Principal GNC Engineer

Please Note: To conform with the United States Government Space Technology Export Regulations, the applicant must be a U.S. citizen, lawful permanent resident of the U.S., conditional resident, asylee or refugee (protected individuals as defined by 8 U.S.C. 1324b(a)(3)), or eligible to obtain the required authorizations from the U.S. Department of State.

At Cesium Astro
, we are developers and pioneers of out-of-the-box communication systems for satellites, UAVs, launch vehicles, and other space and airborne platforms. We take pride in our dynamic and cross-functional work environment, which allows us to learn, develop, and engage across our organization. If you are looking for hands‑on, interactive, and autonomous work, Cesium Astro is the place for you. We are actively seeking passionate, collaborative, energetic, and forward‑thinking individuals to join our team.

We are looking to add an experienced Principal GNC Engineer I to our team. If you are great at what you do, enjoy working in a startup environment, and are passionate about developing GNC systems for leading‑edge spacecraft, and aerospace communication systems, we would like to hear from you.

In this position, you will draw on your experience on previous spacecraft to operate on a small team in the design and analysis of GNC systems for Cesium Astro satellites and payloads. You will be responsible for Guidance, Navigation, and Control through all stages of design, integration, test, and operations. As such, you will perform trade studies, lead design reviews, create models, and complete simulations and system testing.

You will build, test, and fly hardware and software.

As a Cesium Astro spacecraft team member, you will work on a small team to develop satellites and put them in orbit. Your work will have a direct impact on the success of the company. You will work closely with the engineering team, program management to ensure the successful build and launch of our satellite. Element will be the largest, most powerful rideshare satellite in LEO.

We’re launching eight of them in the next four years, starting with our first launch this year. Together, our small team will design, build, and iterate to reduce mass and cost while increasing performance, reliability, and manufacturability of a new generation of satellites. Let’s build!

• Master of Science (MS), or Doctorate (Ph.D.) degree in Aerospace Engineering from an accredited university or institution
• Minimum of 9 years of industry experience in satellite attitude and orbit systems
• Deep expertise in spacecraft attitude estimation, guidance, and control, including nonlinear state estimation theory and implementation (e.g., Extended Kalman Filters (EKF), Multiplicative EKF (MEKF), Unscented Kalman Filters (UKF), or other nonlinear observers); coordinate frame transformations; linear algebra; and nonlinear systems
• Experience with multiple spaceflight missions from concept to operations
• Experience in low earth orbit satellites
• Experience with post‑CDR test failures and on‑orbit failures that guide your design and test philosophies
• Experience with successful and unsuccessful recovery from on‑orbit failures
• Experience in conceptualization, architecture design, requirements specification, design, test, and operations of various GNC architectures and components
• Familiarity with space mission simulation tools such as STK, Basilisk, GMAT, or Free Flyer
• Experience defining spacecraft trajectories and orbital requirements
• Fluency with Python and C++, or other modeling languages
• Familiarity with spacecraft mission design including events, pointing modes, maneuver planning, and operations
• Excellent written and verbal communication skills

• Demonstrated experience designing, implementing, tuning, and validating flight‑grade state estimators, including covariance propagation, bias estimation, sensor fusion (e.g., IMU, star tracker, GNSS, magnetometer), and Monte Carlo‑based performance analysis
• Experience performing observability analysis, estimator consistency analysis (e.g., NEES/NIS), and robustness evaluation under sensor degradation or fault…