Jupiter’s Moon Europa: So far, all evidence points to life there. This is how hard the current corona wave is hitting China

The rippled icy crust encasing Jupiter’s moon Europa is up to 15 kilometers thick. Scientists are fairly certain that there is an ocean up to 100 kilometers deep and possibly salty. It is said to have twice as much water as all the world’s oceans combined.

On our planet, the oceans teem with life. They house the most extreme forms of all organisms and the largest creatures on Earth. There are those that survive freezing or boiling temperatures. Some do not require light or oxygen, but do require sulfuric chemicals. Terrestrial life exists under both Arctic and Antarctic sea ice, near extremely cold deep-sea vents and hydrothermal vents. “So far, there is nothing preventing exotic life forms in the ocean around Jupiter’s moon Europa,” said Andreas Riedo, an astrophysicist at the University of Bern.

It is part of the “Juice” mission of the European Space Agency (ESA). Aboard an Ariane 5 rocket, the spacecraft is expected to lift off from South America’s Kourou spaceport in April this year, bound for Jupiter’s three icy moons, Europa, Ganymede and Callisto. The 700 million kilometer journey will take eight years before the probe begins to answer the question of all questions: Are the conditions right for the icy moons to support life?

Rock is kneaded like dough

For a long time it never occurred to anyone that life could exist as far from the sun as the gas giant Jupiter and its moons. The zone between Venus and Mars was considered a habitable zone – it was assumed that it was too cold further away. However, data from previous space probes drew astronomers’ attention to the icy moons, whose surface temperatures can drop to minus 180 degrees. For example, the “Galileo” mission of the American space agency NASA, which orbited Jupiter for almost eight years from 1995 and flew past all its major moons: the researchers involved already realized then that there is probably not only a global ocean in Europe . The magnetic data indicated that Jupiter’s moons, Ganymede and Callisto, also have salt and liquid water of global proportions under the icy crust.

The energy needed to keep the water liquid and not freeze comes from tidal friction: the planet Jupiter’s gravity pulls and tears at the moons so hard that the rocks inside knead like dough. This creates frictional heat.

In addition to liquid water, life as we know it also needs the right chemistry to form important building blocks of life, such as amino acids. “The six main elements are hydrogen, carbon, nitrogen, oxygen, phosphorus and sulfur,” says Andreas Riedo. Especially in the icy moon Europa, the ocean is believed to be rich in these elements. Because the water is in direct contact with the rock on the ocean floor. There is therefore a chance that the minerals will be washed away from the rock crust.

The tides can also warm Europa’s mantle rocks so much that magmatic volcanic eruptions feed the oceans with minerals. At least that’s what computer models suggest.

Water fountains on Europe

“Juice” will not land on the icy moons to take water samples directly, but will only fly past them. However, it is known that the ice crust of Europa breaks from time to time and the ocean water then flows out in fountains. The crust of frozen water is dotted with huge, glacial fissures through which jets of water sometimes spew. “The goal is for the probe to fly through such fountain eruptions and take samples to determine the chemistry of the oceans,” says Riedo.

There are ten scientific instruments on board “Juice”, one of which was developed at the University of Bern. It is a very sensitive mass spectrometer, the «Neutral and Ion Mass Spectrometer» (NIM). It is designed to capture the chemical composition of the thin atmospheres of the icy moons during a probe flyby.

The probe and its instruments will have to operate in an inhospitable environment. Jupiter’s sunlight, for example, is 25 times dimmer than Earth’s, so the probe would need huge solar panels to collect enough energy.

The probe also undergoes temperature fluctuations of several hundred degrees during its journey through space. A special insulating cover is designed to keep the temperature stable inside the instruments.

Then there is also the radioactive radiation that falls on Europa from Jupiter. It is stronger than anywhere else in our solar system. In fact, Jupiter’s radiation belt is thousands of times stronger than Earth’s. “It’s like taking a bathing holiday in the middle of the Gösgen nuclear reactor,” says Peter Wurz. He is a professor at the Physics Institute of the University of Bern and head of the NIM instrument. Protective shields are therefore needed to shield the sensitive electronics of the instruments. The creatures in the ocean, if there are any, are protected by the miles of ice sheet.

A probe should land on Europa

Almost at the same time as “Juice,” a good year later in October 2024, NASA will also send a space shuttle to Jupiter. The probe, dubbed Europa Clipper, will not target all three icy moons, but only the most promising, Europa. At least 44 flybys are planned. “This will provide us with a wealth of information about the chemistry of the European ice surface and ocean,” says Wurz.

However, neither “Juice” nor “Europa Clipper” will definitively prove life on Europa, they can only give indications of it. For definitive proof, a landing probe on the icy moon must take measurements on the spot. This is exactly what NASA is planning with “Europa Lander”. “We really hope that we will fly with our instrument,” says Wurz.

Because the Bern team is already working on “Origin”, an instrument that should show signs of life on Europe. With this instrument, laser pulses are aimed at the surface to be examined, causing small amounts of material to dissolve. This can then be analyzed on site in the landing probe’s miniature laboratory for the presence of various amino acids and other chemical building blocks of life. The instrument will soon be tested in extreme locations on Earth, such as Antarctica and the Atacama Desert.

It’s important, Wurz says, that the two missions “Juice” and “Europa Clipper” properly map the surface of the icy moon Europa to identify an ideal landing site for the landing probe. “We need to find a place where you can land and where the chance of finding traces of life is greatest, which is near a fountain.”

Drilling through ice takes too long

Initially, NASA thought about equipping the probe with an ice drill. But, “Studies showed it would take two years to pierce the rock-hard ice to the ocean,” says Wurz. In itself that would not be bad, but the strong radioactive radiation on the surface of Europa destroyed the unit that sends the data from the measuring instruments to Earth within a month. It is therefore important to use the little time that remains after landing as efficiently as possible for measurements. “In principle, of course, the landing unit could be equipped with a huge protective shield. But that would be extremely expensive and a very inefficient use of resources,” says physicist Wurz.

NASA’s plan is to use the landing probe to take samples from a depth of about four inches below the surface. That is a depth where the complex chemistry is protected from the harmful radiation that would erase the traces of life.

There is still no well-thought-out concept for “Europa Lander”, nor an exact timetable. The space shuttle will not leave until the 2030s at the earliest. Patience is the most important quality of an astrophysicist, says Wurz. But the signs of finding alien life are better than ever. “I do believe that we will discover life in the next 10 to 20 years.” (aargauerzeitung.ch/cpf)