Mass Estimation of Small Asteroids during Fast Flybys using Swarms of Spacecraft

It is challenging to measure the mass of an asteroid in a high-speed spacecraft flyby, especially for the small 50-140 m diameter asteroids that are the primary concerns for planetary defense. Prior work on improving the mass measurement capability of flybys has focused on deploying single-use test-masses from a host spacecraft and tracking them using relative measurements. Instead of test-masses, this research studies the possible mass measurement performance from using multiple full spacecraft to perform the flyby. We find that with interspacecraft measurement accuracies of 0.1 mm/s for range-rate and 1 m for range, four spacecraft can measure the mass of 140 m asteroids to better than 15 $$%$$ % 1 σ σ for flyby speeds up to 20 km/s, or 50 m asteroids up to speeds of 5 km/s. With a better intersatellite range-rate measurement accuracy of 0.1 μ μ m/s, four spacecraft can measure the mass of 50 m asteroids for speeds up to 20 km/s as well. These results demonstrate the capabilities required to measure asteroid masses in most planetary defense scenarios.