Mercury: technology to withstand extreme temperatures

It's such an ambitious and complex space mission that 85% of the technology used is new.

And it's entering the less-studied planet of the solar system, it's like entering a "pizza oven" of extreme temperatures, according to the European Space Agency.

Saturday, the launch of the mission is scheduled for 13:45 GMT. BepiColombo, whose name recalls Guiseppe "Bepi" Colombo (1920-1984), an Italian mathematician, engineer and physicist, devoted much of his life to the study of Mercury and collaborated with NASA on an earlier mission to the planet.

BepiColombo is a joint project of European and Japanese space agencies, which cooperates with Russia and the United States. This is only the third mission to Mercury.

"Going to Mercury is very complicated, it takes more energy than going to Pluto," he told BBC World. Mauro Casale, responsible for the development of the scientific segment of the mission field.

A complex maneuver braking and overflights of several planets to reach the orbit of Mercury, whose study is very difficult from Earth.

"Observations from the ground are almost impossible because Mercury is so close to the Sun that it totally hides it. You have to go, "added Casale.

"Technology did not exist"

More than 80 companies from 12 countries have developed the advanced technology needed for the mission.

"For the extreme conditions of Mercury, the technology did not exist, especially for the temperatures that can pass from 450 degrees Celsius during the day to minus 180 degrees at night"explained to BBC World Santa Martinez, coordinator of scientific processing and archiving of BepiColombo.

Not only are the temperatures extreme. "Solar radiation is ten times more intense than the solar radiation we have on Earth, the infrared radiation emitted by the planet is 20 times greater than on Earth, the ultraviolet radiation is also very high and there are solar winds that can reach 400 km per second"

Among the new technologies are the solar panels of the three components of the mission, two satellites or orbiters, a European and a Japanese, and a transfer module using an electric propulsion to propel them.

"The solar panel of the European orbiter is composed of a mixture of solar cells and reflectors, so that it does not heat very hot," said Martínez.

The antenna paint is also special in order to preserve the white color for maximum reflectivity, and there are special ducts that dissipate heat.

"Another thing that was developed specifically for the mission is an insulation layer, like a Multilayer insulation blanket, who calls in English multilayer insulation. All parts of the satellite are covered with this type of layer in order to isolate themselves from the temperatures, "said Martinez.

Why does the European Space Agency compare the fact of arriving at Mercury at the entrance in a "pizza oven"?

The comparison is due to "the temperatures that are in Mercury resemble those that you have in a Pizza oven. So we usually use this comparison to express the heat of the planet. "

Nine overflights

The trip to Mercury could take six months if it were direct, but BepiColombo It will take 7 years to reach the planet.

"If we went directly to Mercury, we would arrive in six months, but we would arrive so fast that we could not put the satellites in orbit around the planet," he told BBC World. Sara de la Fuente, coordinator of scientific planning and operations of BepiColombo.

"First of all, we are in an orbit very similar to that of the Earth, we must also reduce it and slow down the satellite, we have to reach a relative speed with respect to the planet that is practically zero."

Mariner 10 crossed Mercury but did not gravitate. Messenger was launched in 2004, arrived on the planet in 2011 and orbited it until 2015, when its fuel was exhausted.

But Messenger reached a distance of 15,000 km from Mercury. BepiColombo instead explores other parts of the planet at a distance of only 1500 km.

In order to place the satellites in orbit, the mission will require nine maneuvers of assisted gravity or overflight ",ao on Earth, two to Venus and six to Mercury"explained De la Fuente.

Once in orbit, the Japanese satellite "which continually bypasses itself over a period of four seconds will be mainly devoted to the study of Mercury's environment and its magnetic field".

"And the European orbiter will focus more on the planet itself, on the inside, on the surface and on its morphology as well as on the magnetic field."

For Sara de la Fuente, it's "a unique opportunity because we can get what we call double-point measurements with the two satatellites at different distances"

Mysteries

Mercury is the great unknown of the solar system and scientists expect BepiColombo to help decipher some of the many mysteries of the planet.

"Mercury is a very particular planet, because it is very close to the Sun and has characteristics that other planets in the solar system do not have," said Casale.

"It has for example the particularity of a magnetic field, like the Earth, which does not exist on Mars or Venus. This implies that the inner structure of the planet has characteristics that were thought to be incompatible with Mercury's proximity to the Sun, since it is necessary for the inner core to have a liquid component that was not thought to exist. "

The magnetic field of Mercury is very small, it represents only 1% of that of the Earth and it is moved compared to the center of the planet, which does not happen on Earth, according to Casale.

Messenger detected ice water at the mercury poles and one of the tasks of BepiColombo will be to confirm these ice deposits and to determine their quantity and composition, that is, whether they come from comets or have a different nature.

"He shrunk"

"There are many other characteristics of Mercury that are very special. It's a planet that has shrunk, it lost part of its extension once cooled. Think of a planet in its original form as a fireball that has gradually cooled down and lost some of its volume, which has not yet been well understood, "Casale said.

"A quantity of volatile materials has also been detected, which seems to be incompatible with the mercury's proximity to the Sun and apparently indicates that the planet has formed in a place much farther from the Sun, and then he has moved mysteriously to where he is now. All of this must be investigated. "

The study of mercury is also essential to understand the evolution of the solar system and its planets, including the Earth.

"The study of the birth of Mercury will teach us a lot about the evolution of the solar system."

"And you can extrapolate this knowledge to what is happening on the planets outside the solar system, because many people are away from their soles very similar to those between Mercury and the Sun," Casale added to BBC Mundo.

"The fact that Mercury has a magnetic field is fundamental to search for planets where there might be life as we know it, because this magnetic field is the only mechanism that protects us from the solar wind."

The mission has an estimated cost of approximately USD 2,000 million and it will end with the collision of its modules on Mercury in 2027 or 2028.