The U.S. is joining Italy and Japan on a trip to Mercury. Once there, the joint mission will determine the makeup and history of a planet that's been difficult to study because of its proximity to the sun.
NASA Administrator Charles Bolden visited Rome last week and signed an agreement with the Italian Space Agency. The spacecraft for the mission, called BepiColombo, is being built and tested now. Estimated time of arrival: 2022.
BepiColombo aims to learn about the minerals and elements Mercury is made of, according to the European Space Agency. It will also determine whether Mercury's core is molten and the origin of its weird magnetic field.