AggieSat Lab - Engineering Subsystems

AggieSat Lab engineering students are responsible for the design, assembly and testing of all AggieSat Lab satellites. Each satellite is divided up into multiple subsystems with students assigned according to their time and interests.

Subsystems

Command & Data Handling: Command & Data Handling acts as the central control for processing of all data and commands aboard an AggieSat satellite. This term is broad as it encompasses the underlying software architecture that promotes the flow of commands from ground station crews to individual satellite components designed to carry out experiments. C&DH must direct all commands to an appropriate experiment, allocate time for that experiment to run given power or time constraints and return any experimental data back down to ground crews in an efficient yet standardized manner.
Client: Client is a generic term applied to any software required by ground operations to communicate with an AggieSat satellite. Software written as a Client will contain the ability to acquire ground stations by either directly interfacing with them or by utilizing a central server which will collect and store data from multiple distributed stations. Client allows ground crews to select from a wide range of commands to send to a satellite and the ability to process and store all data received from the satellite.
Web Developement: All development concerning web accessible material about AggieSat Lab falls under Web Development. Goals for future development concerning online material include support for web accessibility standards that promote standardization of web applications and assistive technology. Standards that will be supported in current and future work include XHTML 1.1, CSS 2.1, WCAG 2.0 and Section 508 of the Rehabilitation Act. Another task of web development is to continuously analyze current trends in web standardization to insure future compatibility while maintaining minimal overhead associated with maintenance of web material.
Global Positioning System: With modern demand for autonomous rendezvous and docking between satellites, accuracy of a satellite's location is critical. Global Positioning Systems provide real time location information to C&DH systems aboard satellites for determining its relative location in space. By coordinating its position with that of another satellite, both would have the capability to dock with each other provided the accuracy of the GPS device is adequate. GPS devices utilized by AggieSat Lab are provided by NASA for testing and implementation within current and future AggieSat satellites.
Structure: Structure consists of design, analysis, production and testing of a satellite. Structure works with all of the physical components of a satellite and ensures that they meet NASA and safety standards. Some of this quota includes the use of approved materials, performing static and thermal analyses, assembly and integration, and vibration testing of the satellite.

Communications: Communications oversees the exchange of information either between multiple satellites or between a satellite and ground station. This consists of the components of the communication process such as the antenna, radio hardware, the receiving ground station, analysis, and testing. From the analysis and testing processes, the communication systems must be able to overcome atmospheric interference, doppler effect, power constraints, orbital limitations, frequency limitations, pass spectrum analysis, and meet desired wave propagation times.
Electrical Power System: The Electrical Power System handles the processing, collection, storage, and distribution of the satellite's power. EPS designs, examines, creates and tests the components of the power system which are made up of solar panels, batteries, circuit boards, and the accompanying harnessing.
Attitude Determination & Control: AggieSat satellites can be outfitted with a three axis stabilization and control system. With an ADC system, a satellite would posses the capability to maneuver to pointing attitudes for communications passes (pointing at College Station and other ground sites) , positions required for sun tracking to maximize solar power acquisition, and for setting up viewing conditions for Stereo camera tests. An ADC system would contain reaction wheel assemblies, one per axis, to provide torque for these maneuvers and use magnetometer and GPS data to obtain spacecraft position in relation to the Earth's magnetic field and the GPS constellation.
Stereo Vision: AggieSat3's primary mission is to serve as a test bed for stereo vision technologies as a solution for obtaining data for relative navigation. In future systems, stereo eyes onboard a spacecraft may someday be able to identify, track, and compute range and orientation of other objects in space. This would allow autonomous spacecraft to move successfully in relation to other spaceborne objects including the International Space Station, supply vehicles, and even derelict spacecraft. To do this, proper camera systems and computer algorithms must be available that complete the complex computations needed. AggieSat3 will carry a stereo system and provide image scenes from orbit that will be used to develop the first generation of algorithms for vision based relative navigation. The lab intends to find out whether or not a system such as this can reliably assemble a stereo scene from two space images. If this can be done, the lab will work on algorithms of increasing complexity; first tackling the range to target problem, and then eventually attitude determination, and object identification.