[greggarious]

Here's a fun exercise in speculation: How long does HN think it will be between confirming life (e.g. bacteria), confirming life (e.g. mammals / bugs), and confirming intelligent life?

(Never is an an acceptable answer for all 3, but please state why you hold your position)

[rybosome]

I think we're nearly at confirmation of basic alien life. IIRC there are talks of missions to Europa as early as the 2020's, and I would honestly be surprised if no microbial life was found there. Liquid water, chemical processes that could support chemosynthesis, a likely abundance of organic compounds and protection from radiation and cosmic rays are all critical factors. That may even extend to larger fish-like life...there's a chance that the moon's icy shell releases oxygen into its interior liquid ocean in large enough quantities to promote the freakishly-large growth we enjoy. If we don't discover larger multi-cellular life within our solar system (perhaps also on Titan, though that seems less likely), then it'll be many, many years before we discover it. Interstellar travel is a massive hurdle. =)

Intelligent life, though...that's tricky. Given the size of the universe, it is almost certain that there is other intelligent life but who knows whether or not it survives long enough to come into contact? Discovering another civilization would be one of the most incredible experiences I can imagine, so I certainly hope it happens (peacefully) within my lifetime.

[lumpypua]

Can't speak to likelihood of discovering life on Europa but it would be fucking awesome.

To be clear, microbial life in no way entails higher life. It's only by the insanely chance event of the eurkaryotic cell emerging that sophisticated multicellular life became possible on earth. Even if life is common in the universe, sophisticated multicellular life is extremely rare.

The selective pressures on bacterial life favors small size and rapid reproduction, jettisoning any unnecessary genetic material.

Mitochondrial ancestors relieved those pressures in a couple ways. Once the eukaryotic cell developed, multicellularity has evolved several times. All the cool things (multicellularity, eyes, flight) have evolved independently a bunch of times, and the eukaryote has happened only fucking once. Here's a deeper explanation of why it's so rare: http://rstb.royalsocietypublishing.org/content/368/1622/2012...

Even if life is common in the universe, multicellular life is extremely rare because the evolution of eukaryote-esque organisms is extraordinarily rare and chance.

Edit: That is to say, there's a strong case that step 4 is the Great Filter: http://en.wikipedia.org/wiki/Great_Filter#The_Great_Filter

[rybosome]

> Can't speak to likelihood of discovering life on Europa

Honestly, me neither. I'm just a software engineer who is excited about space and hopes for the best. =)

> but it would be fucking awesome.

Wouldn't it? Holy hell, that would be wonderful. I hope it happens soon. Discovering life on Europa would be our generation's moon landing.

Thanks for the clarification. My knowledge of biology is limited, so I imagined each step (crude self-replicating molecules -> sophisticated DNA -> the cell -> etc.) being roughly as unlikely as the next. I had no idea eukaryotic cells were such a massive jump.

Earlier today I was watching a documentary about the Kepler telescope's search for exoplanets[0] that estimated the number of planets in our galaxy at 10^19. So many of those planets are unsuitable for any life, microbial or otherwise, but such a large number fills me with hope that the unlikely miracle of eukaryotic evolution could happen more than once. Then again, there are very plausible interpretations of the Drake equation[1] that pin the number of intelligent civilizations in our galaxy to less than 5...maybe even 1...so who knows?

[0]: https://www.youtube.com/watch?v=DD6QHP9ouuU [1]: http://en.wikipedia.org/wiki/Drake_equation

[lumpypua]

Yah there's really good explanation of why eukaryotes are jump posted up above!

http://ronbarak.tumblr.com/post/25996121029/life-is-it-inevi...

[gojomo]

There's a respectable contingent of scientists that believe Martian microorganisms were already confirmed 38 years ago by the Viking Lander experiments:

http://news.nationalgeographic.com/news/2012/04/120413-nasa-...

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

A future mission should definitely include a biologically-useful microscope, as suggested by USC neurobiologist Joseph Miller in the National Geograhic article linked above. Miller, also a former NASA space shuttle program director, is one of the proponents of the idea that the 1976 Viking results already demonstrated life.

[raverbashing]

However, the discovery of perchlorates severely weaken the results of that experiment

[gojomo]

The Wikipedia language suggests the existence of perchlorates (discovered in other Martian soil in 2008) could have destroyed organics during the 1976 test heating, thus explaining some of the negative results from Viking – leaving the positive 'Labeled Release' result more credible. That's the interpretation of the paper described at:

http://www.sciencedaily.com/releases/2010/09/100904081050.ht...

That article is currently footnote #28 of the Wikipedia article, describing the 2010 paper referenced as footnote #25. Another footnoted reference from 2011 (#29) disagrees. But presumably, all that perchlorate-related reasoning was available to the authors of the 2012 paper defending the positive result.

[raverbashing]

This is an interesting interpretation

The chlorometane results were a true result after all.

However, I have the impression that, organics, in contact with perchlorates (or any strong oxidant) will result in CO2

Also, it was repeated one week later, with no results

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

[marcosdumay]

> However, I have the impression that, organics, in contact with perchlorates (or any strong oxidant) will result in CO2

With enough perchlorate, it will. But with smaller amounts of it, there's a huge number of possibilities, including products that are more complex than the reactants.

[snowwrestler]

I think we will confirm life within 50 years by reading the spectra of distant planets and finding free oxygen in the atmosphere. As far as we know, that can only happen if living creatures are replenishing it.

I think it's unlikely that we will find life anywhere else in our solar system. It's possible that we'll evidence of past life on Mars, but not current. Basically, it's just way too cold or way too hot everywhere but Earth.

edit to add: I hope we do not discover intelligent life until we travel to distant star systems ourselves. If it discovers us here, the outcome will almost certainly be terrible for us, based on the long Earth history of species encountering species.

[gloriousduke]

> way too cold or way too hot

This isn't as big of a concern as it once might have been. See extremophiles.

> It's possible that we'll evidence of past life on Mars, but not current.

If life takes hold anywhere and has any amount of (geologic) time to spread, I'm guessing only an extremely powerful gamma ray burst or other high energy event could completely exterminate it. It might be impossible to sterilize the earth at this point without completely destroying it, and even then there'd probably be microbes in the resulting meteors, etc (until our sun dies at least).

[FranOntanaya]

> Basically, it's just way too cold or way too hot everywhere but Earth.

That's not really true. Only a thin layer of Earth's crust and atmosphere are great for life. Such Goldilocks layers aren't that uncommon if we look at all boundary climates on each body (subsurface sea boundaries, polar boundaries, higher atmosphere boundaries, etc), and not just the boundary analog to Earth's.

Even Mercury has free standing water ice. Somewhere between that ice and the scorched plains there's going to be a somewhat comfy place.

[bdamm]

There are regions of relative temperature stability, such as towards the poles.

I think the outlook for intelligent life in the solar system, other than us, is very bleak for them. If there are whales on Europa, Titan, or Enceladus then it would seem easier for us to damage their ecosystem than the other way around. Unless, of course, they've infiltrated our political systems and are steering us towards self destruction.

[zbyte64]

I would think the simple life we would see in our solar system would be less sophisticated then bacteria. Confirming plants and animals outside of earth would mean looking beyond our solar system and in 20-30 years we should be able to see the color of the planets Kepler has found. Once we can get a few pixels off a planet we can start to tell if photosynthesis is occurring. So for the first two categories my money is on 15/30. For intelligent life I can't even make a good guess.

[danbruc]

Another question is in which order this would happen - if there is no other life in the solar system it might very well happen that we find (signs of) intelligent life before simple life.

[grecy]

> we find (signs of) intelligent life

Or it finds us.

[givan]

If we will find them then this is an intersection on our technology advancements and proximity of such lifeforms, considering how little effort is currently put on space exploration it will take extremely long, things will probably accelerate when we find alternatives to the primitive combustion engine that makes fuel tanks bigger than rockets and makes the process very expensive.

If they will find us and this only means more advanced intelligent life then this obviously can happen any time or might already happened and can be delayed by us not being considered ready/worthy for contact or according to many conspiracy theories our governments considers we are not ready.

[palmer_eldritch]

1. Before the end of century, there's probably some around the solar system 2. Never 3. Never

I don't think we'll ever go beyond the solar system and that the only place with complex life in the solar system is the Earth.

[NARKOZ]

This will take decades to resolve. Random blasts of methane will be very hard to characterise in any methodical way.

[k-mcgrady]

If we put humans on Mars do you think we could find the source quickly/quicker than using robots? Is it a case of the robots finding signs of life and humans confirming them and getting the specifics? I'm asking because I'm not all that informed on this but from what I can tell robots have very specific missions so may not be able to find life even if they detect the signs.

[Retric]

Assuming equivalent spending Robots are a much better option. But, a manned mission is likely to get ~10-100+x what unmanned missions get so it's hard to say.

Also, those rovers did a really wide range of things for their cost. From driving around 40km and taking pictures to analyzing chemistry and even testing for "wobbles" in the planet's rotation that would indicate a liquid core. Sure, they cost ~500 million a pop, but compare that to 100's of billion for a manned mission that might never reach Mars and things don't look so hot.

[anigbrowl]

They'll assay them to see the ratio of different carbon isotopes. http://www.scientificamerican.com/article/nasa-rover-finds-m...