Where In Our Solar System Are We Most Likely To Find Life? | Hacker News Reader

Where In Our Solar System Are We Most Likely To Find Life?

forbes.com

21 pointsthealexknapp15 comments

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Earth

Sorry. Couldn't resist :)

Nah. It's an incredibly stupid title.

We are all thinking it!

Spoiler: Mars is at number 3.

And we know that Mars is slim pickings as far as life goes.

What we should be doing is terraforming Mars with life from Earth, not sterilizing everything we send there.

Compared to Earth, we know very little about Mars. Purposefully contaminating our craft (or worse, starting any sort of terraforming operations now) before we fully understand the planet would make efforts destined for failure at best, and produce unforeseen consequences for the planet at worst.

We've attempted similar things here on Earth in the past without fully understanding the consequences, with the ecological disasters to show for it.

Better for us to more fully understand that planet first.

I doubt a better understanding can happen without sending humans, and there's no way to put humans about Mars without also releasing Earth life. Do you oppose a manned mission to Mars?

Besides, there's still zero evidence of life on Mars. There's no ecology to disrupt.

>Besides, there's still zero evidence of life on Mars. There's no ecology to disrupt.

That remains to be seen. The scientific community feels that the absence of evidence so far does not rule out the possibility.

Today's announcement should bring us closer to finding out. http://www.theguardian.com/science/2015/sep/28/nasa-to-revea...

That's been trivially falsified by the tremendous leaps in our understanding of the planet from each successive probe we've sent. For example, we only recently got indications of the likely presence of significant quantities of perchlorates in Martian soils, which has dramatic consequences for any possible effort at terraforming.

As for 'no ecology', we're a very long way from being in any position to say that.

Edit: I can't reply to WalterBright's comment, so I'll reply here. I didn't talk about having to prove anything. It's a matter of balance of evidence. What percentage of the possible biomes on Mars have we tested and how thoroughly did we test them? I'd argue less than 10% of the most life-hostile biomes and those only cursorily. That's way too low a fraction to have any confidence that Mars is dead. Sure, we can't test every grain of sand on the whole planet, we have to draw the line somewhere, but for now we've barely scratched a small part of the surface.

GK Chesterton applies here;

"In the matter of reforming things, as distinct from deforming them, there is one plain and simple principle; a principle which will probably be called a paradox. There exists in such a case a certain institution or law; let us say, for the sake of simplicity, a fence or gate erected across a road. The more modern type of reformer goes gaily up to it and says, “I don’t see the use of this; let us clear it away.” To which the more intelligent type of reformer will do well to answer: “If you don’t see the use of it, I certainly won’t let you clear it away. Go away and think. Then, when you can come back and tell me that you do see the use of it, I may allow you to destroy it."

The point being that unless you understand something you're very much better off not changing with it, because you can't possibly understand the consequences of that action.

Mars might be devoid of life, and contaminating it might have no negative impact, but unless you know that's the situation it's better not to introduce potentially negative changes.

What would you consider definitive proof of no life on Mars?

I wouldn't, obviously, as it's impossible to prove a negative. :)

I imagine there's a reasonable level beyond which the benefits of terraforming outweigh the probability of finding life though, but where that point is would be defined by scientists far more qualified than me. Whatever that point is though I think it's quite clear that we're a long way from reaching it.

We've figuratively, and literally, barely scratched the surface of Mars.

The scientists will have to decide before people are sent there, because you can't sterilize people.

These are the definitions of the Drake Equation:

   R* = the average rate of star formation in our galaxy
   fp = the fraction of those stars that have planets
   ne = the average number of planets that can potentially support life per star that has planets
   fl = the fraction of planets that could support life that actually develop life at some point
   fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
   fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
   L = the length of time for which such civilizations release detectable signals into space[8][9]

I think the most interesting thing is as a sort of a map of human knowledge. Fill in the blanks with your best answer at this point.

We know some stuff about some of these, but very little about others. I think we can make sensible guesses at the first three, and the last two and Drake's Equation allows us a large margin of error. The likelihood of life developing and the likelihood of intelligence developing however… we don't have much. A weird thing about both these things is that we are the only example we know of. Even earth, which has demonstrated an ability to develop both, seems to have done both only once. All life on earth shares an ancestry. Intelligence is debatable, but by a definition that carries the potential to build technology proving its intelligence to extra terrestrials we are the only example.

We can be reasonably certain that if we start from Eukaryotic life, eyes will evolve. Technology building and intergenerational knowledge accumulation is less certain. Even if you start with humans, it's not obvious that technology will evolve. Homo existed for quite a while, even with individuals very similar to us before getting on this technology curve. Thousands of generations (or tends of thousands, depending on your definitions) of being smart, social bipedal apes anatomically similar to us with no apparent evidence that the invention of pornography-capable smartphones are forthcoming.

We have similarly little evidence about life's chances of emerging. Some sort of replication process that has evolutionary potential would be a decent definition in this context. How likely is that? Do we actually need the "ingredients" common to Europa and Earth? Is Earth's "ingredient list" even ideal? Is organic chemistry the only way to do things? I think our ongoing invention of complex machines is, perhaps, a counterexample.

Back to the Drake equation, I think any time we can fill in one of the variables, tighten up our margins of error or otherwise add knowledge to this knowledge map, we are making interesting progress.

TLDR: At this point in time the existence of both life and intelligence must be assumed to involve ancient, god-like extraterrestrials.

>TLDR: At this point in time the existence of both life and intelligence must be assumed to involve ancient, god-like extraterrestrials.

Surprisingly, that assumption (and that it must be assumed) is a touchy subject at this point in time.

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