Junior Mechanical Engineer Leidos is seeking a motivated Mechanical Engineer to support critical national security missions in Reston, Virginia. This role focuses on the assessment, reverse engineering, and characterization of complex above-ground and subterranean facilities located in denied-access environments. The successful candidate will apply mechanical engineering principles to analyze facility designs, spatial layouts, operational workflows, and supporting infrastructure to determine functional capabilities and mission relevance. You will evaluate facility systems, model critical infrastructure, identify vulnerabilities, and contribute technical insights that support complex intelligence and defense initiatives. This position is ideal for an engineer who enjoys solving challenging problems in situations where complete information is rarely available. The ideal candidate combines curiosity, analytical thinking, and engineering rigor with exceptional attention to detail. Working alongside experienced engineers, analysts, and government personnel, you will contribute to mission-critical assessments in a fast-paced, collaborative environment. Primary Responsibilities Reverse Engineering & Facility Characterization Analyze and characterize the physical and functional attributes of facility layouts, building architecture, and operational workflows within denied-access environments to determine facility purpose, capability, and operational capacity. Vulnerability Assessments Evaluate facility and infrastructure designs to identify security vulnerabilities, single points of failure, operational bottlenecks, and potential mission impacts. 3D Modeling & Simulation Develop high-fidelity 3D models and conduct engineering simulations to replicate facility operations, workflow efficiencies, and structural or mechanical limitations. Infrastructure Analysis Apply multidisciplinary engineering knowledge to assess supporting facility systems, with a primary focus on Mechanical, Electrical, and Plumbing (MEP) integration and functionality. Technical Documentation & Reporting Translate field-collected data, intelligence information, and engineering assessments into comprehensive technical reports, CAD/BIM products, and simulation-based analyses for Department of Defense stakeholders. Research & Development Support customer-approved research and development initiatives independently or as part of a multidisciplinary team to advance analytical methodologies, modeling capabilities, and mission solutions. Required Qualifications Candidates for consideration must possess an in-scope and active TS/SCI Polygraph clearance and the ability/willingness to maintain this clearance while holding this position. U.S. Citizenship is required. ​Working knowledge of engineering principles, theories, concepts, and techniques, with the ability to apply them to technical and mission-focused challenges. Bachelor's degree with 2+ years of relevant experience, or a Master's degree with less than 2 years of relevant experience. Relevant experience includes facility analysis, infrastructure vulnerability assessments, and mechanical engineering within commercial, Department of Defense, or Intelligence Community environments.

MEP Systems Knowledge:

Understanding of Mechanical, Electrical, and Plumbing (MEP) system design, integration, and operational functionality within complex industrial or military facilities, including specialized containment systems, filtration systems, and backup power infrastructure. Ability to identify industrial HVAC equipment, estimate system size and capacity, and assess operational capabilities through visual analysis. Ability to evaluate, organize, and utilize large datasets from diverse sources, including field-collected data, equipment technical manuals, and existing facility models. Experience with 3D modeling, engineering analysis, and physical simulation methodologies. Familiarity with interpreting engineering drawings, facility layouts, blueprints, and intelligence-derived technical data. Ability to make sound technical judgments with incomplete information and clearly communicate assumptions, information gaps, and recommended paths forward. Preferred Qualifications Two or more years of field experience working with industrial HVAC systems, including air-cooled and water-cooled chillers, condensers, cooling towers, air handlers, heat exchangers, boilers, and related equipment. Working knowledge of air management systems supporting critical environments, including medical laboratories, clean rooms, chemical laboratories, and similar specialized facilities. Hands-on experience with advanced Building Information Modeling (BIM) and engineering simulation tools, including Autodesk Revit, VENTSIM, ETAP, and other industry-standard CAD and modeling platforms. Experience supporting forensic engineering investigations, industrial accident analyses, or Department of Defense facility vulnerability studies. Professional Engineer (PE) license and/or Project Management Professional (PMP) certification. Experience identifying mechanical system vulnerabilities and developing effective corrective actions. #ASBA #Snakehead If you're looking for comfort, keep scrolling. At Leidos, we outthink, outbuild, and outpace the status quo — because the mission demands it. We're not hiring followers. We're recruiting the ones who disrupt, provoke, and refuse to fail. Step 10 is ancient history. We're already at step 30 — and moving faster than anyone else dares.

Original Posting:

August 14, 2026 For U.S.

Positions:

While subject to change based on business needs, Leidos reasonably anticipates that this job requisition will remain open for at least 3 days with an anticipated close date of no earlier than 3 days after the original posting date as listed above.

Pay Range:

Pay Range $69,550.00 - $125,725.00 The Leidos pay range for this job level is a general guideline only and not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, applicable bargaining agreement (if any), or other law.