ESA’s BepiColumbo continues its journey to Mercury by making another flyby … of Mercury! This is the third of six planned flybys of its destination planet, each of which gives the spacecraft a gravitational deceleration. Eventually, it’ll slow down enough to go into its final operational orbit.
In the most recent flyby on June 19, 2023, the spacecraft sped past the planet’s night side and took a series of images from 236 km (145 miles) above Mercury’s surface. From these 217 images, the BepiColumbo team created a movie of the flyby, which includes a 3D scene.
Simulations of the formation of the solar system have been largely successful. They are able to replicate the positions of all the major planets along with their orbital parameters. But current simulations have an extreme amount of difficulty getting the masses of the four terrestrial planets right, especially Mercury. A new study suggests that we need to pay more attention to the giant planets in order to understand the evolution of the smaller ones.
There’s a star system out there with three super-Earth planets and two super-Mercuries. Super-Earths are fairly familiar types of exoplanets, but super-Mercuries are rare. Those are planets with the same composition as our own Mercury, but larger and denser. Yet, here’s HD 23472, showing off two of eight known super-Mercuries in the galaxy.
BepiColombo recently had its first close flyby of Mercury, its eventual mission target, and got to snap some pictures to commemorate the event. Even at this early stage of the mission, these images are some of the clearest we have ever had of the innermost planet.
BepiColombo made a quick visit to Venus in August and is on to its next rendezvous. On October 1st it’ll perform a flyby of Mercury, the spacecraft’s eventual destination. This visit is just a little flirtation—one of six—ahead of its eventual orbital link-up with Mercury in late 2025.
The quick visit will yield some scientific results, though, and they’ll be just a taste of what’s ahead in BepiColumbo’s one-year mission to Mercury.
So much in the astronomy community revolves around the decadal survey. Teams of dozens of scientists put hundreds of hours developing proposals that eventually try to impact the recommendations of the survey panel that influence billions of dollars in research funding over the following decade. And right now is the prime time to get those proposals in. One of the most ambitious is sponsored by a team led by researchers at John Hopkins University Applied Physics Laboratory (APL). Their suggestion – it’s time to land on Mercury.
Astronomers have an excellent habit of naming large projects after deserving contributors to their field. From Nancy Grace Roman to Edwin Hubble, some of the biggest missions are named after space exploration pioneers. When ESA and JAXA sat down to figure out a name for their new Mercury probe, they would have come across an important name early in their research – Giuseppe “Bepi” Colombo – the man who helped plan the Mariner 10 Mercury mission.
Telescopes have captured meteoroids hitting the Moon and several spacecraft imaged Comet Shoemaker–Levy 9 smacking into Jupiter in 1994. But impacts as they happen on another rocky world have never been observed.
However, the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging) mission may have seen an impact take place back in 2013. In looking at archival data from the mission, scientists found evidence of a meteoroid impact on Mercury. While this data isn’t a ‘no-doubt’ photo of the event, it does tell scientists more about impacts and how they affect Mercury’s wispy-thin atmosphere.
In the image, the Earth hangs serenely in between BepiColumbo’s magnetometer boom (on the right) and its medium-gain antenna (on the left).
But the Earth flyby wasn’t without its tense moments. The spacecraft relies on solar power, and during the loop around Earth it had to spend some time in our planet’s shadow – and out of the sun. To prepare, the mission scientists made sure that BepiColombo was fully charged and nice and warm before the maneuver.
And on April 10, the date of the flyby, it all went swimmingly.
The spacecraft is on a long, winding journey sunwards towards the smallest planet in the solar system, making loop after loop first around Earth, then Venus a couple times, then Mercury itself half a dozen times before parking itself in orbit. The frequent loops are necessary because at launch BepiColombo was traveling at the same speed as the Earth in its orbit (29.78 km/s), and needs to match that of Mercury (47.36 km/s), and it does so by borrowing some energy from the planets themselves.
Once BepiColombo reaches Mercury, it will separate into two individual probes: the Mercury Planetary Orbiter and the Mercury Magnetospheric Orbiter. The twin orbiters will attempt to answer several challenging riddles about the planet nearest to the sun, like the origins of Mercury’s faint-but-still-there magnetic field and atmosphere, and the craters pitting its surface.
But it will take a long time to get there. BepiColombo’s final arrival at Mercury isn’t scheduled until December of 2025, showing how reaching the inner planets of our system can be sometimes more difficult than journeys outward – it turns out that doing planetary dances is more challenging than you might think.