An Imaging System for Automated Characteristic Length Measurement of Debrisat Fragments

The debris fragments generated by DebriSat's hypervelocity impact test are currently being processed and characterized through an effort of NASA and USAF. The debris characteristics will be used to update satellite breakup models. In particular, the physical dimensions of the debris fragments must be measured to provide characteristic lengths for use in these models. Calipers and commercial 3D scanners were considered as measurement options, but an automated imaging system was ultimately developed to measure debris fragments. By automating the entire process, the measurement results are made repeatable and the human factor associated with calipers and 3D scanning is eliminated. Unlike using calipers to measure, the imaging system obtains non-contact measurements to avoid damaging delicate fragments. Furthermore, this fully automated measurement system minimizes fragment handling, which reduces the potential for fragment damage during the characterization process. In addition, the imaging system reduces the time required to determine the characteristic length of the debris fragment. In this way, the imaging system can measure the tens of thousands of DebriSat fragments at a rate of about six minutes per fragment, compared to hours per fragment in NASA's current 3D scanning measurement approach. The imaging system utilizes a space carving algorithm to generate a 3D point cloud of the article being measured and a custom developed algorithm then extracts the characteristic length from the point cloud. This paper describes the measurement process, results, challenges, and future work of the imaging system used for automated characteristic length measurement of DebriSat fragments

An Imaging System for Satellite Hypervelocity Impact Debris Characterization

This paper discusses the design of an automated imaging system for size characterization of debris produced by the DebriSat hypervelocity impact test. The goal of the DebriSat project is to update satellite breakup models. A representative LEO satellite, DebriSat, was constructed and subjected to a hypervelocity impact test. The impact produced an estimated 85,000 debris fragments. The size distribution of these fragments is required to update the current satellite breakup models. An automated imaging system was developed for the size characterization of the debris fragments. The system uses images taken from various azimuth and elevation angles around the object to produce a 3D representation of the fragment via a space carving algorithm. The system consists of N point-and-shoot cameras attached to a rigid support structure that defines the elevation angle for each camera. The debris fragment is placed on a turntable that is incrementally rotated to desired azimuth angles. The number of images acquired can be varied based on the desired resolution. Appropriate background and lighting is used for ease of object detection. The system calibration and image acquisition process are automated to result in push-button operations. However, for quality assurance reasons, the system is semi-autonomous by design to ensure operator involvement. This paper describes the imaging system setup, calibration procedure, repeatability analysis, and the results of the debris characterization

Design Considerations for Miniaturized Control Moment Gyroscopes for Rapid Retargeting and Precision Pointing of Small Satellites

This paper presents the design as well as characterization of a practical control moment gyroscope (CMG) based attitude control system (ACS) for small satellites in the 15-20 kg mass range performing rapid retargeting and precision pointing maneuvers. The paper focuses on the approach taken in the design of miniaturized CMGs while considering the constraints imposed by the use of commercial off-the-shelf (COTS) components as well as the size of the satellite. It is shown that a hybrid mode is more suitable for COTS based moment exchange actuators; a mode that uses the torque amplification of CMGs for rapid retargeting and direct torque capabilities of the flywheel motors for precision pointing. A simulation is provided to demonstrate on-orbit slew and pointing performance

Configuration of 3U CubeSat Structures for Gain Improvement of S-band Antennas

Nano- and pico-satellites in low earth orbit (LEO), unlike their larger counterparts, have more stringent limitations on antenna design due to power constraints that govern the operational frequency and size that defines the mass and volume constraints. High bandwidth applications use higher frequencies and require higher transmission power. High gain antennas can reduce the transmission power requirements. CubeSat’s with body-mounted solar cells are limited in power generation due to limited surface area. Deployable solar panels offer a solution to the limited power by maximizing the surface area of solar cells exposed to solar radiation. The metallic deployable solar panel support structure can be exploited to behave as an electrical ground and microwave signal reflector for a high gain antenna in several configurations. This paper presents multiple novel high-gain S-band antennas that exploit the structure of a 3U CubeSat equipped with deployable solar panels for gain improvement. The configuration of the satellite is designed to operate in a low drag configuration by operating outside of the passive gravity gradient stabilized attitude by using passive or active attitude control. Gain improvements of more than 3 dB are obtained through careful packaging. The antenna configurations have a gain of more than 7dBi and bandwidth of more than 10MHz. Analysis is provided with considerations of power, satellite coverage, as well as attitude stability. This technique of improving antenna gain can be extended to higher as well as lower frequency of operation

EdUCE, Educate Utilizing CubeSat Experience: A Pragmatic Approach to Shatter Barriers to Space

The Educate Utilizing CubeSat Experience (EdUCE) project uses CubeSats to further develop and incorporate an innovative STEM approach to enhance scientific knowledge of K-12 students and teachers. Space technology is an advanced form of engineering that combines aspects of aerospace, mechanical, electrical, and computer engineering. In brief, EdUCE’s multidisciplinary science teachings provide a foundation to the early education of students. Through practical hands-on experiences into the design of complex engineering systems, the student understands applications and relationships for each discipline and their impact in engineering. Small satellites are used as the mechanism to deliver STEM concepts. At the University of Florida (UF), the Advanced Space Technologies Research and Engineering Center (ASTREC), a National Science Foundation Center, has been coordinating this activity fulfilling a charter goal to promote this approach among local K-12 schools and like-minded community organizations. This paper discusses the methodology, the activities, the systems developed, the practices, and the future actions based on past lessons to increase awareness of space technology and, in general, the human capacity development process through space system engineering outreach programs to engage K-12 students and teachers. To improve global awareness, associations with universities in other countries have been established and their role is also detailed