The Small Explorer program (SMEX) is an effort within NASA to fund space exploration missions that cost no more than US$120 million. Extending the larger Explorers program, it was started in 1989.
The first set of three SMEX missions were launched between 1992 and 1998. The second set of two missions were launched in 1998 and 1999. These missions were managed by the Small Explorer Project Office at NASA's Goddard Space Flight Center (GSFC). In early 1999, that office was closed and with the announcement of opportunity for the third set of SMEX missions NASA converted the program so that each mission was managed by its Principal Investigator, with oversight by the GSFC Explorers Project.
NASA funded a competitive study of five candidate heliophysics Small Explorers missions for flight in 2022. The proposals are Mechanisms of Energetic Mass Ejection – eXplorer (MEME-X), Focusing Optics X-ray Solar Imager (FOXSI), Multi-Slit Solar Explorer (MUSE), Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS), and Polarimeter to Unify the Corona and Heliosphere (PUNCH).
In June 2019 NASA selected two heliophysics Small Explorer missions for flight - PUNCH and TRACERS.
List of missions
|SAMPEX||SMEX-1||Explorer-68||3 July 1992||Ended: 30 June 2004 |
Reentered: 13 November 2012
|TOMS-EP||2 July 1996||Single instrument: Total Ozone Mapping Spectrometer 3.|
|FAST||SMEX-2||Explorer-70||21 August 1996||Ended: 4 May 2009|
|SWAS||SMEX-3||Explorer-74||6 December 1998||Ended: 21 July 2004|
|TRACE||SMEX-4||Explorer-73||2 April 1998||Ended: 21 June 2010|
|WIRE||SMEX-5||Explorer-75||5 March 1999||Spacecraft equipment failure |
Reentered: 10 May 2011
|RHESSI||SMEX-6||Explorer-81||5 February 2002||Ended: April 2018 |
Decommissioned: 16 August 2018
|GALEX||SMEX-7||Explorer-83||28 April 2003||Ended: May 2012 |
Decommissioned: 28 June 2013
|SPIDR||SMEX-8||Scheduled for 2005||Cancelled, instrument not sensitive as expected|
|AIM||SMEX-9||Explorer-90||25 April 2007||Operational|
|IBEX||SMEX-10||Explorer-91||19 October 2008||Operational|
|NuSTAR||SMEX-11||Explorer-93||13 June 2012||Operational|
|IRIS||SMEX-12||Explorer-94||28 June 2013||Operational|
|GEMS||SMEX-13||Scheduled for 2014||Cancelled, expected cost overrun|
- "Explorers Missions". NASA. Archived from the original on 23 March 2010. Retrieved 28 August 2015. Cite uses deprecated parameter
- Mason, G. M.; Baker, D. N.; Blake, J. B.; Boughner, R. E.; Callis, L. B.; et al. (1998). SAMPEX: NASA's First Small Explorer Satellite. IEEE Aerospace Conference. 21–28 March 1998. Aspen, Colorado. 5. pp. 389–412. doi:10.1109/AERO.1998.685848.
- "Welcome to the Small Explorer's Web Site". NASA. 18 February 2000. Archived from the original on 17 August 2000.
- Brown, Dwayne (28 July 2017). "NASA Selects Proposals to Study Sun, Space Environment". NASA. Retrieved 7 December 2017.
- "Announcement of Opportunity: Heliophysics Explorers Program, 2016 Small Explorer (SMEX)" (PDF). NASA. 13 July 2016. NNH16ZDA005O.
- Mendoza-Hill, Alicia (25 August 2017). "Heliophysics Small Explorers 2016 Announcement of Opportunity: Concept Study Report Kickoff" (PDF). NASA / Launch Services Program.
- "NASA Selects Missions to Study Our Sun, Its Effects on Space Weather". NASA. 20 June 2019.
- "NASA - NSSDCA - Spacecraft - Details". Nssdc.gsfc.nasa.gov. 21 March 2017. Retrieved 20 April 2018.
- "NASA cancels space science mission". spacetoday.net. 4 June 2003. Retrieved 28 April 2018.
- Berger, Brian (7 June 2012). "GEMS Spacecraft Team Appeals NASA Cancellation Decision". Space.com. Retrieved 28 April 2018.
- Soffitta, Paolo (2017). IXPE the Imaging X-ray Polarimetry Explorer. UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XX. Bibcode:2017SPIE10397E..0IS. doi:10.1117/12.2275485. 103970I.