Boston University Student Proposal for Deployable Solar and Antenna Array Microgravity Testing
PI: Theodore Fritz, Boston University
PI: Theodore Fritz, Boston University
The Boston University student Satellite for Applications and Training (BUSAT) project is a hardware development program developing a scientific nanosatellite platform for future multi-mission use with a minimum of non-recurring engineering cost. The primary goal of the microgravity flight campaign is characterization and demonstration of the mechanical responsiveness of two key hardware components: a solar panel deployment system and an antenna array deployment system. In doing so, BUSAT intends to create standardized, low-cost, and reliable nano- and pico-satellite mechanical bus subsystems for future use by defense, civilian and academic spaceflight projects.
- TA12 Materials, Structures, Mechanical Systems and Manufacturing
BUSAT's modular design is based on a standard 10 cm cube that is capable of functioning as an independent orbiting radio transponder and scientific satellite in the 3U CubeSat format, but can also scale up to a 27U nanosatellite configuration. The cubes are fixed within a modular exoskeleton that supports solar panels and communication antennas. Because of the common universal interfaces between cubes, any cube can be relocated and re-oriented within the satellite to suit mission requirements, such as the need for apertures or instrument pointing. Rather than create unique power and communication systems for each payload or mission, BUSAT sets a common physical layer, software and mechanical protocol design and is assembled in less than two hours (instrument delivery to test and integration phases). The mechanical solar panel and antenna deployment assemblies are also completely modular, allowing maximum flexibility in mounting orientation and location.
Utilizing the Triangular Advanced Solar Cells ("TASC Cells") available from Spectrolab Photovoltaic Products, nine of the 10 cm x 10 cm scalable antenna panels are mounted to a 30 cm x 30 cm aluminum substructure and constrained during launch by a TINI Aerospace Frangibolt™. BUSAT’s antenna arrays also built in a 1U configuration. Based on the concept of a tape measure, the flat spring-material flexible antenna system is capable of deploying to the correct orientation from multiple contained configurations.
The solar panel deployment system makes use of a non-pyrotechnic, fracturing bolt device which allows for spring hinges to swing the panels into an open position. As the panels open, antenna boxes positioned underneath them will extend spring-loaded, flexible antenna coils into predetermined orientations and will fix them in this orientation for the duration of the space mission. Due to the nature of these stored energy devices it is highly desirable to analyze their responsiveness in the closest approximation possible to actual condition. With several components moving simultaneously, it is important to establish that the antenna extension does not interfere with solar panel deployment while both devices are in the process of locking in place. Multiple parabolic flights are desired in order to obtain results with different hardware configurations and orientations. These tests are intended to establish the most reliable deployment strategy which will allow for the highest possibility of success in space-ready versions of these two components.
The BUSAT mechanical deployment subsystem is currently at TRL 5-6. Due to the successful repeated deployments in the microgravity environment, the solar panel deployment mechanism (kinematic mounting structure, TINI Frangibolt™ mounting assembly, custom hinges) have progressed to TRL 6. The antenna assembly progressed to TRL 5, and lessons learned during the microgravity flight campaign are feeding back to a modified design.
The result of the BUSAT program will be an integrated satellite bus that utilizes reliable, low cost, highly adaptive, standardized components. The direct results of this test plan will create the blueprints for an “off the shelf” communications and solar panel deployment mechanism that can be integrated into nearly any cube-sat sized satellite project. CubeSats missions are currently in all stages of development throughout the defense, civilian and university space research communities. Trade studies are currently underway to identify future customers in each of these communities, and seek to identify mission developers interested in minimizing the cost of development and launch.
- Conduct at least 40 complete deployments in microgravity, some of which will be free-float deployments
- Collect video data for each deployment to qualitatively analyze deployment success
- Collect accelerometer data for each deployment to quantitatively characterize the spacecraft inertial response
The BUSAT microgravity test rig is composed of three major subsystems: a support structure, a hinged aluminum solar panel support substrate, and an antenna deployment module. The structure is designed to replicate the BUSAT mechanical satellite structure and to provide adequate control in the free-flight test configuration. The deployable antenna array is based on very thin spring steel and is a low-tech, low-cost response to the need for long UHF/VHF antennas that fit in the limited physical envelope of small secondary payloads.