The Zero-Horizontal-Velocity Orbital Release Experiment: A Proposal for a Critical Test of Earth's Gravitational Predictions

The trajectory of a body released at high altitude with zero horizontal velocity relative to a chosen reference frame is one of the most conceptually transparent predictions of classical and relativistic gravitational theory, yet a dedicated, purpose-built, publicly instrumented demonstration of this specific configuration — as distinct from orbital deployments, ballistic re-entries, or drop-tower experiments — has, to the author's knowledge, never been executed as a stand-alone experiment with the reference frame, release conditions, and predicted trajectory stated a priori and made falsifiable. This paper develops the Zero-Horizontal-Velocity Orbital Release Experiment (ZHVORE): a fully specified experimental proposal in which a payload is carried to a prescribed orbital altitude and released with its velocity vector nulled with respect to the geocentric, non-rotating (Earth-Centered Inertial, ECI) frame, so that in the absence of non-gravitational forces its subsequent motion is purely radial infall governed by r̈ = −GM⊕/r². We derive the full equations of motion in both the ECI and Earth-Centered, Earth-Fixed (ECEF) frames, obtain closed-form and numerical solutions for the radial fall time, terminal velocity, and Coriolis-induced apparent deflection as observed from the rotating Earth, and specify a complete engineering and instrumentation design (orbital insertion and velocity-nulling sequence, GNSS/laser-ranging tracking, redundant inertial measurement, telemetry) capable of resolving the predicted trajectory to sub-meter and sub-millisecond precision. We are explicit, in the interest of scientific honesty, that this experiment is not expected to distinguish Newtonian gravitation from general relativity at any presently achievable precision, nor to overturn a body of gravitational evidence that is already overwhelming; rather, its scientific value lies in providing an unambiguous, single-configuration, pre-registered, and independently reproducible confirmation of 1/r² radial free fall and frame-dependent Coriolis deflection, together with a fully specified falsification criterion. We quantify the technical difficulty of achieving a true zero-horizontal-velocity release — which requires cancelling the body's inertial tangential velocity of several hundred meters per second at orbital altitude, not merely its velocity relative to the launch vehicle — and we present a multi-parameter sensitivity and uncertainty analysis, a scientific risk assessment, and a staged roadmap toward experimental validation. The paper concludes with a full complement of transparency statements (funding, data availability, conflicts of interest, ethics, and author contributions) appropriate to a theoretical and experimental-design manuscript.