On or after this SAM.gov notice, the final text for the Announcement of Opportunity (AO) 2026 Astrophysics Small Explorer (APSMEX) will be available for download from the NASA Solicitation and Proposal Integrated Review and Evaluation System (NSPIRES) at https://nspires.nasaprs.com. Click on the word “Solicitations” at the top of the NSPIRES landing page and then on the next page enter the number “NNH26ZDA011O” in the search box or use the direct URL provided below. This “Description” is not a complete or verbatim summary of the AO. It is the responsibility interested parties to visit and monitor regularly the two listed internet sites (links) for any amendments or other updates. Please also open and carefully read the attached PDF file named “9JuneEmail.pdf”. The 9JuneEmail attachment is copy of the text that NSPIRES sent to Science Mission Directorate (SMD) List Serv subscribers and includes other and earlier, important dates such as for the submission of a MANDATORY Notice of Intent (NOI) and a virtual Preproposal conference that are prior to the listed Date Offers Due. After reading the full AO on NSPIRES, please address any comments and questions only via email to both the primary and alternative points of contact listed and use " APSMEX26” in the subject line.