
Keeping Mars Earth-free - jonasracine
http://www.nytimes.com/2015/10/06/science/mars-catharine-conley-nasa-planetary-protection-officer.html
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danieltillett
We are only about 4.4 billion years too late. Mars has be bombarded by Earth
rocks (ejecta from large meteor events) for billions of years. Some of these
rocks were ejected under conditions where bacterial spores inside them can
survive the trip to Mars. I fully expect we will find life on Mars that looks
just like Earth life.

There is actually a good case to be made that life originated on Mars given
that it had liquid water on the surface earlier than the Earth.

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drewblaisdell
> Some of these rocks were ejected under conditions where bacterial spores
> inside them can survive the trip to Mars. I fully expect we will find life
> on Mars that looks just like Earth life.

I hope that, if we do find life on Mars, we are able to discern whether it
came from Earth at some point or originated on Mars.

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danieltillett
This is actually my biggest worry with the search for life on Mars - if we
find life and it is related to life on Earth is it native or is it Earth-life
contamination that came with the spaceship? There will be no easy way to tell.

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eveningcoffee
Genomics. Organisms from current Earth and early Earth should have vastly
different genome.

It would be more tricky to determine if life originates from Earth or Mars if
we make an assumption that early life went through many iterations.

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danieltillett
If only it were so simple. The problem is we are not sure of all the genetic
diversity of the life we have on Earth, especially the extremophile bacteria
and archea [1] that are the most likely to survive the trip to Mars as
contaminants.

My best guess is we will find organisms related to microbes on Earth. The
really interesting thing is we might find organisms that are more distantly
related than the our current last common ancestor. This would be amazing as we
would then know that life originated on Mars and came to Earth later.

1\.
[https://en.wikipedia.org/wiki/Extremophile](https://en.wikipedia.org/wiki/Extremophile)

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cam-
We didn't keep continents Europe/Asia free when we populated them. Horses,
sheep, wheat, etc to the Americas and Australia were important advances.

I bet when we start populating other worlds, they will become Terran for the
simple reason that the ecosystem around us is great for supporting us.

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mhurron
> the ecosystem around us is great for supporting us.

Except we suck at supporting it. The idea of humanity terraforming another
planet are hilarious, we can't run one that was handed to us running and self-
sufficient.

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qrendel
Introducing a dominant civilization to a planet would more likely cause a sort
of regression towards the mean in ecosystem diversity, at least over the
short- to medium-term. In a highly complex and delicately-balanced ecosystem
(i.e. Earth) it tends to reduce diversity as species and ecosystems are pushed
aside, whereas in a non-existent ecosystem (i.e. Mars) it would cause
something to exist in the first place, even if the system isn't as complex as
what evolved on Earth over billions of years.

There would certainly be more life on Mars after it was colonized, not less -
even if that at first only consists of a few dozen species used to support
humans.

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guard-of-terra
You should not overstate how Earth ecosystem is "delicately balanced". Large
deserts where vegetation used to be. Ice ages (and inter-ice periods) really
messed up northern fauna: all megafauna went extinct, wooly rhinos, mammoths,
sabertooth tigers, etc. Without them the ecosystem is incomplete and
disbalanced.

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Retra
Compared to what? What parameters are you 'balancing?'

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guard-of-terra
In my opinion, balanced ecosystem is one that a) diverse, b) produces as much
as life as possible for a given landscape.

Why diverse? Diverse ecosystems are more resilient against shocks, changes and
diseases.

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iandanforth
To cut to the chase we should ignore these concerns and begin plans for
terraforming Mars. If you really want to go through the ins and outs of why
this is the end-game, please read Red/Green/Blue Mars by Kim Stanley Robinson.

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mc32
Sometimes I think we should just let the Russians or Chinese take over
planetary exploration.

I'm not sure what it is about Europeans and Americans where we want to
preserve things. If we're going to colonize Mars, contamination will happen,
no question. Maybe we'll eradicate everything unique to the planet, but it's
inevitable.

If we are going to survive as a species, we'll need peoples who are willing to
push forth without pussyfooting.

Sure, it's nice of you want to study pristine environments but I don't think
you can maintain the environment pristine once you have humans there in any
way.

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pmontra
My take: the Grand Tour ending into Italy, the Roman ruins and the resulting
cult of ancient stuff as time delivered them to us. That's why it's anathema
in the western world to even think about restoring the Colosseum to its
original form (I'd love to hear its architect about it) or painting the Greek
statues with their original colors [http://io9.com/5616498/ultraviolet-light-
reveals-how-ancient...](http://io9.com/5616498/ultraviolet-light-reveals-how-
ancient-greek-statues-really-looked)

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SCAQTony
The planet has lost a profound majority of it's water and consequently it is
ostensibly dead or dying a slow death. Whatever microbes are alive there one
must suspect that is probably less diverse than it once was when Mars had an
ocean. Perhaps adding more bio diversity to that planet might even help it. Of
course we should add this diversity once we find out what life is there if any
so as to make responsible choices.

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littlewing
That's on the surface, at least. We keep learning how life on our own planet
exists places far below sea level, and not just in the ocean. The same could
be true for any number of celestial bodies in the known universe.

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danieltillett
Actually most life is found below the surface of the earth - you can find
bacteria (and archea) a few km down in the earth.

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roflchoppa
So what happens if people get to Mars, are they in control of the planet? Or
does the country that ships them out there maintain them as constituents?

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JBReefer
That's basically what happened with the discovery of the new world -
maintaining control with slow communication and inability to project power
over the seperating distance doesn't really work

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aggie
North America had considerable natural resources which allowed the colonies to
be self-sufficient in short order. An equivalent transition to sovereignty
could still happen on Mars but it would probably look much different and last
much longer.

