SAIC is seeking a Lead Cybersecurity Engineer / Information Systems Security Manager (ISSM) to serve as a subject matter expert (SME) in the development of cybersecurity best practices. In this role, you will drive secure architecture, system resiliency, RMF/ATO compliance, and cyber risk management across mission systems that support U.S. Space Force command and control operations. This position is based in El Segundo, CA, and focuses on supporting the Horizon program within the Space C2 Program Management Office. As part of this role, you will be collaborating closely with the Space Systems Command's (SSC) Battle Management Command, Control & Communications (BMC3) Program Executive Office. You will work directly with government, technical, and industry stakeholders to shape cybersecurity strategy, secure cloud and enterprise architectures, and ensure the protection of mission-critical space capabilities. Fun stuff you will do on the job: Lead design and implementation of cybersecurity controls across multi-domain and multi-enclave systems. Serve as ISSM and ensure compliance with JSIG, CNSSI 1253, NIST SP 800-37/53, and RMF. Manage ATO activities using tools such as eMASS or XACTA. Support secure architecture and integration for cloud-based development and operations environments. Assess vulnerabilities and develop mitigation strategies throughout system lifecycles. Oversee security policy implementation, configuration management, auditing, incident handling, and contingency planning. Lead and mentor cybersecurity and ISSO personnel. Provide security engineering expertise in areas such as cryptography, cross-domain solutions, system integration, and secure infrastructure. Advise program leadership on cybersecurity posture, risks, acquisition activities, and system readiness. Prepare security documentation, briefings, and technical reports supporting enterprise and mission decisions.