Science

The 'BepiColombo' approaches Mercury, the mysterious planet with double sunrises and temperatures of 430 degrees


Recreación de la sonda 'BepiColombo' sobrevolando Mercurio.
Recreation of the probe ‘BepiColombo’ flying over Mercury. THIS

The space mission BepiColombo, of The European (ESA) and Japanese (JAXA) space agencies, plans to arrive this Saturday (about one thirty in the morning, Spanish peninsular time) at Mercury, the mysterious planet closest to the Sun where a day lasts almost two terrestrial months , double sunrises can be observed, temperatures between 430 degrees and minus 180 degrees and many answers are saved about the origin of our planet and the galaxy. The Institute of Astrophysics of Andalusia (IAA-CSIC) participates in one of the fundamental scientific tools: a laser altimeter called Bela, which will allow the elaboration of the most detailed map of the planet’s surface.

Mercury is an inferno where the surface temperature, when the Sun hits directly, is half the temperature of the lava from the La Palma volcano. And also, at night, an icy terrain where the thermometer falls more than 600 degrees with respect to the day. It is located between 77 and 222 millions of kilometers from Earth, according to the trajectories of both planets, and their proximity to the main star of our system (58 million kilometers) gives it a peculiar rate of rotation and translation: it takes the equivalent of turning on itself to 58 days and 15 Earth hours and in circling the Sun alone 88 days. In this way, there are only three days every two years. During the long sunrise of Mercury, in some points of the planet, and due to its unique orbit, when two thirds of the Sun are seen, it seems that it recedes and hides, to come out again four Earth days later through the same place on the planet. horizon.

Mercury takes the equivalent of 16 days and 15 Earth hours and in circling the Sun alone 88 days. In this way, there are only three days every two years.

But beyond the singularities conferred by its position in the Solar System, Mercury can provide many answers about the origin of the Earth and the Milky Way. José María Madiedo, doctor in Chemistry and Physics and researcher at the Institute of Astrophysics of Andalusia, affirms: “More than telling us where we are going, he will tell us more about where we come from, about the origin and evolution of the Solar System.”

The probe BepiColombo , named after the Italian scientist Giuseppe Bepi Colombo (1920 – 1984), is today, after three years of travel, more than 100 millions of kilometers from Earth to fly over Mercury at about 198 kilometers high. It will do it again six more times until it is in orbit at 2025.

A difficult maneuver

This lengthy maneuver is because it would take immense energy to get in a straight line. In this way, the BepiColombo , which is today three times closer to the Sun than our planet, has to take advantage of the gravity of other celestial bodies (twice it has passed through Venus and once through Earth in this case) to accelerate, as if it were a slingshot. On the contrary, it needs to prolong the maneuvers for years to decelerate passing through different heliocentric orbits and with gravity assistance.

David Galadí Enríquez, astrophysicist at the IAA, explains that “giving energy to a spacecraft costs the same as take it off. Reaching Mercury is very expensive in terms of thrust energy and that explains why there have been few missions. ”

has succeeded and accurately. Elsa Montagnon, Head of Operations for the probe, affirms that it has been thanks to the ground stations: “We know where our spacecraft is and, with this information, the Flight Dynamics team knows how much we need to maneuver to be in the right place to gravity assist ”.

El Bela, with Andalusian participation, will make the most detailed map of Mercury’s surface using the reflection of a laser beam sent from the probe. By measuring how long it takes for the beam to come and go, the distance to the surface is calculated and thus can be mapped with great precision

David Galadí Enríquez, astrophysicist at the IAA

And now the scan begins. Two of the three cameras carried by the BepiColombo will immediately start sending images. And although they will not be the most relevant, they will open the book of science. Some of the scientific instruments will also begin their work. Johannes Benkhoff, ESA mission scientist, says: “We are looking forward to seeing the first results of measurements so close to the surface of Mercury.”

One of the most significant measurements of Mercury will be made by the Bela, a laser altimeter in which the Andalusian Institute of Astrophysics participates. The instrument, Galadí explains, “will make the most detailed map of Mercury’s surface using the reflection of a laser beam sent from the probe. By measuring how long it takes for the beam to come and go, the distance to the surface is calculated and thus can be mapped with great precision. ”

This mission and its instruments allow us to study a mysterious galaxy companion difficult to explore from Earth. In this sense, Madiedo explains that Mercury, one of the terrestrial planets together with Venus, Mars and Earth, “is very difficult to observe with telescopes due to its position with respect to our planet and its proximity to the Sun.”

Mercury is the only other example magnetic field on a solid planet. The magnetic field interacts with the solar wind and protects the Earth from cosmic rays that would destroy the external atmosphere. Without it, there would be no life

One of the most relevant aspects of the mission, according to the IAA scientist, is to clarify the origin of Mercury’s magnetic field, the same as that of Earth, but much weaker. Neither Venus nor Mars (it disappeared there three million years ago) nor the Moon have it. For Galadí, this is one of the fundamental aspects of the mission: “Studying the structure of Mercury’s magnetic field can help improve models of the Earth’s magnetic field. A problem we have in science is to make a model of something of which there is only one example, and Mercury is the only example we have at hand of a magnetic field on a solid planet ”. The magnetic field interacts with the solar wind and protects the Earth from cosmic rays that would destroy the external atmosphere. Without it, there would be no life.

“Another mystery around Mercury”, adds Madiedo, “is its density . It is known that it has to have a fairly large amount of iron inside, but observations made from a distance have not allowed us to detect this metal. ”

Madiedo also clarifies that it is intended to obtain answers about whether the mantle of Mercury is solid or liquid, “if it is molten like that of the Earth, like the magma that rises to the surface by the volcano de la Palma ”, and if this circumstance makes it a geologically very dynamic planet due to plate tectonics.

The mission will clarify questions for which today we do not have answers, such as how these planets are formed so close to their star, what composition they have, from what materials the solar system was formed, how it evolves, what is the composition of the thin Mercurian atmosphere and what are the exoplanets that are also very close to their star

Jose Ma Ría Madiedo, doctor in Chemistry and Physics and researcher at the Institute of Astrophysics of Andalusia

The European probe will also investigate whether there are traces of water in the polar areas, in craters that escape the influence of such changes sudden temperature between day and night. Not because Mercury is a candidate for its exploitation —Madiedo believes that “it would be more feasible to do it from asteroids” —but in order, according to the Andalusian scientist, “to clarify questions for which today we do not have answers, such as, for example, How these planets are formed so close to their star, what composition do they have, from what materials the solar system was formed, how it evolves, what is the composition of the thin Mercurian atmosphere and how are the exoplanets that are also very close to its star. ”

The proximity to the Sun, the extreme temperatures and the geological history of Mercury give its surface a rugged configuration, with steep slopes (steep slopes) that, according to Galadí, are named after famous ships in the history of mankind, such as Santa María , in honor of one of the ships with which Columbus arrived in America.

The Mariner was the first space probe to visit Mercury in the first decade of the seventies. It was followed by Messenger , launched in 2004. Eleven years later, it crashed, as planned after running out of fuel, on the surface of Mercury and opened a crater of 16 meters. Madiedo highlights that the BepiColombo will be able to study “fresh material” of this geographical feature created by man and see hidden aspects by the most superficial layers. The European probe will deploy in 2025 two orbiters: one its own planetary and the other magnetospheric, from the Japanese agency JAXA.

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