Mars Exploration Rover mission page https://mars.nasa.gov/mer/overview/ mission page Mars Exploration Rover Mission Overview we dispatch robotic probes NASA Mars Rover Mars Exploration Rovers mission page we dispatch robotic probes Opportunity https://mars.nasa.gov/mer/overview/ Mars Expedition Rover mission Mars Exploration Rover MER-B mission page Opportunity Mars Exploration Rover "Mars Exploration Rover Mission: Overview" Opportunity Rovers Mars Rover we dispatch robotic probes were launched in 2003 Opportunity Mars Rovers Mars Exploration Rover Mission: Overview mars.nasa.gov were launched in 2003 mission page were launched in 2003 mission page Opportunity