Say hello to Mercury, that pesky rock that always seems to be in retrograde ruining your life.
A spacecraft operated by the European Space Agency and Japan made its final fly-by over the planet’s barren, pockmarked surface yesterday.
This is the third time a spacecraft has visited Mercury in the history of space exploration.
BepiColombo’s three monitoring cameras snapped detailed black-and-white photographs as it drifted just 295km above the innermost planet.
‘The first thing that strikes you is the incredible clarity of the images, which is particularly impressive when you consider that the monitoring cameras that took them have to withstand such extreme temperatures,’ Caroline Harper, the head of space science at the UK Space Agency, told Metro.
‘Mercury can reach 430°C during the day, which is hot enough to melt metal, but at nighttime, it can drop to around -180°C, much lower than the Poles here on Earth.’
The images, taken around 6am (UK time, not Mercury time, by the way), show a row of craters near the north pole.
Mercury’s ancient volcanoes – which might still be slightly active today – can be seen. The wrinkly surface of the plains, called Borealis Plantia, formed billions of years ago after the lava solidified.
‘The volume of lava making up Borealis Planitia is similar in scale to mass extinction-level volcanic events recorded in Earth’s history, notably the mass extinction event at the end of the Permian period 252,000,000 years ago,’ European space officials said today.
The region is far quieter – and colder – these days. The Prokofiev, Kandinsky, Tolkien and Gordimer craters never see the sun so are among the coolest parts of the solar system.
Harper said there could be something pretty neat tucked inside the craters.
‘The exciting thing here is that we think these craters could contain water ice,’ she said, ‘and that’s something BepiColombo will investigate further.’
BepiColombo also captured images of Caloris, a 1,500km diameter basin that is the scar left from what is estimated to have been a 100km diameter object smashing into the planet.
The probe took the images by gliding over the planet’s ‘terminator’ – the boundary between the sides of the planet that are either in permanent day and nighttime.
‘This mission is important because Mercury hasn’t been studied much up to now,’ Harper said.
‘Studying Mercury can tell us more about how our solar system evolved, and about how exoplanets orbiting other stars form.’
How Mercury wound up being so cracked, crinkled and jumbled is still unclear. By studying its composition, geology and magnetic field, scientists hope to find an answer, Harper said.
The planet, however, is tethered to the sun, rising and setting with the star from our perspective on Earth. So whether it be the naked eye or powerful astronomical observatories, getting a good look at Mercury comes with the risk of looking directly at the blinding sun.
Landing anything on it is out of the question – its surface is hot enough to melt lead.
Getting to a place like Mercury is a lot like running down a steep hill – it’s tough slowing down near the bottom.
‘Bepi has had to conduct multiple gravity assist manoeuvres, or planetary flybys, which use the gravity of Mercury itself and other planets to brake and steer the spacecraft, and to slow it down enough to be able to drop into orbit around Mercury without shooting straight past,’ Harper said.
She added: ‘The challenges of building a spacecraft that can work in such a hostile environment mean that a lot of it had to be developed from scratch, so there was a lot of specialised technology innovation needed here on Earth, some of which was led in the UK.’
BepiColombo, which first took off in 2018, uses British-made electric propulsion.
As solar panels soak up some rays, the system makes charged particles called ions from xenon, a rare gas used to create plasma beams and powerful lights. BepiColombo blasts these ions from its backside to propel it forward.
This was a mission decades in the making, first proposed as early as 1993. It did a flyby last month, giving astronomers their first clear view of Mercury’s south pole.
With its job done, Bepi will spend two years cruising around the sun before getting roped into Mercury’s orbit by 2026. The craft will then split in two and, from 2027, gather more data about the mysterious planet for the following year.
‘These flyby images are an indication of the quality of data we can expect from Bepi,’ said Harper, ‘and we’re really looking forward to seeing what this highly innovative mission can do when it gets into orbit next year.’
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