• Mission Last Thule is flat and pancake shaped
  • Dwarf planet.Face to face with Pluto

The small New Horizons spacecraft has made history twice. On July 14, 2015, the public was excited to fly over Pluto and offer images never seen of the dwarf planet. Earlier this year, the probe returned to global attention when it reached Ultima Thule, a celestial body of the mysterious Kuiper belt, so far the most distant object ever visited by a ship.

During these "visits", New Horizons has obtained data on the most distant celestial bodies in our environment and obtained information that helps us understand how our solar system was born. Although more than 13 years have passed since its launch, the probe is still working perfectly, and it could have another 20 years of life left.

One of the people who will decide the next destination of the probe is the planetary scientist Alan Stern (New Orleans, 1957), principal investigator of the mission. The astrophysicist spent decades trying to get NASA to commission a mission to Pluto, and his insistence has been vindicated by the data obtained in the overflights, which have revolutionized everything we know about the farthest zone of our planetary system. From Lisbon, Stern talks with THE WORLD about the challenges that New Horizons still has ahead.

Ultima Thule, photographed by the probe 'New Horizons'NASA

Why was Pluto's flyby so revolutionary? Until now we thought that the dwarf planets were "simpler" than the big ones. We always assumed that they had no geothermal activity, because being smaller, we thought they would have "cooled." In our flyby we discover that Pluto has an impressive complexity, with geothermal activity, an atmosphere with wind and even seasonal cycles, glaciers covering millions of kilometers, a vast ocean ... We do not understand how these things exist there, and we will spend the next decades trying to decipher the mystery. Why did you decide to set Ultima Thule as the next probe destination? Because it offers us a perfect opportunity to study how dwarf planets are formed. Pluto has a diameter of about 2,400 kilometers - roughly the length of Europe - but Ultima Thule is about the size of the city of Lisbon, and objects like this are supposed to come together to create larger masses with the passage of weather. For decades we thought that these unions were the result of high-speed collisions, but the data that New Horizons has sent us so far indicates that, in fact, it was a slow, smooth, almost gentle fusion. Are you still waiting to receive all the information obtained during the overflight? Yes, all the information obtained at the beginning of 2019 will not reach us until the end of the summer of 2020. The delay is due to distance, but also to the reduced data transmission rate and the large distance to which it is. The probes of the Voyager mission of the late 1970s had transmitters with greater capacity, but part of our goal was to build a probe 10 times lower than Voyager's . It was like building a car for a tenth of normal: we had to cut, and in this case it was like staying with a radio that only emits AM waves. Has that austerity been noticed in any other aspect? The probe works great and could remain active until the end of the 1930s. During that period our goal is to continue exploring the Kuiper belt and continue learning about how our solar system was formed. Pluto is the farthest planet we've explored, but we want to break our own record and go even further. What can you tell us about Dragonfly, the mission that NASA has just announced? It is an incredibly complex and difficult expedition. We will send a kind of octocopter to Titan, one of Saturn's moons, which has an atmosphere, liquids, active geology, climate ... Within our solar system it has the environment most similar to what was on Earth in its origins. The idea is that Dragonfly lands and takes off up to 10 times, obtaining information about the geology and astrobiology of that place over several years. Last month was the 50th anniversary of the arrival of Neil Armstrong to the Moon, what do you think About those who claim that the era of astronauts is over, and that the special exploration must be done by robots? I think it would be crazy to stop having astronauts. My friend Steve Squires, the director of the Mars rover mission, often says that what they managed to do after five years was equivalent to what the Apollo mission astronauts had done on a weekend. Robots are great for dangerous environments for humans, but humans are tremendously effective. The best thing is that there is work together, with robots as tools to expand our capacity. With more and more distant missions, do you think we will come to live with life out there? Yes. There is a trillion planets in our galaxy and in many there is water. It is very likely that life is a common phenomenon in the universe, and that even technological civilizations are common. Are you surprised by the enthusiasm generated by the New Horizons mission? Human beings are fascinated by exploration. Be it with Magellan going around the world, or with the first polar travelers, or the pioneer astronauts. Exploration makes us proud of our species and gives us hope that the future to be discovered is better than the present. Do you identify with those explorers of the past? Sure, but also with those of the future. For me it is a pride to follow the path forged by the discoverers of yesteryear, motivating the next generations, who will be the first to travel and live by our solar system.

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