The Transiting Exoplanet Survey Satellite (TESS) scans the sky from a highly elliptical high-Earth orbit in stable 2:1 resonance with the Moon — one TESS orbit for every two lunar orbits, with a period of about 13.7 days. Perigee is near 108,000 km and apogee near 376,000 km, keeping TESS above the Van Allen radiation belts while the Moon's gravity is phased to cancel long-term perturbations. This resonant orbit, also used by IBEX, provides uninterrupted sky coverage for transit photometry. TESS has discovered thousands of exoplanet candidates around nearby bright stars, including TOI-700 d, a potentially habitable Earth-sized world 100 light-years away.