Journey to the Stars

Imagine a frozen world, ancient and approximately 4.5 billion years old. It is barely warmed by the distant rays of the Sun, and its surface is covered with a thick layer of ice. This intriguing world is smaller than our Moon but slightly larger than Pluto. Its name is Europa, the sixth satellite of Jupiter and one of the largest moons in our solar system. What makes Europa truly captivating is its potential to host life. Astronomers consider it one of the most promising places in our solar system to search for new forms of life.

Beneath Europa's icy shell lies a vast saltwater ocean with depths ranging from 40 to 100 miles. While hidden beneath an estimated 10 to 20 miles of ice, this ocean holds the possibility of being a habitable environment. Astronomers speculate that plumes of water erupt from cracks in the ice, releasing the contents of Europa's ocean into space. However, accessing this deep ocean environment would pose significant challenges for any future life-seeking missions.

Fortunately, there is evidence suggesting the existence of shallower water pockets located closer to the moon's surface, possibly less than one mile beneath the ice. This discovery increases the likelihood of life existing on Europa and potentially simplifies the search for these life forms in future missions.

The revelation of these shallow pools came about through a stroke of luck. Riley Kohlberg, a scientist leading the research, stumbled upon a colleague's presentation showcasing double ridges on Europa's surface. These ridges reminded Kohlberg of similar formations observed on Earth. While rare on our planet, Europa boasts a higher abundance of such ridges. Further studies suggest that these ridges might result from a specific cycle similar to one observed on Earth. In this cycle, liquid water freezes and thaws inside an ice sheet, creating a two-peaked structure due to the high-pressure environment. If the processes on Europa mimic this cycle, it would provide evidence of shallow waters on the moon.

The unique conditions on Europa, including temperature, pressure, and chemistry, present challenges in understanding the behavior of the ice and the size and depth of the water pockets. Nevertheless, it is reasonably clear that these under-ice environments are likely shielded from Jupiter's harsh radiation, increasing the chances of life existing on Europa.

Let's return to the intriguing aspect of Europa's ocean being salty. The red streaks observed on the moon's surface might be attributed to the chemical content of these streaks, which are likely a frozen mixture of water and salts. This composition is unusual and does not match any known substance on Earth. Additionally, the presence of yellow spots on Europa's surface could be linked to the presence of sodium chloride, commonly known as table salt.

Scientists have attempted to recreate Europa's conditions in laboratories, combining water, table salt, freezing temperatures, and high pressure. These experiments have resulted in the formation of a new kind of solid crystal, which may exist at the bottom of Europa's ocean and on its surface. Despite this knowledge, many mysteries remain, and researchers eagerly await the answers to these questions, which may come to light around 2030.

In 2030, NASA's Europa Clipper mission is expected to reach Europa. This mission will conduct several close flybys, seeking to determine the potential existence of life on the moon. The European Space Agency's Juice (Jupiter Icy Moons Explorer) mission is also planned to visit Europa in the coming years. Exciting discoveries lie ahead as these missions explore the mysteries of Europa.

Now, let's explore the concept of sound in space. Contrary to popular belief, space is not a silent void. While we cannot hear sound in the vacuum of space itself, there are instances where sound can be experienced on other planets or within specific environments. If a space body possesses an atmosphere or some form of gas, water, or solid surface, sound can exist. However, to hear sound on other planets, we would need to be in close proximity to their atmospheres.

For example, let's consider Venus. Its dense atmosphere, often referred to as a "thick chemical soup," would dramatically alter the way sound is perceived. If one were somehow able to survive on Venus and speak, their voice would become significantly louder and different in tone. The denser atmosphere would amplify sound, resulting in a distinct and peculiar auditory experience.

On Earth, we can somewhat grasp the concept of sound in denser atmospheres by comparing it to being submerged in water. Sound travels much faster and more effectively in water compared to air, with speeds reaching almost a mile per second, depending on water temperature. Imagine sitting in a room with no sound sources and experiencing absolute silence. Now, submerge your head in water and notice how that silence transforms into a cacophony. You can hear the slightest movements, the pulsation of your blood, and even the workings of your own body. It's a surreal and somewhat eerie sensation.

While sound cannot propagate through the vacuum of space, there are intriguing exceptions. In regions where space dust is present, particles may be densely packed, allowing them to produce faint sounds. However, these sounds would be extremely quiet and would only travel over short distances. In 2003, NASA recorded a real space sound from the Perseus Galaxy, located 250 million light-years away. The frequency of this sound, a B flat 57 octaves below middle C on the piano, is too low for the human ear to detect.

Within spaceships, small pockets of air allow for the transmission of sound. Astronauts inside spacesuits would also hear sounds clearly, including their own breathing and blood circulation. However, two astronauts flying side by side, even in close proximity, would not be able to hear each other. This discrepancy arises from the absence of a medium for sound transmission in space. As a result, astronauts rely on radio communication devices to communicate effectively.

It's worth noting that if, theoretically, one were to venture outside their spacesuit in space and miraculously survive, they could potentially hear the sounds occurring within the spaceship. This transmission would occur through bone conduction, where sound vibrations travel through the metal casing of the spacecraft and directly into the body, bypassing the ears. Bone conduction is a phenomenon utilized in some headphones and other technologies. However, conducting such an experiment in the vacuum of space is highly discouraged.

In popular culture, we often hear dramatic sound effects accompanying space scenes in movies. While these cinematic representations add to the storytelling experience, the reality is that sound cannot travel in space due to its vacuum nature. Sound requires molecules like air or water to vibrate and propagate. Nevertheless, within our atmosphere, we are constantly emitting radio waves into space, albeit limited to a range of 110 light-years. Fortunately, this limitation shields us from the overwhelming cacophony of cosmic events, including solar flares and nearby supernovas.

In conclusion, the vastness of space holds numerous wonders and mysteries yet to be fully understood. From the potential for life on distant moons like Europa to the absence of sound in the vacuum of space, each revelation invites us to contemplate the extraordinary nature of our universe. While we may never experience the soundscape of space firsthand, our exploration and understanding of the cosmos continue to expand, enriching our knowledge and inspiring us to uncover the secrets that lie beyond.