why NASA is considering a mission to the mysterious planet

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Uranus, the seventh planet in our solar system, should become the object of NASA’s next orbital mission, if the latter follows the recommendations published on Tuesday by the American scientific community. Knowing more about Uranus would lift the veil of one of the gray areas of our solar system and perhaps better understand the exoplanets.

It’s time to dump her and move on. NASA’s next big space mission should focus on the planet Uranus. This is at least the recommendation made Tuesday, April 19, by the National Academies of American Sciences in its ten-year report on U.S. space priorities. A piece of advice that, in the past, has always been followed by the US space agency.

Man has visited only once this neighbor so far from Earth, which is the penultimate planet in the solar system, only a little closer to the Sun than Neptune. It was the ‘Voyager 2’ probe that approached it for a few hours on January 24, 1986. That is, we know almost nothing about Uranus.

Uranus, a unique planet in more ways than one

It is defined as an ice giant that would be the coldest planet in the solar system with an atmospheric temperature of about -220 ° C. It is also known that a year on Uranus, the time it takes to orbit the sun, lasts 84 Earth years. According to the few data collected, either by the ‘Voyager’ probe or by telescopic observations, its surface is not solid and there are oceans of liquid diamonds.

“We are not really sure of its composition and its name as an ice giant can be usurped,” said Ravit Helled, an Israeli planetary scientist in the astrophysics department at the University of Zurich, contacted by France 24.

These unknowns are one of the main reasons for a great mission to travel to Uranus. Although missions to Mars or the Moon have multiplied and we are beginning to gather accurate information about other stars and exoplanets, there are still almost absolute gray areas in our own solar system. . “It’s as if we were telling you that there is still an unknown ocean on Earth, wouldn’t you like to explore it?” Asks Laurent Lamy, an astrophysicist at the Paris Observatory, contacted by France 24.

This natural curiosity about our “immediate” environment – a very relative notion since Uranus is between 2.6 billion and 3.2 billion kilometers from Earth – is also nourished by the unique characteristics of the planet. In particular, its rotation: it rotates on itself around a horizontal axis and not vertical, like all other known planets. As a result, it appears to be rolling like a ball as it revolves around the sun. A peculiarity that “would be the result of a collision with another celestial body, according to the most accepted theory,” explains planetary scientist Ravit Helled.

This cosmic shock could have even moved Uranus from its initial orbit. “We also don’t know if it was formed in situ – that is, where we see it today – or elsewhere,” said the Israeli astrophysicist.

It’s not just the planet itself that interests scientists. These many moons – 27 bearing all the names of characters from Shakespeare and the works of the British poet Alexander Pope – also hide many mysteries. Some, for example, appear to be oceanic worlds that could harbor life forms, and “exploring them would allow us to learn more about potentially habitable places in our galaxy,” says Chloe Beddingfield, an astronomer at NASA’s Ames Research Center in California. ). ), interviewed by Space.com.

A “missing link”

Uranus also represents – with Neptune – “a link that is missing in our understanding of the planets that exist in space,” says Laurent Lamy. They have often been called “mini-Saturns” or “super-Earths” because they are of intermediate size (about four times the size of Earth). But in reality, it is not just a matter of size, they are the only two representatives of our solar system of a family of separate planets, governed by their own rules.

The importance of these “Uranus-like” planets has only grown with the discovery of exoplanets [qui se trouvent en dehors de notre système solaire]. These observations showed that “planets of comparable size and density to Uranus appear to be very common in space,” notes Ravit Helled. More so, in any case, than Earth-like planets or giants of Saturn’s caliber.

Therefore, an orbital mission around Uranus “would make it possible to complete our understanding of the variety of planetary systems accessible to our solar system and have a relevant reading grid to analyze more distant systems,” sums up Laurent Lamy.

If Uranus is so unique and could prove to be the key to better understanding a large number of exoplanets, why did you wait so long to decide to go there? “It is technologically very difficult to go to a planet in the outer solar system [à partir de Jupiter] and we’re just starting to be able to do that, ”says Ravit Helled.

A long and expensive bet

Going there is already an adventure. Prepare a mission for the still unknown depths of the solar system: decide the scientific goals, the most appropriate tools, the probe launcher, and so on. – It should take about ten years, according to a report by the American National Academies of Sciences. The journey itself should last at least another ten years … While in 1969 it only took four days to reach the moon.

Eventually, the probe would probably remain in orbit for another decade in order to make the trip profitable and get the most data possible. Therefore, it is necessary to provide a source of energy that will last over time without risk of breakdown or damage. “This is a major technological challenge and the best solution seems to be the atomic battery. This is also one of the reasons why NASA, which has this technology called radioisotope thermoelectric generator (or RTG), is embarking on the adventure before Europe, which has been thinking about exploring Uranus for a decade, but does not have an atomic battery, ”says Laurent Lamy of the Paris Observatory.

Therefore, it is a very long-term mission that will be expensive. NASA estimates that this project should cost at least $ 4.2 billion … for results that may not materialize for decades. And it is perhaps, in short, one of the most daring bets of NASA and the Academies of Science: in a world increasingly dominated by the imperative of immediacy where everyone wants everything right away, launch a mission to Uranus would show that there are still areas. in which we can take our time to advance in human knowledge.

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