The lead scientist for the day works with a mission engineer to encode scientific intent using a tool called Constraint Editor, for example, specifying that one activity must come before or after another or at a particular time of day. These constraints are strictly enforced by a scheduling tool called MAPGEN that the engineers use later in the process. However, entering constraints without omissions or errors is very difficult. The MAPGEN team asked the Human-Computer Interaction (HCI) team in the Human Factors Research and Technology Division at NASA Ames to design the Constraint Editor to support the efficient and accurate capture of scientific intent through the mission critical uplink process.

The HCI team worked with lead mission scientists and engineers to design Constraint Editor. As the HCI team understood the problem, they realized scientists could not keep the large number of constraints (often more than 100) in their heads. Successful execution of the task required a representation of constrained activities, activities not yet constrained, and a real-time view of the state and correctness of the developing plan. The HCI team iterated with JPL through several prototypes of the tool. Concurrently, the HCI team provided mission scientists and engineers training on the tool and concept of constraint-based planning. The HCI team worked with JPL to transform the mindset of experienced scientists and engineers from the familiar method of hand sequenced plans to a method involving automated constraint satisfaction. The combination of the HCI design and focused training has led to the successful adoption of constraint-based planning and of the tool for the Mars Exploration Rover's 2003 mission.