Post by glactus on Nov 12, 2011 0:58:17 GMT
The search for life is largely limited to the search for water - we look for exoplanets at the correct distance from their stars for liquid water to splash and flow freely on their surfaces, we 'follow the water' on the red planet Mars, and SETI scans radio frequencies in the 'water hole' between the 1,420MHz emission line of neutral hydrogen and the 1,666MHz hydroxyl line.
An Xoplanet far away
There are two very good reasons why our attention is so strongly focused on water.
First, it's an efficient solvent for biological chemistry, allowing molecules to move around in cells, and has properties that are friendly to life - a high heat capacity, the ability to remain in liquid form across a wide temperature range, and a molecular density that forces molecules to organize themselves, rather than the water organizing around the molecules.
A new distant world
Secondly, the biosignatures of a water-based chemistry are a lot easier for us to identify remotely Moreover, the most important fact about water's relationship with life is that it is here on Earth. "Some argue that is the only important thing about water," says Chris McKay of NASA's Ames Research Center. McKay is an astrobiologist and planetary scientist who specializes in hunting down alien environments and then asking the question, 'could something live here?', rather than deciding what is and isn't habitable beforehand.
An artist's rendering of an Xoplanet
Suppose, though, that life needn't be constrained to a water-based chemistry; would we be able to recognize the signatures of such life and the habitats in which it lives? From one perspective, water seems such a good match for life because it may be the only match - no other liquid has the properties or abundance that water has.
One point four billion kilometers from the Sun orbits Saturn, the majestic ringed planet. Saturn is a gaseous world with an atmosphere of hydrogen and helium, and no discernible rocky surface below.
However, among its retinue of icy moons is Titan, bigger than the planet Mercury and swathed in a dense cloak of hydrocarbon smog suspended in its nitrogen-rich atmosphere. It's the only moon in the Solar System to have an atmosphere, and it has intrigued astronomers ever since Gerard Kuiper detected methane there in 1944.
When the joint NASA-ESA Cassini-Huygens mission arrived in the Saturnian system in 2004, the truth about Titan was revealed. Infrared cameras and radar on Cassini showed a world driven by black, oily rivers and lakes, whilst the Huygens probe plunged through the opaque atmosphere to land on a soggy floodplain, but not one damp with water.
Suppose life could exist in an environment like this; it would be a whole new category of habitable planet, one where liquid methane replaces liquid water, consequently leading to an entirely different habitable zone, one that is farther out from a star than the liquid water zone
To see superb 22 minute video of our search for habitble worlds just click on the link below. Has sound
www.youtube.com/watch?feature=player_detailpage&v=crXepPkd9EM
Credits: These are non copywrite images
Text: This is part text only. See full text and all scientists involved at Space Daily.com
www.spacedaily.com/reports/The_Methane_Habitable_Zone_999.html
Video by YouTube
An Xoplanet far away
There are two very good reasons why our attention is so strongly focused on water.
First, it's an efficient solvent for biological chemistry, allowing molecules to move around in cells, and has properties that are friendly to life - a high heat capacity, the ability to remain in liquid form across a wide temperature range, and a molecular density that forces molecules to organize themselves, rather than the water organizing around the molecules.
A new distant world
Secondly, the biosignatures of a water-based chemistry are a lot easier for us to identify remotely Moreover, the most important fact about water's relationship with life is that it is here on Earth. "Some argue that is the only important thing about water," says Chris McKay of NASA's Ames Research Center. McKay is an astrobiologist and planetary scientist who specializes in hunting down alien environments and then asking the question, 'could something live here?', rather than deciding what is and isn't habitable beforehand.
An artist's rendering of an Xoplanet
Suppose, though, that life needn't be constrained to a water-based chemistry; would we be able to recognize the signatures of such life and the habitats in which it lives? From one perspective, water seems such a good match for life because it may be the only match - no other liquid has the properties or abundance that water has.
One point four billion kilometers from the Sun orbits Saturn, the majestic ringed planet. Saturn is a gaseous world with an atmosphere of hydrogen and helium, and no discernible rocky surface below.
However, among its retinue of icy moons is Titan, bigger than the planet Mercury and swathed in a dense cloak of hydrocarbon smog suspended in its nitrogen-rich atmosphere. It's the only moon in the Solar System to have an atmosphere, and it has intrigued astronomers ever since Gerard Kuiper detected methane there in 1944.
When the joint NASA-ESA Cassini-Huygens mission arrived in the Saturnian system in 2004, the truth about Titan was revealed. Infrared cameras and radar on Cassini showed a world driven by black, oily rivers and lakes, whilst the Huygens probe plunged through the opaque atmosphere to land on a soggy floodplain, but not one damp with water.
Suppose life could exist in an environment like this; it would be a whole new category of habitable planet, one where liquid methane replaces liquid water, consequently leading to an entirely different habitable zone, one that is farther out from a star than the liquid water zone
To see superb 22 minute video of our search for habitble worlds just click on the link below. Has sound
www.youtube.com/watch?feature=player_detailpage&v=crXepPkd9EM
Credits: These are non copywrite images
Text: This is part text only. See full text and all scientists involved at Space Daily.com
www.spacedaily.com/reports/The_Methane_Habitable_Zone_999.html
Video by YouTube