The Department of Defense, specifically the Air Force Research Laboratory (AFRL), is seeking proposals for the APPEAR (Aperture Projects for Passive Engineering and Advanced Research) initiative, aimed at developing advanced passive sensing technologies for contested environments, including space. The primary objective is to explore and enhance current antenna apertures and investigate new techniques to improve signal detection, focusing on both single and shared aperture applications across various platforms. This initiative is critical for ensuring effective situational awareness and operational success in military operations, particularly in the context of Great Power Competition. Interested parties should prepare Direct to Phase II proposals, demonstrating prior Phase I-like efforts, with submissions due by June 25, 2025. For more information, visit the official solicitation page at DoD SBIR/STTR.