SWIFT: Sailcraft Charging Analysis Along Sun–Earth Line at <i>L</i> 1

The Space Weather Investigation Frontier mission aims to reveal whether local or global processes drive mesoscale heliospheric structures that can affect the solar wind-magnetosphere coupling. To achieve this, a sailcraft, equipped with fields and plasma instrument suites, will be placed at at sun–Earth sub-Lagrange point [Formula: see text] to monitor Earth-bound solar wind. One possible challenge with solar sails is spacecraft charging due to the large collection area of the sail relative to the sailcraft chassis, which can interrupt instrument operation, introduce noise to scientific measurements, or potentially damage subsystems. Using Nascap-2k, simulations were performed to investigate the interactions between solar sails and the solar wind over a range of solar wind conditions and the tilt angle between the sail and sun. The electric potential of the sailcraft with respect to the plasma and sheath structure surrounding the sailcraft were determined under the various solar wind conditions. It was found that the potential relative to the solar wind is smaller than 10 V under all ambient space conditions when the solar sails were electrically connected to the sailcraft bus. This meets the requirements not only to detect superthermal electrons and energetic ions but also to detect core electron and ion populations.