The European Space Agency (ESA), together with the Japanese Agency for Aerospace Exploration (JAXA), will launch its first satellite to Mercury this Saturday, October 20. On board an Ariane 5 from the European Spaceport of Kurú (French Guiana), BepiColombo will head to the planet closest to the Sun with the aim of discovering many of the secrets that he still keeps jealously. The launch is scheduled for 1.45 GMT (3.45 CEST).
BepiColombo will be the third probe to visit Mercury after that of Mariner 10, launched in the mid-70s, and Messenger, which operated between 2011 and 2015, both from NASA (BepiColombo will be based on the discoveries and questions raised by this mission) .
The two scientific orbiters are: the Mercury Planetary Orbiter (MPO or 'Bepi'), of the ESA, and the Mercury Magnetospheric Orbiter (MMO or 'Mio'), of the JAXA. And it will be the Mercury Transfer Module (MTM), built by ESA, which will transport both to Mercury using a combination of solar-electric propulsion and gravitational assist maneuvers.
The MPO will observe the planet from its orbit, studying the composition, topography and morphology of its surface and its interior, while the MMO will focus on the study of the planet's environment and its magnetosphere. It will be the first time that two orbiters make coordinated and simultaneous observations from different points of the Mercury environment.
Specifically, BepiColombo will try to solve how Mercury originated and how it evolved from then until now. To do this, it will study its surface and its interior, the composition and dynamics of its exosphere, the structure and dynamics of its magnetosphere and the origin of its magnetic field. In addition, experiments will be conducted to test Einstein's theory of General Relativity.
It will also help scientists to better understand the formation and evolution of the Solar System, thus contributing to the understanding of how the innermost planets of other extrasolar systems are formed and evolve.
The mission will also seek confirmation of the existence of water ice and if it comes from comet impacts, while trying to answer why its magnetic field is 400 kilometers away from the center of the planet.
BepiColombo will take more than seven years to reach its destination. During these years, the mission will once fly over the Earth, twice Venus and six times Mercury, before entering orbit, an event scheduled for March 2026.
As reported by the Higher Council for Scientific Research (CSIC), the Power Devices and Systems Group of the Microelectronics Institute of Barcelona of the CSIC has developed and manufactured one of the "most critical" electronic components of the BepiColombo mission.
In particular, it deals with the protection diodes of the photovoltaic cells of the solar panels. The CSIC has explained that these components (700 in total, between the two probes that will orbit Mercury) are located next to the solar panels to protect them in case of failure of one of the cells, and will be exposed to very extreme temperatures (300ºC during the direct exposure to the Sun and 150ºC below zero in the eclipse phase behind the planet).
The two probes are the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO), each with its own solar panel.
For the devices to withstand these extreme conditions, the team led by Professor Philippe Godignon has developed diodes with silicon carbide, a new semiconductor that is replacing silicon in many applications of power electronics, such as the car electric. ALTER Technology of Madrid has also participated in this project, carrying out the tests and qualification for the diode space.
The state agency attached to the Ministry of Science, Innovation and Universities has indicated that the challenge was to develop a semiconductor device capable of withstanding extreme temperatures and preserve the functioning of solar panels. "The solar panels of the ship will be arranged in horizontal lines connected, it is necessary to achieve that, even if one fails, the others continue to work," said Godignon.
Therefore, each of these solar cell lines will have a high voltage diode in series, an electronic component that will allow disconnect the faulty line and ensure that the operation of the adjacent cells is guaranteed.
Mercury is the planet closest to the Sun (it gets closer to just over 46 million kilometers during its perihelion) and it is also the smallest in the Solar System. These circumstances lead to its study with space probes being more complicated than is usual in this type of mission.
In fact, one of the main challenges of the mission is the enormous gravity of the Sun, which makes it difficult to put the ships in a stable orbit around Mercury, so it takes even more energy to send a mission to Pluto.
After launching, and once out of Earth's "gravity well", BepiColombo will have to constantly brake against the gravitational attraction of the Sun. The MTM ion thrusters will provide the low propulsion needed during the long cruise phase, employing previously proven technologies in the GOCE mission of the ESA for the study of terrestrial gravity and the SMART-1 mission to the Moon.
In addition, being the planet closest to the Sun, will have to withstand extreme temperature changes, ranging from -170º to 450º C, but also a solar radiation ten times more intense, an infrared flow 20 times higher than in the Earth, a very intense ultraviolet radiation and the solar wind blowing at a speed of 400 kilometers per second, among others.
In fact, the environment of the planet forced to redesign many components of BepiColombo, especially solar panels and thermal insulation. In addition, it also uses a solar electric propulsion that is unprecedented for exploration missions of the Solar System of ESA.