2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/169200Deflecting an asteroid from an Earth impact trajectory requires only small velocity changes, typically of the order of microns per second, if done many years ahead of time. For this, a highly precise method of determining the need, magnitude, and direction of a deflection is required. Although the required precision can be achieved by much less accurate extended observations, an intrinsic resolution of $μ$m/s permits the live monitoring of nongravitational orbital perturbations (Yarkovsky effect), and of a deflection effort itself. Here, it is proposed to deploy on the asteroid's surface multiple radio units to form a phased array capable of measuring radial velocities relative to Earth to about 1 $μ$m/s and ranges to 5 m. The same technology can also be used for scientific applications such as very-long baseline radio astronomy, milli-Hertz gravitational wave detection, or mapping of the solar wind.Space PhysicsInstrumentation and Detectorstext