Hypothetical asteroid 2023 PDC mass measurement via Doppler gravimetry in a reconnaissance flyby

Rapid reconnaissance flyby missions are highly desirable for planetary defense due to their ability to quickly characterize a potentially hazardous asteroid. However, traditional flybys lack the ability to measure some of the most important characteristics of an asteroid: mass, density, and porosity. These highly related features are needed to estimate potential damage to Earth and to plan mitigation strategies. Using standard Earth-based ranging and Doppler tracking of the spacecraft as it flies by is not sufficient for the smaller asteroids that are of most concern for planetary defense. In this study, we apply a new technique, Doppler Gravimetry (DopGrav), to the 2023 Planetary Defense Conference hypothetical impact scenario. DopGrav supplements traditional Earth-based tracking of the flyby spacecraft with Doppler and optical measurements from the spacecraft to one or more test-masses that can pass much closer to the asteroid. We augmented the scenario reconnaissance flyby mission with a 6U CubeSat test mass, and use a similar concept of operations to what was demonstrated by LICIACube and DART. We show that with this addition, it would be possible to measure the mass of the hypothetical asteroid to better than 3% 1 sigma. This would greatly increase the utility of such a flyby reconnaissance mission and if the scenario were real it would allow for a much more tailored response to mitigate the asteroid.