Operational Mass Measurement for Flyby Reconnaissance Missions of Potentially Hazardous Asteroid

TL;DR

This paper investigates a rapid method for measuring the mass of hazardous asteroids during flybys using a host spacecraft and CubeSat, focusing on intersatellite measurement techniques and their effectiveness across different asteroid sizes and flyby speeds.

Contribution

It introduces a novel approach combining high-precision laser and Doppler systems for mass estimation during flybys, improving sensitivity for small, fast-moving asteroids.

Findings

Laser-based intersatellite ranging enables mass measurement of 50-100 m asteroids.

Radio-frequency measurements are ineffective for small asteroid mass determination.

Timing of final maneuver critically affects measurement success, especially for small objects.

Abstract

This study evaluates a technique for determining the mass of a potentially hazardous asteroid from a high-speed flyby in the context of a rapid reconnaissance planetary defense scenario. We consider a host spacecraft that dispenses a small CubeSat, which acts as a test-mass. Both spacecraft perform approach maneuvers to target their flyby locations, with the host targeting a close proximity flyby and the CubeSat targeting a distant flyby. By incorporating short-range intersatellite measurements between the host and the CubeSat, the mass measurement sensitivity is substantially improved. We evaluate a set of proposed host and CubeSat hardware options against the 2023 and 2025 Planetary Defense Conference hypothetical threats, as well as a hypothetical flyby of 2024 YR4. These scenarios differ predominantly in their flyby speeds, which span from 1.7 to 22 km/s. Based on these scenarios, we demonstrate that a typical radio-frequency intersatellite measurement is ineffective for asteroids with diameters relevant to planetary defense (i.e., 50 - 500 m). However, we find that augmenting the system with a laser-based intersatellite ranging system or a high-precision Doppler system can enable mass measurements of asteroids as small as 100 m across all cases, and as small as 50 m for the slower (< 8 km/s) cases. The results are very sensitive to the timing of the final maneuver, which is used to target the low-altitude flyby point. This presents an operational challenge for the smallest objects, where optical detection times are comparatively late and the optical navigation targeting knowledge converges too slowly.