BepiColombo launches this weekend to unravel the mysteries of Mercury – and beyond

Mercury is a tiny greyish metal ball that is shrinking, an unpretentious neighbor that's easy to forget – but do not laugh at the possibility that the little world can rewrite our understanding of our solar system and those around us.

Scientists have not visited the most inland planet since 2015, but that will change with the launch of a mission this week: BepiColombo, a joint project of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). BepiColombo will be launched from Kourou, French Guiana, at 9.45pm. EDT 19 October (20:14 GMT) on an Ariane 5 rocket; you can watch the live launch on Space.com with the kind permission of ESA.

The long interval in the missions has not occurred because the planet is boring. "Mercury is a challenge in so many ways: get there, stay there, and then many outstanding issues need to be resolved," Zoe Joe Zender, deputy project manager at ESA for the BepiColombo mission told Zoe. . "It's kind of a mystery – maybe one of the last mysteries of Earth's planets." [Most Enduring Mysteries of Mercury]

The problem, you see, is that when scientists bring together what they know about the entire solar system and explain how it came about, Mercury continues to mess with them. It is the black sheep of the planetary family, with a host of strange features.

Take, for example, its incredible density, with its massive metal core surrounded by a thin rocky shell, like a planetary M & M. Ignore Mercury and the planets align perfectly, from the least dense in the center to the densest at the edge of the solar system. But this model leaves scientists wondering how such a dense planet could have formed so close to the sun. (An idea is that a giant impact stole most lighter materials, but it's still only a hypothesis.)

Scientists, therefore, want more information on mercury to be incorporated into their solar system training models, in the hope of finding an explanation that can even explain its strange traits.

But it is not just about our solar system, because our neighborhood also represents hundreds of other planetary systems identified by scientists over the past two decades. Early results suggest that these neighborhoods often host an exceptionally dense planet near their stars, just like Mercury, which makes the puzzle even more important to solve.

"We are discovering more and more solar systems every day," Nancy Chabot, scientist in planetary science at the Johns Hopkins University Applied Physics Laboratory, told Space Space, who worked on the company's latest mission. NASA in Mercury. "We will first look here, to understand how our own solar system has formed, to interpret all of this around us."

BepiColombo to the rescue

Fortunately for the perplexed scientists, BepiColombo will be uniquely placed to unveil some of Mercury's deepest secrets. "BepiColombo has the tools to thoroughly investigate everything from inside to exosphere," Slavin told Space.com. Slavin, who evoked the thin layer of gas surrounding the planet as an extremely humid atmosphere, studied magnetic fields at the University of Michigan and collaborated on research on one of BepiColombo's instruments. "It's going to be very exciting," said Slavin. I said. "This is the stage of global research where we finally get definitive answers to all the questions we have generated on [NASA’s] Mariner 10 [mission, which flew by the planet three times in the 1970s] and MESSENGER [(NASA’s Mercury Surface, Space Environment, Geochemistry and Ranging mission)]. "

BepiColombo, which cost nearly $ 2 billion, according to Spaceflight Now, is made up of two separate spacecraft, the European Mercury Orbit and the Japanese Magnetosphere Orbit, nicknamed Mio. The two were put together in an arrangement that measures 6 meters high for the seven-year trip to Mercury. once they arrive, they separate but continue to work in tandem for at least a year. [Photos of Mercury from NASA’s Messenger Spacecraft]

Having two spacecraft on the tiny planet will allow scientists to take unprecedented measurements of Mercury's magnetic field by keeping a spacecraft inside the bubble of this field and one outside of it. this. It is quite unusual for such a small planet with a seemingly solid core to possess a magnetic field, and being so close to the sun means that it is constantly bombarded by a large flow of charged particles. in the solar wind.

Here on Earth, the interaction of solar wind and magnetic field causes a spatial weather which, when it is particularly intense, can cause power outages. But our magnetic field is much stronger and the solar wind that reaches us is much weaker. "We can now study another case and an extreme case, with a strong solar wind and a weak magnetic field, in order to understand how it works," Go Murakami, scientific manager of the JAXA project for BepiColombo, told Space.com.

But this is only one aspect of BepiColombo's long list of tasks. Other instruments will study the planet itself, from its surface to its deepest. Geological questions BepiColombo should help scientists understand its past volcanic activity and why the planet, which is already very small, is shrinking. As part of his studies, he will build on the work of MESSENGER during the years 2010.

Take, for example, the small hollows that dot the surface of the planet. "They were one of the examples of why we are sending spaceships to places we've never been to before," Chabot said. "It was a whole new relief that was discovered when MESSENGER went into orbit."

The current idea is that the hollows are caused by the rock actively sublimating – jumping directly from the solid to the gas – on the surface, and that the process is still going on today. "It looks like a kind of volatile, something that was there and then exposed to the surface of Mercury, which is hot and close to the sun," said Chabot. "But it is very tense, because we are in this situation only since 2011."

And there is another more poignant way that BepiColombo can follow in the footsteps of MESSENGER: by photographing the crater probably about 16 meters wide created when the spaceship, ran out of fuel 11 years after its launch, hit the planet. Now, this abrupt end could be the beginning of a new science if scientists can have a good look at the rubble that the impact has brought to the surface. "We know exactly when that happened," said Chabot, which means that they can study how the rock has aged.

BepiColombo has only one problem: it will take seven years to the spacecraft to orbit Mercury. Along the way, the probe will fly over the Earth once, Venus twice and Mercury six times, in a complicated dance designed to avoid the sun's massive attraction.

"We still have a very long way ahead of us," said Zender, but we are all very excited to start this long journey now. "

Email Meghan Bartels at [email protected] or follow her. @meghanbartels. follow us @Spacedotcom and Facebook. Original article on Space.com.