NASA large strategic science missions

NASA's large strategic science missions or large strategic missions, formerly known as Flagship missions or Flagship-class missions,^[1][2] are the costliest and most capable NASA science spacecraft. Flagship missions exist within all four divisions of NASA's Science Mission Directorate (SMD): the astrophysics, Earth science, heliophysics and planetary science divisions.

The James Webb Space Telescope launched in December 2021. By the time it launched, JWST cost about US$10 billion.

"Large" refers to the budget of each mission, typically the most expensive mission in the scientific discipline. Within the Astrophysics Division and the Planetary Science Division, the large strategic missions are usually in excess of US$1 billion. Within Earth Science Division and Heliophysics Division, the large strategic missions are usually in excess of US$500 million.^[3][2] "Strategic" refers to their role advancing multiple strategic priorities set forth in plans such as the Decadal Surveys.^[2] "Science" marks these missions as primarily scientific in nature, under the Science Mission Directorate (SMD), as opposed to, e.g., human exploration missions under the Human Exploration and Operations Mission Directorate (HEOMD). The lines can be blurred, as when the Lunar Reconnaissance Orbiter began as a directed mission from the HEOMD, and was later transferred to the SMD.

Flagship missions are not under the purview of any larger "Flagship Program", unlike, e.g., Discovery-class missions that are under the purview of the Discovery Program. Unlike these competed classes that tender proposals through a competitive selection process, the development of Flagship missions is directed to a specific institution — usually a NASA center or the Jet Propulsion Laboratory — by the Science Mission Directorate.^[2][1] Flagship missions are developed ad-hoc, with no predetermined launch cadence or uniform budget size. Flagship missions are always Class A missions:^[4] high priority, very low risk.^[2]

Missions

NASA Large Strategic Science Missions^[2]

Mission name	Mission start	Mission end
Planetary Science Division
Viking 1, 2[5]	1975	1982
Voyager 1, 2[5]	1977	Operational
Galileo[5]	1989	2003
Cassini[5]	1997	2017
Mars Science Laboratory/Curiosity rover[6]	2011	Operational
Mars 2020/Perseverance rover + Ingenuity helicopter[6]	2020	Operational
Europa Clipper[6]	2024	Operational
NASA–ESA Mars Sample Return Mission[7]	2028–30	Proposed
Uranus Orbiter and Probe	2032	Proposed
Enceladus Orbilander	2038	Proposed
Astrophysics Division
Hubble Space Telescope[8]	1990	Operational
Compton Gamma Ray Observatory[8]	1991	2000
Chandra X-ray Observatory[8][9]	1999	Operational
James Webb Space Telescope[10][11]	2021	Operational
Nancy Grace Roman Space Telescope[12][13]	2027	In development
Habitable Worlds Observatory[14][15]	2040	Proposed
Heliophysics Division
Solar Dynamics Observatory[16]	2010	Operational
Van Allen Probes[16]	2012	2019
Magnetospheric Multiscale Mission (MMS)[17]	2015	Operational
Parker Solar Probe[18]	2018	Operational
Earth Science Division
Terra[19][20]	1999	Operational
Aqua[19][20]	2002	Operational
ICESat[21]	2003	2010
Aura[20]	2004	Operational
Joint Polar Satellite System (JPSS) ─ a constellation[21]	2011	Operational
Plankton, Aerosol, Cloud, ocean Ecosystem (PACE)[22]	2024	Operational

Of the four Great Observatories, only the Spitzer Space Telescope is not a Flagship mission. Initially budgeted at US$2 billion, Spitzer was downscoped to a medium-size mission of US$720 million.^[2]

See also

• Spaceflight portal

• Discovery Program – Solar system exploration program by NASA
• New Frontiers program – Series of space exploration missions being conducted by NASA