PDA

View Full Version : Discussion: The Ends of the Earth



Fraser
2005-Aug-18, 05:15 PM
SUMMARY: Pamela Conrad is an astrobiologist with NASA's Jet Propulsion Laboratory. She recently gave a lecture explaining how to searching cold deserts on Earth will help scientists understand environments that life could be hiding in the rest of the Solar System. The following article is the first part of an edited transcript of her presentation.

View full article (http://www.universetoday.com/am/publish/the_ends_of_the_earth.html)

What do you think about this story? Post your comments below.

cran
2005-Aug-18, 11:27 PM
What a great intro to the topic... I hope I don't miss the next instalments :)
Pamela touches on some of the themes and points that have been widely discussed here at UT.


So what would constitute proof? If you want to say that something has been proven, you have to achieve a certain level of consensus in the scientific community, otherwise your peers will tear you into little bits and pieces in the literature. Of course, there is never a complete consensus: that&#39;s why we nasty scientists fight with each other endlessly. But we have to at least come up with terms. We can agree or disagree with each other&#39;s theories, but we have to agree on the terms and the measurements. <_< sound like anyone here? :D


Complex polymers also could be biomarkers. Of course, plastic is a complex polymer. Then again, we made the plastic. So this whole distinction between natural and unnatural - if humans made it, it&#39;s still biogenic. So think about that. My car is a biosignature. What kind, I&#39;m not sure. (Seth) SETI, take note... <_<


If I were looking for life on another planet or a moon, I would look for places where interesting chemistry could happen, so that the ultimate evolution of that chemistry could create a living system. I would think about places like Europa, which has an ocean beneath ice. I would think about other places where ice exists, like comets. I would think about Titan, Saturn&#39;s moon. I would think about all those places where interesting chemistry occurs, because chemistry is clever. You can get all kinds of interesting molecules. I think that&#39;s an excellent summary... places where interesting chemistry happens... B)

GOURDHEAD
2005-Aug-19, 02:29 AM
I am amused by how I was confused. There is an embedded ambiguity in the wording of the title of this thread. I expected it to deal with how the Earth (or life on it) might end and in how many ways this could happen. I enjoyed the article linked and remain a hyper-zealot about the abundance of life in the universe and feel that carbon in water based critters have a large advantage.

cran
2005-Aug-19, 07:51 AM
Yeah, I think the title was a bit of a marketing ploy to suck you in... <_<

But, I have to agree with you, G; whilst I don&#39;t discount the possibility of other chemical foundations, CI chondritic chemistry (carbon, hydrogen, oxygen, nitrogen, with silicates, ferrics, and minor phosphates for structural purposes) does seem to have all the advantages, including reasonable abundances as far as we can observe :D

certainly, the natural molecule-building capabilities of carbons or hydrocarbons are unmatched, as are the thermal and electrochemical properties of water - so, the probablities must be higher that any life we may encounter &#39;out there&#39; will have similar physical chemistries - the danger to us (and conversely to them) may be susceptibility to viral and bacterial variations - ala &#39;war of the worlds&#39; - our common cold might be a lethal virus to them (and vice versa) <_<

Eric Vaxxine
2005-Aug-19, 01:45 PM
We earth dwellers operate in what we call visible light. Could life evolve outside of this spectrum in any way?
What I am really asking is, could there be organisms alive that we might not be able to see, without looking in different wavelengths? <_<

The overriding question people state.... IS there other life?
What happens when we find there is?

Microscopic - handle with care
Intelligent animal -ish - ?
Anything remotely human ish clever - ?


I think Europa must have a few wriggly things swimming around.

cran
2005-Aug-20, 01:29 AM
We earth dwellers operate in what we call visible light. Could life evolve outside of this spectrum in any way?
Most certainly, Eric... even here on Earth, there are quite complex creatures who sense and emit in wavelengths we can only detect artificially...
birds and many insects, for instance have visual senses that reach well into the ultraviolet.... some birds also can detect magnetic field lines...
bats, elephants and cetaceans (whales and dolphins etc) have developed senses for infrasound and/or ultrasound...
some so-called &#39;blind&#39; animals actually sense and/or emit in the infrared part of the spectrum...
experiments have shown that many plants can detect and respond to audible sound wave frequencies (ie, some have shown improved health and growth by being exposed to classical music from a sound system for many hours per day, compared with a &#39;control group&#39;...)
and then there are many many species (particularly in the microbiota) that sense their environment chemically or electrically (ie, they respond only to changes in the surrounding chemistry, or to electrochemical impulses)... :)
we are still only beginning to grasp the possibilities... B)

Eric Vaxxine
2005-Aug-22, 09:03 AM
Thanks Cran. Do you have any knowledge about a planned survey of Europa?

cran
2005-Aug-22, 10:36 AM
Only rumours and wishlists, Eric; perhaps if you checked out the NASA website and searched for planned future missions ... as far as I know, Europa is fairly high on their &#39;to do&#39; list (but not getting the same attention as Mars, or the proposed base on the Moon...) ;)
The success of the Galileo mission did fuel desires for more probes to Europa, and possibly Ganymede, with orbitals (like Cassini for Saturn) to survey Io and possibly Callisto... :unsure:
Early plans for a Europa probe included a lander which would then proceed to &#39;drill&#39; into the ice... probably using a combination of heat source and the lander&#39;s own mass - less of a &#39;drill&#39; as we understand it and more of a slow sinking... the ice would refreeze above the lander, so a relay station would have to remain on the surface to send data to the orbital... the relay and descending probe may well need to be linked by optic or similar cable - this means that a reasonable estimate of the depth of hard ice will have to be made before the probe is sent from Earth - if the &#39;drill&#39; probe does break through the hard ice, it will probably stop to maintain the link with the surface, and release a submersible probe (or even a large number of micro- or nano- probes - greater coverage for the same total mass package) to work through the expected &#39;slush&#39; layer and hopefully into open (but very dark) ocean... two definite targets will be sought; one is the source of the surface discolouration (possibly a form of algae similar to that seen in surface ice on Earth; possibly a ferric pseudo-evaporite?) seen concentrated along fissures - the other is any possible solid core; potentially ferro-silicate with significant organics (the total mass equation allows for a small solid core) - a bonus would be sufficient internal heat due to tidal forcing to promote &#39;hot vents&#39; from the core. :D
Whether the recent announcement and focus on putting people back on the Moon, and then on to Mars, has &#39;shelved&#39; any plans for Europa, I don&#39;t know - I certainly hope not, and as a potential site for life, Europa actually came out slightly ahead of Mars and Titan, because of the Galileo mission... <_<

Jakenorrish
2005-Aug-23, 02:02 PM
We and many other creatures have evolved our eyesight to suit our conditions. Deep sea fish have also evolved their senses to be able to &#39;see&#39; in their environment. I think that if we&#39;re looking to guess as to what may be present on Europa then the deep sea creatures we have here on Earth are worth contemplating.

We can only imagine the intense pressure that possible deep sea creatures on Europa would be under. We know however that highly evolved and skilled creatures survive without ever being exposed to a single ray of sunlight on Earth at intense pressure. I for one would be very surprised that if we do detect liquid water under the ice on Europa, and if there are vents giving out heat from the moon&#39;s internal core, there isn&#39;t any life on it.

cran
2005-Aug-23, 04:57 PM
I&#39;m with you on that one, Jake :)
The recent close surveys of small parts of the ocean floor have really opened our eyes to the possibilities... not only have we found thriving communities around hot vents, gaining energy from within the earth and feeding on sufides ... but deep sea corals (where they should not exist&#33; 2km below surface and less than 4C... and species only previously known from fossils... the geomorphologists and palaeogeographers are now having to rethink the once &#39;iron-clad&#39; concept that ancient coral deposits meant warm shallow seas...)... and &#39;cold seep&#39; communities on what was thought to be deserted abyssal plains... these guys live off the methane that slowly seeps out of the ocean sediment ... and there are some amazing images of these communities on the banks of hyper-dense (hypersaline) lakes on the ocean floor - with waves and tide marks&#33;
Life seems to be incredibly tenacious and adaptable ... and I have an idea about that (and evolution) ... but that&#39;s another story... :D

lswinford
2005-Aug-23, 05:01 PM
And what of plants? There are some frankly amazing motive, communicative, and sensory features in the plant side of life.

Then too, now that I think of it, I&#39;ve an uncle that sometimes points to his front yard when arguing with me, "that tree stump has more smarts than you&#33;" That and my ex-wife kept insisting that I wanted a wife with the IQ of a houseplant.

Yeah for plants being more, and in more places, than we expect them too be.

cran
2005-Aug-26, 08:08 AM
Originally posted by lswinford@Aug 24 2005, 01:01 AM
Then too, now that I think of it, I&#39;ve an uncle that sometimes points to his front yard when arguing with me, "that tree stump has more smarts than you&#33;" That and my ex-wife kept insisting that I wanted a wife with the IQ of a houseplant.

...and you said to your uncle, "if that tree was so smart, how come it let you cut it off at the knees?.." :D
and never mind what you might have said to the ex-wife... <_<
:lol:

yep, the variety of plants is great... just hope triffids don&#39;t turn up&#33; :o