For many years, there has been speculation about whether there is life on other planets, but what about a moon? First of all, what is the definition of “life”? According to scientists Chyba and Phillips, the most common definition for life is “a self-sustained chemical system capable of undergoing Darwinian evolution.” However, when searching for remote forms of life on other planets, this definition may not necessarily work. We instead fall back on the idea of “life as we know it,” which means a life that requires liquid water, certain chemical elements, and a source of free energy, which is basically energy that can be converted to do things. If these were available on another planet, life could be possible! The world that scientists have the most hope of being able to support life as we know it in our solar system is Jupiter’s moon Europa. Europa is not too hot, not too cold, but could be just right for extraterrestrial life.
The term habitability is defined as planetary conditions suitable for human life. There is now a less-strict definition of habitability, and that is the stability of liquid water at a world’s surface. Liquid water becomes very important in the formation of life. For example, life on Earth solely depends on water. The ocean just below the surface on Europa implies that this definition of habitability of life should be expanded. If it is possible that terrestrial life could exist without being on the surface, then there would be way more possibilities for extraterrestrial biospheres. The main question is whether life can form at depths such as the bottom of the ocean. If not, then the only place life will ever exist is on Earth, but if so, then Europa’s world could possibly have its own biology.
To get a sense of what Europa is made of, its outer shell is made of ice. Just beneath this ice is a subsurface ocean of liquid water, which rests above its metallic and rocky core. The most convincing evidence of a subsurface ocean comes from scientific testing of magnetic fields. The magnetic field that belongs to Europa has to have a global conducting layer near the surface, which is best explained as a salty ocean. This salty ocean below the surface doesn’t freeze into ice because of geothermal and tidal heating. The tidal heating is from the friction created by the two moons on either side of Europa, and the geothermal heating comes from the planet’s warm core. If you are curious as to what life could possibly form in this Europan ocean, it is important to note that it is not very likely for large marine life to form. This is primarily because the low levels of oxygen in the ocean. Along with liquid water and livable chemical elements, life requires a source of free energy. Hydrothermal vents, like hot springs in an ocean floor, could supply the energy needed (through methane production) to create life. Another possible source of free energy comes from radiation. Radiation from Jupiter’s magnetic field produces simple organics and oxidants at Europa’s surface. If there is a way to get these oxidants to liquid water layer, then this could provide a source of energy to support a Europan ecosystem. In order for this to happen, there must be an exchange between the top layer of ice and the subsurface ocean. To break the thick ice layer surface, Europa’s ice boulders could collide to break up the terrain, causing mixture between layers and potential energy. The only problem with radiation is that when these charged particles hit the surface, it causes erosion, which is a process known as sputtering. Another problem comes from gardening, where small parts of meteors smash into the surface. The reason this is so bad is that gardening and sputtering interfere with important compounds found on Europa’s surface. Just imagine someone bombarding our Earth with chunks of rock constantly; this could not be a good thing.
When scientists decide to actually start searching for life on Europa, they should use these helpful tips. They should try to land and investigate where liquid water from the ocean has recently reached the surface, which could take a lot of researching to find. They should check and measure the abundance of chemical elements found there. They should also bring parts of the ice back with them for further investigation. This hypothesis of life on Europa needs much research and exploration in order to find out what the planet is capable of. But for now, I think it is safe to say that we have no need to worry about Aliens on another planet.
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Works Cited
Chyba, Christopher F., Phillips, Cynthia B. “Possible Ecosystems and the Search for Life on Europa.” Proceedings of the National Academy of Science 98.3(2001): 801-804.
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