A Broad Agency Announcement (BAA) is a contracting vehicle employed by the US Government's Research and Development (R&D) community to encourage investigation into areas that might be otherwise ignored or underfunded.
It typically seeks responses from industry, academia, and Federally Funded Research and Development Centers, also known as FFRDCs.
Respondents to the BAA produce a proposal which is then vetted by a group of Subject Matter Experts. Those proposals found worthy are recommended for funding.