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, October 19 (0145 GMT on Saturday), according to the Japan Aerospace Exploration Agency (JAXA).
Few spacecraft have visited Mercury because of the planet's proximity to the sun—less than 60 million kilometers (37.3 million miles) away compared with Earth's almost 150 million kilometers (93 million miles)—which makes any trip there challenging. Surface temperatures on the planet can reach highs of over 400℃ (750℉) during the day and drop to -170℃ (-275℉) at night.
BepiColombo will reach its orbit of Mercury 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 study Mercury's surface and internal composition, to determine the planet's iron content and examine why its core is partially liquid. MMO will collect data on the planet's magnetosphere and its interactions with the sun.