Gnomon Shadow Test Procedures

Task Description: Measure the shadow cast by the gnomon pin onto the gnomon base at various angles to confirm it can measure shadows to the specified accuracy.

Completion Deadline: 17 Nov. 2020

Team Member: Matt, Ali

Resources Required: EM Gnomon, EM sample plate, EM payload structure, bright light source, dark room, turn table, protractor

Verification Activities: V-PLD-0260, V-PLD-0270, V-PLD-0280

Pass Criteria: Confirm that the gnomon can:

1) Measure solar incidence angles of up to 50 degrees from the gnomon pin vector;

2) Measure solar incidence angles to at least a 5 degree resolution;

3) Measure the rotational resolutions to at least a 15 degree resolution.

Test procedure:

Part A: Incidence Angles

1. Place the protractor underneath the turn table while keeping the protractor angles visible;

2. Place the payload assembly, including the EM structure, sample plate, and gnomon, onto the centre of the turn table on its +Y face;

3. Turn off the lights and turn on the light source, while keeping the light as far from the test apparatus as practical;

4. Rotate the apparatus so that the sample plate is parallel to the incoming light;

5. Slowly rotate the turn table counter clockwise until the gnomon pin's shadow just touches the edge of the gnomon. Record this angle;

6. Slowly rotate the turn table counter clockwise in 5 degree increments, until the structure shades the gnomon pin, and record where the shadow is on the gnomon at each interval;

7. Confirm if the gnomon was able to measure each angle to a 5 degree accuracy.

Part B: Rotational Angles

1. Place the payload assembly, including the EM structure, sample plate, and gnomon, onto the centre of the turn table on its -Z face;

2. Turn off the lights and turn on the light source, while keeping the light as far from the test apparatus as practical;

3. Rotate the apparatus so that the structure's +X face is normal to the light source

4. Slowly rotate the turn table counter clockwise in 5 degree increments until the gnomon pin's shadow is just covered by the EM structure's shadow, and record where the shadow is on the gnomon at each interval;

5. Confirm if the gnomon was able to measure each angle to a 15 degree accuracy.