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Are Those Spidery Black Things On Mars Dangerous?

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Re: Are Those Spidery Black Things On Mars Dangerous?

#71

Post by jlgreco »

betterth wrote: post #70
jlgreco wrote: post #65

Earlier quoted context omitted.

It really does. However, one should keep in mind that humans have overzealous pattern-matching engines. We are really good at erroneously seeing things that we recognize.

And when it comes to Martian geography, we are hopelessly bad at judging scale. It's very easy to be several orders of magnitude off without a guide or legend.

True. While there are examples of life getting this large or larger on Earth (blooms, clonal colonies, etc), this seems unexpectedly large for a planet that seems otherwise lifeless.

Re: Are Those Spidery Black Things On Mars Dangerous?

#72

Post by TallGuyShort »

ry0ohki wrote: post #66
debacle wrote: post #38

A good image of the formations is on Wikipedia: http://upload.wikimedia.org/wikipedia/commons/0/0c/PIA11858_...

It seems like we'd be able to tell if they are geysers or something else by having a few frames of photos? A geyser would be moving in some way you'd think?

My understanding was that the shapes shown in the pictures are the debris piles left after the geysers.

Re: Are Those Spidery Black Things On Mars Dangerous?

#73

Post by jlgreco »

nollidge wrote: post #63
brador wrote: post #55

Earlier quoted context omitted.

How did they get here?

They evolved. For plants to be on Mars, either A) the immeasurably chaotic process of evolution yielded carbon-based, cellular, stationary, metabolizing, photosynthetic, reproductive things on two planets with vastly different geological and climatic histories, or B) Earth-borne plant material, which has evolved to the point that it can only produce a viable organism in certain rather specific environmental niches on…

Re: Option A

We obviously are operating with an extremely limited dataset (currently of size "1"), but there are a few things we can look at that may tell us something about the likelihood of particular characteristics evolving.

We know that flight has evolved on Earth at least four completely distinct times (no common flying ancestors): birds, bats, bugs, and pterosaurs. The basics of eyes are thought to share a common ancestor, but complex image forming eyes are thought to have evolved dozens of times.

I'm sure there are many better examples; I have only studied biology in my spare time as an adult, so maybe a biologist can step in.

The basic idea though is that since the driving force behind the change is not random certain general ideas are likely to keep on popping up over time. Now, are the building blocks likely to be the same? Hard to say, the chemistry for carbon based life works particularly well, but there are hypothetical alternatives. I can't speak to which is more likely than the other.

The question of "how likely is this" is really quite involved.

Re: Are Those Spidery Black Things On Mars Dangerous?

#74

Post by its_so_on »

jlgreco wrote: post #60
brador wrote: post #55

Earlier quoted context omitted.

How did they get here?

If we ever confirm life on Mars (or anywhere else for that matter), I really hope we don't find that it shares a common ancestor with life on Earth. Panspermia is cool, but two instances of abiogenesis in a single solar system? That is huge . Here's to hoping it's life, but not as we know it.

"I really hope we don't find that it shares a common ancestor with life on Earth".

Could you give a definition here (of 'common ancestor'), please?

I don't have an angle here, I'm just trying to understand your statement better.

-

tagged #rational

Re: Are Those Spidery Black Things On Mars Dangerous?

#75

Post by jlgreco »

jlgreco wrote: post #60
brador wrote: post #55

Earlier quoted context omitted.

How did they get here?

If we ever confirm life on Mars (or anywhere else for that matter), I really hope we don't find that it shares a common ancestor with life on Earth. Panspermia is cool, but two instances of abiogenesis in a single solar system? That is huge . Here's to hoping it's life, but not as we know it.

@its_so_on:

>"I really hope we don't find that it shares a common ancestor with life on Earth". Could you give a definition here, please?

I cannot respond to you directly, but sure. When I say I hope there is not a "common ancestor" I mean that I hope life on Earth and life anywhere else we may discover it do not have "common descent" (http://en.wikipedia.org/wiki/Common_descent). That is strongly believed to be the case with all life we have encountered so far. This is also a pretty good wikipedia page about this: http://en.wikipedia.org/wiki/Last_universal_ancestor

Re: Are Those Spidery Black Things On Mars Dangerous?

#76

Post by rapind »

betterth wrote: post #70
jlgreco wrote: post #65

Earlier quoted context omitted.

It really does. However, one should keep in mind that humans have overzealous pattern-matching engines. We are really good at erroneously seeing things that we recognize.

And when it comes to Martian geography, we are hopelessly bad at judging scale. It's very easy to be several orders of magnitude off without a guide or legend.

So you're saying it is a Chow Chow looking down on us.

Re: Are Those Spidery Black Things On Mars Dangerous?

#77

Post by stephengillie »

wtracy wrote: post #35
mikeash wrote: post #20

Earlier quoted context omitted.

There is, to a first approximation, no atmosphere on Mars. To a slightly better approximation, there is an atmosphere on Mars, but only enough to cause trouble, not enough to actually be useful for anything.

There's enough atmosphere for Nasa to seriously consider deploying airplanes: http://en.wikipedia.org/wiki/Mars_aircraft

We've had the discussion: https://news.ycombinator.com/item?id=4261806

A cessna would need wings as large as a 747 and be traveling about mach 1 to take off, iirc.

Re: Are Those Spidery Black Things On Mars Dangerous?

#78

Post by skeletonjelly »

stephengillie wrote: post #77
wtracy wrote: post #35

Earlier quoted context omitted.

There's enough atmosphere for Nasa to seriously consider deploying airplanes: http://en.wikipedia.org/wiki/Mars_aircraft

We've had the discussion: https://news.ycombinator.com/item?id=4261806 A cessna would need wings as large as a 747 and be traveling about mach 1 to take off, iirc.

Thats an awesome metaphor! Going to use this one, thanks.

Re: Are Those Spidery Black Things On Mars Dangerous?

#79

Post by JonnieCache »

jlgreco wrote: post #65
DougWebb wrote: post #59

Earlier quoted context omitted.

That looks so much like mold.

It really does. However, one should keep in mind that humans have overzealous pattern-matching engines. We are really good at erroneously seeing things that we recognize.

Correction: humans are overzealous pattern-matching engines.

Re: Are Those Spidery Black Things On Mars Dangerous?

#80

Post by jlgreco »

JonnieCache wrote: post #79
jlgreco wrote: post #65

Earlier quoted context omitted.

It really does. However, one should keep in mind that humans have overzealous pattern-matching engines. We are really good at erroneously seeing things that we recognize.

Correction: humans are overzealous pattern-matching engines.

Eh, we have other things as well. Meat for one. ;)

Maybe you could say that we are meaty pattern matching engines.

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