Impact of Plasma-Induced Arcing on ISS Touch Temperature

Abstract

To date, the International Space Station (ISS) has been one of the largest objects flown in lower earth orbit (LEO). The ISS utilizes high voltage solar arrays (160V) that are negatively grounded leading to pressurized elements that can float negatively with respect to the plasma. Because laboratory measurements indicate a dielectric breakdown potential difference of 80V, arcing could occur on the ISS structure. The paper identifies anodized aluminum surfaces, chromic acid and sulfuric acid anodized, on the ISS, which could arc due to plasma charging. An assessment of the effects of plasma-induced arcing on these ISS anodized surfaces, with and without concurrent micrometeoroid and orbital debris (MM/OD) impacts has been completed. The purpose of this study was to assess the loss of thermal control capability of the anodized surfaces on ISS if the Plasma Contactor Units (PCUs) were not continually operated as ISS is constructed and operated. The study considers six cases for the arcing Chromic Acid Anodized Aluminum (CAA) surfaces or Sulfuric Acid Anodized Aluminum (SAA) with no Micrometeoroid/Orbital Debris impacts (MM/OD), with MM/OD impacts that completely penetrated the anodize layer, and with MM/OD impacts that partially penetrated the anodize layer. The Marshall Space Flight Center (MSFC) performed analyses to provide the data giving the size and depth of penetration of MM/OD impacts. All six cases documented the thermal control properties of the anodized layers throughout the ISS life without PCU operations.