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Frame
The Frame is what houses the satellite's internal components. It is designed to integrate's all required sub-systems and adheres to SpaceX's structural launch requirements. Details of its design, manufacture, verification and validation are listed below. This document was written in reference to CTS-SAT-1, also called FrontierSat. Throughout this document it will be referred to as SAT1.
All subteams affect the frame, all subteams require the frame to house their components adequately so that they may be used effectively. How subsystems work will not be described in detail. How they must be installed is described in detail, and references to appropriate documents are listed below.
Attitude Determination and Control System (ADCS)
The ADCS system requires very specific integration into the frame. Its function is to determine the orientation of the CubeSat, and point in the desired orientation. The ADCS used for CTS-SAT1 was a CubeADCS-1 (no longer sold). It was composed of a main control board (CubeControl), connected to the interface board (CubeConnect), three reaction wheels, three CubeCoils and a main computer (CubeComputer). Our configuration also included two CubeSense cameras, which serve as fine sun sensors. We opted to not use an added CubeStar, star tracker since we decided the added pointing accuracy was not required. These were all part of the "main" ADCS unit fastened to the frame on the PC104 stack as one integrated unit. This main unit must be placed within
The ADCS also had one magnetometer, this must be placed on the outside of the CubeSat. The magnetometer is used to orient the SAT during detumbling. Detumbling being the period immediately after being ejected from the Launch Vehicle into orbit. The magnetometer is a 80mm long boom which deploys so that the sensor at its end can detect earth's magnetic field without electro-magnetic interference from the SAT. The magnetometer is wide enough that it fits within the SAT's protrusion tolerance of 6.5mm from the surface.
The ADCS also has 10 optional coarse sun sensors which are ideally placed on each surface of the SAT. Hence ideally six are used at a minimum. These are used for increased pointing accuracy during flight by determining the orientation of the SAT in relation to the sun.
Two fine sun sensors are also included with the ADCS. Ideally one is placed facing the sun and one is placed facing the earth. When setting up the ADCS, one is typically labelled as "Nadir" and one "Zenith". These have a much greater increase in pointing accuracy than the coarse sun sensors. These are also mounted the main ADCS assembly, thus they must visibility through the frame to the outside.
RF Communications Antenna
The Communications antenna is used to communicated with CalgaryToSpace's ground station. The antenna currently being used by SAT1 is an ISISpace, four pronged deployable antenna. It must be oriented such that two of the deployed prongs are perpendicular to the earth for best performance. The prongs are deployed from the antenna using a burn wire mechanism. All four smallest sides of the antenna must be exposed to space to allow the prongs to deploy properly. The external dimensions of the communications antenna allow for easy integration with CubeSat frames since it allows for rails to go through each corner and it overall smaller than 100mm by 100mm.
GPS Antenna
The GPS antenna used for SAT1 is a Talisman XXL889XF-3 (adhesive tape). It must be placed so that it is exposed to the outside of the frame to communicate with GPS antennas above it. GPS satellites are typically in high earth orbit, so the GPS antenna must be pointed in the zenith direction for best performance. This antenna has no flight heritage, so it endured slightly more "engineering scrutiny" than other components selected which had flight heritage. Ideally, the GPS antenna does not have any other components on that same face than where it is installed to prevent interference. It also should ideally have an aluminum back plate so there is no interference directly below it. This was not done due to size constraints of the SAT. It was instead installed on the top plate of the communications antenna. Since the SAT is supposed to do a 90 degree rotation during its flight, it was also placed here because it would have the same orientation in reference to the GPS satellites above it before and after this 90 degree rotation. An adhesive version was selected to avoid modifying the top plate of the communications antenna.
Communications Daughterboard
The daughterboard selected is a GomSpace NanoDock DMC-3. The daughterboard adheres to the PC-104 dimensions and holds both the RF communications receiver and the GPS receiver. Both receivers are held onto the frame with standard M2.5 fasteners. The main constraint on the daughterboard was wiring related, but this will be elaborated on in another section of the wiki.
On Board Computer (OBC)
The OBC controls everything in the SAT. It must be connected to most systems of the SAT. During its development it was very important for structural and electrical sub-teams to communicate about where some connectors would be to account for the room required for electrical harnesses. Mechanically, it adheres to the PC-104 dimensions.
Electrical Power System (EPS)
The EPS of SAT1 is an ISISpace ICEPS2 daughterboard and a battery pack. Both the daughterboard and battery pack should ideally be close to each other since they are are wired together. All solar panels are connected to the EPS, so having it central to the SAT is best to reduce wiring. Both the daughterboard and battery pack adhere to the PC-104 mechanical standard.
Mini-Plasma Imager (MPI) The MPI is our main scientific payload for CTS-SAT1. It was developed by Dr. Burchill at UofC. The main constraints of the MPI are the its frontal slit must be exposed and pointing in the opposite direction of the SAT's velocity. This is so that it can record energy from ions in the atmosphere and measure their energy. The MPI's main analyzer must be electrically grounded from the rest of the SAT to not interfere with measurements of the MPI. To create this grounding, the MPI uses PEEK fasteners and sheets on critical surfaces to prevent metal to metal contact with sensitive components.
Deployable Composite Lattice Boom The DCLB (herein referred to as the "Boom") was developed at UofC by Dr. Nick Elderfield. It is a continuous carbon fiber 3D printed boom which uncoils from the SAT. A picture will be taken of the boom with the piCam camera to ensure it was properly deployed. The Boom is held in a coiled state with the use of a small dyneema chord. A nichrome wire runs along this, when a voltage is applied the dyneema wire is burned through and the Boom is released.
Camera To take pictures of the Boom, the SAT has a SkyFoxLabs piCam mounted directly above. The camera must be mounted correctly to the frame, and is using aluminum standoffs. The camera is our main optical payload on the SAT, thus it is the main reason that off gassing is a concern.
All sub-teams are affected by the frame, as is stated in the previous section, performance of all sub-team's components are dependent on where they sit within the main structure of the SAT.
A CubeSat's frame achieves two main functions:
1 - Adhere to all dimensional standards set by CalPoly standards and/or Launch Provider(LP)
a) Dependent on if LP is selected, if not default is to use CalPoly standards rev 14.1: https://static1.squarespace.com/static/5418c831e4b0fa4ecac1bacd/t/62193b7fc9e72e0053f00910/1645820809779/CDS+REV14_1+2022-02-09.pdf
2 - House all components of the SAT so that they can perform optimally.
a) All components properly located within frame. Including all electrical and other specific requirements. b) All components are in the correct temperature range throughout flight.
3 - Protect all components from the harsh environment of a rocket launch.
a) At a minimum, frame adheres to random vibration standards set by LP. b) Optimally, frame is also tested with sine burst, shock test and quasi-static vibration test.