The exploration of Mercury has long had a minor role in the space interests of the world. It is the least explored inner planet. As of 2025, the Mariner 10, MESSENGER, and BepiColombo missions have been the only spacecraft that have made close observations of Mercury. MESSENGER made three flybys before entering orbit around Mercury. BepiColombo, a joint mission between the Japan Aerospace Exploration Agency (JAXA) and the European Space Agency, is to deliver two probes into Mercury orbit in 2026, having previously made six flybys of the tiny planet. MESSENGER and BepiColombo are intended to gather complementary data to help scientists understand many of the mysteries discovered by Mariner 10's flybys.