Discovery is an ongoing program that offers the scientific community the opportunity to assemble a team and design exciting, focused investigations that complement NASA's larger planetary science explorations. The goal is to achieve outstanding results launching many smaller missions using fewer resources and shorter development times than past projects with comparable objectives. The main objective is to enhance our understanding of the Solar System by exploring the planets, their moons, and small bodies such as comets and asteroids.

The 2006 NASA Strategic Plan identifies the following goal for Planetary Science : "Advance scientific knowledge of the origin and history of the solar system, the potential for life elsewhere, and the hazards and resources present as humans explore space." NASA's Science Mission Directorate (SMD) has responsibility for defining, planning and overseeing NASA's space and Earth science programs.

The Solar System Exploration Roadmap, published by NASA in September 2006, is drawn as a 30-year planning horizon, against the backdrop of the Presidential Initiative, "The Vision for Space Exploration." It excludes the Moon and Mars, which are covered in other Roadmaps. The scientific foundation of the Roadmap is a set of fundamental questions based on five objectives adopted in 2003 by NASA's then Office of Space Science, in response to the National Research Council's Decadal Survey, but modified to reflect the context of the exploration goals of the Vision for Space Exploration:

  1. How did the Sun's family of planets and minor bodies originate?
  2. How did the Solar System evolve to its current diverse state?
  3. What are the characteristics of the Solar System that led to the origin of life?
  4. How did life begin and evolve on Earth and has it evolved elsewhere in the Solar System?
  5. What are the hazards and resources in the Solar System environment that will affect the extension of human presence in space?

The Roadmap describes a balanced series of small (Discovery Program), medium (New Frontiers Program), and large (flagship) class missions and their enabling technologies, supported by a balanced program of research and analysis, and creative education and public outreach.

The Science Plan for NASA's Science Mission Directorate 2007-2016 further defines NASA's vision for the scientific exploration of our planet, other planets and planetary bodies, our star system in its entirety, and the universe beyond.

All these documents can be accessed on the SMD's Science Strategy page which contains Current Strategy Documents, Community Input documents, and Past Strategy Documents.

To accomplish its prime objective of enhancing our understanding of the Solar System, the unique approach of the Discovery Program is to:

  • increase flight rates
  • contain total mission costs
  • improve performance through the use of new technology
  • broaden university and industry participation, and
  • increase public awareness of solar system exploration.

Discovery was among the first NASA programs to require a plan for education and public outreach, as NASA recognized the importance of communicating the excitement and meaning of space exploration to the public. Innovative methods that support national education initiatives are being developed to reach students of all ages. The vast possibilities available through the Internet greatly strengthen this effort.

Discovery advocates the testing and use of new technologies and applications. Each mission works with industry to transfer technologies used in the mission, especially those that enhance science acquisition and reduce cost.

Missions listed below were competitively selected under the Discovery Program. A mission is assigned to a division once the mission launches.