Competed missions historically cost less and fly more frequently than NASA’s high-profile flagship missions, which generally cost upwards of $2 billion and fly once per decade. NASA attempts to fly five Discovery-class missions and two New Frontiers missions every decade (congressional budgets permitting), with a $500 million cost cap on Discovery and a $900 million cost cap on New Frontiers. These cost caps are designed to limit NASA’s exposure to cost overruns, enabling more missions and allowing for more novel, higher-risk designs.
Also distinct is the political authority granted to NASA to pursue competed missions. Flagship missions represent the agency’s top scientific priorities, are assigned to a primary NASA center for implementation, and then must secure a funding commitment from the White House’s budgeting office and obtain a “new start” approval by Congress. Only then can NASA begin making long-term contracts and commitments necessary to build a large and complex spacecraft. In contrast, Discovery and New Frontiers missions are pre-authorized by Congress; NASA can select missions within those classes as frequently as funding allows. In theory, this provides more rapid development opportunities.
Competed planetary missions are science-focused and scientist-led. This is again distinct from flagship-class missions, which, while science-focused, are led by an existing NASA center. Competed missions are led by Principal Investigators (PIs) who assemble both a science and engineering team to submit a detailed proposal to the space agency for the type of mission they’d like to pursue. The scientific payload and team are proposed wholistically by the very individuals who will then implement the mission. This elevates scientific leadership to the top of the decision-making process and generally leads to a more copacetic (albeit smaller) science team.