A British-built spacecraft fitted with Star Trek-style “impulse engines” is on its way to Mercury, the planet closest to the sun.

BepiColombo blasted into space from the European space port at Kourou, French Guiana, at about 2.45am UK time on Saturday. It was carried on top of an Ariane 5, the European Space Agency’s (ESA’s) most powerful rocket.

After a tense countdown in French, the rocket rose slowly above a ball of orange flame and thundered into the sky before disappearing into cloud.

Experts say BepiColombo could not only shed light on the mysteries of our neighbourhood’s smallest planet, but also offer new insights into how the solar system formed and even provide vital clues as to whether planets found orbiting other stars – so-called exoplanets – could be habitable.

“If we want to understand our Earth and how life can [begin] on Earth and maybe on other planets, we have to understand our solar system,” said Joe Zender, the deputy project scientist for BepiColombo.

Much progress has been made in the matter, Zender said, but there is a snag. “There is one problem really, which is Mercury. Mercury doesn’t fit.”

Among the puzzles is the planet’s surprisingly high density and that it is thought to have a core that is at least partly molten. With some exoplanets orbiting very close to stars cooler than our own, finding out more about the first rock from our sun has become a pressing matter.

The BepiColombo mission is a €1.6bn (£1.4bn) joint venture between the European Space Agency (ESA) and the Japanese space agency, Jaxa.

The mission has a hefty price tag, but is arguably something of a bargain because BepiColombo involves not one orbiter but two. Once the spacecraft has been delivered into orbit around Mercury by the ESA-built Mercury transfer module, it will split to lose a protective sunshield and release the Mercury magnetospheric orbiter, built by Jaxa, and the Mercury planetary orbiter, built by ESA.

Mercury is only 58m km from the sun, but it has rarely been in the spotlight. Just wo previous missions have examined the planet’s properties – Nasa’s Mariner 10 probe, launched in 1973, and the more recent Messenger mission, which launched in 2004.

The latest endeavour takes its named from the late Giuseppe “Bepi” Colombo, a professor at the University of Padua who was a key figure in devising Mariner 10’s Mercury flybys.

ESA’s BepiColombo Mercury mission thrives on ambition and co-operation Read more

Both previous missions threw up intriguing results, including that Mercury has a magnetic field. This was a surprise given its leisurely pace of rotation – it takes 59 Earth days to spin on its axis – and the idea that because of its small size, the planet’s core would have cooled and become solid, precluding the existence of a magnetic field. Mercury’s magnetic field is also offset by 20% of the planet’s radius, meaning certain features at the south pole are different to those at the north.

Mercury was also found to have an exosphere, a very thin layer above the surface composed of atoms and molecules that have come from the crust and solar wind.

Before BepiColombo can examine such phenomena, however, it must negotiate two major hurdles.

“The heat is really severe, 450C on one side, but don’t forget the other side is -180C,” said Dr Suzanne Imber, of the University of Leicester, who is a co-investigator on MIXS – one of the Mercury Planetary Orbiter’s 11 instruments – and also worked on Messenger. Our spacecraft “is going from one to the other over a few tens of minutes … our instruments have to operate around room temperature.”

The Japanese orbiter will spin 15 times a minute to avoid being toasted, like a kebab on a barbecue, while the European orbiter will be wrapped in a special multi-layer blanket and have a radiator for protection.

Getting to Mercury is also a head-scratcher. “Mercury is a small body close to the sun, so you could fly straight towards Mercury and get there in a few months, but you can’t stop because the sun’s gravity sucks you in,” said Imber.

The answer is to arrive slowly via an elegant series of laps, with the spacecraft swinging by Earth, Venus and Mercury before entering an orbit in late 2025, then splitting and beginning operations in early 2026.

“We are passing once by the Earth, twice Venus and six times Mercury,” said Zender. “We are going so close to the individual planets that we can use their gravitational forces to change our direction for the next step.”

Artist’s impression of the BepiColombo spacecraft shortly after launch. Photograph: ESA/ATG medialab

The team also plan to examine features of Venus including its internal structure, its chemical composition and its interaction with solar radiation.

Once in orbit around Mercury, the instruments will set to work. An x-ray telescope, MIXS will help to shed light on the makeup of the planet.

“We are going to know in really incredible detail what the surface of Mercury is made of,” said Imber, adding that the team can probe deeper down, too. “When you form an impact crater what you find is that layers of material from under the surface are lifted by the impact and land on the surface,” she said.

Prof Nicolas Thomas, the co-project manager of the Bela instrument aboard the Mercury Planetary Orbiter, said he wanted to investigate the planet’s curious surface features.

“A planet will shrink as it cools and Mercury has cooled a lot. We think the planet has cooled in such a way that its radius has been reduced by 8km over its history,” he said. “There are huge great cliffs that we suspect have been created by this process where this shrinking has gone on but some bits have shrunk and other bits haven’t shrunk quite so much.”

It is a phenomenon Bela will help investigate. “What we do is that we take a seriously large, very scary powerful laser and we fire it up to about 1,000km away from the planet and then we wait for six to 10 milliseconds and we look at the reflected pulse,” said Thomas. By looking at the time it has taken for the light to return, the team can calculate the contours of the surface below, essentially mapping Mercury.

Flight into the furnace of Mercury could bring us closer in hunt for alien life Read more

The BepiColombo mission is expected to last for two years once the orbiters are in position, but the team say it might continue for longer. Once over, the orbiters will be crashed into the planet’s surface.

Prof Emma Bunce of the University of Leicester, who heads the MIXS instrument team, said after watching the launch: “I didn’t know what to expect but it was absolutely amazing, just spectacular, the way it lit up the whole sky and the way the sound eventually reaches you. Quite emotional really.

“You think about the instrument you’ve worked for so many years on sitting on top of that rocket and you hope it’s going to be OK.”</s>Arianespace marked another mission accomplished for science tonight as its heavy-lift Ariane 5 successfully sent BepiColombo – Europe’s historic first mission to Mercury, organized in cooperation with Japan – on its way toward the solar system’s smallest and least-explored terrestrial planet.

Ascending from the Spaceport’s ELA-3 launch complex at 10:45:28 p.m. local time in French Guiana – the planned precise moment of liftoff – Ariane 5 lofted its passenger during a flight lasting just under 27 minutes, with the multi-segment BepiColombo spacecraft deployed into an Earth escape orbit.

As the nearest planet to the Sun, exploring Mercury is key to acquiring knowledge of how terrestrial planets originate and evolve, as well as to understand how conditions supporting life arose in the solar system, and possibly elsewhere. Mercury also is known as the “Swift Planet” because its orbital period around the Sun of 87.97 days is the shortest of all the planets in the solar system.

The BepiColombo mission is being carried out jointly by the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). After arriving in late 2025, the spacecraft – built under the industrial leadership of Airbus – will examine the peculiarities of Mercury’s internal structure and magnetic field generation, as well as how the planet interacts with the sun and solar wind.

With a liftoff mass calculated at 4,081 kg., BepiColombo consists of two orbiters: the Mercury Magnetospheric Orbiter (MMO) and the Mercury Planetary Orbiter (MPO); as well as two additional elements: the Mercury Transfer Module (MTM), and the Magnetospheric Orbiter Sunshield and Interface Structure (MOSIF).

BepiColombo is scheduled for a one-year nominal mission at Mercury, with the possibility for a one-year extension. It was named after Italian mathematician and engineer Giuseppe “Bepi” Colombo, who was known for his work related to Mercury.

In post-launch comments from the Spaceport, Arianespace Chief Executive Officer Stéphane Israël congratulated both ESA and JAXA – and underscored his company’s continuing contributions to space research and science at the service of such institutions.

“Today’s new success marks the beginning of a seven-year trip for BepiColombo, taking advantage of gravitational assistance from Earth, Venus, and Mercury,” said Israël. “Arianespace is very proud to have contributed to this new major scientific quest!”

He added that Arianespace’s latest Ariane 5 launch was special because of its Earth escape flight profile, and “would not have been possible without our European launchers ‘dream team!’ It showed the versatility of Ariane 5, so let me doubly congratulate all of the partners for this new success.”

The Ariane 5 launch – designated Flight VA245 – was the 23rd major scientific mission performed by an Arianespace family vehicle to date, following deployments of such high-profile passengers as Rosetta, the Mars Express and Venus Express space probes, Gaia, Herschel, Planck and Aeolus. It also underscores Arianespace’s primary objective to guarantee Europe’s independent and reliable access to space.

“We are standing on the shoulders of giants, and the giants are all of you!” said Guenther Hasinger, the ESA Director of Science, in acknowledging the participants in BepiColombo’s development, its launch and the scientific mission to follow. He also thanked Arianespace for Ariane 5’s exact on-time liftoff and the spacecraft’s accurate deployment.

JAXA Senior Vice President Shizuo Yamamoto highlighted the excellent cooperation at the Spaceport launch site of Arianespace, ESA, the CNES French agency and the industrial teams that contributed to sending BepiColombo on its way to Mercury.

BepiColombo is the 51st mission (and 73rd spacecraft) launched by Arianespace for ESA. It also is the 121st Airbus-produced spacecraft lofted by Arianespace, which has a backlog of 22 additional satellites to orbit for this manufacturer on future flights.

As Arianespace’s seventh launch in 2018, Flight VA245 follows other heavy-lift Ariane 5 missions performed this year on January 25 (carrying SES-14 and Al Yah 3), April 5 (DSN-1/Superbird-8 and HYLAS 4), July 25 (four Galileo satellites) and September 25 (Horizons 3e and Azerspace-2/Intelsat 38).

Also conducted earlier in 2018 was Arianespace’s medium-lift Soyuz mission on March 9 (with four O3b satellites); plus a light-lift Vega flight performed August 22 (Aeolus).

At the completion of tonight’s mission, Arianespace’s Stéphane Israël announced early November as the timing for the company’s next flight, which will utilize a Soyuz launcher to orbit Europe’s Metop-C polar-orbiting meteorological satellite for the EUMETSAT satellite agency.</s>This is the first European mission to the solar system's innermost planet, and the first expedition to leave for Mercury in 14 years.

For the first time in more than 14 years, a spacecraft is headed toward Mercury — the smallest and innermost planet of our solar system. Known as BepiColombo, the spacecraft’s mission is to unravel the secrets of this enigmatic planet and to find out all that it can about Mercury’s atmosphere, magnetic field, and geology.

As the Inquisitr previously reported, the BepiColombo mission represents a collaboration between the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) — with both space agencies sending in their own probe to investigate the planet closest to the sun.

“BepiColombo is the first European mission to Mercury, the smallest and least explored planet in the inner solar system. It is the first Mercury mission to send two science orbiters to make complementary measurements of the planet’s dynamic environment at the same time,” explained ESA officials.

While ESA will be deploying the Mercury Planetary Orbiter (MPO), JAXA is providing the Mercury Magnetospheric Orbiter (MMO) — which this summer was given the name “Mio,” which translates as “waterway” or “fairway.”

“It is a fitting name denoting how far the MMO mission has come, navigating its course past important research and development milestones. It also carries the connotation of wishing the spacecraft a safe journey,” JAXA announced in June.

The two orbiters will be packed inside a transport module that launches tonight from Guiana Space Center in Kourou, French Guiana.

“The joint ESA and JAXA BepiColombo mission is ready for liftoff at the start of a journey to discover more about planetary oddball Mercury,” ESA tweeted earlier today.

The module will blast off into space atop an Arianespace Ariane 5 rocket, which is scheduled to soar to the skies at 9:45 p.m. EDT, notes Space. The BepiColombo module is slated to be deployed about 26 minutes after launch, and is expected to get in touch with mission control soon after that.

To watch the spacecraft fly off to Mercury, tune in to the ESA website and follow the live coverage starting from 9:15 p.m. EDT.

“Walk with us to the launchpad!” the mission’s team tweeted a few hours ago.

Should anything arise to hinder tonight’s launch, liftoff will be pushed back by 24 hours. The mission has a very wide launch window, which lasts until November 29.

The spacecraft will be spending the next seven years flying in the direction of the sun — similar to NASA’s Parker Solar Probe. Just like the U.S. probe, BepiColombo will also swing by Venus for gravity-assist maneuvers — and venture as close as possible to Mercury.

“On its 7.2 year journey to the innermost planet, BepiColombo will fly by Earth once, Venus twice and Mercury six times before entering into orbit,” ESA officials detailed in a news release.

According to The Conversation, the BepiColombo spacecraft is named in memory of Giuseppe (Bepi) Colombo, an Italian mathematician and engineer who first proposed gravity-assist flybys for spacecraft.

This is only the third spacecraft to journey to Mercury, after NASA’s Messenger and Mariner 10 missions set out to map the planet in August 2004 and in November 1973, respectively.

While Messenger orbited Mercury between 2011 and 2015, Mariner 10 performed three flybys of the planet in 1974 and 1975 — and was the first to discover the planet’s thin atmosphere and magnetic field.</s>In this photo provided by European Space Agency (ESA), The Ariane 5 rocket carrying BepiColombo lifts off from its launch pad at Kourou in French Guiana, for the mission to Mercury, Saturday, Oct. 20, 2018. (ESA via AP)

TOKYO (AP) — European and Japanese space agencies said an Ariane 5 rocket successfully lifted a spacecraft carrying two probes into orbit Saturday for a joint mission to Mercury, the closest planet to the sun.

The European Space Agency and the Japan Aerospace Exploration Agency said the unmanned BepiColombo spacecraft successfully separated and was sent into orbit from French Guiana as planned to begin a seven-year journey to Mercury.

They said the spacecraft, named after Italian scientist Giuseppe "Bepi" Colombo, was in the right orbit and has sent the first signal after the liftoff.

ESA says the 1.3 billion-euro ($1.5 billion) mission is one of the most challenging in its history. Mercury's extreme temperatures, the intense gravity pull of the sun and blistering solar radiation make for hellish conditions.

The BepiColombo spacecraft will have to follow an elliptical path that involves a fly-by of Earth, two of Venus and six of Mercury itself so it can slow down before arriving at its destination in December 2025.

When it arrives, BepiColombo will release two probes — Bepi and Mio — that will independently investigate the surface and magnetic field of Mercury. The probes are designed to cope with temperatures varying from 430 degrees Celsius (806 F) on the side facing the sun, and -180 degrees Celsius (-292 F) in Mercury's shadow.

Scientists hope to build on the insights gained by NASA's Messenger probe, which ended its mission in 2015 after a four-year orbit of Mercury. The only other spacecraft to visit Mercury was NASA's Mariner 10 that flew past the planet in the mid-1970s.

Mercury, which is only slightly larger than Earth's moon, has a massive iron core about which little is known. Researchers are also hoping to learn more about the formation of the solar system from the data gathered by the BepiColombo mission.

It is the second recent cooperation between the Europeans and the Japan Aerospace Exploration Agency. JAXA's Hayabusa2 probe dropped a German-French rover on the asteroid Ryugu earlier this month.</s>Final preparations were underway on Friday for the launch of a joint mission by European and Japanese space agencies to send twin probes to Mercury, the closest planet to the sun.

An Ariane 5 rocket is scheduled to lift the unmanned spacecraft into orbit from French Guiana shortly before midnight, the start of a seven-year journey to the solar system’s innermost planet.

The European Space Agency says the 1.3 billion (US$1.5 billion) mission is one of the most challenging in its history. Mercury’s extreme temperatures, the intense gravity pull of the sun and blistering solar radiation make for hellish conditions.

The BepiColombo spacecraft will have to follow an elliptical path that involves a fly-by of Earth, two of Venus and six of Mercury itself so it can slow down sufficiently before arriving at its destination in December 2025.

Newly developed electrical ion thrusters will help nudge the spacecraft, which was named after Italian scientist Giuseppe “Bepi” Colombo, into the right orbit.

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When it arrives, BepiColombo will release two probes – Bepi and Mio – that will independently investigate the surface and magnetic field of Mercury. The probes are designed to cope with temperatures varying from 430 degrees Celsius (806F) on the side facing the sun, and -180 degrees Celsius (-292F) in Mercury’s shadow.

Scientists hope to build on the insights gained by Nasa’s Messenger probe, which ended its mission in 2015 after a four-year orbit of Mercury. The only other spacecraft to visit Mercury was Nasa’s Mariner 10 that flew past the planet in the mid-1970s.

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Mercury, which is only slightly larger than Earth’s moon, has a massive iron core about which little is known. Researchers are also hoping to learn more about the formation of the solar system from the data gathered by the BepiColombo mission.

It is the second recent cooperation between the Europeans and the Japan Aerospace Exploration Agency. JAXA’s Hayabusa2 probe dropped a German-French rover on the asteroid Ryugu earlier this month.</s>European and Japanese space agencies said an Ariane 5 rocket successfully lifted a spacecraft carrying two probes into orbit Saturday for a joint mission to Mercury, the closest planet to the sun.The European Space Agency and the Japan Aerospace Exploration Agency said the unmanned BepiColombo spacecraft successfully separated and was sent into orbit from French Guiana as planned to begin a seven-year journey to Mercury.They said the spacecraft, named after Italian scientist Giuseppe "Bepi" Colombo, was in the right orbit and has sent the first signal after the liftoff.ESA says the 1.3 billion-euro (USD 1.5 billion) mission is one of the most challenging in its history.Mercury's extreme temperatures, the intense gravity pull of the sun and blistering solar radiation make for hellish conditions.The BepiColombo spacecraft will have to follow an elliptical path that involves a fly-by of Earth, two of Venus and six of Mercury itself so it can slow down before arriving at its destination in December 2025.When it arrives, BepiColombo will release two probes — Bepi and Mio — that will independently investigate the surface and magnetic field of Mercury.The probes are designed to cope with temperatures varying from 430 degrees Celsius (806 F) on the side facing the sun, and -180 degrees Celsius (-292 F) in Mercury's shadow.The ESA-developed Bepi will operate in Mercury's inner orbit, and JAXA's Mio will be in the outer orbit to gather data that would reveal the internal structure of the planet, its surface and geological evolution.Scientists hope to build on the insights gained by NASA 's Messenger probe, which ended its mission in 2015 after a four-year orbit of Mercury. The only other spacecraft to visit Mercury was NASA's Mariner 10 that flew past the planet in the mid-1970s.Mercury, which is only slightly larger than Earth's moon, has a massive iron core about which little is known. Researchers are also hoping to learn more about the formation of the solar system from the data gathered by the BepiColombo mission."Beyond completing the challenging journey, this mission will return a huge bounty of science," said Jan Wörner, ESA Director General, in a statement.JAXA President Hiroshi Yamakawa, who earlier managed the project, said, "We have high expectations that the ensuing detailed observations of Mercury will help us better understand the environment of the planet, and ultimately, the origin of the Solar System including that of Earth."It is the second recent cooperation between the Europeans and the Japan Aerospace Exploration Agency. JAXA's Hayabusa2 probe dropped a German-French rover on the asteroid Ryugu earlier this month.</s>Kourou, French Guiana, Oct 20 (EFE).- BepiColombo, the first European space mission to Mercury, successfully took off from the European spaceport in Kourou Saturday, enroute to the smallest planet of our solar system, which is also closest to the Sun, in an attempt to decipher its many unknowns.



The Ariane 5 rocket took the transfer module and the two scientific orbiters, the Planet Orbiter, developed by the European Space Agency (ESA) and the Mercury Magnetospheric Orbiter by its Japanese counterpart, JAXA, with whom the mission is jointly launched, left the Kourou space centre in French Guiana at 01.45 GMT on Saturday (22.45 local time on Friday).</s>TOKYO: A European-Japanese spacecraft set off on a treacherous seven-year journey to Mercury to probe the solar system's smallest and least-explored planet.

The BepiColombo mission, only the third ever to visit Mercury, blasted off from Europe's spaceport in French Guiana aboard an Ariane 5 rocket at 10:45 p.m. local time on Friday (0145 GMT on Saturday), according to the Japan Aerospace Exploration Agency (JAXA).

"Launching BepiColombo is a huge milestone for ESA (the European Space Agency) and JAXA, and there will be many great successes to come," ESA Director General Jan Woerner said in a statement.

"Beyond completing the challenging journey, this mission will return a huge bounty of science."

Few spacecraft have visited Mercury because of the planet's proximity to the sun - less than 60 million kilometres (37.3 million miles) away compared with almost Earth's 150 million kilometres - which makes any trip there challenging.

Surface temperatures on the planet can reach highs of over 400 Celsius (752F) during the day and drop to minus 170C (minus 338F) at night.

NASA's Mariner 10 probe, launched to Mercury in 1973, mapped around 45 percent of the planet's surface, and its MESSENGER mission took off over three decades later in 2004 to complete the survey.

BepiColombo, named after 20th century Italian mathematician and Engineer Giuseppe (Bepi) Colombo, will slingshot off the Earth's gravitational field one-and-a-half years after launch before picking up speed on its journey. It will fly past Venus twice and then fly by Mercury six times before slipping into its orbit around December 2025.

At that point, it will release two separate spacecraft it is carrying, ESA's Mercury Planetary Orbiter (MPO) and JAXA's Mercury Magnetospheric Orbiter (MMO).

MPO will then study Mercury's surface and internal composition, to determine the planet's iron content and examine why its core is partially liquid.

JAXA's Mercury Magnetospheric Orbiter (MMO) will collect data on the planet's magnetosphere.

Both orbiters will study the planet for one year, with scope for possible one-year extension.</s>BERLIN (AP) — Final preparations were underway Friday for the launch of a joint mission by European and Japanese space agencies to send twin probes to Mercury, the closest planet to the Sun.

An Ariane 5 rocket is scheduled to lift the BepiColombo spacecraft into orbit from French Guiana late Friday, after which it will begin its seven-year journey to the solar system's innermost planet.

The European Space Agency says the 1.3 billion-euro ($1.5 billion) BepiColombo mission is one of the most challenging in its history. Mercury's extreme temperatures, the intense gravity pull of the Sun and blistering solar radiation make for hellish conditions.

The spacecraft will have to follow an elliptical path that involves a fly-by of Earth, two of Venus and six of Mercury itself so it can slow down sufficiently before arriving at its destination in December 2025.

Newly developed electrical ion thrusters will help nudge the spacecraft, which is named after Italian scientist Giuseppe 'Bepi' Colombo, into the right orbit.

When it arrives, BepiColombo will release two probes — Bepi and Mio — that will independently investigate the surface and magnetic field of Mercury. The probes are equipped with special insulation to cope with temperatures varying from 430 degrees Celsius (806 Fahrenheit) on the side facing the Sun, and -180 degrees Celsius (-292 Fahrenheit) in Mercury's shadow.

Scientists hope to build on the insights gained by NASA's Messenger probe, which ended its mission in 2015 after a four-year orbit of Mercury. The first spacecraft to visit Mercury was NASA's Mariner 10 that flew past the planet in the mid-1970s.

Mercury, which is only slightly larger than Earth's moon, has a massive iron core about which little is known. Researchers are also hoping to learn more about the formation of the solar system from the data gathered by the BepiColombo mission.

It is the second recent cooperation between the Europeans and the Japan Aerospace Exploration Agency.

JAXA's Hayabusa2 probe dropped a German-French rover on the asteroid Ryugu earlier this month.

Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.</s>The BepiColumbo spacecraft, a joint European-Japanese mission to Mercury, rocketed away from Earth to begin its seven-year trek to the innermost planet.

The BepiColombo spacecraft launched October 19th, at 9:45:28 p.m. EDT, atop an Ariane 5 rocket from an equatorial launch site in Kourou, French Guiana, beginning a seven-year journey to Mercury. The voyage began perfectly, atop towering pillars of flame that lit up the early morning sky and remained visible until the side boosters burned out 2 minutes later, leaving the steady light of the main rocket stage visible as a greenish point in the sky.

BepiColombo’s journey will return it to Earth, past Venus twice, and take it by Mercury six times before finally settling in to orbit on December 5th, 2025. The mission is a combined effort of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA).

Getting to Mercury is difficult — so difficult that fewer spacecraft have visited Mercury than have visited Saturn. NASA has sent two spacecraft: Mariner 10, which completed three flybys (all over the same hemisphere) in 1974 and 1975, and Messenger, which accomplished its orbital mission from 2011 to 2015.

Messenger was one of NASA’s low-cost Discovery missions. It accomplished a lot with its diminutive payload, producing a global photo map as well as more detailed maps of topography and composition in the northern hemisphere. (The spacecraft’s elliptical orbit took it too far from the southern hemisphere for detailed mapping.) Messenger made discoveries about Mercury’s magnetic field and the tenuous cloud of atoms that fly in space around the planet, confirmed the presence of ice at the poles, and identified places with relatively recent geologic activity. But it left us with more new questions than it answered old ones — as any good survey mission should do.

How can the terrestrial planet with the biggest iron core have so little iron in its crust? Why is its core so big? How can its crust have so much sulfur when it’s the closest planet to the Sun? Why is its magnetic field shifted to the north of the planet’s center? Why do some of Mercury’s craters have dark rays, and others bright? What process formed the bizarre Swiss-cheese features called “hollows”?

Two Spacecraft in One

BepiColombo will bring flagship-class science to Mercury to answer questions both old and new. It comprises two science spacecraft. One, the Mercury Planetary Orbiter (MPO), was built by ESA and will operate in a nearly circular orbit close to the planet. The other, Mercury Magnetospheric Orbiter (MMO), was built by JAXA and will fly in a much more elliptical orbit, far from the planet. The two will always be in the same orbit plane, making it easy to do simultaneous observations of the behavior of the magnetic field and particles in different locations near Mercury.

BepiColombo’s science package recapitulates Messenger’s but with sharper and broader vision and the advantage of two spacecraft. Both probes carry magnetometers, to study how Mercury’s internally generated magnetic field responds to buffeting from the active Sun. Both carry instruments to study the planet’s exosphere — the neutral atoms and ions knocked off Mercury’s surface by incoming radiation. MMO also has a dust counter, something Messenger didn’t have.

MPO has cameras and spectrometers to take photos and compositional measurements of the surface. From its nearly circular orbit, MPO will get much closer to Mercury’s surface and obtain much sharper images than Messenger could, placing its observations in context with the benefit of Messenger’s map. MPO will try to understand the composition of Mercury’s crust and the nature of its volcanic activity, and will search for evidence of the timing of Mercury’s shrinking along near-surface faults. Messenger hinted at small-scale faults on which shrinking could be occurring today; MPO will try to determine if the innermost planet is still active. Scientists are particularly interested in seeing Mercury’s south pole up close and in detail for the first time, to find out whether it has reservoirs of ices and organic-rich materials, as the north pole does.

It’s not easy to get to Mercury. A spacecraft has to shed a huge quantity of angular momentum to get close to the Sun and settle into orbit around the small planet. BepiColombo will be getting a ride from a third spacecraft built by ESA, the Mercury Transfer Module (MTM). MTM will use solar-electric propulsion, its huge solar panels powering ion thrusters that will continuously fire for most of the journey. Shortly before arriving at Mercury, BepiColombo will drop the MTM, thus avoiding the requirement of slowing down into Mercury orbit with all that extra mass.

BepiColombo has a long way to go, but it’s accomplished the most dangerous part of its mission — the launch. Mercury Orbit Insertion in December 2025 should be a piece of cake by comparison. By the time the spacecraft completes its sixth flyby of Mercury in January of that year, it will be traveling slow enough to be captured naturally, by Mercury’s own gravity, the seventh time the planet and spacecraft meet.

Until then, enjoy this replay of the launch (which starts 38 minutes into the clip)!
Arianespace launches the European Space Agency–Japan Aerospace Exploration Agency probe BepiColombo from Guiana Space Centre as it begins a 7-year journey to Mercury. It is the final mission of the Horizon 2000+ program.