some lower life (germs, plants, non-sentient animals) would not be out of the question. Conditions may be marginal for our exact kind of life, but something people could adapt to reasonably, without having to do extensive terraforming or being forced to live in shelters on rations 24-7.

So, what is the technological "soonest" we would've been able to make this determination, before we started sending probes and manned exploratory missions? Assume this planet is in our own solar system, so we have technologies available that were used to learn about our own planets IRL.

 

[sojourner]

^well, in real life, technologically soonest would have been when we first sent probes to the planets. That is how we found out both Venus and Mars were uninhabitable.

In other words, your real question is when we could have confirmed the habitability of a planet, whether it be yay or nay. History tells us the answer is the late 60's to early 70's.

 

[Starkers]

Interesting thread. I wonder, if we had determined in 1970 say that Venus or Mars was habitable, would it have made a difference to the space programmes of various nations? It strikes me that there'd be a lot more public pressure to visit and colonise habitable Venus than the airless moon or the uninhabitable Mars. Especially if you don't have to haul loads of food/water/oxygen there in order to survive.

 

[SilentP]

I can certainly see a massive push toward mass space flight once a planet in this solar system was discovered. Who would be making the push would be a different question.

At the late 60s/early 70s, the technology and capital for space flight seemed to rest solely with a few governments, but if there was the potential for resources, I could see attempts by some companies (mining for example) to make their own attempts at space travel, or at least funding government projects so they could get their own interests involved in project consideration.

 

[Asbo Zaprudder]

...but if there was the potential for resources, I could see attempts by some companies (mining for example) to make their own attempts at space travel, or at least funding government projects so they could get their own interests involved in project consideration.

I don't really see that happening from an economic standpoint until space elevators were established. The cost of transporting mass between the two gravity wells would be prohibitive unless some unique compound or element were only available on one of the planets. For example, at present, we have no serious interest in mining low-gravity objects such as the moon and asteroids. Another habitable body in the solar system would be best exploited by one-way colonization.

 

[Deckerd]

...but if there was the potential for resources, I could see attempts by some companies (mining for example) to make their own attempts at space travel, or at least funding government projects so they could get their own interests involved in project consideration.

I don't really see that happening from an economic standpoint until space elevators were established. The cost of transporting mass between the two gravity wells would be prohibitive unless some unique compound or element were only available on one of the planets.

Unobtanium?

 

[Asbo Zaprudder]

Unobtanium?

Yep, it would require some strategic resource that we don't have on Earth already, even if we only have access to small quantities (keeps the price high). There's methane and other hydrocarbons aplenty on Titan, but I doubt that we'll be exploiting that resource anytime soon.

 

[SilentP]

Fair point.

Come to think of it though, how would someone go about staking their claims to resources on a planet? First group to the planet gets the whole package? Only able to claim jurisdiction for an area around any bases left there?

 

[Deckerd]

I don't think anyone could just turn up and say "this is mine" like Red Dwarf's cat. They would need to have the means to mine to hand in order to stake a claim. Otherwise why bother even going? Just send flags down to the surface. The other way of doing it is to carve it all up back home, as they did with Antarctica. The problem with that is that it's only going to work if everyone has a means of protecting their "territory" from quicker settlers. Either way, it would require some form of settlement and humans, once they're on their bit of turf, generally claim independence. Ultimately you would have new planetary political alliances which Earth would end up having to trade with rather than running from a distance.

 

[Asbo Zaprudder]

There are UN treaties about such things, which makes extraterrestrial bodies such as the Moon and planets off limits -- a bit like Antarctica. However, if someone did discover some really useful resource, you can bet that they'd wriggle out of such legal constraints.

http://en.wikipedia.org/wiki/Outer_Space_Treaty

 

[Deckerd]

The practicalities involved will probably mean that it will have to be a joint venture between nations.

 

[Asbo Zaprudder]

The practicalities involved will probably mean that it will have to be a joint venture between nations.

Hah, well I guess I won't be buying shares in that venture then.

 

[Jax]

I was thinking about the idea of exploring another habitable world when I saw this thread title and without suits its impossible/highly dangerous even if any such planet is Earth like. Our immune systems for example would probably be torn to shreads by alien bacteria/viruses.

Could we adpat and if so how long would a colony of people need to live there for ?

 

[Deckerd]

It depends what you mean by 'habitable'. The current choices would need an artifical environment for people to inhabit. This could be pressurised buildings, as in Outland, or domed environments like the Eden Project, or underground structures to offset extremes of temperature, climate and bombardment from the sun. All of these would require a huge investment to get them up and running but they would have controlled environments so the chances of picking up viruses would be probably less than on Earth.

 

[Asbo Zaprudder]

My guess is that cross-contamination could be a big problem. Even if planet X's equivalents of viruses and bacteria couldn't exploit our DNA and biochemistry, we might infect their biosphere, and we might still be susceptible to infectious protein agents similar to prions. If life on planet X were similar but stereochemically reversed, with left-handed DNA and sugars, and right-handed amino acids, we'd probably starve to death unless we polluted the planet with our own biochemically suited plant life.

Like the conquistadors, we might return to earth with neo syphilis, and the indians would die en masse of nuovo smallpox.