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 the policy of the then-NASA administrator Daniel S. Goldin of "faster, better, cheaper"[2] 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 U.S. participation in spacecraft operated by other space agencies, for example by contributing a single scientific instrument.
The result was a request for rapid studies of potential missions and NASA committed funding in 1990.
[140] What would be the NEAR spacecraft mission was formally selected in December 1993, after which began a 2-year development period prior to launch.
[146] In October 1997, NASA selected Genesis and CONTOUR as the next Discovery missions, out of 34 proposals that were submitted in December 1996.
[147] The five finalists were:[148] In July 1999, NASA selected MESSENGER and Deep Impact as the next Discovery Program missions.
[151] Three candidates were shortlisted in January 2001 for a phase-A design study: Dawn, Kepler space telescope, and INSIDE Jupiter.
[158] There were three finalists for this Discovery selection including GRAIL (the eventual winner), OSIRIS, and VESPER.
[159] The three finalists were announced in October 2006 and awarded US$1.2 million to further develop their proposals for the final round.
[166] In February 2014, NASA released a Discovery Program 'Draft Announcement of Opportunity' for launch readiness date of December 31, 2021.
[175][176] The final Announcement of Opportunity was released on April 1, 2019, and proposal submissions were accepted between then and July 1, 2019.