The Simbio-Sys instrument aboard the European-Japanese BepiColombo mission has achieved first light, successfully powering up its three optical channels in their final configuration and capturing its first image after nearly eight years of interplanetary travel toward Mercury.
The milestone occurred on September 15, less than two weeks after the spacecraft separated from the module that carried it during the long cruise to the innermost planet. Telemetry data confirmed that all systems are functioning correctly, and the instrument is now being prepared for the scientific observations that will begin when BepiColombo enters its nominal mission around Mercury in April 2027.
Simbio-Sys, short for Spectrometers and Imagers for MPO BepiColombo Integrated Observatory System, is one of the mission's flagship scientific instruments. It was designed to observe Mercury from complementary perspectives, combining stereoscopic and high-resolution imaging with data on the composition of the planet's surface.
The instrument's three channels will work in synergy to build a complete portrait of Mercury. The Stereo Imaging Channel will capture images from two different angles as the spacecraft orbits the planet, enabling the first global three-dimensional map of Mercury at a resolution of up to about 60 meters per pixel. That will allow scientists to identify craters, tectonic structures, volcanic features and other surface characteristics.
The High Resolution Imaging Channel will provide images at roughly 6 meters per pixel, revealing much smaller surface details than the global mapping. It will be particularly useful for studying impact craters, geological structures and volcanic processes that have shaped the planet.
The Visible and Near-Infrared Hyperspectral Imager will analyze light reflected from the surface in the visible and near-infrared ranges. Rather than simply showing how the terrain looks, it will reveal what materials and minerals it is made of, allowing composition data to be linked to surface shape and geological history.
«The first light of Simbio-Sys is a particularly significant moment for the entire instrument team: after almost eight years of interplanetary cruise, the instrument has acquired its first images,» said Raffaele Pepe, the Italian Space Agency's manager for scientific and industrial activities of the Simbio-Sys instrument. «These images represent above all a confirmation of the instrument's state of health and allowed us to verify the correct functioning of the acquisition systems after such a long and complex journey.»
Gabriele Cremonese, a researcher at the National Institute for Astrophysics who serves as the instrument's scientific lead, noted that although this was the first attempt to observe the sky with Simbio-Sys, the team was able to capture several stars as bright points with the Stereo Imaging Channel. «We are extremely satisfied with this result, because it confirms the instrument's potential to guarantee excellent performance once we begin observing Mercury,» he said.
The achievement reflects a broad international collaboration built over many years. The core team comprises 118 scientists and engineers from twelve countries, supported by numerous researchers and young scientists involved in preparing observations, managing the instrument and analyzing data. Italy plays a leading role: the Italian Space Agency supported the instrument's development with backing from the French space agency CNES, while the National Institute for Astrophysics leads its scientific component.
BepiColombo is a joint mission of the European Space Agency and the Japan Aerospace Exploration Agency dedicated to studying Mercury. The first light of Simbio-Sys marks a key step toward the scientific phase of the mission, when the instrument will begin returning the detailed images and compositional data that scientists have been preparing to collect for nearly a decade.