The International COSPAS-SARSAT Programme is responsible for a global satellite-based search and rescue (SAR) distress alert detection and information distribution system, best known for detecting and locating emergency beacons activated by aircraft, ships and backcountry hikers in distress. This paper reports on findings from an Australian research project “Resilient Emergency and Search and Rescue Communications (RESARC)” in which new satellite communications technologies were studied to provide secure and reliable two-way messaging for scenarios where network infrastructure does not exist or is significantly degraded. This is highly relevant for emergency responders in remote and disaster-stricken areas. A demonstration with live satellite links took place in the Adelaide Hills, working alongside the current system. Potential threats to security of messages sent over the satellite links were identified and a secure communication design was implemented that ensures confidentiality, integrity and authenticity of data transmitted messages while also protecting against unauthorized access.