2019.A.3.4. CubeSat complemented Radio science Small body exploration: Survey of Phobos and HO3

Author(s)

Hongru Chen (1)
Louise Tomat (1)
Daniel Hestroffer (1)

Observatoire de Paris, France

Session

A.4

Keywords

CubeSats; Radio Science; Small-body mission; 2016 HO3 asteroid

Abstract

CubeSats are small and low-cost spacecraft, and thus less indispensable than a large major spacecraft. They can be deployed to perform audacious experimental flights or landings that their mother spacecraft could not risk performing. Philae, Mascot, and Minerva-II are good examples of Nanolanders in lieu of a large spacecraft in the smallbody exploration, where a prior knowledge of the small target lacks. The BIRDY-3 project is aimed to demonstrate the CubeSat-complemented radio science technology in the small-body exploration.

This work is to investigate the application of radio science experiments with the link between the mothercraft and a CubeSat, especially to the survey of Phobos and HO3 2016. There are many mission proposed to return samples from these small bodies. For Phobos, as it can possibly be ejected from Mars or a captured C-type asteroid, knowing its structure will lead to better understanding of the formation of the early solar system, and also facilitate the proximity operation of the major mission. As for HO3, it can be easily accessed from the Earth. However, because of its small size, observations from the Earth cannot lead to clear information of its mass, gravity, or shape. However, obtaining its gravity is critical to mission operations.

The mothercraft is assumed to park on a stable orbit far from the target. The CubeSat is assumed to fly on an orbit close to the target. The CubeSat orbit is sensitive to the physical properties of the target (e.g. mass, non-spherical gravity coefficients, and orientation angles). The Doppler measurements on orbits of the mothercraft and the CubeSat can be used to estimate the parameters of interest. A covariance study can indicate the estimation accuracy under the accuracy of the Doppler measurement. The resolution of central gravity, C20, C22, libration amplitude can be obtained. The estimation can be used to determine the moment of inertia and thus lead to a better understanding towards interior structure of target (e.g. homogeneous or not, monolithic, or rubble-pile).