Status Report

NASA Draft Astrophysics Explorers Program Solicitations Released for Community Comment

By SpaceRef Editor
January 6, 2021
Filed under , ,

Release Date: 

January 6, 2021

Comments Due: 

February 25, 2021

Identification Number:

NNH21ZDA004J (Draft 2021 Astrophysics Medium Explorer (MIDEX) AO)

Identification Number:

NNH21ZDA005J (Draft 2021 Astrophysics Explorers Missions of Opportunity (APEXMO))


On January 6, 2021, the National Aeronautics and Space Administration (NASA) Science Mission Directorate (SMD) is releasing two draft solicitations for community review and comment: the Draft 2021Astrophysics Medium Explorer (MIDEX) Announcement of Opportunity (AO)and the Draft 2021 Astrophysics Explorers Missions of Opportunity (APEXMO) Program Element Appendix (PEA) for the Third Stand Alone Missions of Opportunity Notice (SALMON-3) AO. Upon the release date, the full text will be available at


The Astrophysics Explorers Program conducts Principal Investigator (PI)-led space science investigations relevant to SMD’s astrophysics programs. Explorer investigations must address NASA’s goals to discover the origin, structure, evolution, and destiny of the Universe and search for Earth-like planets.


Participation is open to all categories of organizations or institutions, U.S. or non-U.S., including educational, industrial, and not-for-profit institutions, Federally Funded Research and Development Centers (FFRDCs), University Affiliated Research Centers (UARCs), NASA Centers, the Jet Propulsion Laboratory (JPL), and other Government agencies.


The comment period for the Draft 2021 MIDEX AO and the Draft 2021 APEXMO PEA ends on February 25, 2021.


The issuance of the Draft 2021 MIDEX AO does not obligate NASA to issue the 2021 Medium Explorer AO and solicit proposals. The issuance of the Draft 2021 APEXMO PEA does not obligate NASA to issue a 2021 Astrophysics Explorers MO PEA and solicit proposals. Any costs incurred by prospective investigators in preparing submissions in response to either of these draft solicitations are incurred completely at the submitter’s own risk.


Comments on either or both drafts may be addressed via email to the Astrophysics Explorers Program Scientist: Dr. Patricia M. Knezek (subject line to read “2021 MIDEX AO”, “2021 MO” or both) at: Responses to comments will be given by email and posted in the MIDEX/MO QAs section on the Astrophysics Explorers Program Acquisition websites at and; anonymity of persons/institutions who submit comments will be preserved. Comments will be accepted by email only.


SpaceRef staff editor.