Status Report

NASA SMD Astrophysics Explorer Solicitations Mandatory NOI Due Date Extended.

By SpaceRef Editor
October 25, 2021
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The National Aeronautics and Space Administration (NASA) Science Mission Directorate (SMD) is releasing two amendments for Astrophysics Explorers Science Investigations via the NASA Solicitation and Proposal Integrated Review and Evaluation System (NSPIRES). NSPIRES is the official source for the details of these amendments and for other updates in the event of a lapse in NASA operations.


Release Date:  October 25, 2021

Notice of Intent to Propose Due: November 4, 2021

Proposals Due: December 9, 2021


1. Solicitation Number: NNH21ZDA018O (Medium Explorer AO): Amendment 1 available at


2. Solicitation Number: NNH17ZDA004O-APEXMO2 (Amendment 21 to the SALMON-3 AO: Astrophysics Explorers Mission of Opportunity Solicitation) available at


These amendments extend the due date for the required or mandatory Notice of Intent (NOI) to propose to November 4, 2021. The proposal due date for both solicitations remains unchanged at December 9, 2021. 


Comments and questions may be addressed in email to: Dr. Linda Sparke, Astrophysics Explorers Program Scientist, (subject line to read “Astrophysics Explorers MIDEX AO” or “Astrophysics Explorers MO PEA” as appropriate). Responses to all inquiries will be given by email and also posted to the Questions and Answers (Q&A) location of the 2021 Astrophysics Explorers Program Acquisition website at Anonymity of persons and institutions who submit questions will be preserved. The period for questions/comments will close three weeks before the proposal due date, and the period for responses will close ten days before the proposal due date.


SpaceRef staff editor.