Engineering topics
Andy Heaton
Publications and source records attributed to Andy Heaton.
Solar Sail Control Actuator Concepts
The thrust produced by a solar sail is a direct function of its attitude. Thus, solar sail thrust vector control is a key technology that must be developed for sailcraft to become a viable form of deep-space transportation. The solar sail community has been studying various sail Attitude Control System (ACS) actuator designs for near Earth orbit as well as deep space missions. These actuators include vanes, spreader bars, two-axis gimbals, floating/locking gimbals with wheels, and translating masses. This paper documents the various concepts and performs an assessment at the highest level. This paper will only compare the various ACS actuator concepts as they stand at the publication time. This is not an endorsement of any particular concept. As concepts mature, the assessments will change.
A High Inclination Solar Mission Enabled by Near-Term Solar Sail Propulsion
Our current understanding of the Sun, its atmosphere, and the heliosphere is severely limited by a lack of good observations of the Sun’s polar regions. A High Inclination Solar Mission (HISM) mission would go into a 0.48-AU circular solar orbit with at least a 60° inclination to conduct long-term observations of the Sun’s poles using both situ and remote-sensing instruments to study the connections between the Sun, the solar wind, and solar energetic particle events. The propulsion requirements to implement HISM are beyond the capability of conventional chemical propulsion and extremely challenging even for highly efficient solar electric propulsion. To enable HISM and a host of other propulsion-intense space science missions, NASA is actively developing solar sail propulsion, capable of continuous low thrust for the extended periods of time required to meet the delta V requirements of HISM. Upcoming solar sail missions include the Near Earth Asteroid (NEA) Scout (2021 planned launch) and Solar Cruiser (candidate for flight in 2024).Solar sails use sunlight to propel vehicles through space by reflecting solar photons from a large, highly-reflective sail. This continuous photon pressure provides propellantless thrust, allowing for very high delta V maneuvers on long-duration, deep-space exploration. Since the Sun supplies the necessary propulsive energy, solar sails require no onboard propellant, thereby potentially increasing useful payload mass. The NASA MSFC Advanced Concepts Office recently completed a detailed mission concept study of HISM based on the solar sail propulsion technologies being developed for NEA Scout and Solar Cruiser. The HISM spacecraft concept envisions carrying a Doppler & Stokes Imager, a coronagraph, magnetometer, Faraday Cup, a plasma spectrometer, and a radio and plasma wave package to meet the science objectives established for a solar polar orbiting mission in the Heliophysics Decadal Survey. This paper will describe the mission concept and its solar sail propulsion system
Attitude Control System for the Solar Cruiser and Future Solar Sail Missions
NASA’s Marshall Space Flight Center (MSFC) is developing the Solar Cruiser solar sail mission to continue to mature solar sail propulsion. Solar Cruiser is a 95kg spacecraft capable of deploying a 1654 square meter solar sail. Solar Cruiser will demonstrate science observation capabilities and navigation in sub Lagrange Point (L1) halo-orbits. Solar Cruiser sail technology can be scaled to larger solar sail missions, including attitude control system and sail membrane and boom technology. Larger solar sails could be used to image the solar poles, enabling Solar Polar Imager (SPI) missions currently prohibitively expensive for propellant-based propulsion methods. Similarly, solar sails can be used to create artificial equilibria and indefinite station-keeping at locations sunward of Lagrange Point one, L1, along the Sun-Earth line (SEL), which can provide space-weather monitor and prediction and reveal discoveries about our Sun and solar system. To achieve the high characteristic acceleration required for larger solar sail missions such as SPI, a solar sail area of approximately 7000 square-meters would be needed. In comparison, the largest solar sail flown to date is the JAXA’s IKAROS mission with a 196 square-meters sail. Attitude control an SPI-size sail poses challenges, including station keeping under solar sail induced torques and thrust vector pointing. In this study, the scalability of the Solar Cruiser sail attitude control architecture to larger sails is studied, such as pointing control performance, mass and power requirements. Solar Cruiser attitude control actuators include propellant-based, such as ion engines, and propellantless options which create differential solar pressures to generate spacecraft torques. Propellantless attitude control includes active translation of the center of mass, Reflectivity Control Devices (RCDs), and tip vanes. The study summarizes the scalability characteristics of the different attitude control architectures for larger solar sail missions.
An Integrated Software Architecture for Solar Cruiser Mission Design and Navigation
Solar Cruiser is a solar sailing mission, riding as a secondary payload to the Interstellar Mapping and Acceleration Probe (IMAP) mission, slated to launch in February of 2025. The Solar Cruiser vehicle will generate thrust via a complex, low-thrust solar sail. The extreme low-thrust nature of the solar sail will leave Solar Cruiser highly sensitive to external environmental effects (such as solar radiation pressure and high-order gravitational perturbations) throughout the entirety of flight. Because of this, preliminary operational optimization routines must be intricately tied to high-order predictive propagation models to ensure the greatest possible confidence in mission success. The Solar Cruiser Mission Design and Navigation (MDNav) team has designed a software tool suite, employing the latest in software containerization technology, to accomplish this task; allowing for seamless development across several users and operating systems. Combining JPL’s Monte toolkit with high-performance optimizers written by the University of Alabama, the proposed architecture allows for instant verification of optimized trajectories within the same development environment that the optimization takes place, removing the need for mission designers and navigators to switch between tools. The MDNav suite image deployment process is separated from the development and operational scripts to be used in flight, which allows for maintaining a low-footprint version control profile without unnecessary file bloating. This paper discusses the historical differences between previous iterations of the Solar Cruiser MDNav tool suite and the current iteration, planned operational interfaces of the tool with other software and subsystems, and the planned path forward in maintaining containerization services for the software throughout the lifetime of Solar Cruiser.
An Integrated Software Architecture for Solar Cruiser Mission Design and Navigation
Solar Cruiser is a solar sailing mission, riding as a secondary payload to the Interstellar Mapping and Acceleration Probe (IMAP) mission, expected to launch in February of 2025. The Solar Cruiser vehicle will generate thrust via a complex, low-thrust solar sail. The extreme low-thrust nature of the solar sail will leave Solar Cruiser highly sensitive to external environmental effects (such as solar radiation pressure and high-order gravitational perturbations) throughout the entirety of flight. Because of this, preliminary & operational optimization routines must be intricately tied to high-order predictive propagation models to ensure the greatest possible confidence in mission success. The Solar Cruiser Mission Design and Navigation (MDNav) team has designed a software tool suite, employing the latest in software containerization technology, to accomplish this task, allowing for seamless development across several users and operating systems. Combining JPL’s Monte toolkit with high-performance optimizers written by researchers at the University of Alabama, the proposed architecture allows for instant verification of optimized trajectories within the same development environment that the optimization takes place, removing the need for mission designers and navigators to switch between tools. The MDNav software suite itself is separated from the development and operational scripts to be used in flight, which allows for maintaining a low-footprint version control profile – thus avoiding unnecessary file bloating. This paper discusses the historical differences between previous iterations of the Solar Cruiser MDNav tool suite and the current iteration, planned operational interfaces of the tool with other software and subsystems, and the planned path forward in maintaining containerization services for the software throughout the lifetime of Solar Cruiser.
Reflectivity Control Device (RCD) Roll Momentum Management for Solar Cruiser and Beyond
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