BepiColombo hugs Mercury – annotated

BepiColombo appears to ‘hug’ Mercury in this image taken by the ESA/JAXA BepiColombo mission on 19 June 2023 as the spacecraft sped by for its third of three gravity assist manoeuvres at the planet.

The image was taken at 20:29 UT (22:29 CEST) by the Mercury Transfer Module’s monitoring camera 3, when the spacecraft was 11 780 km from the planet’s surface. Closest approach took place at 19:34 UT (21:34 CEST) on the night side of the planet at about 236 km altitude. The back of the Mercury Planetary Orbiter’s high-gain antenna and part of the spacecraft’s body is also visible in front of Mercury in this image.

Numerous fascinating geological features are identified on the surface of Mercury.

The dark spot near the top edge of Mercury marks Atget crater. Atget excavated ancient, dark material from deep within Mercury’s subsurface and deposited it on top of younger, brighter volcanic plains within the vast 1550-km-wide Caloris basin, the largest well-preserved impact basin on the planet. Scientists use such observations to understand the order in which different rock types formed during a planet’s evolution. This dark material might represent remnants of Mercury’s initial crust that was later buried underneath lava plains. Atget is named after the French photographer Eugène Atget (1857–1927).

By contrast, Xiao Zhao crater is centred on a bright, star-like pattern of impact ejecta more centrally within this image. These bright crater rays formed immediately after the impact as material was ejected from the crater, but fade into the background over time. This means Xiao Zhao is one of the most recent impact craters on Mercury. Xiao Zhao (active 1130–1162) was a Chinese painter.

At the bottom of Mercury’s globe, dawn is breaking over the eastern rim of the Rembrandt basin, seen here as a dark arc. After Caloris, Rembrandt is the second largest well-preserved impact basin on Mercury with a diameter of 716 km. This colossal impact created some linear scarps that radiate from the basin centre, some of which can be seen in these MCAM images. It is apt that a giant impact basin on Mercury is named after one of the giants of art history, the Dutch artist Rembrandt (1606–1669).

The cameras provide black-and-white snapshots in 1024 x 1024 pixel resolution. The image has been lightly processed to best bring out the details of the planet’s surface.

Some imaging artefacts such as horizontal striping are also visible.  In this view, north is to the upper left corner.

The gravity assist manoeuvre was the third at Mercury and the sixth of nine flybys overall. During its seven-year cruise to the smallest and innermost planet of the Solar System, BepiColombo makes one flyby at Earth, two at Venus and six at Mercury to help steer on course for Mercury orbit in 2025. The Mercury Transfer Module carries two science orbiters: ESA’s Mercury Planetary Orbiter and JAXA’s Mercury Magnetospheric Orbiter. They will operate from complementary orbits to study all aspects of mysterious Mercury from its core to surface processes, magnetic field and exosphere, to better understand the origin and evolution of a planet close to its parent star.

Click here for a non-annotated version of this image.

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