TRACKER GUIDE & MISSION EXPLAINER
BepiColombo Tracker: Journey to Mercury and Mission Architecture
BepiColombo is a joint ESA-JAXA mission designed to study Mercury with two scientific orbiters. The tracker above uses JPL Horizons ephemerides to show the cruise and arrival trajectory, current distance, light time and Sun-centred vector.
The mission launched on October 20, 2018 aboard an Ariane 5. Reaching Mercury is difficult because a spacecraft must lose substantial orbital energy while avoiding excessive heat. BepiColombo combined solar-electric propulsion with flybys of Earth, Venus and Mercury.
Three spacecraft travelling together
During cruise, ESA's Mercury Planetary Orbiter and JAXA's Mercury Magnetospheric Orbiter, Mio, travel with the Mercury Transfer Module. Near Mercury, the stack separates and the two science orbiters enter complementary polar orbits.
MPO will investigate Mercury's surface, composition, interior and surrounding environment. Mio concentrates on the planet's magnetic field and magnetosphere. Together they can distinguish spatial changes from time-dependent variations more effectively than one spacecraft.
How the tracker should be read
Horizons provides position and velocity vectors for the mission identifier. SpaceTracker.live samples and interpolates those ephemerides. During gravity assists and arrival operations, the true mission geometry is complex; the compressed scene is only a guide.
A change in Earth distance can be caused by both the spacecraft path and Earth's own motion. Sun distance is especially important near Mercury because solar radiation and thermal design shape operations.
Educational questions
- Why is slowing down toward Mercury harder than simply falling toward the Sun?
- How do gravity assists change velocity without consuming equivalent propellant?
- Why are two orbiters better for studying a changing magnetosphere?
- How does solar-electric propulsion differ from a short chemical-engine burn?
- Why must the visual compress interplanetary distances?
Accuracy and status
ESA listed Mercury arrival activities for late 2026 with a sequence of manoeuvres continuing into 2027. Mission schedules can be updated, so official ESA pages should be used for operational milestones. The tracker is limited to ephemeris position and does not report spacecraft health or separation events.
Mercury as an engineering destination
Mercury combines intense sunlight with long cold nights, a weak magnetic field and an orbit deep inside the Sun's gravity well. BepiColombo must manage thermal exposure during cruise and science operations while carrying two observatories with different goals. The tracker gives a geometric context for that engineering problem: Sun distance affects heating and power, Earth distance affects communications, and arrival velocity determines how difficult capture will be. Following these quantities through the approach is more informative than treating the mission as a straight line from Earth to Mercury.
Frequently asked questions
Why does BepiColombo need so many flybys?
Mercury is deep in the Sun's gravity well. Flybys and electric propulsion remove orbital energy gradually and manage arrival speed.
Is BepiColombo one spacecraft?
The cruise stack contains a transfer module and two science orbiters that will separate for Mercury operations.
What will the two orbiters study?
MPO focuses on the planet and its environment; JAXA's Mio focuses strongly on the magnetosphere and solar-wind interaction.
Does this tracker show official arrival manoeuvres?
No. It displays ephemeris-derived position. Use ESA operations updates for manoeuvre status.
Sources and further reading
Educational-use note: SpaceTracker.live is an independent educational website and is not an official mission-control service. Positions, paths, distances and pass predictions are computed from third-party orbital elements or ephemerides. They may be delayed or approximate and must not be used for navigation, collision avoidance or safety-critical decisions.
Last reviewed: August 21, 2026