Excelsior would be a fitting name for the rover because it means "Ever upward" in Latin. The rover is going to be sent to explore the surface of Mars, gather data and samples, and better prepare us to land humans on Mars someday. No one has ever landed a manned spacecraft on Mars, and that would be a step upward in scientific progress. Also, the rover is going to try to find out if there was ever life on Mars, which would be another step up for scientific research. This mission is helping to pave the way for scientific breakthroughs such as landing a manned spacecraft on Mars, of discovering signs of life there. Ever Upward, or Excelsior, would capture the reasons for the mission, so that is why it would be a great name.