The seven-year journey to Mercury, the final flyby of the planet in its near future

People often think that it is easier to let gravity pull them toward a massive object than to pull them away from that massive object. If this process is a simple fall, this idea is certainly correct. But if you want to start from a stable orbit and reach another stable orbit that is already orbiting a massive object, it is not just that simple.

Take visiting Mercury, for example. Mercury orbits at an average distance of 36 million miles from the sun, while Earth orbits the sun at an average radius of 93 million miles. At this position, Mercury's orbital speed is about 1.6 times that of Earth (the Earth's speed is already 30 kilometers per second), and scientists need to do a lot of work to get the spacecraft to match this speed. In space flight, a key parameter is delta-v, the net change in velocity required to get from point A to point B. If you want to go from the Earth to Mercury, you need a very high delta-v speed, so scientists must carefully design a plan to get close to Mercury.

The BepiColombo spacecraft sent by the European Space Agency to Mercury will undergo a 7-year journey, during which it will pass through different planetary orbits at least 9 times. It will use the angular momentum (and gravity) of the planet's orbit to enable the spacecraft to withstand The sun's gravity finally made "gentle contact" with Mercury, a planet located deep in the sun's gravity well. BepiColombo actually consists of two spacecraft: an orbiter with instruments such as telescopic imaging, spectrometers (including gamma rays and neutrons - used to look for signs of water freezing), and a separate orbiter to study Mercury's magnetic environment.

The BepiColombo spacecraft was launched into a heliocentric orbit similar to the Earth in October 2018. It will pass through a series of planetary orbits and will eventually be captured by the gravity of Mercury in December 2025 to stabilize it. into its polar orbit. On April 10, 2020, the BepiColombo spacecraft achieved the first important planetary "contact". At that time, the BepiColombo spacecraft passed by the Earth, and the closest distance was only about 12,700 kilometers. In the process, it not only provides a beautiful perspective on the Earth (the distance shown is about 220,000 kilometers), but also serves as a necessary reminder that there is more to explore beyond our daily research. It requires human perseverance.

Related knowledge

Mercury (Latin: Mercurius; English: Mercury) was called the star in ancient China; by the Western Han Dynasty, the astronomer Sima Qian, the author of "Historical Records? Tianguan Shu", observed it from actual observations It was discovered that Chenxing was gray in color, which was associated with the "Five Elements" theory, and black was used to match Mercury, so it was officially named Mercury [13].

Mercury is the smallest and closest planet to the sun among the eight planets in the solar system, but it has the largest eccentricity among the eight planets [Note 1], with an orbital period of 87.969 Earth days. Seen from the Earth, it rendezvous with the Earth about once every 116 days, and its revolution speed is much faster than other planets in the solar system. Mercury's rapid motion led to its name in Roman mythology as Mercury, the fast-flying messenger god. Because the atmosphere is extremely thin and cannot effectively retain heat, the temperature difference between day and night on the surface of Mercury is extremely large, the highest among the planets in the solar system. The temperature in the equatorial region can reach 432°C during the day and drop to -172°C at night. The temperature in the polar regions remains below -172°C all year round. Mercury has the smallest axial tilt of any planet in the solar system (about 1 to 30 degrees), but it has the largest orbital eccentricity [Note 1]. Mercury is approximately 1.5 times farther away at aphelion than at perihelion. Mercury's surface is filled with large and small craters and looks similar to the moon and other moons, indicating that its geology has been inactive for billions of years.

BepiColombo (English: BepiColombo, Japanese: ベピ?コロンボ) is a Mercury exploration project jointly launched by ESA and JAXA on October 20, 2018[1] . This program includes two orbiters: the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO).

The project is named after the Italian mathematician, scientist and engineer Giuseppe Colombo (Bepi Colombo). He was the first to implement planetary gravity boost technology on the Mariner 10 mission in 1974.

Author: Caleb A. Scharf

FY: Lindsey07

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