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TRYAD
History of our Mission
The Terrestrial Rays Analysis and Detection (TRYAD) project uses 2 small satellites called CubeSats to measure gamma rays produced by high altitude thunderstorms. The two CubeSats, TRYAD 1 and TRYAD 2, will use a science instrument to detect and measure the gamma rays. The science instrument is under development by the University of Alabama in Huntsville in collaboration with NASA Goddard Space Flight Center. The two CubeSats carrying the science instrument will be developed by AUSSP students with mentoring from professors.
In the early 1990s, the space–based Compton gamma ray observatory discovered totally unexpected sources of gamma rays coming from Earth. Bright flashes of gamma rays were originating in high altitude lightning clouds. They were called Terrestrial Gamma Ray Flashes or TGF's. Since then, several theoretical models for the mechanisms of TGF's have been proposed. One of the unknowns about TGF's is their spatial structure: beam width and tilt. Large satellites measuring gamma rays cannot verify these models as several simultaneous measurements are required.
CubeSats are uniquely qualified to provide multipoint measurements in space. They are cheap, low mass, launch as secondary payloads, and can be built in a few years on a relatively modest budget.
With funding from the National Science Foundation, researchers at the University of Alabama in Huntsville (UAH) and at Auburn University (AU) are working together to build two CubeSats fitted with gamma ray detectors. The UAH team is developing the gamma ray detector using scintillating material. The AU team is developing two CubeSats capable of housing and handling the gamma ray detector.
Once launched, the AU team will command and control the two satellites and UAH will plan the operations and analyze the data. The Goddard Space Flight Center is developing the light collector for the gamma ray detector. A high bandwidth radio will be used to transmit high data rates from the satellites to ground stations. The mission will use the Globalstar system for communication between the CubeSats and the ground station.
Terrestrial Gamma Ray Flash
The two CubeSats are developed by teams of AU students with mentoring by faculty members. Teams are developing:
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the satellite structure
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deployable panels
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the power system
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the communication systems
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the on-board computer
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electronic circuits
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the software
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the attitude determination and control system.
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thermal analysis of the satellite system
This is a complex system that requires good organization and adherence to a well defined process. The teams are managed by students following the NASA systems engineering rules under faculty guidance.
The TRYAD Satellite System
The two CubeSats are electrically powered and must generate their own electricity. This is accomplished by using high performance photo-voltaic solar panels that charge 10 lithium-ion batteries. Power is conditioned and distributed to the rest of the CubeSat over several voltage lines (3.3V, 5V, 10V)
There is an on-board computer (OBC) that controls satellite functions and communicates with the ground station at AU. The OBC is a BeagleBoneBlack or BBB.
There is a subsystem that controls the orientation of the CubeSat. This is necessary to keep the science instrument facing Earth and to keep the antennas facing upward, away from Earth, to communicate with the GPS network of satellites and the Globalstar network of satellites. These satellites are in a higher orbit than the TRYAD CubeSats. So, to face them, the antennas must point away from Earth and towards higher orbits. The subsystem that controls the orientation of the CubeSats is called the Attitude Determination and Control System (ADACS). Magnetometers, sun sensors, and rate gyros are used for attitude determination. Reaction wheels and magnetic torquers are used to reorient the CubeSats in the proper direction.
To communicate with the ground station, each CubeSat has a Linkstar Duplex radio and a Simplex. The Linkstar Simplex is a broadcasting radio, and the Duplex is a transceiver.
The CubeSat structure is a rectangular box made of aluminum 6061. It keeps all other components safely fastened. This is especially important during launch, as the rocket is a hellish environment. The Mechanical team is in charge of structure and mechanical systems of the CubeSats.
Space is a very taxing thermal environment for any spacecraft. When exposed to direct sunlight, spacecraft surfaces get very hot. Alternatively, when exposed to the depths of space, spacecraft temperatures get very cold. The science instrument, batteries, and electronic components must be protected against the onslaught of temperature swings. Several strategies are implemented to prevent component failure. For instance, batteries are kept above 0˚C by a heater. The science instrument cannot face the Sun or the cold depths of space. To accommodate this, the science instrument faces Earth, to keep its temperature within the desired range.
The software team has their work cut-out for themselves. They must design an overall CubeSat Manager that keeps track of conditions and reacts to those conditions to keep the CubeSat operating properly. An orbit propagator calculates the position of the CubeSat at all times to help with managing its functions. There is an attitude manager, a power manager, a communications manager and a science instrument manager. The science instrument manager is responsible for turning the science instrument on and off, collecting the gamma ray data, and time tagging it. Then, it stores the data for later transmission to the ground. This is a very complex system and the TRYAD project needs hard working and dedicated software developers.
Types of Work and Skills Required/ Developed
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Design of mechanical parts using SOLIDWORKS
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Orbiting simulations using STK
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Electrical power budget: power IN from the solar panels and power OUT to the various electrical components of the satellite - like a bank account, we need to keep a positive balance
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Electrical design: schematics and board layout for our printed circuit boards
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Thermal simulations of all components of the satellite making sure their temperatures stay within their operating ranges. These simulations are created in Thermal Desktop
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Software for satellite control: we use Python and C/CodeComposer Studio, SQL. You will learn GitHub and how to work within a project repository.
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Leadership skills development: management and systems engineering.
Management and Systems Engineering
A team of managers and systems engineers support all engineering activities. The work follows NASA's systems engineering method, where managers help set goals, define a plan of attack, and implement the plan using advanced management tools used by successful engineering teams across the nation.
Systems engineers are in charge of overseeing the work, helping with issues, making sure documentation gets done, proper testing procedures are implemented and the requirements and specifications of the TRYAD project are adhered to.
Industry and government agencies are looking for good managers and systems engineers. The TRYAD project is providing you with a great opportunity to learn systems engineering in a realistic project environment. When companies send their recruiters to campus, they are surprised to find out how well our students are versed in this important topic.
Status of TRYAD
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The satellite development work is done in phases:
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(1) Design
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(2) Building or Fabrication
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(3) Testing and verification
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(4) Preparation for launch
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(5) Launch on a rocket
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(6) Space Operations
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(7) End of Life
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The TRYAD mission is in the fabrication phase (2)
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Both hardware and software teams are actively building
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Our next phase is testing