Wednesday 8 January at 06:59 Italian time the probe Bepi Colombo of the European Space Agency and the Japan Aerospace Exploration Agency carried out the sixth and final flyby (in jargon fly-by) from the surface of Mercurygiving us splendid new images of the planet closest to the Sun. The orbital maneuver was performed to put the probe on a trajectory that will take it into orbits the planet towards the end of 2026. The probe, which bears the name of the Italian astronomer, expert on Mercury, Giuseppe Colomboflew over the surface alone 295km high near the north pole of the planet. The images released by M-CAM monitoring chamber they show both the initial and subsequent phases of the flyby, giving us a complete perspective of the transition from the cold area not illuminated by the Sun to the illuminated one. The pictures show craters whose the bottom is perpetually in the shademaking them among colder areas of the Solar System, e plains more brilliant of the rest of the surface since of volcanic origin. Many mysteries surround Mercury, the planet closest to the Sun, but also among the least studied, such as the composition of the surface and its formation. Mysteries that the Bepi Colombo probe hopes to solve starting from 2026.
How the flyby of Mercury went
The probe Bepi Colombo carried out the sixth and last close flyby of Mercury lJanuary 8th at 06:59passing to approx 295km of height from the surface, near the regions of North Pole. The images released by ESA show the sequence of events well. The probe passed at its closest point over the cold shadowed area of the planet, only to pass over the north pole 7 minutes later, to then acquire images of the terminator (line that separates the illuminated part of a planet from the shadowed part) and of the northern hemisphere illuminated by the Sun.
The sixth fly-by of Mercury allowed the probe to finally get on the trajectory that will take it orbits the planet towards the end of 2026. The images were the last ones released by M-CAM monitoring chambergiven that before putting into orbit, the section will separate from the orbiting modules Mercury Planetary Orbiter of ESA, the European Space Agency, e Mercury Magnetospheric orbiter of JAXA, the Japanese Space Agency.
What Bepi Colombo discovered during the overflight
There first image (below) released by the probe was obtained near the North Pole of Mercury. It shows some of the craters of Mercury whose frozen bottom And perpetually in the shademaking them some of the coldest places in the Solar System, despite Mercury being the planet closest to the Sun. These craters could contain water, one of the mysteries that Bepi Colombo will have to solve. Visible at the bottom left are the craters Henri and Lismer from the volcanic plains of Borealis Planitiawhich were filled with lava during a volcanic eruption that occurred 3.7 billion years ago.
There second image below, obtained 5 minutes after the first, shows how the volcanic plains occupy a large part of Mercury’s surface. At the bottom left you can see the Caloris basinwhich with its 1500 km in diameter, is the largest impact crater of Mercury. One is visible above boomerang structurelighter than the rest of the surface, formed from one lava flow. Its proximity and similar color to the Caloris basin suggest that the two are connected, so one question Bepi Colombo will have to answer is whether the lava moved outward from the Caloris basin or vice versa.
Both the before and after images below show how Mercury is basically a particularly dark planetwhich reflects 2/3 as much light as the Moon does. The young structuresfor example originating from eruptions, they are clearerwhile older ones are darker. Scientists don’t know what causes the material on the surface to become darker, partly because the composition of the surface itself is poorly understood. The last image shows the young man on the left Fonteyn craterwhich formed just 300 million years ago, and whose youth is evident by the brightness of impact debris radiating from it.
Why is Mercury rarely visited?
Contrary to what one might think, send a probe towards the internal regions of the Solar System is more complicated to send it outwards. This is because a probe launched from Earth has an initial orbital velocity that is more or less equal to that possessed by the Earth in its orbit around the Sun. If there was a “brake” in space, pressing it would cause the probe to slow down and stop moving around the Sun. Sun, reaching it simply by falling into it.
To be able to go towards the interior of the Solar System you must therefore cancel out the Earth’s orbital velocity of approximately 30 km/s. The way to do this is to use fuel to lose speedso as to be sucked by solar gravity towards the interior of the Solar System. The closer you get, the more speed you have to lose. This is why it is difficult to go to Mercury: it is not further away, but it takes a while great effort to slow down enough to get so close to the Sun.
