Despite being closest to the Sun, Mercury is the most ignored terrestrial planet in the solar system. It's had to sit back and watch while Earth, Mars and even Venus get all the attention. At night, if you listen closely, you can hear Mercury screaming into the dark void of space, begging for love.
Thankfully, someone's listening — the thirsty planet will be getting a pair of visitors very soon. Next year, the European Space Agency (ESA) and Japan Aerospace Exploration Agency (JAXA) will send two spacecraft — the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO) — to scope out the rocky planet in a joint endeavour called BepiColombo. While we've known about the mission for some time, last week, the BepiColombo stack successfully completed its final test for launch configuration. It's one step closer to takeoff, which is scheduled for October 2018.
It will take a minute to get to Mercury, of course — the spacecraft won't arrive until late 2025. BepiColombo will use gravity assists from Earth, Venus and Mercury, as well as thrust from solar-electric propulsion, to reach the planet. Once there, the pair will separate and spend about a year in separate orbits, measuring Mercury's "interior, surface, exosphere and magnetosphere", telling us more about the evolution of the planet and the solar system at large, according to the ESA. If all goes well, there's a possibility the both missions could be extended another year.
The last time Mercury had company was NASA's MESSENGER mission, which culminated in 2015 after it spent four years orbiting and investigating the planet. Before that, Mercury's only friend was NASA's Mariner 10, which whizzed by the planet three times in 1973. Some salient mysteries remain — for example, how frequently does the planet have Mercury-quakes? What else could we learn about the planet's geological history from its enormous cliffs and chasms?
At the very least, BepiColombo will provide much-needed company to much-overlooked Mercury. It's OK, little guy, we can't all be Saturn.