The Case Against Fossil Fuels

Another essay assigned for the class Energy & the Environment (Fall Semester 2018, CU Boulder) asked students to develop either a prosecutor's argument convicting human use of fossil fuels of causing an increase in global temperature or a defense attorney's argument for a "not guilty" verdict. Admittedly glossing over much of the data, I chose to focus on just a few simple concepts to make my point.

     Greenhouse gases are a fairly well-studied component of planetary atmospheres. Included in the list of the most prominent—capable of regulating and/or destabilizing the climate on a given planet—are water vapor, carbon dioxide, and methane. These gases tend to trap solar energy radiated from the surface of a planet (measured as its albedo) that would normally make it back to space and have relatively little impact on the equilibrium temperature at the planet’s radius from its parent star. And, if mechanisms exist on planets which continue pumping more greenhouse gases into their atmospheres—carbon sources such as volcanic eruptions—without other mechanisms to pull those gases back out (called carbon sinks), the actual surface temperatures of those planets exceedingly deviate from their equilibrium temperatures. A perfect example in our very own solar system is that of Venus. While the equilibrium temperature of Venus should be around -43 degrees Celsius, the actual surface temperature is over 500 degrees Celsius! Why? The atmosphere of Venus is mostly carbon dioxide, which traps much of the incident radiation from the Sun, and there are no known mechanisms to pull any of that carbon dioxide from it. Venus is a slow rotator (its day is longer than its year) and it is geologically dead with no magnetic field. But, we can learn much from examining the impact of greenhouse gases on global temperatures. So, what does it mean for us here on Earth?

     Ice core samples from Antarctica have allowed accurate depictions of the natural fluctuations of Earth’s climate for at least the past 800,000 years. As well, since 1958 accurate measurements have been taken at Mauna Loa in Hawaii of the carbon dioxide content of the atmosphere. These measurements clearly indicate an upward trend, and, when superimposed on the ice core data from the past 1000 years, is quite unprecedented, as shown in the figure from the textbook Energy and the Environment (3rd Edition):

     Earth has gone through a series of global temperature fluctuations in its billions of years. From glaciations and ice ages to warmer, more moderate climates, the natural processes regulating outgassing and carbon sequestration—volcanic eruptions, plate tectonics, atmospheric composition, and ocean temperatures—have allowed long periods over which slow fluctuations in Earth’s climate occurred. But, human activities in just a few centuries have caused a wild deviation from the slowly regulated climate of the past. Since the industrial revolutions of the 18th and 19th centuries, humans have been dumping vast amounts of carbon dioxide, methane, and many other combustion and industry products, into the Earth’s atmosphere. We have created many carbon sources by pulling hydrocarbons out of the ground and burning them; but, we have created virtually zero carbon sinks over the same amount of time. And some of the most impactful carbon sinks that already exist—the oceans—are being warmed by this atmospheric feedback loop; i.e. the warmer the oceans, the less CO2 they are capable of absorbing. (This is how a runaway greenhouse effect accelerates!) We’ve also increased the human population exponentially and created an industry of gigantic agriculture that now contributes to more than half of the methane released into the atmosphere by anthropogenic means. An expectation of no repercussions would be inexcusably foolish!

     It is very clear that human activities have been releasing hundreds of millions of tons of greenhouse gases into the atmosphere each year for decades. It’s also very clear what happens over time to atmospheres that experience a runaway greenhouse effect: Hotter, drier summers; colder, harsher winters; and wildly unpredictable, more severe weather phenomena such as hurricanes. But, we only live an average of 80 years on this planet so of course it seems reasonable to think that because we might not see a significant difference over the course of our lifetimes then it must not be that significant. But, we would be wrong and stupid to think so arrogantly. When the natural fluctuations of Earth’s climate have occurred over the course of thousands, hundreds of thousands, or even millions of years, the only insignificant thing around would be the average human lifespan. But that doesn’t preclude the possibility of having a significant impact on that climate, as all current data indicate we have increased the CO2 concentration in Earth’s atmosphere to levels never seen in several hundred thousand years.

     Point blank: We are negatively impacting Earth’s atmosphere. All evidence points directly to human activities. And if we want to still have a habitable world for generations to come, then we better get serious about transitioning from fossil fuels to carbon neutral and so-called ‘alternative’ energy sources. The debate is over. We either act now or we deserve whatever we get for being such a pathetic, potential-squandering species.

Resources

Bennett, J. O., Donahue, M., Schneider, N., & Voit, M. (2017). The cosmic perspective. Boston:

     Pearson.

Ristinen, R. A. (2016). Energy and the environment. Place of publication not identified: Nielsen

     Bookdata.

Rothery, D. A., Gilmour, I., Sephton, M. A., & Anand, M. (2011). An Introduction to 
     Astrobiology. Cambridge: Cambridge University Press.

A Sensible Energy Solution

     An assignment given in the class Energy and the Environment (Fall 2018, CU Boulder) called for students to write a letter to the CEO of an energy company as a sort of call-to-action. And if you have been following this blog and reading my content for the past several years, you'll probably understand that I wanted nothing more than to go on one of my usual tangents about how this economic model is destroying the planet; how we have a monetary system with disadvantage built right in; social stratification--you know, the things that this entire blog revolves around. But, I finally took a step back and tried to think of a transitional solution to this problem. I asked myself how I could possibly convince billionaires to reduce their massive profits to provide sensible, sustainable, clean energy solutions. Here is what I came up with:

To whom it may concern:

     It was recently calculated that several tons of arsenic are produced in the waste ash at your facility each year costing consumers millions in additional cleanup costs. While this is alarming by itself, perhaps even more frightening is the general lack of willingness among the biggest energy providers around the world to even consider a transition to other sources. So, I’ve come up with a proposition that could be the game-changer we need on this planet. A few things first, though.
     In the decades since WWII, the United States swiftly transitioned from a massive manufacturing economy to a massive service economy. But even the service industry has been overhauled recently by the rise of social media. Point blank: If your service sucks as a company in 2018, you’re going to fail faster than the time it takes to upload the viral video that destroys you. So, companies must remain at the cutting edge of social trends and keep up with consumer demand. That means meeting the wants and needs of customers—not creating monopolies and sacrificing the health of your customers and the environment in order to appease shareholders! Sure, people want (and, quite frankly, need) energy; but not at the expense of the planet their children will inherent one day. We’ve seen the charts; we’ve heard the arguments; and so have you. The data are clear. And we all know what the possibilities are with 21st century technology. So, enough with the obfuscation and doublespeak!
     When I make a purchase nowadays, there are three main things I look for in a product or service: Reliability, versatility, and quality. I want the product I purchase to actually function the way I was told it would and the services I purchase to actually be performed the way I was told. The products should also be multi-faceted and perform a wide range of functions in all-in-one packages while the services should follow suit. Finally, my products better last a long time and include lifetime warranties. Enough with planned obsolescence!
     In terms of energy, however, I have a slightly different outlook. That is, we currently have the technology and resources to transition into a global economy that produces 100% of its energy with clean, dependable, safe sources, such as solar, wind, wave, tidal, and geothermal. But, we willfully choose not to in lieu of creating markets for the shareholders of energy giants such as yours. This is wrong and detrimental to the greater population and we all know it. So, what can we do to compromise and move forward sustainably?
     The service sector I mentioned earlier is something in which you should seriously consider taking a larger role. It’s simple, really. What you can do is offer Swap-Out packages to homeowners and HOAs. Start the transition by creating a new market that offers both rentals and buy-outs for energy installation packages. Here’s how it might work:

1. Stop putting up ridiculous billboards that say things like, “Wind stops. The sun sets. Choose coal!” Seriously. I can’t even roll my eyes hard enough to convey just how idiotic that sounds.
   
2. Invest in, buy, or partner with solar, wind, wave, etc. companies.
   
3. Retrain your employees at the coal-burning facilities to install and maintain solar,
   wind, wave, etc. packages (depending upon region).

4. Work with governments (local, state, and federal) to create tax incentives to install the packages.
   
5. Create contracts with customers that offer at least three options:
   
   1. Rental: The contract would include tiers of payments based upon the size
      installation. The packages would still be owned by your company and liability insurance would be split between the renter and your company (that is fair and we both know it). Part of the rental fees would also go toward maintenance costs (i.e. hiring the retrained coal plant employees, veterans, etc.).
      
   2. Buy-out: This contract would include an option to actually sell energy back to the grid and would require the homeowner to carry their own liability insurance. The packages would be fully owned by the homeowner but the maintenance would, by law, have to be conducted by you. This, of course, requires a lifetime contract. (Yes, you read that correctly: lifetime contract.) This contract must have periodic renegotiation (say, every 5 years or so) to adjust for property sales, inflation, and other economic factors. This option not only guarantees jobs to maintain the new, on-site, mini-grids on the consumers’ properties, but it also should minimize the amount of resources used to maintain the larger grid already in place.
      
   3. College Option: This option pays the tuition of select students choosing to pursue a career in the field of energy production. The student will be fully trained to immediately enter the work force upon graduation. Paid internships and on-the-job training will be a requirement for completion.
      

     I realize the markets that have been created will be upset by these changes but let’s face facts and also realize that the planet itself doesn’t care about us. Or our markets. If we think that we can continue dumping millions of tons of greenhouse gases into the atmosphere without building carbon sinks and also without repercussion, then, quite frankly, we are an arrogant failure of a supposedly intelligent species and we deserve the onslaught of erratic weather and geological phenomena Earth has in store for us... But, as the leader of an energy giant capable of making the decisions to swiftly make this transition we need to make, the onus truly is on you to make it happen as quickly as possible. Make the right call. Be a leader.

Sincerely,

Kyle Benjamin

The Search for Life in the Universe: Europa, Titan, and Enceladus

     Throughout the history of humankind, a seemingly-inherent penchant for exploration, coupled with various climatic events, has driven the proliferation of the human species across planet Earth. Whether nomadic bands of hunter-gatherers were searching for newer, more abundant sources of food, or simply exploring for its own sake, homo sapiens successfully populated the Earth through a journey that began thousands of years ago in south-central Africa and took several dozen centuries. But, even with all that humankind has accomplished, and with all the introspective and extrospective information accumulated in the past four centuries alone, there is much left to explore both on the surface and in the oceans of this majestic world. Moreover, there is an entire universe out there—unimaginably vast and just waiting to be discovered. But, humans tend to get easily distracted by both forms of intergovernmental conflict (within and between governments), wars, manufactured controversy, and a host of other trivialities, ultimately veering the species off that road to cosmic discovery. Nevertheless, space programs the world over have managed to send spacecraft on trajectories that have taken them from precariously close to the Sun1 to beyond the heliosphere of the solar system2. Several rovers have successfully descended through the Martian atmosphere34 and one on Saturn’s moon Titan5; an orbiter/lander package was even sent to an asteroid6! And, while all of this exploration has been done in the hopes of gaining a deeper understanding of how life arose on Earth and whether or not it happened elsewhere in the cosmos, an extraordinary wealth of knowledge has been amassed regarding the physical and chemical properties of the cosmos itself. But, before drawing the lines of evidence for otherworldly life in this solar system, a few questions should first be answered: What is life? Are there certain elements that are considered crucial for life? How common are these ingredients? And, what processes exist on Earth have been identified as possible catalysts for the transition from inorganic to organic molecules?

A Definition of Life

     For many centuries, philosophers the world over struggled to explain this experience called ‘life’. The elements that formed everything around were simple: earth, water, air, and fire. Life itself was viewed as something rather peculiar—especially human life. And somehow humans were supposed to strive for the good life, as Aristotle put it in his Nicomachean Ethics.7 In retrospect, however, something always seemed to be missing from these arguments: hard evidence. Thought experiments can take one but so far; it is only when unbiased physical, chemical, and biological experiments bear out the facts of reality through the accumulation of evidence that such claims should be accepted. And even then, uncertainties should always be taken into account. Perhaps this perspective seems obvious in the highly technical, information- driven world of today but it certainly wasn’t always the case. The concepts of innocent until proven guilty and evidence-based reasoning are relatively new in human history. Before the Renaissance began sometime in the 14th century, people largely took things at face value with very little thought—burning ‘witches’ alive and massacring countless ‘others’ that dared to question any form of assumed, typically divine, authority. In fact, life seemed to be defined in terms of that authority: God > kings > other humans > animals > everything else in the universe. But, this geocentric, authoritative perspective left much to be desired. Observations began to contradict doctrine which eventually led to a revolution in thinking. Life, it turned out, wasn’t so simply defined.

     Although the debate rages on today, at least in philosophical circles, biologists and chemists have in recent years joined it in an effort to standardize the definition of life. Among the many that have been posited over the decades, the definition that perhaps best encompasses humankind’s present understanding was proffered by Gerald F. Joyce in the 1990s and then included in an anthology released in 2008 called Extraterrestrials: Where are They?: “In a very broad sense, living organisms turn food into offspring. They metabolize food and use the energy derived from the food to produce offspring, that is, to produce more life. Among biologists and biochemists a working definition of ‘life’ is: ‘a self-sustained chemical system capable of undergoing Darwinian evolution’.”8 Objections to this definition remain but it suffices for the purpose of this essay.

Follow the Water

     Perhaps the most essential substance in which countless reactions can take place is water in its liquid form. Known as ‘the universal solvent’ for its ability to dissolve an array of other substances, water is a polar molecule with a negatively charged oxygen atom opposite two positively charged hydrogen atoms that are spaced 104.5° apart. This arrangement makes it “sticky”, a characteristic ultimately derived from electromagnetic forces; it also means that water is capable of conducting electricity when salts are dissolved in it. These properties prove essential in the synthesis of other molecules that could lead to self-sustaining chemical systems. Thus, the catchphrase for finding life throughout the astrobiology and space exploration community has unsurprisingly become “follow the water”.9 Since Earth harbors life everywhere liquid water exists, then a reasonable supposition would be that where there is water, there is life.

SPONCH for Life

     The chemical systems that eventually gave rise to biological entities here on Earth can be described by the acronym SPONCH. Sulfur, phosphorus, oxygen, nitrogen, carbon, and hydrogen are the key elements to life on Earth, and, considering the relative abundances of these elements throughout the universe, presumably life elsewhere. So, if a search for life in the universe is to remain as objective as possible, a focus on these six elements and the many molecules that can be made from them, as well as environments with temperatures and pressures conducive to biological processes, can be considered reasonably unbiased. Carbon, the most chemically active element on the periodic table, is the basis for millions of molecules and its ability to readily form strong, stable bonds (even with other carbon atoms and some metals) makes it the most logical choice for a molecule long-lived enough to build self-sustaining, evolving systems. Silicon is chemically similar to carbon and has also been considered as a possible basis for life; however, its weaker bonds and completely different oxidation product—the solid silicon dioxide (SiO2)— present problems with known biological processes. For example, can the polymers formed by silicon remain stable in varying environments and for long enough to become biologically active? How would the mechanism by which this solid waste product is readily removed function? And, what kinds of silicon compounds could be used as energy sources? Of course, this line of questioning could likely continue ad infinitum, but it is clear that in the prebiotic race toward ‘self-sustaining chemical systems’, carbon is the winner.

     Organic molecules are divided into large (lipid collections, carbohydrates, proteins, and nucleic acids) and small (fatty acids, sugars, amino acids, and nucleotides) varieties that perform a number of important functions in living systems. Combining these organic molecules through a process involving the loss of water is called polymerization and allows such ‘macromolecules’ to form. Both lipids, such as fats and oils, and carbohydrates called polysaccharides store energy while proteins perform a range of tasks. Nucleic acids, composed of smaller building blocks called nucleotides, are essentially the replication factories of biological molecules; deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) being two of the most important (Rothery, Gilmour, Sephton 2011). But, in order for living systems to perform the myriad functions necessary to subsist and for evolutionary processes to proceed, lipids and proteins form membranes within carbohydrate/amino acid ‘shells’ that maintain stable environments. Thus, it can be stated with reasonable confidence that these cells are what can be considered life. And some of the places thought to have been possible crucibles for certain forms of life are at the bottom of the ocean floor near geothermal vents called black smokers that eject superheated mixtures of water and mostly sulfides while providing an immediate environment capable of sustaining certain forms of so-called extremophiles. So, having arrived at a reasonable definition of life (of course, several details were glossed over and many others were not mentioned, such as chirality, the RNA world, panspermia, the top-down and bottom-up approaches, and the details of boundary layers), some of the most promising possible environments for its existence elsewhere in the solar system can now be examined: Jupiter’s moon Europa and Saturn’s moons Enceladus and Titan.

To the Moons of Jupiter

At 5.2 AU, Jupiter is more than five times the distance from the Sun to the Earth and gets around 25 times less solar irradiance than here on Earth. The magnetic field of this gas giant is more than 20,000 times that of Earth, making life a much more difficult prospect on the surfaces of bodies orbiting close to the planet. Dozens of moons are in orbit around the Jovian world but only the inner Galilean moons—specifically Europa—are of present interest in this search for life. Io, Europa, and Ganymede are in a 4:2:1 orbital resonance, which keeps their orbits eccentric, while Callisto has an orbital period of just under 17 days with no resonance. (Orbital resonances tend to cause tidal heating as these satellites make their way around their orbits. Moons that are mostly rocky become geologically active when presented with the stresses of tidal forces.) In fact, Io is the most geologically active body in the entire solar system with many confirmed volcanoes currently erupting. But, in cases where moons have rocky cores surrounded by thick layers of ice, the rock-ice interface presents a situation where the tidal heating causes at least some of the ice to melt and form either a localized or a global ocean. Since the surface temperature of Europa ranges from around -160 degrees Celsius at the equator to less than -220 degrees Celsius at the poles, no known life can exist there. However, if the situation is similar to that of at least portions of the Earth’s oceans, black smokers could also exist in the subsurface ocean of Europa— confirmed by the Galileo spacecraft10—providing a possible energy source on which extremophiles of some sort might thrive. Plumes ejecting material from the surface have been observed by the Hubble Space Telescope:

"The perspective that plumes on Europa are fed by a subsurface ocean offers an opportunity to study the ocean composition and investigate its habitability. Europa is widely considered one of the likeliest candidate bodies in our solar system able to support biological activity [Shapiro and Schulze-Makuch, 2009]. Due to the association of liquid water with life, biological activity would most likely be found in an ocean beneath Europa’s ice crust. The plumes offer a unique chance to directly sample subsurface material in situ from space. (Southworth, Kempf, and Schmidt, 2005)"

     The Galileo mission delivered some of the most spectacular images of Jupiter and, related specifically to this discussion, of Europa. These data revealed a moon made of water ice and silicate rock with a tenuous atmosphere of mainly oxygen and a likely iron-nickel core that, through tidal heating, is responsible for the situation of either warm ice or liquid water beneath the icy, mostly crater-free surface. Features resembling icebergs and tilted blocks on Earth are visible while a so-called “brown gunk” covers much of the crust, possibly the result of radiolysis of salts—a reasonable guess considering the thin oxygen atmosphere is almost certainly produced by the radiolysis of water. Some sort of process similar to tectonics exists on Europa, as evidenced by the stretched and cracked surface:

Figure 1: An enhanced true color image of the surface of Europa from the Galileo spacecraft. (NASA11) Despite the cracking and other tidal distortions responsible for the observed plumes, Europa surprisingly boasts one of the smoothest surfaces in the solar system. It is estimated that the icy crust is only about 10 to 15 miles thick.

     A future mission with multiple flybys and perhaps several passes through the plumes themselves to collect particles for analysis could further confirm the existence of biogenic material. However, any spacecraft that orbits Jupiter must be overbuilt to some degree in order to withstand the effects of such a massive magnetic field. While electromagnetic shielding is certainly required, one failure of any component of such shielding could spell disaster for missions costing billions of dollars. And such an unfortunate event would mean that it would be several years—perhaps 10 or more—before another mission (assuming approval) could be at the Jovian system for similar investigations. Thus far, Pioneer 11 and 12, Voyager 1 and 2, Cassini- Huygens, and the Galileo missions have visited or flown past Jupiter giving us new perspectives and new insights each time as successive spacecraft were equipped with better instrumentation. NASA’s proposed Europa Clipper Mission is supposed to launch sometime in the 2020s and is host to a suite of scientific instrumentation focused on studying this possible abode for life12, including an ice-penetrating radar to accurately determine the thickness of Europa’s crust.13 Landing a rover on the surface of Europa would be a herculean undertaking filled with serious risks involving electromagnetic shielding and choosing the proper landing location. However, it is well within the realm of possibilities given the current state of technology. And, finding life anywhere outside of Earth would perhaps be the most important human discovery of all time. So, the possible reward seems to far outweigh the risks involved in such an important mission. Other possibilities where life might have developed separately are Saturn’s icy moon Enceladus and its large moon Titan.

The Jewel of the Solar System

Figure 2: The first colored image from the

Huygens lander of the surface of Titan. The

Cobbles are water ice. (NASA - Dr. David R.

Williams.)

On October 15th, 1997, the Cassini-Huygens spacecraft launched from Cape Canaveral Air Force station in Florida with the goal of studying the Saturnian system. A collaborative mission between the European Space Agency, the Italian Space Agency, and NASA, the spacecraft reached Saturn June 30th, 2004.14 The Cassini orbiter and Huygens lander were both successful; the former having now delivered nearly 20 years’ worth of data; so much that it is still being analyzed over a year after making its dramatic “Grand Finale” plunge into Saturn to avoid contaminating any moons that might harbor life. The Huygens lander was delivered to the moon Titan—the second largest moon in the solar system—and successfully landed January 14th, 2005.15 Through radar imaging, Titan showed signs of prebiotic chemistry, cryovolcanism, impact cratering, and dune field formation. Among the most fascinating discoveries have been the presence of methane lakes and that methane functions similarly to the way water functions on Earth in the hydrologic cycle; there might even be an underground ocean of liquid water with hydrothermal vents. The atmosphere is composed of nitrogen (about 96%), methane, and ethane, and has a pressure of 1.5 bar at the surface, similar to that on the surface of Earth. As well, Titan has a thick photochemical smog layer in the upper-middle part of the atmosphere. In short, all of ingredients necessary for life exist on Titan.16 Extending far beyond its original mission, the Cassini orbiter has provided some of the most spectacular images ever taken of another planetary body. It is no wonder that Saturn is known as The Jewel of the Solar System:

Figure 2: January 19, 2013 - This is a composite of images taken through red, green, and blue filters that shows the F, G, and E rings from around 753,000 miles from Saturn. The pale blue dot of Earth is shown toward the lower right of the image indicated by the white arrow. (PIA17171; Published July 22, 2013.)17

At around 300 miles across, the small, icy moon Enceladus is about the size of Colorado and has been identified as a second possibility for life, due to the likely existence of a subsurface ocean. By 2008, a set of geologic features dubbed tiger stripes were identified in the southern hemisphere. These so-called tiger stripes are at least 100 degrees Celsius warmer than the surrounding surface, indicating some type of geologic heating (likely tidal). In December of 2011, a series of high resolution images were taken of Enceladus. But, one of the most breathtaking views of this Saturnian satellite was taken over a year before on November 30th, 2010 and clearly shows geysers erupting from the surface:

Figure 3: Taken with the narrow-angle camera, this Cassini image across Enceladus’ south pole shows a series of geysers erupting. The Cassini orbiter eventually flew through these plumes to analyze their composition, identifying organic compounds, volatile gases, water vapor, silica, CO, CO2, and salts.1819 A few theories have attempted to model these geysers and are detailed by Southworth, Kempf, and Schmidt (2015) in a paper regarding both Europa and Enceladus.20

Future missions to the Saturnian system would likely put significant focus on this small but promising world. Investigations of a next-generation orbiter could include a dust collector for proper analysis of plume ejecta—responsible for Saturn’s E ring—and several high-resolution imaging systems across the range of spectra. A lander would make exploration of the surface and possible subsurface ocean much more fruitful in its returns since only so much can be learned from orbit. However, finding a landing site free from debris or giant, spikey ridges will doubtless be extremely challenging. It might require including instrumentation to analyze imaging data in real-time and then choosing a landing site. Next, the challenge of driving a rover on a moon that is almost 750 million miles from Earth would perhaps be just as exciting as successfully landing one there. But, the insight gained from such an endeavor would certainly prove invaluable—a mission well worth the financial undertaking. For example, a seismometer can be utilized to determine the internal structure as the moon is stressed under tidal forces, possibly answering the question of the source of Enceladus’ geysers definitively. And the rover could drill into the icy surface or release a tethered, shielded piece of radioactive material onto it to melt through; perhaps to eventually reach an underground ocean and explore via a tethered submersible. The possibilities are only limited by the resources involved in conducting such missions.

A Brief Comparison of Europa and Enceladus

     With all that has been discovered about each of these moons, Europa and Enceladus present very different challenges that must be taken into account—especially if a budgeting issue forces a decision for one mission over the other. Jupiter is closer and Europa has been officially considered the most likely place in the solar system for life, but Jupiter’s huge magnetic field presents a significant engineering problem for probes and rovers moving through it. Saturn is almost twice the distance of Jupiter so it receives far less solar radiation but has a much smaller magnetic field requiring far less shielding, as evidenced by the Cassini-Huygens mission. Europa is also around six times the diameter and has an escape velocity nine times that of Enceladus. So, it is clear that many factors must be considered in a massive cost-benefit analysis if such a choice must be made.

Final Thoughts

     In any case, one thing is certain: In the search for life in the universe, a return to both Europa and Enceladus is necessary, while a return to Titan would likely prove useful. It is absolutely amazing what has been accomplished by the space program in the United States considering the budget constraints over the past 50 years. To put it into perspective, the proposed defense budget for FY2018 was around $640-billion21 while NASA’s proposed budget for the same fiscal year sits at just over $19-billion22. It appears plenty of funding exists to drop bombs on people around the world that are different but the coffers apparently come up short when budgeting for planetary exploration that could prove just how similar humans are at a fundamental level. But, with the advent of the privatization of space, perhaps in just a few years some of the companies that have established themselves in the past decade or so, such as SpaceX and Blue Origin, will see the value in such exploration and aim for these possible abodes for life. There is no doubt that such a discovery will be considered the greatest achievement of humankind: It would mean we definitely are not alone. From there it is easy to follow the lines of logic to begin asking questions about intelligence. With thousands of exoplanets already confirmed, and an entire universe presumably filled with innumerable others, the likelihood of intelligent life existing elsewhere in the cosmos might just be inevitable.

Resources

Aristotle. (2009). The Nichomachean Ethics (D. Ross, Trans.). London: Oxford University Press.

         Diamond, J. M. (1999). Guns, germs, and steel: The fates of human societies. New York: W.W.           Norton & Company.
Joyce, Gerald F. (1993), The RNA World: Life before DNA and Protein, Website,                                         https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980211165.pdf.

Rothery, D. A., Gilmour, I., Sephton, M. A., & Anand, M. (2011). An Introduction to Astrobiology.             Cambridge: Cambridge University Press.
Southworth, B. S., S. Kempf, and J. Schmidt (2015), Modeling Europa’s dust plumes, Geophys. Res.           Lett.,42, 10,541–10,548, doi:10.1002/2015GL066502
Shapiro, R., and D. Schulze-Makuch (2009), The search for alien life in our solar system: Strategies             and priorities, Astrobiology, 9, 335-343, doi: 10.1089/ast.2008.0281.

Zuckerman, B., & Hart, M. H. (Eds.). (2008). Extraterrestrials: Where are they? Cambridge:                       Cambridge University Press.

Web, Online Journal, and Other Sources

1. http://parkersolarprobe.jhuapl.edu/
   
2. https://voyager.jpl.nasa.gov/mission/status/
   
3. https://mars.nasa.gov/mer/home/
   

      4. https://mars.nasa.gov/msl/

5. https://solarsystem.nasa.gov/missions/cassini/overview/
   
6. http://sci.esa.int/rosetta/
   
7. http://classics.mit.edu/Aristotle/nicomachaen.html
   
8. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980211165.pdf
   
9. https://www.nasa.gov/vision/earth/everydaylife/jamestown-water-fs.html
   
10. https://solarsystem.nasa.gov/missions/galileo/overview/
    
11. https://photojournal.jpl.nasa.gov/catalog/PIA19048
    
12. https://solarsystem.nasa.gov/moons/jupiter-moons/europa/in-depth/
    
13. https://www.jpl.nasa.gov/missions/europa-clipper/
    
14. https://www.jpl.nasa.gov/missions/cassini-huygens/
    
15. https://nssdc.gsfc.nasa.gov/planetary/titan_images.html
    
16. Notes from ASTR2040, Fall 2016.
    
17. https://solarsystem.nasa.gov/resources/15868/the-day-the-earth-smiled-sneak-
    preview-annotated/
    
18. https://solarsystem.nasa.gov/news/13020/the-moon-with-the-plume/
    
19. https://solarsystem.nasa.gov/resources/16074/encroaching-shadow/
    
20. https://agupubs-onlinelibrary-wiley-
    com.colorado.idm.oclc.org/doi/epdf/10.1002/2015GL066502
    
21. https://csbaonline.org/research/publications/senator-mccain-and-outlining-the-fy18-
    defense-budget
    
22. https://www.nasa.gov/sites/default/files/atoms/files/fy_2018_budget_estimates.pdf