Test Procedure (STK - Systems Tool Kit simulation)

Overview:

This testing and simulation procedure ensures that the CubeSat's pointing system is accurately aligned and capable of performing its intended functions within the space environment, minimizing the risk of mission failure and maximizing mission success.

1. Preparation:

   • Test components of the station:
     • Test Helmholtz’s ability to generate the magnetic field

   Cage Magnetic Field Direction	Magnetic Field Strength (A/m)	How the X component of the magnetorquer would move	How the Y component of the magnetorquer would move
   (0,0,1)	1	N/A	N/A
   (1,0,0)	1	0°, 180°, 360°	90° CW, 270° CCW
   (1,1,0)	1	45° CCW, 315° CW	45° CW, 315° CCW
   (1,1,1)	1	45° CCW, 315° CW	45° CW, 315° CCW
   (0,1,0)	1	90° CW, 270° CCW	0°, 180°, 360°

   Set up a controlled testing environment that mimics the conditions the CubeSat will experience in space with all required (this will be done utilizing the Helmholtz cage and STK)

   • Low Earth Orbit Simulation: (160 km to 2000km above Earth’s surface)
     1. Open software and create new scenario
        1. Define mission start and stop dates
        2. Include terrain data
        3. Insert objectives like Satellite and Facilities (ground station) into scenario
        4. Propagator incorporates external forces
           1. Gravity: $F= mGM/R^2$
           2. Control temperature using regulation system only if necessary
        5. Simulate Atmospheric drag by adjusting pressure in the testing chamber to match low Earth orbit conditions.

        • Must consider the following:

          • Shape model

          • Drag Coefficient: kept as constant but not true in reality

          • Drag Area: amount of drag the object experiences during flight

            

          • Area to Mass Ratio

          • Solar Flux/Geo Magnetic

            

                      Atmospheric drag - Velocity per rev 
            

            

                 Force of Drag
            

        • Mimic solar activity by adjusting the intensity of sun simulator

        • Solar Radiation Pressure (SRP)

          

        • Other: mass & thermal behaviour (solar flux, thermal conductivity)

     2. Insert Attached Objects menu
        1. Sensors
        2. Receivers for ground stations
           1. Receiver’s figure of merit: (G/T) = (receiver gain divided by system noise temperature)
        3. Transmitter
   • Sun Synchronized Orbit Simulation (SSO): 600 to 800km in altitude

     1. Open software and create new scenario

        1. Define mission start and stop dates to specific dates
        2. Include terrain data
        3. Insert objectives like Satellite and Facilities (ground station) into scenario
        4. Propagator incorporates external forces
           • Gravity :
           • Control temperature using regulation system only if necessary
        5. Simulate Atmospheric drag by adjusting pressure in the testing chamber to match low Earth orbit conditions.

           • Must consider the following:

             • Shape model
             • Drag Coefficient: kept as constant but not true in reality
             • Drag Area: amount of drag the object experiences during flight

             

             • Area to Mass Ratio
             • Solar Flux/Geo Magnetic

             

             Atmospheric drag - Velocity per rev

             

             Force of Drag

     2. Mimic solar activity by adjusting the intensity of sun simulator

        1. Solar Radiation Pressure (SRP)

           

        2. Other: mass & thermal behaviour (solar flux, thermal conductivity)

NOTE: communication hardware, power subsystems, flight processors, mechanical issues, thermal and radiation are all previous failures

• 2.3 CubeSat Failure Causes: https://vtechworks.lib.vt.edu/server/api/core/bitstreams/74092525-d090-4316-a57d-7be503e04807/content

1. Initial Alignment:

   1. Align the CubeSat's initial orientation with a known reference direction of interest (+-0.5 degrees error)

2. Sensor Data Collection:

   1. Make sure all components of the CubeSat are on and well functioning

      1. CMG gyroscope
      2. Magnetorquer
      3. Sun simulator

   2. Exemplar vector positioning differences calculated through MATLAB:

      Vector Differences - UTAT

   3. Monitor and collect data from each sensor to determine the CubeSat's orientation relative to chosen reference frame

   CubeSatUnitVectors.m

3. Magnetic Field testing:

   1. Obtain magnetic field reading from Helmholtz cage and compare it using the magnetometers.
   2. Conduct visual inspections to confirm that the CubeSat’s pointing direction aligns with the expected magnetic field direction.

4. Data Analysis:

5. Calibration Adjustment:

6. Repeat Testing:

7. Documentation:

https://vtechworks.lib.vt.edu/server/api/core/bitstreams/74092525-d090-4316-a57d-7be503e04807/content

Application of this testing:

• Pointing the antenna to the ground