NASA envisages an orbital mission devoted to this mysterious planet. A long -term program, which will be expensive and where everything remains to be done.
by Pierre Barthélémy
In January 1986 and August 1989, the NASA travel -2 probe flew successively – and quickly – Uranus and Neptune, sending us the first images of these other blue planets. And then, nothing. For more than thirty years, while several missions devoted to Mercury, Venus, Mars, Jupiter and Saturn have left the earth, no robotic explorer has returned to the two planets most distant from the solar system, which however hold the ‘Opinion of researchers, the keys to his training.
This is why, in 2022, the American academies of science, engineering and medicine in their decennial report devoted to planetology, recommended as number one for NASA an ambitious mission focused on Uranus, the most accessible Of the two frozen giants, located 2.9 billion kilometers from the sun (compared to 4.5 billion for Neptune). This is also why, in Science of February 17, Kathleen Mandt, specialist in the exploration of the solar system at Johns-Hopkins University (Maryland), drives the point home by describing the interest of such a program, while stressing that ‘You have to launch it quickly.
In the boxes for a long time, the mission in question already has an acronym for work, UOP, for “Uranus orbit and Probe”. The idea consists in sending two devices together: the first will be orbit around Uranus to study it from every angle, and the second, a “suicide bomber” probe, will sink into the atmosphere of the planet in order to to make measurements there. These in situ statements are particularly important in that they can help decide between the different Uranus formation scenarios within the gas and dust disc that surrounded the sun after its birth, there are a little more than 4 , 5 billion years. By ricochet, they will allow researchers to understand how the material was distributed in this primordial disc.
a “lying” planet
Many other questions arise about Uranus, this planet presenting many quirks. The first, not the least, is the extreme inclination of its axis of rotation. Uranus is, so to speak, “lying down” on the ecliptic level and therefore alternately presents its poles in front of the sun. Consequently, during the summer, which lasts about twenty years (the period of Revolution of Uranus is eighty-four years), the southern hemisphere of the planet remains in the shadows, and the situation s ‘reverse in winter, where the northern hemisphere is plunged into darkness. This switch on the side could have been caused by a collision with a solid body. As Kathleen Mandt writes, “this orientation causes extreme seasonal atmospheric variations (…) but the observations of the mist and the clouds from the earth cannot provide enough information to explain atmospheric circulation and wind regimes “.
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