AST SpaceMobile is building the first and only global cellular broadband network in space to operate directly with standard, unmodified mobile devices based on our extensive IP and patent portfolio and designed for both commercial and government applications. Our engineers and space scientists are on a mission to eliminate the connectivity gaps faced by today’s five billion mobile subscribers and finally bring broadband to the billions who remain unconnected. Position Overview We are seeking a Lead Systems Engineer to support AST SpaceMobile's growing defense business, applying our commercial space-based broadband solutions to government and defense missions. Based in Lanham, MD, this role serves as the primary systems engineering interface between our commercial satellite network capabilities and defense customer requirements. The ideal candidate holds an active TS clearance and brings deep experience translating defense mission needs into system-level solutions.  Key Responsibilities: * Serve as the lead systems engineer for defense-focused programs, owning requirements definition, architecture, CONOPs defintion, integration, and verification across the full system lifecycle * Translate defense customer mission needs and operational concepts into system-level and subsystem requirements with clear traceability * Lead requirements flow-down and allocation across satellite, ground, and communications subsystems * Interface directly with government customers, program managers, and defense contractors to align technical baselines and manage change * Lead system-level trade studies, risk assessments, and design reviews (SRR, PDR, CDR, TRR) for defense programs * Coordinate with commercial engineering teams to identify capability gaps and drive adaptations of AST's SpaceMobile network for defense mission requirements * Support proposal development, technical volume authoring, and Basis of Estimate (BoE) for new defense business opportunities * Maintain system engineering artifacts including ConOps, ICDs, verification plans, and traceability matrices * Mentor junior systems engineers on defense programs and champion systems engineering best practices across the team  Qualifications  Education: * Bachelor's degree in Systems Engineering, Electrical Engineering, Aerospace Engineering, or a related technical field. Advanced degree preferred. Experience: * A minimum of 8 years of systems engineering experience, with at least 4 years supporting DoD or defense programs. * Active Secret (S) security clearance required; TS/SCI eligible preferred.  Preferred Qualifications: * Experience with active or passive RF systems engineering in a defense or aerospace context * Experience with systems engineering tools for requirements management, modeling, and verification (e.g., JAMA, or equivalent) * Familiarity with RF propagation, link budgets, and RF system performance analysis in contested or space-based environments * Experience supporting C2, ISR, or PNT mission applications * Prior experience at a commercial space company, defense prime, or government lab * Active TS/SCI clearance  Soft Skills: * Strong interpersonal skills and ability to work effectively with government customers, defense contractors, and internal commercial engineering teams * Excellent written and verbal communication skills, including experience briefing senior government or military stakeholders * Meticulous attention to detail to ensure accuracy of all technical documentation and program deliverables * Strong analytical and problem-solving skills with the ability to manage competing priorities across multiple programs * Self-starter with a proactive mindset and the ability to operate with limited supervision  Technology Stack: * Requirements management and systems engineering * Microsoft Office Suite (Word, Excel, PowerPoint, Project) * Systems modeling and analysis tools (MATLAB/Simulink, STK, or equivalent)  Physical Requirements * Ability to work in a standard office environment and use a computer for extended periods * Ability to travel up to 25% to customer sites, government facilities, and other AST SpaceMobile locations as needed * May require occasional work in a laboratory or satellite operations environment Additional Requirement This position requires an active U.S. government security clearance, or the ability to obtain one. U.S. citizenship is required. This job description may not be inclusive to the duties and responsibilities listed. Additional tasks may be assigned to the employee from time to time or the scope of the job may change as needed by business demands.  AST SpaceMobile is an Equal Opportunity, at will Employer; employment is governed on the basis of merit, competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.