Retrieving Dynamics and Control of Tethered Sampling Method for Minorbody Exploration

In this paper, dynamics behavior of tether retrieval with a reel mechanism in a tethered sampling method in deep space is discussed. The tethered sampling method proposed by authors is investigated as a candidate for soil sample collection method of minorbodies for the next minorbody exploration mission. The method consists of three phases: 1) shooting a corer together with a tether, 2) inserting the corer into a surface and collecting soil in the corer, 3) pulling back and retrieving the corer with the tether. This paper mainly deals with dynamics of the tether and corer in the recovery phase, and numerical simulations and fundamental experiments of the tether dynamics are conducted using a tether control mechanism. A tether tension control is proposed and tether and corer coupled dynamics are made clear by the numerical simulation. Moreover, experimental investigations are conducted by using a sampler horn and a reel mechanism which can control the tether tension and measure the tether length and velocity. The results of the experiments are compared with the results of the numerical simulation to show the feasibility of the proposed method.