Two spacecraft, the joint European and Japanese BepiColombo mission, are nearing Mercury after a nearly decade-long voyage to the solar system's smallest planet. The linked spacecraft separated from their cruiser on Thursday, marking the home stretch of their journey.
Controllers confirmed the separation via radio signals from the European Space Agency's control center in Germany, over 124 million miles away. "It's a brilliant moment," said lead project scientist Geraint Jones.
The BepiColombo mission, launched in 2018, is named for an Italian mathematician involved in NASA's Mariner 10 mission to Mercury in the 1970s. The spacecraft will enter orbit around Mercury in November and split in December to map and study the planet from different altitudes. As of Thursday, the mission still had 2 million miles to travel.
This is only the second spacecraft to explore Mercury, the planet just slightly larger than Earth's moon. NASA's Messenger was the first. "How tiny Mercury is and still it holds some of the biggest mysteries of our solar system," said mission manager Santa Martinez.
BepiColombo has traveled more than 6 billion miles on its indirect route, requiring nine planetary flybys to reduce its energy sufficiently to be captured by Mercury's orbit. The mission's final flyby occurred in January 2025, providing images of Mercury's impact craters and volcanic plains.
Beginning next spring, science instruments aboard the spacecraft will study Mercury's magnetic field, its internal structure, and surface geology, including features believed to be eroding as minerals vaporize from rocks. Despite surface temperatures that can exceed 800 degrees Fahrenheit (427 degrees Celsius), the planet's poles remain frigid and contain shadowed craters with ice.
Engineers designed the spacecraft to withstand the extreme conditions near the sun, described by European Space Agency mission operations chief Ignacio Tanco as akin to "operating with a very hot pizza oven running right on your back."
Science observations are scheduled to commence next spring. The European Space Agency is funding the majority of the mission's approximately $2 billion cost.