A tiny dot surrounded by a light yellow halo. Five billion kilometers away from us the Sun is nothing but a speck of dust of the sky, a little bigger than the other stars of the firmament. This premise allows us to talk about Pluto, the last outpost of our planetary system. A mass of rock lost in the universe, far away from our eyes until 1930 when the astronomer Clyde William Tombaugh showed it to scientists for the first time. Until today we had seen it thanks to blurred pictures, t of the observations by the telescopes and of the extraordinary mission Voyager. It has taken years of studies, analysis calculations to arrive at the face-to-face that will be staged at 13:39 on July 14 of this Italian. A date that will not only celebrate the outbreak of the French Revolution but also the day on which man has overcome a new obstacle to the full understanding of what surrounds him. All thanks to the probe New Horizons, an extraordinary NASA mission began in 2006. This is a true miracle of engineering will be our eye on Pluto, the most distant and mysterious brother of the Earth.
The “kiss” will last only two hours, when the spacecraft will pass at the minimum distance from this small planet: 12,500 km from the surface, a platitude in astronomical distance terms, considering that the Moon orbits us at a distance of 400 thousand kilometers. In those minutes New Horizons will fly to 50 thousand kilometers per hour snapping dozens of photos at a resolution of 1 pixel to 500 meters. Just enough to get a complete picture that will serve to dissolve many of the Pluto’s riddles. Many concern its composition and size and some features that the scientific community took into account in order to exclude it from the list of planets in the solar system, a few months before the departure of the probe, declassifying it into a planetoid among the protests of many of its admirers. A decision that could be overturned by this American mission if the tests will have satisfactory results.
Another aspect to take into account concerns its shiny heart-shaped structure and four large dark spots, each as big as the US state of Missouri, and equally spaced from each other. These spots run along the equator and could be uplands or plains, or brightness variations on a completely smooth surface. But the verdict on Pluto will not be immediate, in that phase the spacecraft will be engaged in collecting data using seven cutting-edge tools, including the “Long Range Reconnaissance Imager” (Lorri) camera, or the detector dust “Sdc” (Student dust counter), built – as the name suggests – with the precious contribution of the students. The first sign of life of Horizons will only come when Europe it will be night, after a journey of five hours at the speed of light. And its content will be more or less this: “All right, I survived the encounter.” This is not a banality, because at those distances and depths of the cosmos everything can happen, including irreparable damage that would break off years of hope. A thunderous applause, as for the landing of Curiosity on Mars in 2012, will confirm that nothing went wrong. “I hope to see a very active and dynamic planet” wished prof. Bill McKinnon – Washington University in St Louis – a member of the study group.
Meanwhile Horizons has already told us something about its special observed planet. The first thing is that Mars is not the only red planet in the solar system. But in the case of Pluto, the color does not depend on rusty iron but, probably, on hydrocarbon molecules, the result of the meeting between the sunlight, cosmic rays and methane atmosphere of Pluto. The probe then will give us also the first images of Charon, the main satellite of the planet, which measures slightly more than half of its “lord”. Two icy majesties that will be shown to us as never before. The NASA mission will then look for other moons in addition to those already known as Styx, Hydra, Cerberus and Night. Then it will pass over, observing the Sun eclipse from there to capture its rays. It will dive into the darkness towards the Oort cloud, the cradle of comets, another wonder in the immensity of the cosmos.
Translation provided by Maria Rosaria Mastropaolo