Each mission has a cost cap, at a lower level than a mission from NASA’s New Frontiers or Flagship Programs. As a result, Discovery missions tend to be more focused on a specific scientific goal (rather than serving a general purpose).
The Discovery Program was founded in 1990 to implement then-NASA Administrator Daniel S. Goldin’s policy of “faster, better, cheaper” planetary science missions. Existing NASA programs had specified mission targets and objectives in advance, then sought bidders to construct and operate them. In contrast, Discovery missions are solicited through a call for proposals on any science topic, and assessed through peer review. Selected missions are led by a scientist called the Principal Investigator (PI) and may include contributions from industry, universities, or government laboratories. The Discovery Program also includes Missions of Opportunity, which fund US participation in spacecraft operated by other space agencies (e.g. by contributing a single scientific instrument). It can also be used to re-purpose an existing NASA spacecraft for a new mission.
