Mars Express is a space mission launched by the European Space Agency (ESA) in 2003 to explore the planet Mars. It was the first mission to orbit Mars since the 1990s and aims to study the planet's geology, atmosphere, and potential for past life. The spacecraft carries a suite of scientific instruments to gather data and images of the Martian surface. Since its arrival at Mars in 2004, Mars Express has made significant discoveries, including evidence of water ice and seasonal changes on the planet. Its findings have contributed to our understanding of Mars' climate and geology, helping scientists learn more about the planet's history and potential for habitability.