As time passes by, one of the key objectives yet to be achieved is the search for life beyond our Earth. Undoubtedly, the universe is essentially the bigger thing there is; it comprises of innately everything that exists – from stars to planets to molecules to atoms and to everything else in between. The size of the universe compels us to thus, approach the idea of exploration for life in the beyond in a more detailed-specific, focused way. To do so, we would have to put in place conditions to narrow our search. One of the key factors that would help us do so is to compare the environment and state of Earth (where life flourishes) and limit our study to places that condone similar conditions: source of energy, presence of particular chemical compounds, and temperatures allowing the existence of liquid water. Hence, I would like to propose a mission to explore the depths of Jupiter’s icy moon Europa, which exactly consists of the aforementioned factors and conditions appealing to the presence of extraterrestrial life.
Scientists have often described Europa as an “ocean world” as after decades of previous research, exploration and analysis of spacecraft observations, evidence regarding the presence of an ocean of liquid water, underneath Europa’s icy surface, has been found. Although, in comparison, Europa’s diameter is only 1/4 of Earth’s, it’s average ocean depth is 100km (Earths’ is 4km), and so it is to no surprise that Europa contains 50% more liquid salt-water than Earth. Scientists have further strengthened this affirmation by evaluating the crack on the icy moon’s surface. They say that these cracks have formed as a result of tidal forces on the ocean, beneath the surface of the moon. This tendency occurs due to Europa’s orbit – as its orbit takes it closer to Jupiter, the tides on the ocean under the icy surface rises higher than normal – and these constant increases and decreases in the tides on the ocean have led to cracks being formed on the moon’s surface. Moreover, scientists firmly believe that this vast body of liquid water beneath the surface of Europa is the key for potential life to evolve on the planet. Europa is also thought to consist of vents to the mantle, similar to those found on Earth, and so discovery of the presence of these vents could provide insights into the thermal environment in Europa which is another primary factor for life to evolve. Thereby, the two primary areas of research that I would like to propose are the explorations of the presence of liquid water below Europa’s surface as well as of thermal vents leading to the mantle.
The reason behind the mysterious existence of liquid water beneath the surface is due to Europa’s tides. As Europa orbits Jupiter, its inner components and exterior icy shell contracts and relaxes. The extensive heat within Europa’s interior may not be sufficient for water to exist on the icy-cold surface, but what is important to consider that this heat is more than enough to sustain a vast ocean of liquid water underneath the outer frigid shell. However, exploration of liquid water is not the only factor that could perpetuate the possibility of the evolution of extraterrestrial life. It is necessary to ensure that Europa holds the potential and the right chemistry to model the building blocks of life, and it is also vital to ensure that Europa is able to produce a reliable source of energy. The aforementioned presence of tides in Europa may also permit interactions between the ocean and the rocks on the moon’s sea floor. The chemical reactions resulting from this interaction would inherently provide a well founded source of energy, in addition to corroborating the building blocks to sustain life.
Jupiter is around 500 million miles from the Sun which is about 5.2 AU (Astronomical Units) and Europa orbits the planet at about 417,000 miles. These numbers are evidently colossal and so the question that remains is, since energy is a necessity for life to survive, how does the icy moon far from the Sun obtain energy? The presence of energy on Europa is fueled by chemical reactions. Although the surface of the moon comprises of tremendous amounts of radiation and so would not condone life on its surface, it surprisingly allows for life to evolve in the ocean beneath the the icy crust. This intense radiation causes water molecules to split – Hydrogen leaves the surface entirely, and Oxygen remains. This ‘leftover’ Oxygen is very reactive and so could be used in chemical reactions, which in turn could produce energy. If the released energy from all the chemical reactions reached the ocean, it would be able to stimulate the growth and evolution of microbial life. If there are hydrothermal vents in Europa, similar to those found in Earth’s oceans, that underground water could be releasing chemical nutrients to fuel life.
Astrobiologists have studied and found out that the there are three things necessary for life to survive: suitable temperatures that allow liquid water to exist, carbon-based molecules, and source of energy. Europa, indeed, tends to possess all three factors, and so I would like to propose a mission to Europa to:
- Assess and evaluate the chemicals that constitutes not only the surface, but also the ocean below the surface.
- Analyze the tidal heating and ocean properties in Europa which may be a sign that liquid water exists underneath the surface.
- Understand the interactions between the icy surface and the ocean.
In summary, the upcoming decades insinuate fascinating discoveries at Europa. The Jupiter Europa Orbiter mission would take us all one step closer to understanding the possibility of life beyond Earth. Exploration of Europa’s surface composition, surface-ocean interactions and liquid water beneath the surface would unravel exciting, new discoveries while simultaneously improving our knowledge of the primordial Earth.