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David C. Folta

Publications and source records attributed to David C. Folta.

Geometrical Analysis of Station-Keeping Strategies About Libration Point Orbits

Throughout the years, different strategies have been proposed for the station-keeping around the libration point orbits. In this paper, a geometrical comparative analysis is performed between different approaches making use of the Floquet modes reference frame. Two particular station-keeping procedures are considered: the commonly used velocity constraint at the plane crossing, and the Floquet mode approach. The first method finds the Δv that ensures that the x component of the velocity vector is zero at a plane crossing, whereas the Floquet mode approach finds the Δv that cancels the unstable mode in the Floquet reference frame. It will be seen that both approaches have some basic common geometrical features, even when they are compared using high-order techniques.

station keeping

Chapter 15: Propulsion System

During mission design, many trades are made that have varying levels of impact on the spacecraft. The types of subsystems that are selected affect the spacecraft mass,volume, power, and cost. Choosing the right propulsion system for a CubeSat mission is key to that mission’s success. There are many CubeSat propulsion systems on the market today. The CubeSat community desires to understand how to assess the available propulsion systems and how to apply them to their mission designs. The purpose of this chapter is to inform the reader of the key factors that must be considered when evaluating and applying these systems for various missions.

CubeSat

Fast Earth-Mars Roundtrip Trajectories to Reduce Health and Safety Risks for Crewed Missions

The extended mission duration of a crewed Mars mission compounds integrated risks to crew health and safety. Shortening mission duration would therefore have a direct impact on reducing many human health and performance risk factors. This paper describes trajectory feasibility analyses performed to examine trajectory options for a fast crewed mission to Mars. Studies were conducted to examine options with short overall mission durations (≤ 400-day roundtrip) and options that focus on minimizing astronaut time in deep space, while allowing for longer Mars surface stays. Trade studies were performed to determine ∆v requirements for a range of launch dates, Mars orbit periods, Mars stay times, and Earth-to-Mars flight time maxima. The implications of a Venus gravity assist are also described. The analyses presented here build on and specifically aim to optimize and address key concerns of assumptions made in previously published studies of fast crewed Mars missions.

Mars

Application of Tisserand's Criterion and the Lidov-Kozai Effect to STORM's Trajectory Design

The Solar-Terrestrial Observer for the Response of the Magnetosphere (STORM) concept recently completed its Phase A design funded by NASA's Heliophysics Medium-class Explorers program. The mission design required a lunar gravity assist to insert the single spacecraft into a 30-Earth-radii circular geocentric science orbit inclined 90 degrees to the ecliptic. STORM's trajectory design leveraged several interesting gravitational effects from third bodies. This paper describes our application of Tisserand's criterion for finding feasible transfers and lunar gravity assist trajectories, and the Lidov-Kozai effect to design a maneuver-free science orbit optimization and decommissioning strategy.

tisserand criterion

Mitigating the Impact of Momentum Unloads on Station Keeping Around Libration Point Orbits

The Space Weather Follow On (SWFO) observatory will observe the Sun from L1, collecting solar wind data and coronal imagery, while providing early warning for space weather events. SWFO is a ride-share mission on SpaceX Falcon9 that is carrying IMAP. The spacecraft will be operated by NOAA and is expected to launch in February 2025. In order to meet NOAA’s operational requirements SWFO must maintain a Sun-Earth-Vehicle (SEV) angle between 4 and 13 degrees for at least 5 years. This constraint drives the size of the Lissajous orbit. SWFO is required keep a Sun pointing attitude in order to perform the Sun observations. Frequent Momentum Unloads are required to desaturate its reaction wheals. Station-keeping maneuvers are required to stay in orbit around L1, they are planned to be performed every 30 days.

Libration Point Orbits

Mitigating the Impact of Momentum Unloads on Station-Keeping Around Libration Point Orbits

Station-keeping maneuvers are required to maintain a spacecraft close to a Libration point orbit, where the size of these maneuvers depends on different perturbations and any unmodeled forces. In many missions, despite being small, frequent momentum unloads can have a large impact on the size of station-keeping maneuvers. In this paper we will show that applying momentum unloads in the Linear Approximation of the Non-Escape (LANE) direction can significantly reduce their impact on the station-keeping delta-v budget.

Libration Point Orbits