Propellantless attitude control of solar sail technology utilizing reflective control devices (a) approach: in order to reach our research goals, we have identified the 5 following tasks: task 1:…

This is a USD 200,000.00 Cooperative Agreement awarded by the National Aeronautics and Space Administration (NASA) to the University of Maryland, College Park. The contract supports research into propellantless attitude control of solar sail technology using reflective control devices. The key tasks include optical characterization of polymer-dispersed liquid crystal (PDLC) devices on glass substrates, analysis of attitude controllability based on the measurements, fabrication and testing of flexible PDLC devices on polyimide film, and high-intensity solar environment testing of scale devices. This effort aligns with NASA's research goals in advanced solar sail propulsion systems for future deep space missions. The contract has no set-aside designation.

Propellantless attitude control of solar sail technology utilizing reflective control devices (a) approach: in order to reach our research goals, we have identified the 5 following tasks: task 1: optical characterization of pdlc devices on glass: 1. This task will focus on the optical characterization of pdlc devices on glass substrates to determine the optical properties needed to determine switchabiliy of radiation pressure and attitude control performance. 2. Detailed description of the steps to this approach: a. Fabrication of pdlc devices on glass substrates with thicknesses ranging from 6M to 50M using techniques that we have already developed. B. Measure turn-on voltage necessary for switching from transparent to diffusely reflective for the different pdlc thicknesses. C. Estimate power consumption as a function of effective area due to leakage current within device. D. Measure angular and wavelength dependent transmission and reflection from devices. E. Separation of diffuse and specular components of reflectivity. 3. Expected outcome: a. Quantitative optical data that describes transmission and reflection from pdlc devices for use in predicting performance in attitude adjustment based on radiation pressure. B. Quantitative information about power requirements of device. Task 2: calculate and analyze attitude controllability based on task 1 measurements: 1. This task will use the optical data obtained in task 1 to quantitatively compute the expected attitude control performance of the proposed technology based on the predicted radiation pressure. 2. Detailed description of the steps to this approach: a. Compute the force from solar radiation pressure as a function of applied voltage based on the experimentally obtained optical properties. B. Calculate the differential force from solar radiation pressure between transmissive and reflective samples of equal area. C. Estimate moment arms for a practical application of the device for a nominal solar sail design (NEA scout and lunar flashlight solar sail designs should be used for reference). 3. Expected outcome: a. Detailed knowledge of the difference in solar radiation pressure force between the reflective and transmissive states of the pdlc device. B. A realistic model of the control torque that can be achieved with the pdlc device for use in mission design and sailcraft control studies. Task 3: fabrication of flexible pdlc devices on CP1: 1. This task will involve the creation of small scale, flexible pdlc devices for incorporation into a solar sail. 2. Detailed description of the steps to this approach: a. Create transparent, flexible film for glass-free encapsulation of pdlc using CP1 coated with indium tin oxide (ITO). A small dielectric spacer layer (e.g. SIO2) will be used to avoid shorting the device as IT is folded (FIG. 5C). B. Disperse index-matched microparticles within the pdlc as a spacer layer. 3. Expected outcome: a. Flexible pdlc device with a minimum size of 5 CM x 5 CM. Task 4: optical and mechanical testing of flexible pdlc devices on CP1: 1. This task will involve the optical and mechanical testing of the flexible pdlc device created in task 3. The pdlc device will need to be folded (or rolled) in a manner identical to that used for NEA scout and lunar flashlight. 2. Detailed description of the steps to this approach: a. Device will be rolled with variable bend radii starting with 1 CM and decreasing until device breakdown. B. Optical response will be determined as a function of applied voltage before and after bending. 3. Expected outcome: a. Storage volume requirements of this system for the pdlc device. B. Data on the survivability of the pdlc device while folded and stowed. Task 5: testing of devices at scale (8 CM in one dimension) in msfcs high intensity solar environment test (hiset) system environment: 1. This task will involve the creation of 8 CM wide flexible pdlc devices and testing