Juno probe dives near Europe

Imagine a desolate desert. Under your feet a layer of ice a kilometer thick. In some places there are deep cracks in the ice, from which geysers hundreds of kilometers high directly into space.

There is no atmosphere here where life can breathe freely and nowhere on the surface are there traces of plants, trees, lakes, seas, or anything else we associate with life here on Earth.

These are the harsh conditions on Europa, which orbits the largest planet in the solar system Jupiter. But if you ask if anyone in their right mind would really look for life in this bleak ice kingdom, astronomers’ answer is yes.

“The study of Europa is very interesting, because it contains twice as much water in the oceans as the ice sheet that exists on Earth,” explains Professor John Leif Jorgensen. illustrator flag.

He works at the Danish Institute for Space Research DTU Space, which supplied the so-called stellar cameras to the Juno probe, which is currently in orbit around Jupiter.

At the end of September, Juno dives near Europe. At just 355 kilometers above the moon’s surface, the probe will make measurements that can teach astronomers more about the moon’s interior and the conditions of living things, including by examining giant geysers that could actually stimulate life.

The broken valve changed Juno’s course

The Juno probe, which is about the size of a small passenger car, is named after the goddess who was married to the main Roman deity Jupiter. It was launched on August 5, 2011, and after nearly five years of travel, it has reached its destination.

However, when Juno was about to enter orbit around Jupiter and slowed down from a speed of about 250 thousand kilometers per hour, a malfunction in one of the valves in the rocket engine almost caused the probe to explode. Fortunately, NASA engineers checked all the valves before starting the rocket engine.

Broken valve forced NASA to release her original planto launch the rocket engine and put Juno into orbit closer to Jupiter.

The probe orbited Jupiter twice in a 53-day orbit before being placed in an orbit of just 14 days for the rest of the journey. The shorter orbit shortened the waiting time between Juno’s scientific measurements.

However, the valve problem meant that NASA decided to leave the probe in its 53-day orbit around the poles of the giant planet for safety reasons. That in turn means that Juno is now headed for one of the most likely places for life in the solar system.

Jupiter melts icy moon

The main purpose of Juno’s voyage was to study Jupiter. Using the JunoCam camera, the probe took, among other things, the first images of the gas giant’s north pole, and the instruments on board measured the gas giant’s strong magnetic field.

Jupiter rotates so fast that a day is only 9.5 hours long. The high speed of rotation flattens Jupiter, so that the planet bulges slightly at the equator. This is where we find an explanation for how a barren icy moon like Europa contains liquid water.

Since Europa orbits relatively close to Jupiter – at a distance of about 671,000 kilometers, twice the distance between Earth and the Moon – Jupiter’s gravity is kneading Europa like mud between two fingers.

The process generates so much energy that the ice in the moon’s interior melts into a giant liquid ocean. Hydrothermal vents on the ocean floor can also contribute heat and salt, improving conditions for life.

Ballet dancing with the moons

Jupiter’s bulge at the equator also plays an important role when Juno approaches Europe at the end of September.

To make the probe alternately far from and very close to the planet, Juno’s orbit around Jupiter is very elliptical.

This method was chosen because Jupiter is surrounded by giant radiation belts, about 10,000 times more powerful than those on Earth that over time destroy the probe’s electronics and computers on board.

An elliptical orbit means Juno can alternately “dip its toes” in Jupiter’s radiation and take measurements near the planet, then at the opposite end of the orbit, put the electronics at a safe distance.

However, Jupiter’s bulge is gradually changing the way the probe orbits the planet. In the middle of 2021, Juno had the opportunity to pass the largest moon in the solar system, Ganymede.

Although the main engine was malfunctioning, they managed to do so with the help of the probe’s twelve small rocket nozzles and Ganymede’s gravity Juno’s short orbit From 53 to 43 days and at the same time adjust the route, so that it became possible to cross Europe at an altitude of only 355 kilometers.

From there, Juno will be able to make very accurate measurements of the icy moon.

Europa’s gravity will then be used to shorten the probe’s orbital period to 34 days, which in 2023 will bring Juno closer to the volcanically active moon Io.

“The altitude of the flight over Europe was determined on the basis that it could take us further to Io. We are, in a sense, dancing with the moons, which helps to save fuel,” says Jon Leif Jorgensen.

Heaters contain building blocks

When Juno passes near Europa on September 29 – at an altitude lower than the International Space Station’s orbit around Earth – we hope it will capture images of one of the moon’s most exciting features.

“We don’t know how often cracks form in the ice, but we do know that there are geysers a few hundred kilometers high. This is a real water jet. During Cassini’s flight, we were lucky enough to see geysers on Enceladus (an ice moon around Saturn, so.) And we hope to experience the same with Juno in Europe,” says Jon-Lev Jorgensen.

During the Cassini flight, a spacecraft passed near the springs of Enceladus in 2008-2009. Then the probe measured the presence of organic molecules, and possibly amino acids – the building blocks of life.

Perhaps the same particles are found in Europa geysers. But it is likely that the final evidence of life on the unusual moon will be confirmed as soon as possible by future spaceflights such as Juice or Europa clipperwhich at the end of the decade will come closer to the icy moon.

However, John Leif Jorgensen would be surprised if there were no living creatures on Europe.

“Yes. That would be surprising. Europe has all the conditions for life. There is a higher probability of finding life on Europe than on Mars.”

If John Leif Jorgensen is right, and future flights actually show that there is life on the icy moon – if only life is microscopic – it will be the largest scientific discovery in human history.

So we are not alone in this universe.