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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 Tuesday by the American scientific community. Knowing more about Uranus would lift the veil on one of the gray areas of our solar system and perhaps better understand exoplanets.
It’s time to go back or rather go there for real. NASA’s next major space mission should focus on the planet Uranus. In any case, this is the recommendation made Tuesday, April 19, by the American National Academies of Sciences in their 10-year report on US space priorities† Advice that has always been followed in the past by the American space agency.
Man has only visited this very distant neighbor once, the penultimate planet of the solar system, just a little closer to the sun than Neptune. It was the ‘Voyager 2’ probe that had approached him for a few hours, January 24, 1986† In other words, we know practically 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 – be it from the ‘Voyager’ probe or from telescopic observations – the surface is not solid and there would be oceans of liquid diamonds†
“In reality, we are not sure of its composition and the name of ice giant can be appropriated,” said Ravit Helled, planetary scientist at the University of Zurich’s Department of Astrophysics, contacted by France 24.
These unknowns are one of the main reasons justifying a great mission to travel to Uranus. Although the number of missions to Mars or the moon has multiplied and we are beginning to collect accurate information about other stars and about exoplanets, there are still almost absolute gray areas in our own solar system. “It’s like telling you that there is still an unknown ocean on Earth, wouldn’t you want to explore it?” asks Laurent Lamy, astrophysicist at the Paris Observatory, contacting France 24.
This natural curiosity about our “immediate” environment – a very relative term since Uranus is located between 2.6 billion and 3.2 billion kilometers from Earth – is also fueled by the planet’s unique features. In particular, its rotation: it revolves around a horizontal axis and not vertically, like all other known planets. As a result, it appears to roll like a ball as it revolves around the sun. An oddity that “according to the most widely accepted theory would result from a collision with another celestial body,” explains planetary scientist Ravit Helled.
It’s not just the planet itself that interests scientists. These many moons – there are 27 all with the names of Shakespearean characters and from the works of the British poet Alexander Pope – also hide many mysteries. For example, some appear to be ocean worlds that could harbor life forms, and “exploring them would allow us to learn more about potentially habitable places in our galaxy,” said 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 missing link in our understanding of the planets that exist in space,” assures Laurent Lamy. They are often referred to as “mini-Saturn” or “super-Earth” because they are average in size (about four times that of Earth). But in reality it is not just a matter of size, they are the only two representatives in our solar system of a family of planets apart, ruled by their own rules.
The importance of these “Uranus-like” planets has only increased with the discovery of exoplanets [qui se trouvent en dehors de notre système solaire]† These observations showed that “planets with a size and density comparable to Uranus seem quite common in space,” notes Ravit Helled. At least more than Earth-like planets or giants of the caliber of Saturn.
Therefore, an orbital mission around Uranus “would make it possible to complete our understanding of the variety of planetary systems accessible in our solar system and to have a relevant reading grid for analyzing more distant systems,” sums up Laurent Lamy. together.
If Uranus is so unique and could prove to hold the key to a better understanding of many exoplanets, why did you wait so long to decide to go there? “It is technologically very complicated to go to a planet in the outer solar system” [à partir de Jupiter] and we’re just barely able to do that,” said Ravit Helled.
A long and expensive bet
It’s quite an adventure to go there. Prepare a mission to the yet unknown depths of the solar system — determine the scientific objectives, the most appropriate tools, the launch vehicle for the probe, etc. — should take about ten years, according to the report of the American National Academies of Sciences. The journey itself should take at least another ten years… Whereas in 1969 it only took four days to get to the moon.
Finally, the probe would likely remain in orbit for another ten years to make the trip profitable and obtain the maximum amount of data. It is therefore necessary to provide an energy source that will last just as long without the risk of breakdown or damage. “This is a major technological challenge and the best solution seems to be the atomic stack. This is also one of the reasons why NASA, which has called this technology radioisotope thermoelectric generator (or RTG), is embarking on the adventure before Europe , which has been thinking about exploring Uranus for ten years, but does not have an atomic battery,” notes Laurent Lamy of the Paris Observatory.
So it is a very long-term mission that will be expensive. NASA estimates that such a project would cost at least $4.2 billion… for results that may not materialize for decades. And it’s perhaps, ultimately, one of NASA’s and the Academies of Science’s most daring bets: in a world increasingly dominated by the need for immediacy where everyone wants everything right away, launching a mission for Uranus would prove that there are still areas in which we can take our time to advance human knowledge.
