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Jupiter has 92 known moons, with four main ones called the Galilean moons: Io, Europa, Ganymede, and Callisto. Ganymede is the largest moon in the solar system, bigger than Mercury.
Jupiter is the biggest and oldest planet in the solar system, forming from the dust and gases left over from the sun's formation 4.5 billion years ago.
Europa is approximately 390 million miles (628 million kilometers) from Earth on average. However, the distance can vary depending on the orbital positions of Jupiter and Earth.
Earth is the only terrestrial world in the solar system, but there are at least six celestial bodies similar to Europa. If Europa is found to be habitable, it could provide valuable insights into how common habitable environments are in the universe as a whole.
Callisto is Jupiter's second largest moon and third largest in the solar system. It is thought to have a subsurface ocean, but much deeper than Europa's, possibly beneath 60 to 120 miles (100 to 200 kilometers) of ice.
Clipper isn't a life-detection mission, but it will be the first to assess whether Europa could sustain life. Understanding this moon will provide insight into others like it, such as Enceladus and Triton.
The images captured by Clipper will enable scientists to investigate how the ice shell moves and breaks apart, and whether it contains sections that slide underneath one another like tectonic plates.
Unfortunately, Clipper can’t land and take samples, but scientists hope to identify geysers from the photos. Images from the Hubble Space Telescope suggest that these geysers may be erupting, and, if they exist, Clipper could fly through a spout and collect a sample for analysis back on Earth.
Clipper won't be orbiting Europa itself because of Jupiter's magnetic field, which is approximately 20,000 times stronger than Earth's. Plus, the field's radiation would destroy any electronics that remain too long inside its influence.
Instead, the spacecraft will travel in and out of the radiation zone to capture high-resolution photos of 95% of Europa's surface, providing scientists with the most detailed map of the moon to date.
Europa isn't the only moon with water beneath its crust; the same is true for Saturn’s Enceladus and Titan, Neptune’s Triton, and Europa's sibling Ganymede.
Clipper will use a device called a spectrometer to investigate the reddish-orange material on Europa's surface and determine its potential origins—whether it's bubbling up from the subsurface ocean, or the result of debris blown into space by the nearby volcanic moon Io.
During the Clipper's initial three years in orbit, it will provide views of Europa's surface, gather information on the dynamics of its ice shell, and determine if geysers spout from its surface.
Space physicist Margaret Kivelson and her colleagues deduced that if Europa contains vast amounts of saltwater beneath its crust, Jupiter's magnetic field could induce a magnetic field on the moon.
In 1996, NASA's Galileo mission beamed back data that suggested Europa possessed a magnetic field, something that is normally only found on larger bodies like the Earth.
Clipper will also be joined by the European Space Agency's Jupiter Icy Moons Explorer (JUICE). This mission will mainly investigate Ganymede and Calisto, but will also pass by Europa and provide an additional opportunity for scientists to learn more about the moon.
Scientists are uncertain about the activity level on the ocean floor of Europa. Some believe that hot, smoking hydrothermal vents, similar to those found at the bottom of Earth’s oceans, could be present there, potentially providing a habitat for microbes, crabs, and worms.
In 1979, NASA's Voyager 2 took high-resolution images of Europa's exterior, showing it was full of long, irregular cracks and relatively devoid of craters, indicating the surface was young and potentially geologically active.
Jupiter's diameter is about 86,881 miles (139,822 kilometers), while Europa's diameter is approximately 1,940 miles (3,122 kilometers). Jupiter is roughly 45 times larger in diameter than Europa, and in terms of volume Jupiter is about 24,000 times bigger.
Europa and its three sibling moons were discovered by Italian astronomer Galileo Galilei in 1610 when he observed four bright dots orbiting Jupiter through his telescope.
NASA's Europa Clipper mission will spend five and a half years traveling to the Jovian system, conducting nearly 50 flybys of Jupiter's moon. Scientists hope to determine if Europa is habitable, as it conceals a vast ocean that may contain twice as much water as all of Earth's oceans combined.
Scientists still have unanswered questions about Europa, which drive the mission's objectives. How thick is its frozen shell? What kind of chemistry exists in the moon's subsurface ocean? And is there geothermal activity on the seafloor that could provide energy to sustain life?
With a radius of 1,635 miles (2,631 kilometers), Ganymede, one of Jupiter's moons, is the largest in the solar system. It is the only known moon with its own magnetic field, which causes auroras like those on Earth.
In 2014, a computer model of Ganymede's interior suggested that the development of primitive life could be possible. The model indicated that the moon's rocky seabed might be in contact with salt water, which scientists believe is a key factor for the development of life.
Titan, Saturn's largest moon, has lakes of liquid methane, a thick nitrogen-rich atmosphere, and complex organic molecules. It may also have a subsurface ocean of water and ammonia. These factors suggest that Titan could potentially support life, albeit in forms unlike Earth's.
As of now, there is no definitive evidence of life on Mars. While past missions returned ambiguous results, current explorations aim to search for signs of ancient microbial life and collect samples for potential return to Earth.
Sources: (NASA) (National Geographic) (The Planetary Society)
See also: What you should do if you see an alien
Scientists believe that Europa's icy shell gets stretched by the pull of Jupiter's gravity as it orbits the planet. This is called tidal flexing, and causes heat inside Europa. The tidal flexing is likely creating enough heat inside the moon to maintain the liquid ocean beneath the surface.
Life as we know it requires chemical elements like carbon, hydrogen, nitrogen, and oxygen, which make up 98% of Earth's living matter. These elements likely formed with Europa and may have been supplemented by organic materials from asteroid and comet impacts. Discovering organic molecules on Europa could indicate if conditions for life ever existed there.
Europa, Juniper's moon, has long captivated scientists with its potential to harbor life. Experts believe there's a salty ocean beneath its icy crust, and, as we know, water is one of the essential ingredients for life. But could this distant, frozen moon really support life? In October 2024, NASA launched Earth's first mission to conduct a detailed scientific investigation of Europa, researching its geology, chemistry, and potential for life, providing more insight as to whether its hidden ocean could be home to microbial life or something more complex.
Could Europa be the next frontier in the search for extraterrestrial life? Click on to find out.
Could Jupiter's moon support life?
NASA is going to find out the answer
LIFESTYLE Solar system
Europa, Juniper's moon, has long captivated scientists with its potential to harbor life. Experts believe there's a salty ocean beneath its icy crust, and, as we know, water is one of the essential ingredients for life. But could this distant, frozen moon really support life? In October 2024, NASA launched Earth's first mission to conduct a detailed scientific investigation of Europa, researching its geology, chemistry, and potential for life, providing more insight as to whether its hidden ocean could be home to microbial life or something more complex.
Could Europa be the next frontier in the search for extraterrestrial life? Click on to find out.