[Image description: A textured sphere representing Mercury is shown with magnetic field lines compressed on the sunward side and streaming out into a tail on the nightside. The BepiColombo spacecraft’s trajectory is drawn passing through the magnetosphere from dawn to dusk, close to the planet’s surface. Various features in the magnetosphere are depicted and labelled with text. Following the order in which they were detected by the spacecraft, this includes the bow shock, magnetopause, low-latitude boundary layer, cold ion cloud, plasma sheet horn and ring current.]
On Sunday 1 December 2024, BepiColombo will fly past planet Mercury for the fifth time, readying itself for entering orbit around the Solar System’s mysterious innermost planet in 2026. The spacecraft will fly between Mercury and the Sun, getting to within 37 630 km from the small planet’s surface at 15:23 CET. This is much farther than its first four flybys of the planet, when BepiColombo flew as close as 165–240 km from the surface. What makes this flyby special is that it will be the first time that BepiColombo’s MERTIS instrument is able to observe Mercury. This radiometer and thermal infrared spectrometer will measure how much the planet radiates in infrared light, something which depends on both the temperature and composition of the surface.This will be the first time that any spacecraft measures what Mercury looks like in mid-infrared wavelengths of light (7–14 micrometres). The data that MERTIS will collect throughout the mission will reveal what types of minerals the planet’s surface is made of, one of the key Mercury mysteries that BepiColombo is designed to tackle. BepiColombo’s other science instruments will monitor the environment outside Mercury's magnetic field. Among other things, they will measure the continuous (but changeable) stream of particles coming from the Sun known as the solar wind. The other instruments switched on during this flyby are the magnetometers MPO-MAG and MMO-MGF, the MGNS gamma-ray and neutron spectrometer, the SIXS X-ray and particle spectrometer, the MDM dust monitor and the PWI instrument which detects electric fields, plasma waves and radio waves.
Mercury in motion... One of the #BepiColombo selfie-cameras captured Mercury today as the spacecraft rushed by the planet at almost 3 km per second. 🛰️💨 This time-lapse of unprocessed images was captured during 10:26-11:18 UTC today (11:26-12:18 CET), between 53700 and 48000 km from the planet's surface. 📸
On 8 January 2025, the ESA/JAXA BepiColombo mission will fly just 295 km above Mercury's surface, with a closest approach scheduled for 06:59 CET (05:59 UTC). It will use this opportunity to photograph Mercury, make unique measurements of the planet’s environment, and fine-tune science instrument operations before the main mission begins. This sixth and final flyby will reduce the spacecraft’s speed and change its direction, readying it for entering orbit around the tiny planet in late 2026.
BepiColombo is reaching its closest approach to Mercury now during its sixth encounter with the planet. It's 06:58:52 CET, and the spacecraft is 295km from the surface. #bepicolombo
Here's an image taken 5.5 hours before closest approach, when #bepicolombo was 44950 km from Mercury's southern hemisphere. The planet is at the bottom of the picture, below two of the spacecraft's booms.
Images and other scientific data from this morning's close approach to Mercury by #bepicolombo are safely on the ground! We'll be sharing images from the closest approach tomorrow.
The ESA/JAXA BepiColombo mission has been cruising towards Mercury since October 2018. With just one year to go until it arrives at its destination, what has the mission achieved so far? And what can we expect from its two spacecraft after they enter orbit around the Solar System’s smallest and least-explored rocky planet? During the last seven years, BepiColombo has swung past Earth once, Venus twice and Mercury six times. Aside from investigating the planets, the mission monitored solar activity and studied how the Sun's gravity affects radio signals by bending spacetime itself. The mission’s main ‘science phase’ will only start after ESA’s Mercury Planetary Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (MMO, or Mio) spacecraft enter orbit around Mercury, but scientists and engineers have made the most of the mission’s winding journey to its destination. A key highlight has been measurements of Mercury’s magnetic environment during each close flight past the little planet. Mercury's magnetic field shields the planet’s surface from the brunt of the particles flung at it by the Sun, called the solar wind. But because the planet orbits so close to our star, where the solar wind is denser and has a stronger magnetic field of its own, the size and shape of Mercury's protective magnetic bubble change depending on the Sun's activity. Understanding how Mercury’s magnetic field works is one of the key mysteries BepiColombo set out to solve. BepiColombo collected the first magnetic measurements from low over the planet’s southern hemisphere, and reconstructed a map of the planet’s magnetic field. These can be compared to the magnetic field measured during the spacecraft’s flight past Earth in 2020 and flight past Venus in 2021. (Venus doesn’t have a magnetic field, so the magnetic measurements only capture changes in the solar wind hitting the spacecraft.) If you’re curious to hear what a spacecraft ‘feels’ while flying past a planet, you have your pick of sonifications from BepiColombo’s flights past Earth, Venus and Mercury (here and here). These recordings by MPO’s accelerometer capture gravitational tugs on the spacecraft, the effects of temperature changes from entering and exiting the planets’ shadows, and movements of spacecraft components. Arguably the most lauded equipment so far has been the monitoring cameras (M-CAMs) on the Mercury Transfer Module (MTM). These ‘selfie cameras’ were designed to monitor the spacecraft, but also captured hundreds of 1024x1024-pixel planet photos. These showed Earth spinning as BepiColombo approached, bright Venus living up to its nickname ‘the Morning Star’, and countless craters, volcanoes and plains on Mercury.BepiColombo will be the first mission to study Mercury with two spacecraft at the same time. MPO will orbit close to the planet’s surface, and Mio in a larger elliptical orbit. So far, MPO and Mio – the latter nestled inside a protective sunshield – have been stacked on top of their ‘trusty engine’ MTM. Several of the mission’s scientific instruments can’t yet be used, or are partially hindered, until the stacked spacecraft separate after arriving at Mercury in November 2026. Once ‘unstacked’, MPO and Mio can finally use all their instruments to their full potential. For example, instead of the modest black-and-white images taken by MTM’s monitoring cameras, MPO will scan Mercury’s surface in high resolution in X-rays (with imaging spectrometer MIXS), visible and near-infrared light (with stereo camera and spectrometer SIMBIO-SYS) and infrared light (with imaging spectrometer MERTIS). To ensure that we accurately capture Mercury’s topography, MPO’s BELA laser altimeter instrument will measure the precise height and shape of Mercury’s surface.Put together, this data will give us a precise map of Mercury’s surface, and tell us what it’s made of, how it formed, how it changes over time, and what temperature it is. Flying over Mercury’s poles, MPO will also be able to peer into craters filled with permanent shadow – if there is water on Mercury, this is where it would be!And, while both Mio and MPO have already used their magnetometers and some of their particle detectors to investigate Mercury’s surroundings, their measurements will be more sensitive and precise when the spacecraft are separated. After separation, Mio will additionally be able to use its sodium imager MSASI and dust detector MDM to investigate other material near Mercury.
The obvious solution is to blow up Mercury and restore order to the Universe.https://www.bbc.com/future/article/20251223-mercury-the-planet-that-shouldnt-exist
