Monthly Archives: March 2012

A Closer Look at Titan

In my previous post, I made a mention of Saturn’s moon Titan being a possible host for extraterrestrial life. Turns out that Titan was discovered on this very day, March 25, back in 1655 by the Dutch astronomer Christiaan Huygens. Given this fact, I thought it would be fun to take a closer look at this moon. What’s so special about it? Why do astronomers think it could harbor life?

Source: NASA

A major point of interest is that Titan is the only moon discovered so far that has a substantial atmosphere. It’s atmosphere is about 1.5 times as thick as Earth’s and, like Earth’s, is dominated by nitrogen (McKay, 2005). Along with nitrogen, the atmosphere is rich in organic compounds such as methane and other hydrocarbons (Lemonick, 2010). Obviously, these conditions are very different from what we see here on Earth, but astrobiologists think that  the atmosphere provides precursors for, and can sustain, life. Experiments conducted at the University of Arizona have demonstrated that DNA/RNA bases cytosine, adenine, thymine, guanine, and uracil and amino acids glycine and alanine can be produced from the ingredients in Titan’s atmospheric haze (2010).

Source: Wikipedia

Interestingly, Titan’s surface is devoid of liquid water, which seems to argue against its ability to support life. Yet, others argue that life can exist in the liquid methane lakes that dot Titan’s surface, shown in the image above. These lifeforms would use acetylene, ethane, and other organic solids in combination with hydrogen to derive energy for sustenance (McKay & Smith, 2005). Supporting this idea is the fact that certain lifeforms on Earth, microorganisms called methanogens, exist in a similar manner. The science behind this theory is very dense, so I won’t write it all out here. Instead, I refer you to the  2005 paper written by McKay and Smith which discusses the matter. Furthermore, while the surface does not have water, scientists believe that Titan does have a global subsurface ocean, composed of a water-ammonia mix. As Fortes (2002) writes, conditions within this hypothetical ocean, while extreme by terrestrial standards, are such that life could indeed survive.

In 2005, the Huygens probe landed on Titan’s surface, marking the first landing done in the outer solar system. Atmospheric and surface data obtained by Huygens possibly indicated the presence of methanogen-like life (McKay, 2010). However, abiotic chemical or geological processes cannot be completely discounted. Ultimately, it will take many years of study and exploration to uncover Titan’s secrets. But, if what’s been discovered so far is any indication, the undertaking promises to yield intriguing results. I, for one, am hoping that life is one of them.

To read more:

http://en.wikipedia.org/wiki/Life_on_Titan

http://www.astrobio.net/index.php?option=com_retrospection&task=detail&id=1755

http://www.astronomy.com/en/sitecore/content/Home/News-Observing/News/2010/10/Titans%20haze%20may%20hold%20ingredients%20for%20life.aspx

The article by McKay and Smith: http://www.sciencedirect.com/science/article/pii/S0019103505002009

The article by Fortes: http://www.sciencedirect.com/science/article/pii/S0019103500964005

http://www.spacedaily.com/reports/Have_We_Discovered_Evidence_For_Life_On_Titan_999.html


Life Elsewhere? Perhaps in Our Solar System?

Source: Time Magazine

The possibility of life existing elsewhere has fascinated human beings since… well, since humans have been on this planet. With the advancement of space study and exploration, many astronomers have turned their attention to finding planets (or other astronomical bodies) with life. For example, there is the extrasolar planet Gliese 581g. Located 20 light-years away from Earth, 581g orbits within the habitable region around its star and has enough mass (3 times that of Earth) to retain an atmosphere capable of supporting life. There’s also the ongoing SETI (Search for extraterrestrial intelligence) project. The Voyager probes carried golden records which contained scenes, greetings, music, and sounds from Earth for would-be alien listeners. To date, these searches, and others, have not proven fruitful. Yet, personally, I think these are worthwhile endeavors and that, sooner or later, they will pay off. Think about it. Our universe is so vast that it is a virtual certainty that life exists, somewhere out there. The odds that our small corner in the cosmos turned out to be the only place to hit the biological jackpot are ridiculously small.

That said, maybe we don’t have to look too far to find life. In fact, it may be right under our noses, here in this same cosmic corner. Life doesn’t exist on the 7 other planets, but some of the moons surrounding our Jovian neighbors have been garnering interest. Wikipedia has a great article detailing the studies and theories of life on Titan, Saturn’s largest moon. Jupiter’s moon Europa is thought to have an ocean under its icy surface, which could harbor life. Then, there’s Enceladus, whose picture you see above. Like Europa, it is thought to have an ocean. It is also a moon with cryovolcanic activity, with eruptions spewing water, carbon dioxide, carbon monoxide, potassium salts, and other organic materials (Kluger, 2012). With these discoveries, growing numbers within the scientific community consider it a sweet spot for alien life (Lovett, 2011). Much exploration needs to be done, but the excitement over what is known is certainly warranted. And, yes, in the end we may not find anything at all. But, that just means we’ll have to look harder elsewhere.

Or maybe, just maybe, they’ll find us first.

To read more about Enceladus, see:

http://www.time.com/time/health/article/0,8599,2109837,00.html

http://www.nature.com/news/2011/110531/full/news.2011.337.html


Sounds of Our Solar System

Believe it or not, there is sound in space. It’s just not the type of sound we’re used to. The sound waves we normally listen to are mechanical waves, which means that they require a medium to pass through (i.e. air). Space is virtually a vacuum, which is why you wouldn’t hear anything if you stuck your head out of a spaceship.

Electromagnetic waves, on the other hand, can travel through the vacuum of space. The interactions between certain particles results in vibrations that produce electromagnetic waves. With the proper equipment, one can “record” these vibrations. Spend a little time converting those recordings into audio format and voilà! You can “listen” to those recordings. Various satellites and probes, such as SOHO and the Voyager, have done exactly that. For example, here’s SOHO’s recording of our Sun (skip towards the end, near 1:41 or so):

Want to hear our planet? This is Earth:

Jupiter:

And, finally, here’s Saturn composing the soundtrack to your nightmares:

The descriptions of those videos do a decent job explaining how those sounds are being generated, so if my brief introduction didn’t satisfy you, I hope the words of others, who have taken the time to find and make these astonishing works available to the public, does.