We’ve all heard about Mars rovers, the Saturn fly-bys, even the red roadster launched into space by an eccentric billionaire. But, do you know about a little guy named BepiColombo?
Little by cosmic standards—just a bit over 4 tons of Earth weight—this cute fella was taken to space in 2018 (exact same year as the SpaceX PR stunt saw one piece of automotive garbage thrown to spin around the Sun) by Europe’s Ariane 5 rocket and flicked into a very, very odd trajectory towards its destination: Mercury, where it’s expected to arrive in November this year (2026).
» BepiColombo info page on ESA’s website
The trajectory
This is what makes this specific mission so interesting. Mercury moves in a unique orbit, which when averaged over time, makes it the closest planet to Earth (yes, even closer than Venus), and the intuition would dictate that that should make it easy to reach, but, as it sometimes is, it would be dead wrong.
Why does a relatively close jump need more than 8 years, while we (and by “we” I mean uncrewed space vessels) can hop to Mars in mere months?
For the people who aren’t rocket scientists, like you and me, the explanation comes down to the sole task of choosing a trajectory that doesn’t let the Sun speed it up too much for Mercury’s gravity to catch it.
By the time it arrives, our little explorer will have travelled over 10 billion kilometers and made 22 laps around the Sun, on a trajectory that took it as close to our star as 45.4 million km (6 Jul 2022) and as far as 178.9 million km (17 Jul 2019).
If that seems already interesting, get this: instead of burning fuel to propel itself towards its destination like all normal space-faring travelers do, BepiColombo is spending most of it on… braking. And quite a lot of it. ESA’s own line says it best: to get into Mercury’s orbit, “even more energy is needed than sending a mission to Pluto.”
There’s so much stuff pulling it, there’s no shortage of speed, so the main number crunching was when and how much to brake.
The target
Crazy to think that during its journey, it has already flown past Mercury six times, five of them less than 300 km above the surface (1 Oct 2021, 23 Jun 2022, 19 Jun 2023, 4 Sep 2024, 8 Jan 2025).
There’s the final rendez-vous left: this November 2026, after spending 2,954 days in space, BepiColombo will finally drop into orbit around Mercury. After insertion, in December, the two orbiters, ESA’s Mercury Planetary Orbiter (MPO) and Mercury Magnetospheric Orbiter (Mio), will split and move into their science orbits. Though the actual science will start only in April 2027.
The visuals
Oh, and us not being rocket scientists (which we established a bit earlier), we can’t let you go without a good, interactive visual.
Here’s how everything unfolded:
And here’s the interactive demo you can tinker with yourself:
Pssst, funny fact about the demo: don’t tell anyone but it’s a chart, built on the amCharts 5 library:
A regular, run-of-the-mill XY Chart;
Two hidden value axes kept at equal scale;
Line series for the orbits and the trail;
Bullets for the planets;
And another XY Chart with a date-axis timeline with an axis-range playhead.
While you’re here
We have another cool space-related Dojo demo, too:
DataViz Dojo was created by amCharts team. We’re not here to peddle you our data-viz lib. We’re here to have fun with facts, data, cartography, and history, blending it all into beautiful visual stories. Subscribe, follow, or simply check in regularly for more compelling stuff!