Rosetta Mission: A Space Odyssey to Decipher the Origins of the Solar System

It may seem like a lie, but when the Earth was formed, 4.5 billion years ago, temperatures here were much higher than in Piauí. So high that all the water would have evaporated and been lost into space. So, if the Earth couldn't retain it, where did all this water that now covers two-thirds of our planet come from? This is just one of the intriguing questions that the Rosetta Mission sought to answer when it was sent to study a comet up close. But this mission ended up becoming a true space odyssey that presented us with spectacular images, in addition to revealing surprising secrets about these cosmic travelers and the origins of the Solar System.

The idea of ​​studying a comet up close began to take shape in the 1980s with the Giotto Mission. This pioneering ESA mission flew past Halley’s Comet in 1986, passing through the comet’s tail and returning the first close-up images of a comet nucleus. The success of Giotto paved the way for even more ambitious missions, and in 1993, ESA assembled a team of scientists and engineers from around the world to develop the Rosetta Mission. Named after the Rosetta Stone, which made it possible to interpret Egyptian hieroglyphics, the Rosetta probe would be tasked with deciphering what comets have to tell us about the formation of the Solar System and the origins of water here on Earth.

Rosetta was launched in March 2004 aboard an Ariane 5 rocket from the Kourou Space Centre in French Guiana. Its destination: Comet 67P/Churyumov-Gerasimenko, an icy traveler that orbits the Sun every six and a half years between the orbits of Jupiter and Earth.

67P/Churyumov-Gerasimenko, or “Rubber Duck Comet” to its friends, is no ordinary comet. With a peculiar shape that earned it its nickname, 67P is a relatively small celestial object, just over 4 km in diameter, but it holds valuable secrets about the composition and conditions of the early Solar System.

Comets are thought to be leftovers from the formation of the Solar System, frozen chunks of dust and ice that have remained largely intact since the Sun and planets formed. By studying the chemical composition and internal structure of 67P, the Rosetta mission could provide important clues about the formation of planets and the origins of water on Earth.

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But Rosetta’s journey to Comet 67P wasn’t exactly a walk in the park. It was a true space odyssey, a ten-year journey that took it billions of kilometers, crossing the asteroid belt and performing complex gravity assist maneuvers with Earth and Mars to propel the probe toward its destination.

During its visit to the Red Planet in 2005, Rosetta performed its riskiest maneuver yet: a flyby just 250 km from the Martian surface, passing over the night side of the planet. During this maneuver, the probe had to be put into hibernation mode, since its solar panels would not receive power, and as a result, Rosetta was cut off from communication with Earth for 15 minutes. A maneuver so risky that it became known as “The Billion Euro Bet”.

Later in 2007, during its penultimate gravity assist with Earth, the probe once again caused concern among astronomers. This time, not because of a dangerous maneuver, but because Rosetta was mistakenly identified as an asteroid of about 20 meters that could hit our planet on November 13 of that year (“asteroid” 2007 VN84). Fortunately, the confusion was cleared up before the “apocalypse gang” could record a video announcing yet another end of the world. And so Rosetta passed by Earth, receiving a valuable gravitational boost that would take it to Comet 67P.

But not before crossing the Main Asteroid Belt, where it visited two inhabitants of that region, the asteroid Steins in 2008 and Lutetia in 2010, sending back spectacular images and valuable data about these primitive celestial bodies. But the big challenge was yet to come.

In August 2014, after a long journey, Rosetta finally reached its destination: comet 67P. Since its approach, the images sent back by the probe have surprised and excited scientists. Comet 67P looked like a world much more complex than the name of its discoverers (Klim Ivanovych Churyumov and Svetlana Ivanovna Gerasimenko). In addition to its aforementioned rubber ducky shape, scientists discovered steep cliffs, deep craters, dusty plains and jets of gas and dust that were expelled from its surface as the comet approached the Sun. This surprisingly rugged terrain would make the next phase of the mission even more challenging.

The Rosetta Mission had an ace up its sleeve: the Philae probe, a landing module that would be ejected from Rosetta and would attempt to land on the surface of comet 67P, an unprecedented feat in the history of space exploration.

On 12 November 2014, the world held its breath as Philae separated from Rosetta and began its slow descent towards the comet’s surface. The landing, broadcast live by ESA, was a moment of great excitement and apprehension.

Due to the low gravity and the slightly harder and more uneven surface than expected, Philae ended up bouncing around the comet a few times before settling in an area with little sunlight. Despite the setbacks, Philae managed to carry out most of its scientific experiments, sending back valuable data on the composition of 67P's soil before going into hibernation due to lack of power.

For two years, Rosetta orbited Comet 67P, tracking its activity as it approached the Sun and then moved away again. The spacecraft collected unprecedented data on the comet’s chemical composition, revealing the presence of water, carbon dioxide, carbon monoxide, methane, ammonia and other complex organic molecules. This reinforced the idea that comets are like space freezers, preserving the ingredients left over from the preparation of the Solar System.

Analysis of the water present in the Churyumov-Gerasimenko comet showed that its isotopic composition is different from the water found in Earth's oceans, contradicting the theory that the water on our planet originated in comets.

With 67P moving away from the Sun and solar energy waning, ESA decided to end the mission in spectacular fashion. On 30 September 2016, the Rosetta spacecraft performed a controlled landing on the surface of comet 67P, sending back high-resolution images and scientific data until the very last moment.

The Rosetta mission marked a new era in space exploration, demonstrating humanity’s ability to reach and study complex and challenging celestial objects such as comets. The data collected by Rosetta and Philae continue to be analyzed by scientists around the world, helping us better understand the origins of the Solar System, water and even life on Earth.

The Rosetta odyssey, like the Rosetta Stone that inspired its name, has helped us decipher part of the history of our past and better understand our place in this vast cosmic ocean. The mission, which brought together scientists and engineers from around the world, has proven that international cooperation and the pursuit of knowledge are essential for the advancement of humanity. May the Rosetta saga continue to inspire future generations to explore the cosmos and unlock the secrets of the universe!