BepiColombo: Inside Europe’s First Mission to Mercury
BepiColombo is one step closer to making space history. The spacecraft has completed the acoustic, mechanical and vibration tests needed before travelling to the launching site in Europe Spaceport in Kourou, French Guiana. From there, the spacecraft will take a journey of more than seven years.
“Mercury is the least explored planet in the Solar System and the most peculiar of all rocky planets," said Alvaro Gimenez, ESA's Director of Science, during a press conference held at ESA’s European Space Research and Technology Centre today.
The study of the closest planet to the Sun will help allow scientists to develop a better understanding of the early processes in the inner solar system, including how our planet was formed and evolved. BepiColombo will provide unprecedented information on the origin and the evolution of a planet orbiting close to its parent star, which also has a direct relevance to planets in other star systems like Trappist-1.
So far, only two spacecraft have visited Mercury: NASA’s Mariner-10 and Messenger. BepiColombo will build on the legacy of NASAs Messenger, providing complementary and new observations concerning the planet’s interior surface, exosphere and magnetosphere.
BepiColombo is the result of a joint mission between ESA, and the Japan Aerospace Exploration Agency (JAXA). The mission consists of two scientific orbiters: ESA’S Mercury Planetary Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (MMO). The European orbiter is carrying 11 specially-designed instruments, and the Japanese counterpart has five, which are set to explore Mercury's crater-pocked surface, enigmatic magnetism and tenuous, vestigial atmosphere.
Coping with High Temperatures
“BepiColombo is probably the most complicated mission that we have ever done at ESA,” said Gimenez. Mercury’s surface extreme temperatures, ranging from +450 to -180 degrees Celsius, and the Sun’s huge gravity, which makes it difficult to put a spacecraft into steady orbit around the planet, brought up many challenges to the manufacturing team.
To cope with the extreme temperatures, BepiColombo counts with antennas, solar arrays, sun sensors, and multilayer insulation, has temperature-resistant outer layers and protective coatings. All of them have undergone significant testing at ESTEC to prove they can withstand the violent shaking occurring during launch, the harsh radiation environment of space, and the high temperatures that will be encountered close to the Sun once orbiting Mercury.
A 7-year journey
The arrival of BepiColombo at Mercury is planned for December 2025, according to the mission’s Project Manager Ulrich Reininghaus. The spacecraft will be launched in October 2018 on an Ariane 5 from Europe’s Spaceport in Kourou, French Guiana.
The spacecraft will use the gravity of Earth, Venus and Mercury, in combination with the thrust provided by electric propulsion, to reach Mercury. The spacecraft will have a 7.2-year cruise, with one Earth flyby, two Venus flybys and six Mercury flybys.
MPO and MMO will voyage to Mercury together as a single composite spacecraft, with a dedicated transfer module (MTM) providing power and propulsion. A sun shield will protect MMO from solar radiation and overheating during the cruise phase. When approaching the planet, the transfer module will separate and the two spacecraft, still together, will be captured into a polar orbit around the planet. Its altitude will then be adjusted using MPO’s thrusters until MMO’s desired elliptical polar orbit is reached. Finally, the MPO will separate and descend to its orbit using its thrusters. The fine-tuning of the orbits is expected to take three months.
The initial mission at Mercury is planned for one year, with a possibility of extension for another one. However, the mission scientists don’t discard the possibility of extending the life of the mission, although the harsh environmental conditions would determine this.
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