BepiColombo’s first close-up images of Mercury suggest answers to the planet’s secrets


This article originally appeared on The conversation. The post contributed the article to’s Expert voices: Op-Ed & Insights.

David rothery, professor of planetary geosciences, The Open University

The BepiColombo spacecraft – a joint project of European and Japanese space agencies – tipped over to its destination planet Mercury in the early hours of Saturday, October 2. Passing just 200 kilometers from the surface of Mercury, it returned some spectacular images.

For those of us who have worked for a decade or more on this mission, there could not be a better way to celebrate what would have been the 101st birthday of the mission’s namesake, Italian mathematician and engineer Giuseppe Colombo . His revolutionary work in this field has earned him the title of grandfather of the technique of planetary flyover, now more often called “swing-by”.

BepiColombo’s cruise from Earth began in October 2018, and his journey is far from over. It will circle the sun twice in the time it takes for Mercury to circle the star three times (approximately 264 days). This will allow him to join the planet for another swing-by on June 23, 2022.

After a total of six passages of Mercury, the cumulative effect of the planet’s gravity will reduce the speed of the spacecraft to the point where it can orbit with Mercury towards the end of 2025.

Left: The location of the three MCAMs on the mercury transfer module, seen in an exploded view of the spacecraft’s stack. Right: Artist’s impression of the stacked spaceship. (Image credit: left: Micro-Cameras & Space Exploration SA. Right: spacecraft: ESA / ATG medialab; Mercury: Nasa / JPL)

BepiColombo is actually made up of two connected spacecraft and a propulsion unit. During its cruise in interplanetary space, the European orbiter (called the Mercury Planetary Orbiter or MPO) is attached on one side to the interplanetary propulsion unit (or Mercury Transfer Module). On the other, it carries a Japanese orbiter named Mio (or Mercury Magnetospheric Orbiter), as well as a sun visor to keep Mio from overheating.

This stacked configuration obstructs the openings through which sophisticated visible, infrared, and x-ray cameras inside MPO – capable of imaging and analyzing Mercury’s surface in detail – will operate once MPO finally becomes airborne. free. In fact, most of BepiColombo’s scientific instruments will be totally or partially inoperative until each orbiter is released, around December 2025.

Adding cameras

Until a relatively late stage in the planning of the mission, it was assumed that BepiColombo would “fly blind” throughout its cruise from Earth, including during empty passes, which means that no image is missing. would be available as long as the orbit around Mercury had not been reached.

But the level of public interest sparked in 2015 by the images of comet 67P from the Rosetta mission led BepiColombo engineers Kelly Geelen and James Windsor to suggest that lightweight, inexpensive cameras be added to the spacecraft.

At the end of 2016, it was agreed that three small surveillance cameras – each just 2.6 inches (6.5 centimeters) long – would be mounted on the craft. These would take planetary photos during the passages.

It was decided to place these cameras on the Mercury Transfer Module, where they could also monitor the deployment of the solar panels that power the spacecraft, the magnetometer pole used to measure magnetic fields, and communication antennas.

What Bepi saw

During the first passage of Mercury from BepiColombo, the fields of view of surveillance cameras two and three followed the planet. Camera three showed us part of the southern hemisphere, starting with a sunrise view over the Astrolabe Rupes – a striking feature of the name of a French Antarctic exploration vessel.

The Rupes astrolabe is a 250 km (155 mile) long “lobed scarp” – a long, curved structure marking the spot where part of the planet’s crust has been pushed onto neighboring terrain, due to the contraction of the entire planet as it slowly cooled.

There are much smaller equivalent features on the moon, but Mercury is the only nearby celestial body where lobed escarpments are known to occur on such a large scale.

The Rupes astrolabe captures the light of the rising sun, captured at a distance of 735 miles (1183 km). MPO’s transmitting antenna is brightly lit in the foreground, which contributes to a ghosting effect in the middle of the image. (Image credit: ESA / BepiColombo / MTM, CC BY-SA 3.0 IGO)

Four minutes later, the perspective had changed enough to reveal a larger area: including the lava-flooded Haydn Crater, 156 miles (251 km) wide, and Pampu Facula, one of the many bright spots likely formed. by explosive volcanic eruptions. These two characteristics are testimony to Mercury’s long volcanic history, at its peak over three billion years ago, but probably persisting until about a billion years ago.

The Rupes astrolabe is still visible in this image taken at 1,669 miles (2,687 km), allowing a larger area of ​​the planet’s surface to be seen. (Image credit:

Meanwhile, the second camera focused on the northern hemisphere of Mercury, including the region surrounding the Calvino crater: an important location for deciphering what lies in the layers of Mercury’s crust.

It also showed the Lermontov Crater: an area that looks brilliant as it harbors both volcanic deposits and “hollows,” where a currently unknown volatile ingredient in the crust is lost to space via a mysterious process.

At 1,502 miles (2,418 km), Mercury’s northern hemisphere is toward the lower left corner, and a sunlit magnetometer boom is in the foreground. (Image credit: ESA / BepiColombo / MTM, CC BY-SA 3.0 IGO)

NASA’s MESSENGER mission orbiting Mercury between 2011 and 2015, revealing a confusing planet. We still have a hard time understanding its composition, origin and history.

Why Mercury has features like explosive volcanoes and weird, unique hollows on its surface is just one of the issues we hope to solve. Once in orbit, BepiColombo’s advanced payload of scientific instruments will help us better understand how Mercury was formed and what it is made of.

Read more: The more we learn about Mercury, the stranger it seems

In the meantime, these extraordinary passing images at least remind us that we have a healthy spaceship heading to an exciting destination.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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