Mercury is the smallest and least explored planet in the inner Solar System - having only been examined by Nasa's 1974 Mariner probe and 2004 Messenger mission.
The mission is named after the Italian mathematician and engineer Giuseppe Colombo, who derived orbital trajectories to Mercury in the 1970s, and it is expected to last at least one year.
The European Space Agency and the Japanese Aerospace Exploration Agency have been working together to build two spacecrafts called "probes" that will measure the planet's environment at the same time.
To overcome this gravity, a mission meant to reach a stable orbit around the tiny planet of Mercury (with a gravity of just 3.7 m/s) therefore requires an enormous amount of energy-more than is required to send a probe to Pluto. Mercury's extreme temperatures, the intense gravity pull of the sun and blistering solar radiation make for hellish conditions.
Overall, the orbiters will investigate a number of important scientific questions, including how the planet Mercury formed in a stable orbit so close to the Sun.
Little is known about the history, surface or atmosphere of Mercury, which is notoriously hard to explore because of its proximity to the sun. The mission also hopes to study the solar wind, Mercury's inner structure, and how Mercury interacts with the area around the sun. "A collision with the proto-Earth or proto-Venus could be what robbed it of so much of its original rock".
Mercury's atmosphere is so thin that scientists have another name for it: an exosphere.
BepiColombo will be just the third mission to visit Mercury.
This image obtained from NASA shows the Goethe Basin in Mercury's North Pole. BepiColombo will take an even closer follow-up look with a range of instruments.
BepiColombo is made up of two different spacecraft with two very different jobs. Messenger then spent four years at Mercury from 2008. "By combining observations from both orbiters, we will also be in a position to perform what you might call stereoscopic measurements, something that was previously impossible". Obviously, it's going to be very hot, so BepiColombo is loaded with state-of-the-art high-temperature coatings, insulation, a radiator for the Mercury Planetary Orbiter, a special spinning technique for the Mercury Magnetospheric Orbiter and a sunshield for the cruise phase when it can't spin, all to avoid overheating.
The European Space Agency says the 1.3 billion-euro ($1.5 billion) mission is one of the most challenging in its history.
After launch, BepiColmbo must constantly brake, otherwise it will fly straight past the planet! Pacific Time on Friday (10:45 p.m. local time).