A satellite mission concept for high drag environments

Abstract

The United States scientific, military, and academic communities need the ability to maintain a presence within the vast gap in altitudes between where airplanes can fly and where satellites can be sustained in Low Earth Orbit (LEO). The list of potential stakeholders that could benefit from such a platform is long and includes a broad array of interests. The National Oceanic and Atmospheric Administration provides weather forecasts critical to disaster preparedness and response. The military and defense communities provide Signals Intelligence (SIGINT) and imagery (IMINT) that deepen our awareness and preparedness for potential threats to our nation and liberties. Colleges and universities conducting space weather research provide advances in our knowledge of the physical and chemical processes that inform our understanding of our environment on scales ranging from elemental to universal. As satellite altitudes decrease below 300 km, their orbits decay more rapidly due to the decelerating effects of rarefied gas interactions with satellite surfaces, as the satellite passes thought the upper layers of the Earth's atmosphere. The F region of the Earth's Ionosphere extends upward from about 160 km and is characterized by significant concentrations of free electrons. Densities of both neutral rarefied gases and charged particles in these regions vary by orders of magnitude. Day-night variations cycle over roughly 24-hour periods, and long-term variations occur due to the approximately eleven year span between solar maxima and minima. Due to the variability of these atmospheric constituents, many challenges exist for mission designers, ranging from how best to counter drag forces, to protecting against unwanted spacecraft charging. Mission designers are also faced with other inherent challenges because of these low altitude regimes, like Atomic Oxygen (AO) erosion of spacecraft materials, and short contact times. This paper examines the lower bound of satellite flight from a system perspective, presents previous research in the area, and discusses methods that may be able to narrow the gap by implementing sustained force in the satellite's orbital ram direction designed to reduce or eliminate the effect of drag, while minimizing the amount of stored propellant, thereby lengthening satellite lifetimes in these regions and enabling innovative new missions within our scientific, military, and academic communities. The classical Systems Engineering process is used to compare historical mission concepts and present a candidate satellite mission point design.