TOKYO - Japan's Mercury probe Mio, part of the Japan-Europe joint Mercury exploration mission BepiColombo, is on course to attempt to take its first images of Mercury next spring after arriving at the planet later this month, sources close to the matter said Wednesday.
It is expected to capture Mercury's tenuous sodium atmosphere and possibly its terrain, marking the start of preparations for full-scale scientific observations after a 10-billion-kilometer journey over roughly eight years.
Mercury, the planet closest to the Sun, is exposed to extreme temperatures and remains difficult to reach because of the Sun's strong gravitational pull, leaving it relatively unexplored.
BepiColombo is the world's first mission in which two spacecraft, separately developed by the Japan Aerospace Exploration Agency and the European Space Agency, will orbit Mercury simultaneously. Equipped with special heat-protection systems, the spacecraft will conduct observations from different orbits.
Mio was launched from Kourou in French Guiana in October 2018 attached to Europe's Mercury Planetary Orbiter, or MPO, on an Ariane 5 rocket. Reaching Mercury requires a huge amount of energy and the mission carried out nine gravity-assist maneuvers, known as swing-bys, to alter its trajectory and speed while conserving fuel.
The mission's planned arrival, originally scheduled for December 2025, was delayed by a year due to propulsion system problems.
The sole imaging instrument aboard Mio is the Mercury Sodium Atmospheric Spectral Imager. After separating from MPO in early December this year, Mio will photograph Mercury and its surroundings and transmit the images using its own antenna.
The camera is designed to detect light emitted by sodium atoms drifting around the planet, allowing scientists to visualize the extent and variability of Mercury's atmosphere.
The structure of the sodium atmosphere is difficult to observe from Earth because of interference from sunlight, and researchers hope Mio's images will help reveal its behavior.
Project scientist Go Murakami, an associate professor at JAXA, said the team will carefully verify that all equipment is functioning properly before conducting test imaging around March next year.
"We hope the images will be transmitted safely back to Earth," he said.
Murakami said the mission's primary objectives include studying how Mercury formed and evolved, investigating the mechanisms behind its internal magnetic field, and looking into how well the planet's environment can be sustained under intense solar winds, which could offer clues to understanding the birth of Earth and about environments capable of supporting life.
Full-scale scientific observations are scheduled to begin in April next year.
