how to test if a planet is 'livable'?

indianroads said:

No test monkeys, or other creatures to use as test subjects.

The atmosphere can be breathable, but how to test for biological issues (viruses etc) without test subjects?

Click to expand...

Take samples.

Or are you looking for something strictly remote?

If you're testing the atmosphere, presumably you can test the soil, etc.

You need the big-ticket items first....

Atmosphere, water, and gravity. Evapotranspiration in plants (i.e. access to ample sunlight that is filtered through the atmosphere, so it does not kill things). Climate is important.

If the planet is not in the Milky Way, maybe make the planet equal distance from the sun as either Earth, Mars, or Venus is to our sun. This would make it more believable; i.e. it will allow sleuth readers to understand if it is possible or not.

Once these are met, you can send probes or a lifer in prison as a test subject. If he goes, full pardon. One angle you can take, but your decision makers of this won't be looked on too favorable (unsympatheic character) by readers.

Enlightened said:

You need the big-ticket items first....

Atmosphere, water, and gravity. Evapotranspiration in plants (i.e. access to ample sunlight that is filtered through the atmosphere, so it does not kill things). Climate is important.

If the planet is not in the Milky Way, maybe make the planet equal distance from the sun as either Earth, Mars, or Venus is to our sun. This would make it more believable; i.e. it will allow sleuth readers to understand if it is possible or not.

Once these are met, you can send probes or a lifer in prison as a test subject. If he goes, full pardon. One angle you can take, but your decision makers of this won't be looked on too favorable (unsympatheic character) by readers.

Click to expand...

if the planet isn't in the Milky Way, it seems unlikely as heck humans are getting there, even with warp drives -- and even if they did, I've no idea how we'd communicate.

cornflake said:

if the planet isn't in the Milky Way, it seems unlikely as heck humans are getting there, even with warp drives -- and even if they did, I've no idea how we'd communicate.

Click to expand...

Aldis lamps?

cornflake said:

if the planet isn't in the Milky Way, it seems unlikely as heck humans are getting there, even with warp drives -- and even if they did, I've no idea how we'd communicate.

Click to expand...

Lots of means.... Human outposts, teleportation, developmental technologies.... As long as it is plausible. I assume the OP is writing a Sci Fi novel.

I'm imagining a bit but maybe your probe has a supply of human tissue culture to do analysis with in vitro samples. It's not perfect but it's one of the early steps in testing the safety of substances to humans here on earth.

lizmonster said:

Aldis lamps?

Click to expand...

Trans-warp soliton wave generators. Or something.

lizmonster said:

Aldis lamps?

Click to expand...

Lol -- hey, I have a cool shake flashlight that says the beam can be seen really far....

Enlightened said:

Lots of means.... Human outposts, teleportation, developmental technologies.... As long as it is plausible. I assume the OP is writing a Sci Fi novel.

Click to expand...

A human outpost where that'd make someplace outside the Milky Way more plausible though? I know it's sci-fi but still. At warp 10, we're talking 250,000 years away.

cornflake said:

A human outpost where that'd make someplace outside the Milky Way more plausible though? I know it's sci-fi but still. At warp 10, we're talking 250,000 years away.

Click to expand...

Why not? For example, the outpost can serve as a distant teleportation post. Let's say a teleportation post (some object, I chose post) is floating out in space. Each one has a human outpost for its maintenance. Someone, in theory, could teleport from posts A to B to C... to Q. They will be at some planet and ready to go.

Humans know a lot about the Milky Way, our solar system, and so forth. With these posts, someone can travel that 250,000 years in minutes (spaceship and all). For my thinking, it would be more fun, for readers (and for the writer), to bring a distant world into view.

I wouldn't be too concerned about viruses on an alien planet, because (unless one's premise is that life was seeded and transferred between star systems and life forms on the alien planet were very closely related to us), whatever genetic system aliens would have wouldn't be compatible with ours (viruses work by hijacking our cells' genetic machinery via either DNA or RNA). We'd be more likely to catch tobacco mosaic virus, since plants are going to be a closer genetic match to us than anything that evolved on an alien planet.

Could alien equivalents of bacteria or fungi be harmful to us? That's hard to say. It would depend on how similar our biochemistry was. Maybe they could grow on or in our tissues and cause infections, or even if they couldn't reproduce successfully in our bodies, they could possibly engender a massive immune response that would be worse than what they would be able to do to us on their own.

Toxins in the air or water that could cause problems with short or long-term exposure are another possibility. I remember reading a SF book where an alien "plant" species shed filaments that contained a lot of silicon. Exposure led to cancers (similar to ones caused by asbestos exposure) in colonists, so they lived under bubbles.

I think the only way to know for sure, once it was established that an alien planet had a compatible amount of oxygen in its atmosphere and a similar biochemistry to Earth's, would be to send probes to obtain air, water, and soil samples. It's possible we could miss something hazardous, though, if we don't know precisely what we are looking for (for instance, what an alien protein or pathogen that could elicit a dangerous immune response in Earth organisms might even look like).

Even so, I'm guessing human explorers would be cautious with exposing themselves unless they'd tested it on some earth organisms first. If there are ethical concerns with using vertebrate animals, might it be acceptable test on invertebrates, or even on tissues of various kind. It's possible that future biologists would be better at extrapolating system-level responses based on tissue studies than we are now.

indianroads said:

Ok - so you're hanging out in orbit around a planet with an atmosphere, gravity, and temperature that works for people. How to tell if the biology there (viruses and the like... not critters that will eat you) won't kill you? There could be some nasty version of pollen that coats the inside of your lungs and you die of suffocation. Diseases that are carried by the native life - that's like the black death for people but fine for the native creatures.

If you don't have monkeys or something like that to send down, how can you really tell if the planet is habitable?

Would a soil test show things like that?

Click to expand...

Lifer in prison; complete pardon if they are willing to go and experience the environment (with gauges and some basic tests)? Else, you can explain that someone already been in this environment and learned that it is hospitable. If you are looking for that trailblazer experience, you might watch season one, episode one of The 100 (CW network, American TV). One hundred people were sent to live on a planet; they had to know if the conditions were habitable. I do not know if it covers the detail you are after, but you can get an idea how they went about it. The series started in 2014; maybe you can get it On Demand (via your TV provider).

Enlightened said:

Why not? For example, the outpost can serve as a distant teleportation post. Let's say a teleportation post (some object, I chose post) is floating out in space. Each one has a human outpost for its maintenance. Someone, in theory, could teleport from posts A to B to C... to Q. They will be at some planet and ready to go.

Humans know a lot about the Milky Way, our solar system, and so forth. With these posts, someone can travel that 250,000 years in minutes (spaceship and all). For my thinking, it would be more fun, for readers (and for the writer), to bring a distant world into view.

Click to expand...

How many teleportation skips are you talking about for something at best 2.5 million light years away? Also... teleporting entire ships with personnel? I'd buy wormholes a long while before I'd buy that.

Why outside the Milky Way to begin with? It's not distant enough in it??

- - - Updated - - -

indianroads said:

Already handled and explained in the first book of this series (due out in June) - got the idea for the "Slip-Drive" from listening to a Stephen Hawking lecture where he conjectured on possible methods of interstellar spaceflight. Travel isn't as much of an issue as navigation is, which was the whole premise of the first book.

I'm in the outline process for the second book.

Click to expand...

Interstellar is one thing, intergalactic is entirely another, imo.

cornflake said:

How many teleportation skips are you talking about for something at best 2.5 million light years away? Also... teleporting entire ships with personnel? I'd buy wormholes a long while before I'd buy that.

Why outside the Milky Way to begin with? It's not distant enough in it??

Click to expand...

That's up to the author. Maybe posts lose some degree of reliability beyond 500,000 light years. Using posts of 500,000 LY or more can bring added risk and excitement, for readers, if used. I did not mean to try teleporting something like the Death Star through one of these, but a teleportation pod is possible.

I'd piecemeal things over to build new human outposts.

cornflake said:

Interstellar is one thing, intergalactic is entirely another, imo.

Click to expand...

Exactly. One thing I'd want to know is how far in the future this is. For humans to explore our general viscinity could easily take thousands of years. What's the incentive to develop tech to leave the entire galaxy?

If it's been 100,000 years or something, fine (of course I'd also expect evolution to have done osme interesting things). But without a solid story reason, there's no reason to flee the Milky Way.

None of which has anything to do with the OP's original question.

Enlightened said:

Lifer in prison; complete pardon if they are willing to go and experience the environment (with gauges and some basic tests)? Else, you can explain that someone already been in this environment and learned that it is hospitable. If you are looking for that trailblazer experience, you might watch season one, episode one of The 100 (CW network, American TV). One hundred people were sent to live on a planet; they had to know if the conditions were habitable. I do not know if it covers the detail you are after, but you can get an idea how they went about it. The series started in 2014; maybe you can get it On Demand (via your TV provider).

Click to expand...

So add a couple serious criminals to your minimally populated initial settlement?

That doesn't sound so good.

Kim Stanley Robinson's Aurora has an interesting take on this. Scientific American book review

The action takes place on a terrariumlike spaceship in which successive generations are born and die without ever making planetfall, bound for promising worlds orbiting the nearby star Tau Ceti. Mixing equal parts ecology, sociology and astrophysics, Robinson's heart-wrenching, provocative tale makes plain that even though humanity may someday reach the stars, we can never truly escape the pull of Earth.

Click to expand...

After generations on the ship they reach their destination. It looks habitable by all measures but they only go outside in spacesuits. Eventually a person's suit tears.

Spoiler:

Nothing happens at first but there are fights about letting the group back on the ship. When the person gets sick and dies things get even more testy and leads to murdering the people that might be contaminated as they try to get back on the ship. The illness is found to be a kind of prion.

Click to expand...

There's a lot more, but I'll not spoil a good book for you all.

Craig Venter's Global Ocean Sampling Expedition went around the world sampling seawater for microorganisms. The process involved automated sequencing of the biological material that came up in the water. Not sure how many samples were processed, but a whole lot of cataloguing went on.

As long as the alien organisms had DNA or RNA, something like GOSE would be possible -- but remotely operated. (The original ship was called Sorcerer II. RV Warlock might be an alternative name for the space vessel.)

Good topic here, following with interest. Snippets of the points raised thus far remind me of a TV called The 100. It was good for the first season or so, afterward it kind of lost interest...

It's useful to remember that Earth has an oxygen-rich atmosphere ONLY because it has organic photosynthetic life forms that produce the oxygen. Oxygen is chemically very reactive, and would disappear very quickly from the atmosphere if photosynthesis ceased. Detection of free diatomic oxygen in a planet's atmosphere is a strong signal that some form of organic life already exists there.

caw