Can life exist in the harsh conditions of our solar system? Could life evolve and survive under the extreme heat and pressure of Venus, under the icy crust of Mars, or in the oceans of Europa? To find out just how resilient life is, scientists have been looking for answers in some of the most hostile environments on Earth. And in recent years, life has been discovered in the most extreme conditions, previously thought to be uninhabitable. These microorganisms are sometimes called extremophiles.

There are many different classes of extremophiles, which are named according to the environmental conditions in which they thrive. For example, a thermophile is an organism which lives in conditions between 60˚ and 80˚ Celsius. Recently, a thermophile was discovered nearly two miles beneath the Earth’s surface in the Mponeng Gold mine of South Africa. This particular discovery is interesting because these thermophiles are completely devoid of sunlight, surviving on the byproducts of radioactive decay.

Where might we look for extremophiles outside of Earth? Mars is a good place to start. With the recent confirmation of ice in the crust, it is possible that water has trickled deep into the Martian interior, where thermophiles can survive off of radioactive materials like previously discussed. On Earth, we have discovered halophiles, which require high amounts of salt to survive; recently, the Phoenix Lander discovered several different types of salts in the Martian soil, which could be another location to search for life. Other types of extremophiles discovered on Earth may also apply to Mars, such as: xerophiles, hypoliths, and radioresistant extremophiles.

Europa is another great place to look for extremophiles. It is theorized that there is a global ocean beneath Europa’s thick layer of surface ice. Sattelite images of Europa’s surface show a complex system of tectonic activity–places where the ice has broken and liquid water has upwelled to the surface and refrozen. This tectonic activity is likely the result of tidal flexing, due to the gravitational pull of Jupiter. This tidal flexing may also produce hydrothermal vents. Earth’s hydrothermal vents are host to a large amount of biological activity, meaning Europa is a very promising place to look for extremophiles.

There are future plans in the works to search for extremophiles in the Martian crust. Astrobiological missions to Europa, Titan, or elsewhere are probably deep into the future. Given the amount of life discovered in the harshest places on Earth, I will be surprised if we find that our solar system is devoid of life.

Saturn’s largest moon (the solar system’s second largest moon), Titan, was discovered in 1655 by Dutch astronomer Christiaan Huygens. In 1944, Gerard Kuiper demonstrated that Titan’s dense atmosphere has the spectral signature of methane.  Up until the arival of the Voyager 1 in 1980 and Cassini-Huygens in 2004, Titan was somewhat of a mystery with its surface features hidden beneath thick layers of clouds and haze.

Although the surface was still hidden, Voyager was able to learn much about the moon’s planet-like atmosphere. Titan’s huge atmosphere creates a surface pressure of 1.5 bars, a temperature of 94K, and a density of 5.3kg/m3.  This surface temperature is close to the triple point of methane, which could mean that Titan has a methane cycle similar to Earth’s hydrological cycle.           

In 2005, ESA’s Huygens Probe was released from Cassini and entered Titan’s atmosphere. It discovered that Titan and Earth’s atmosphere share a similar altitude/temperature relationship.  On Earth, the temperature decreases with altitude in the troposphere, increases in the stratosphere due to the absorption of UV rays in the ozone, decreases in the mesosphere due to decreasing atmospheric density, and finally increases in the thermosphere due to the release of thermal energy caused by the break up of molecules by solar radiation.  On Titan, the temperature decreases with altitude in the troposphere, and increases in the stratosphere. 

With several Cassini flybys, Titan’s mysterious surface is finally being revealed.  Titan’s surface is incredibly Earth-like with rain-cut river beds, hydrocarbon lakes, and giant equatorial sand dunes.  Much is still unknown about the surface, such as the depth of the lakes, and how the sand dunes are formed.  Cassini Radar observations also confirmed that the entire crust of Titan is floating on top of a massive water ocean.              

With a two year extention to the Cassini mission, including 26 more Titan fly-bys, there is definitely more discoveries to come.  Titan is well worth exploring with complex orbiters and landers, not only to explore Titan’s exotic surface features but also to look for signs of extremophiles.  Any such mission is far off, so in the meantime we can enjoy the only sounds ever recorded on a body other than Earth which were recorded by the Huygens Probe as it descended through Titan’s atmosphere: Sounds of Titan�

Modern philosophers are chiefly good for one thing: They force us to reflect on each our own being. Whether it be as in the extreme case of Descartes who stripped away every knowable thing from his perceptible world less his own self-consciousness i.e. cogito ergo sum, or a more fashionable ‘search for meaning’ as empowered existentialists such as Jaspers, Sarte, and Camus, modern philosophy, beyond any remedial advice for living in the modern age, reminds us how far removed we are from the world to which we hold. If we can’t know the things-in-themselves, then we best know ourselves. Kind of a “…love the one you’re with” sort of directive. And who do we know better than our mirror’s twin?

Being of the tender age 18 and newly initiated to college life, my intellectual depth was so deficient it would need high tide to warrant the term shallow. Nevertheless, if I had anything I had curiosity and a deep desire for acquiring knowledge. You couldn’t have convinced my parents of this at the time, but I turn and ask you, who hits the library looking for a book upon the recommendation of a piece of graffiti? Jumping online is one thing, but back in 1984 a person had to brave the elements, walk to the library, walk up an abundance of stairs, consult a card catalog (50 point bonus for ironic verbal accessory), and then go diggin’. Make no mistake, this activity required an investment of time.

After the encounter with Mr. D___, the pentecostal buffalo (self titled, which I failed to mention in my prior post), I returned my attention to Schopenhauer and The World As Will and Representation. The first two lines of book 1 read:

The world is my representation: this is a truth with reference to every living and knowing being, although man alone can bring it into reflective, abstract consciousness. If he really does so, philosophical discernment has dawned on him. It then becomes clear and certain to him that he does not know a sun and an earth, but only an eye that sees a sun, a hand that feels an earth; that the world around him is there only as representation, in other words, only in reference to another thing, namely that which represents, and this is himself.

I read this particular passage over and over for nearly an hour. I didn’t understand a word of it. The book I held in my hands was of the old, cloth-cover, case bound variety; the linen was worn and frayed and the pages smelled musty as anything I could find in an abandoned root cellar. The small but heavy strokes of the letters on the pages brought to mind a bespectacled shopkeeper mottled with ink smudges, furiously pedaling away on his Gutenberg. In that moment, I felt part of a long tradition reflected in the character and condition of the book I held. Mental fortitude was a strength of my youth where resources were lacking, so I continued reading this passage over and over and over until I understood it.

And finally, I understood.

The most historically observed planet in the solar system, Mars, has been the subject of astronomy since at least 400 B.C. when the Babylonians began making sophisticated predictions of the heavens. Since 1960 there have been 38 attempted missions to Mars, with only 19 successes. This 50% success rate has become known has the Mars Curse.

Perhaps the Mars Curse has been lifted because recent missions have been more successful including 6 of 7 Martian Landers. Included in this figure is Spirit and Opportunity which were launched in June 2003 and designed to last 90 Sols. The Rovers have far surpassed this expectation, with Spirit on Sol 1647, and Opportunity on Sol 1626. The rovers have made several important discoveries, including a patch of nearly pure Silica, which could be a promising place to look for signs of past microbial life. On Earth similar patches of Silica are formed from hot-springs and fumaroles which are both full of microbial life. Also currently on the Martian surface is the Phoenix Lander which has made it share of important discoveries, including: water, clay and several different salts. Water has previously been detected on the Martian surface but this is the first time it has been detected using a direct chemical analysis of the soil.

As knowledge is built, more questions arise, and future missions are being designed to answer such questions. Future mission include the international Mars Science Laboratory which is slated to launch this fall. This Rover will be equipped to determine if organic compounds are present in the soil, and to determine what geological processes may have formed samples of rock. Other future missions may include UAV scout missions, Mars Sample Return, an Astrobiology Field Laboratory, and eventually it will be necessary to send manned missions to Mars.