Galilean moons – The Party Trick Physicist

The 3 Most Likely Places We’ll Find Alien Life in Our Lifetimes

By Bradley Stockwell

If we are ever to find alien life in our lifetimes, there is no doubt that it will most likely be within our own solar system. And I’m not talking about little green men (sorry about the misleading picture), but more likely microbial alien life. In April of this year, NASA’s chief scientist, Ellen Stofan said, “I believe we are going to have strong indications of life beyond Earth in the next decade and definitive evidence in the next 10 to 20 years.”

This is quite shocking considering a little over a decade ago we thought the search for extraterrestrial life was all but dead. For many years scientists narrowly confined the search to something called the “habitable zone”, or informally known as the Goldilocks zone (I like this name better). This is the area within a star system that’s close enough to a star to allow liquid water, but not so close as to boil it away. Because Earth is our only reference for life, it was once thought that liquid water was an essential ingredient to the porridge of it; but as we’ll see later, even now that is being questioned.

Nevertheless our best hope still lies with liquid water and the only places thought to have, or had it at one time, was Earth and Mars. Unsurprisingly these are also the only two planets within our own solar system’s Goldilocks zone. Since Mars has yet to yield any signs of life, the chances of finding alien life in our solar system once seemed pretty grim. However very recent and very credible evidence is showing there is most likely oceans of liquid water far from where we thought it should be in our solar system. Because of this and continuing research on how life forms, the race is back on to find alien life in our solar system and here are the three most likely places we’ll find it.

Enceladus and its geyser spray

1. Enceladus

Enceladus is a small, ice-covered moon of Saturn. Although some may disagree, I list this as the most likely place for three reasons: warm liquid water, organics and the ease of access. In 2005, NASA’s Cassini spacecraft photographed geysers of frozen water shooting up from cracks on the surface of Enceladus. It is almost certain the culprit of these geysers is reservoirs of liquid water beneath the frozen surface formed by something called tidal flexing. Basically there’s this sort of gravitational tug-of-war between Enceladus, its neighboring moons and Saturn itself. These interactions stretch and contract the moon, creating heat which causes the ice beneath the surface to melt and form liquid water. Additionally, Cassini’s instruments also detected organic compounds like methane in the geyser spray and where there’s warm water—speculated to be near boiling temperatures—and organics, there’s the possibility of life. Life has formed in very similar conditions near hydrothermal vents here on Earth. However what really sets Enceladus apart is how easily it would be to snatch up evidence of life if it’s there. Whatever exists in those subsurface water reservoirs is continually being shot up by geysers into space and all we’d have to do is fly by and grab it with a spacecraft. There’d be none of the complications of landing robot drillers on the surface like other icy-moon candidates. Unfortunately, partly due to NASA’s shrinking planetary science budget, there are no planned missions to explore Enceladus.

2. Europa

Europa is another ice-covered moon a little smaller than our own orbiting Jupiter. Like Enceladus and Europa’s two neighboring moons, Callisto and Ganymede, it most likely has liquid water beneath its surface caused by tidal flexing between it, Jupiter and other Jovian satellites. Possibly there’s more water here than in all of Earth’s oceans. It is also speculated that the oceans contain salt because the moon has a magnetic field which means it’s electrically conductive; something fresh water is not. With water, salt and carbon-based organic compounds from comets that have inevitably hit the moon, you’ve got quite the recipe for life. While salt hasn’t been directly detected yet, a probe mission has been proposed for 2025 that will answer all questions about the moon’s chemical makeup. If this chemical makeup is considered life-friendly it will be all the more reason to send a lander to Europa. The problem however lies then with how to drill through 10 miles (16 km) of extremely hard ice. Nevertheless drilling through 10 miles of ice to reach water seems more promising than drilling through the at least 60 miles (100 km) of rock covering Callisto’s and Ganymede’s water.

Titan is the only other place in our solar system to have rain and liquid lakes. It is also the only moon to have a dense atmosphere.

3. Titan

Titan, Saturn’s largest moon and the second-largest in the solar system, would be my favorite outcome for alien life because it would completely rewrite our recipe book for life and expand the possibility of it immensely throughout the rest of the universe. Honestly I was tempted to list it as first, but I felt obligated to give preference to at least two water-bearing moons first. Other than Earth, Titan is the only known place in our solar system where it rains and there are liquid lakes. It is also the only moon in the solar system to have a dense atmosphere. Granted the rain and lakes are made of liquid ethane and methane, but ethane and methane are both saturated hydrocarbons—a.k.a. life-making stuff—and the atmosphere is largely made up of nitrogen just like here on Earth. On Earth ethane and methane are gases, but because the temperature on Titan averages about -290 Fahrenheit (-179 Celsius), they come in all three states of matter—liquid, solid and gas. There’s also a whole methane cycle analogous to Earth’s water cycle which creates similar Earthly weather patterns on Titan.

Just because organic compounds found one way to form into life here on Earth, doesn’t mean that there aren’t a multitude of other ways—in fact I refuse to believe so. In 2010 Sarah Horst of the University of Arizona found all five nucleotide bases (the building blocks of DNA and RNA) and amino acids (the building blocks of protein) among the compounds produced when energy was applied to a combination of gases like those found in Titan’s atmosphere. It was the first time nucleotide bases and amino acids had been found in such an experiment without the presence of liquid water. In 2013 NASA did an experiment of their own and also concluded that complex organic chemicals could arise on Titan based on simulations of the Titan atmosphere. If life were to exist on Titan, it would most likely inhale hydrogen in place of oxygen and metabolize with acetylene instead of glucose and exhale methane instead of carbon dioxide.

The other thing Titan has going for it over the two former candidates is we already know how to get robot landers to the surface because we’ve done it before. In 2005 the Cassini spacecraft dropped the Huygens probe and you can see how eerily similar the surface looks to Earth in this video here. Unfortunately as of right now there are no planned return trips to Titan.

Until next time my friends, stay curious.

Jupiter and Her Moons: Our Key to The Cosmos

By Bradley Stockwell

Everyone at some point in their lives (or so I hope) has experienced the wonderful reverence of stargazing. That allure to look upon the heavens and ask ‘what the hell is that?’ seems to be what makes us human; what separates us from the almost nine million other life forms we share this planet with. The night sky has inspired legends, religions and philosophies; our ancestors used it to navigate and mark the passage of seasons and animal migration patterns. But in our present day, the union between us and our big starry-spotted buddy has faded in some sense. Its full glory is now often hidden behind city lights and the petty dramas of our daily lives or the ones we find on television.

While I too am not immune to getting caught up in the rigors of daily life or the latest Doctor Who episode, it’s not too often you’ll find me under a clear night sky without my neck craned upwards. There’s something viscerally exciting to me about seeing the cosmos nude. This is why instead of grabbing a beer and the television remote after a stressful day, I’ll typically still grab that beer but I’ll reach for my telescope instead. While admittedly this may seem like a nerdy pastime, I’m going to try my best to convince you it’s not.

If you’ve ever traveled to a foreign land, the first time feels almost as if you’re visiting an alien planet. Suddenly your perspective of the world increases and you come back home changed. Looking through a telescope for the first time is much the same. I know the first time I saw Jupiter or the magnificent rings of Saturn suddenly our place in the solar system became very real. You can read and study about something all you want, but it’s not until you experience it firsthand that it truly becomes real.

The winter sky is my favorite time for stargazing, primarily because the most important astrological sight to the history of astrophysics and arguably modern science is visible: Jupiter and her moons. This sight has been the key to opening up the cosmos and has been crucial in defining our universe. The best thing is it doesn’t require a high-powered telescope to see it either. In fact I recommend using an entry-level telescope (no more than $150) to see Jupiter and her moons much like the great Galileo Galilei did for the first time on January 7, 1610.

When Galileo first pointed his homemade telescope towards Jupiter, he described seeing a linear arrangement of three fixed stars, two to the east and one to the west, cutting through the center of the planet. However the following night all three stars were to the west. Then three days later one disappeared and six days later a fourth one appeared. At first he was baffled, but then it dawned upon him that these were not stars but were orbiting moons! They were in fact Jupiter’s four largest moons, Io, Europa, Ganymede and Callisto, which now bear his namesake as Galilean moons. The discovery would be the beginning of a great change in science, but it did not come without challenges.

At the time, the discovery was highly controversial. You can even say Galileo was putting his life at risk by proposing it. A planet with smaller orbiting bodies was in direct offense to the longstanding view of the Catholic Church which placed Earth at the center of the universe and all celestial bodies orbiting around it. The church had a long history of burning ‘supposed’ heretics at the stake for challenging this model. But upon further observations by other astronomers, the evidence was irrefutable. The church eventually conceded and accepted a model proposed almost 70 years earlier by the astronomer, Nicolaus Copernicus. The model, which Copernicus waited until he was on his deathbed to present in fear of being labeled as a heretic, placed the sun, not the earth, at the center of the universe. Obviously this model, now called the Copernican model, would continue to be updated, but it would lay the foundation for others like Johannes Kepler, Isaac Newton, William Hershel, Edwin Hubble and Albert Einstein to further define our universe. Galileo’s discovery would help ignite a scientific revolution during The Renaissance and finally break down the cage in which the Catholic Church put scientific research in.

Jupiter and her moons would again make history when the astronomer, Giovanni Domenico Cassini, observed them between 1666 and 1668. He was the first to notice discrepancies in their orbits. To explain these discrepancies, he theorized that light coming from them must have a finite speed. Shortly after, another astronomer, Ole Romer, took this concept further when he realized that indeed the time it took for Io, the innermost Galilean moon, to orbit was shorter when Earth was closer to Jupiter and longer when Earth was farther away. From these observations, Romer was able to calculate the speed of light; approximately 186,000 miles per second. Putting a speed limit on light would forever change how we view the universe for when we peer into the cosmos we now know we are looking back in time! In fact we can now look at light as far back as the beginning of the universe. A telescope is not only a ship with which to sail the cosmos but also time.

In addition to aiding our view of the universe, Europa, the second innermost Galilean moon, may be a likely candidate for harboring alien life! This moon is covered in a thick layer of ice made of water. Because of heat generated from the contraction and expansion of the moon by Jupiter’s powerful gravitational force, many astronomers believe there is liquid water below the surface which could possibly host microbial life.

Jupiter and her moons is but one of the many wonders awaiting your gazing eyes. Although I am not religious, spying through my telescope is the closest thing I have to prayer. It gives me a better vantage point on life and puts things, or should I say the earth, into a humble perspective. While I’m certain life exists somewhere else in the universe, the right conditions to produce it are rare; and intelligent life, extremely rare. In fact from research and astronomical observations alone, it’s not a stretch to say that out of the hundreds of billions of other planets in the galaxy, Earth may be the only one with advanced life. Granted our galaxy is but one among 350 billion in the observable universe, but this perspective suddenly increases the value of our existence. How lucky are we that the winds of energy that control the cosmos happened to deposit matter in the form of the human race? Regardless of how you believe that came to be, there’s no need for theology to tell you how special your existence actually is. I think if we as humans realized this more, we’d start behaving differently. We’d start looking out for ourselves and this world better because right now as a species we don’t particularly have a universal view on life. It’s rather shortsighted in my opinion. Well until next time, stay curious my friends!