BepiColombo: International Space Mission to Mercury Targets October Launch

BepiColombo, an international space mission to explore Mercury, the closest planet to the Sun, will launch in mid-October from Kourou spaceport in French Guiana—an overseas region of France—aboard an Ariane 5 rocket.

A joint collaboration between the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA), BepiColombo will involve three spacecraft: two orbiters which will conduct the scientific investigations and a "Transfer Module" that will carry these to the planet using a combination of solar power, electric propulsion and nine gravity-assist flybys of Earth, Venus and Mercury itself.

The mission will study Mercury in unprecedented detail, collecting data on its magnetic field, interior structure and surface, and hopefully providing new insights into the origin and evolution of planets that orbit very close to their parent star.

The ESA and JAXA have set a provisional launch time of 9.45 p.m. EDT on October 18, although this is only the first option. The launch window will remain open until November 29, leaving plenty of room for maneuvering in the event that unplanned testing needs to take place or adverse weather conditions arise.

"We have had a great start to our launch campaign in Kourou and are on track for launch in less than 90 days," Ulrich Reininghaus, ESA's BepiColombo project manager, said in a statement. "We have an incredibly packed schedule, but it is great to see our spacecraft building up together for the final time."

Since the spacecraft arrived at Kourou in May, many essential preparations have taken place. Perhaps most importantly, the orbiters have been fitted with their protective blankets, which will protect them from temperatures that could be in excess of 660 degrees Fahrenheit.

The ESA's control center in Darmstadt, Germany, has also been conducting simulations of key operations and non-routine events to prepare for the mission.

The spacecraft will reach Mercury three years after launch to make its first flyby and will insert into the planet's orbit in 2025. The mission is particularly challenging given Mercury's proximity to the Sun, which makes it difficult for spacecraft to reach the planet and survive in the harsh environment.

The three modules of the ESA-JAXA BepiColombo mission to Mercury are pictured here on May 8, shortly after being unpacked at Europe's Spaceport in Kourou, French Guiana. ESA/JAXA–G.Murakami

In fact, only two spacecraft have visited the planet: NASA's Mariner 10, which made three flybys in 1974-1975, and NASA's MESSENGER orbiter, which also made three flybys between 2008 and 2009.

As a result, the planet is poorly understood, highlighting the potential of the latest mission, which is named after Giuseppe "Bepi" Colombo (1920-1984)—an Italian scientist, mathematician and engineer who first implemented the interplanetary gravity-assist maneuver during the Mariner 10 mission. This technique is now commonly used by planetary probes.