Mission Models - Strategic and PI-led
There are two basic models for planning missions within the Science Mission Directorate; strategic and PI-led.
Strategic missions are typically larger missions, but occasionally smaller missions, that are directed to fulfill specific needs or gaps in knowledge. Strategic missions are a “top-down” approach where a mission target and basic goals are identified and delineated by the Science Mission Directorate based on community input from National Academies studies, such as the Decadal Surveys, as well as other advisory groups. Often some or all of the individual instruments on such missions are competed, but the mission itself is assigned to a NASA Center. Some examples of strategic missions include Cassini, James Webb Space Telescope, Ocean Surface Topography Mission and LADEE.
PI (Principal Investigator)-led missions take a “bottom-up” approach, soliciting proposals from the community for entire missions, not just a single instrument. In this case a scientist, the PI, puts together a team comprised of people from universities, industry, government laboratories and small businesses to develop and run the mission. These tend to be small- and medium-sized missions, for example Discovery-Class and SMEX missions, though occasionally are larger as with New Frontiers. The approach encourages creativity and provides opportunities for new entrants into scientific space mission development. Some examples of PI-led missions include Phoenix, MESSENGER and Nu-STAR.
Program/Mission Line Definitions: