Among other things, we get a picture of Mercury’s largest crater, which will be extensively studied by the space probe in a few years’ time.

Space probe BepiColombo has been on its way to Mercury since October 2018. To get the probe into orbit, however, it takes a total of no less than nine flybys: one over Earth, two over Venus and six over Mercury. BepiColombo has already completed four of these ‘gravity pendulums’. And now the mission team can mark another important milestone. Because the second flyby past Mercury is also a fact.

shaving flight

BepiColombo made the closest approach to the innermost planet of our solar system at 11:44 AM on Thursday afternoon. For example, the probe passed a distance of only 200 kilometers above the surface. Shortly afterwards, BepiColombo managed to shoot some photos using one of the three surveillance cameras (which can only take black and white photos, with a resolution of 1024×1024 pixels). And these images – taken at a height of 800 kilometers – are particularly beautiful.

photos

The relevant images can be seen below. At the time of the photo, BepiColombo was moving from the night side to the day side of Mercury, allowing the sun to beautifully illuminate the crater-strewn surface. “I was blown away when the first images trickled in,” said team member Jack Wright. “And then I just got more excited. The images show beautiful details of Mercury, including one of my favorite craters: Heaney.”

In this photo, some of Mercury’s craters – including Heaney crater – are clearly visible. Image: ESA/BepiColombo/MTM, CC BY-SA 3.0 IGO

Heaney is a 125 kilometer wide crater, which is a reminder of Mercury’s former volcanic activity. Researchers are very interested in this volcanic crater. When BepiColombo actually starts with its scientific observations in a few years, Heaney will be studied in detail. The images now produced are therefore only a foretaste of what awaits us in the future, when BepiColombo will conjure up its high-resolution camera and can look at Mercury even better with the help of advanced instruments.

caloris planitia

A few minutes after BepiColombo’s closest approach, the probe also immortalized the 1550 kilometer wide Caloris Planitia; Mercury’s largest crater. The reflective lava in the photo stands out against the dark background. ESA will also take a closer look at this crater. What researchers don’t yet fully understand, for example, is how the volcanic lava in and around Caloris Planitia is much younger than the crater itself. By taking measurements, astronomers hope to learn more about the formation and composition of the crater.

This photo shows off Mercury’s largest crater: Caloris Planitia. Another interesting research goal of the ESA. Image: ESA/BepiColombo/MTM, CC BY-SA 3.0 IGO

The mission team is more than satisfied with the images. “The photos taken during the first flyby of Mercury were good, but these are even better,” said David Rothery of ESA. “The images show many of BepiColombo’s future scientific goals. I really want to understand the volcanic and tectonic history of this amazing planet.”

build on

BepiColombo will build on the data collected by NASA’s Messenger mission, which orbited Mercury between 2011 and 2015. The mission consists of two orbiters: the Mercury Planetary Orbiter (of the European Space Agency) and the Mercury Magnetospheric Orbiter (from the Japanese space agency). Once BepiColombo has entered Mercury orbit, the probe will release both orbiters. Subsequently, these orbiters will study all aspects of the still mysterious inner planet of our solar system: from its core to surface processes, magnetic field and exosphere. And that will hopefully reveal important information about the origin and evolution of the planet that orbits closest to our parent star.

But we are not there yet. First, BepiColombo will have to complete a few close flights. “We now have the second of a total of six flybys behind us,” says team member Emanuela Bordoni. “We’ll be back around the same time next year for our third gravitational pendulum.” So it will be some time before BepiColombo settles into orbit around Mercury; that won’t happen until 2025. Then the exciting mission will really start at the beginning of 2026.