BepiColombo: Exploring Mercury (Pre-Orbital Insertion)

Illustration of BepiColombo spacecraft. Credit: ESA/ATG medialab

Launch Date: October 20, 2018

Launch Site: European space port at Kourou, French Guiana

Launch Vehicle: Ariane 5

Mission Type: Orbiter

Target: Mercury

Dimensions: 3.9 Meters by 3.6 Meters by 6.3 Meters (Combination)

Mass: 4100 (As a whole, including propellant)

BepiColombo is a multi-part spacecraft made in collaboration with ESA (European Space Agency) and JAXA (Japanese Aerospace Exploration Agency). BepiColombo is only the third mission to Mercury, after MESSENGER and Mariner 10.

The Mission

BepiColombo consists of three parts. The science orbiters are Japan's Mercury Magnetospheric Orbiter (MMO) and Europe's Mercury Planetary Orbiter (MPO). The part that does the heavy lifting is the Mercury Transport Module (MTM), which contains four ion engines, but no science equipment. These modules are stacked on top of eachother with MMO on top, MTM on the bottom, and MPO sandwiched in between.

*Note that the timeline is out of date due to launch delays of the spacecraft. Credit: NASA/John Hopkins University Applied Physics Labratory/Carnegie Institution of Washington and ESA/ATG medialab

Two years after BepiColombo launched, it made a flyby of Earth on April 10, 2020. This put the spacecraft on a trajectory to Venus, which it flew by on October 14, 2020. BepiColombo made another flyby of Venus on August 11, 2021. This flyby was just 33 hours after the joint ESA/NASA Solar Orbiter mission also made a flyby of the planet.

Credit: ESA

Later in the year, BepiColombo made its first flyby of Mercury on October 1, 2021. The spacecraft still had a lot of orbital energy to cancel out before it could stay in orbit around Mercury, and its made many more flybys of the planet since then, with the most recent being on June 19, 2023.

Credit: ESA/ATG

BepiColombo still has three more Mercury flybys on September 4, 2024, December 2, 2024, and January 9, 2025. Then it will finally enter orbit on December 5, 2025. After the two science spacecraft separate from the transfer module, science operations will begin. Japan's MMO spacecraft will focus on mapping Mercury's magnetosphere, while Europe's MPO will map the terrain of the planet, among other scientific observations.

The Target

Image of Mercury from NASA's MESSENGER spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie

• Date Discovered: Known To The Ancients
• Radius: 2439.7 Kilometres
• Mass: 3.301x10^23 Kilograms
• Density: 5.43 g/cm^3
• Rotational Period: 58.65 Days
• Orbital Period: 87.97 Days