Geological Sample Mission ICD

The following forms the interface control document (ICD) for the Geological Sample Mission (GSM). This ICD includes a subsystem level summary which is then broken down into the key components of the GSM payload: the sample plate, cameras, and payload controller.

ICD Summary

Mechanical Interface:

Mass: 353.5 g without module shell
757.5 g with structure
Dimensions: See sub-assembly summaries below
Outgassing:
- All mechanical hardware and components compliant
- Payload Samples Likely Compliant (Waiver sent August-2020)
- Payload Cameras unknown but will be conformally coated

Electrical Interface:

Supply Voltage: VBAT (~6.4 +/- 0.4 VDC)
Supply Current: 206 mA (peak)
Peak Power consumption: 850 mW (including control board and one camera)
Peak Power duty cycle: 2.5 minutes every 2 hours during the first 5 days of operations, 2.5 minutes once per day after the first 5 days.
Off-Peak Power Consumption: 50 mW (to be confirmed with physical testing)

Data Interface:

1 CAN BUS line
See Telemetry Table below for telemetry items and frequencies

Payload Telemetry

Note that the 92% cropping rate in the above Payload Telemetry budget is based on this analysis, where an image was taken with the EM payload and the number of pixels for each sample and the gnomon area was counted.

Commands from CDH:

- Turn Payload On/Off (Performed by Power subsystem)
- Turn Cameras On/Off
- Reset Cameras
- Switch to/from low power mode and imaging mode
- Take Image with Camera 1
- Take Image with Camera 2
- Take temperature readings
- Take power-good reading
- Transmit image to CDH

Commands from GND:

- Turn Payload On/Off (Performed by Power subsystem)
- Turn Cameras On/Off
- Reset Cameras
- Switch to/from low power mode and imaging mode
- Take Image with Camera 1
- Take Image with Camera 2
- Take temperature readings
- Take power-good reading
- Transmit image to CDH

Thermal Interface:

Survival Temperatures: -50 to 80 C
Operational Temperatures: -30 to 70 C
Storage Temperatures: -50 to 80 C

Sample Plate

The sample plate is the physical structure that holds the geological samples. It also includes a thermistor to measure the plate's temperature (from which sample temperatures will be inferred via thermal analysis). This plate will be attached directly to the payload module. Note that the thermistor properties are included in the Thermal ICD.

Interface Characteristics

Mechanical Interface:

Mass: 127 g (including samples, fasteners, and other components)
Dimensions:
- Y: 70 mm
- X: 89 mm
- Z: 20 mm
See drawing below for mounting diagram
Outgassing:
- All hardware and components compliant
- Payload Samples Likely Compliant (Waiver sent August 2020)

Thermal Interface:

Emissivity: 0.27 to 0.77 (as dictated by THE)
- Outer surfaces are aluminum, can paint or anodize
Heat Capacity: 114 J/C (approximate)
Survival Temperatures: -50 to 80 C
Operational Temperatures: -50 to 80 C
Storage Temperatures: -50 to 80 C

Sample Plate Interface Drawing

Thermal Coatings

The payload structural components shall be black anodized on all visible areas. The anodized components are summarized in the table below.

Payload Flight Hardware List

Sample Plate Thermistor Mounting

The sample plate thermistor will be mounted to the centre of the sample plate's rear face (i.e. the non-sun-facing side)

Click on the links for drawings of the sample plate, sample plate lid, sample plate rear supports, and sample supports, and samples.

GSM Cameras

The two cameras are used to image the sample plate. Date from these images will be processed by CDH to determine the average R,G, and B intensities of each sample. Both cameras will be controlled by the payload control board.

Interface Characteristics

Mechanical Interface:

Quantity: 2
Mass: 2 x 19 g (not including attachment fasteners)
Dimensions:
- Y: 30.28 mm
- X: 30.48 mm
- Z: 55 mm
  - Note: exact Z-height is dependent on focal distance and is likely slightly less than 55 mm
- Outgassing Characteristics: unknown but board will be conformally coated

Thermal Interface:

Survival Temperatures: -50C to 80 C
Operational Temperatures: -30C to 70 C

Camera Lenses

The cameras will be used with Vision Dimension BL-0147MP13IR lenses. These are S-mount lenses which attach to the cameras using an M-12 male thread along the bore of the lens. The lenses have an infrared filter with the following lens' transmission efficiencies:

420-630nm Tavg> 92%

650 ± 10nm T = 50%

690-700nm Tmax <3%

700-1000nm Tmax <1%

1000-1100nm Tmax <5%

Lens Parameters

BL-0147MP13IR Lens Drawing

Payload Controller

This unit is responsible for controlling the payload cameras, sending images and temperature sensor data from the payload to the spacecraft’s Command and Data Handling Unit (CDH) via a CAN bus transceiver, as well as receiving and executing commands from CDH.

The Payload controller includes a board-mount thermistor for measuring the Payload Controller's temperature and inferring the camera temperatures.

A 3D-PDF of the controller design is available here

Payload Controller Schematics

Payload controller design details, drawings, and schematics are available here.

Mechanical Interface

Mass: <100 g (not including attachment fasteners)
Maximum Dimensions:
- Y: 90 mm
- X: 90 mm
- Z: ~7 mm
Outgassing Characteristics: will be conformally coated

Payload Control Board Assembly with Cameras Mechanical Drawing

Control Board Layout Drawing with Cameras

Control Board Back View with Connection Points

For drawings of the camera support, click here. The camera baffle drawing is available here.

Thermal Interface

Survival Temperatures: Unknown
Operational Temperatures: -40C to 105C
Storage Temperatures: -55C to 150C

Gnomon ICD

The gnomon is being developed by the Space Club at the Interlake School Division and will be mounted onto the Sample Plate.

The following data is preliminary and subject to change. However, the mechanical interfaces should remain constant.

Gnomon Measurement Range

Sun vector angle from 15 to 60 degrees in 5 degree increments

Sun vector rotation in 15 degree increments

The gnomon pattern will be laser etched into the aluminum base. Previously, we investigated laser-bonding the pattern on to the gnomon base using CerMark LM6000. This laser-bonded stencil material was tested on a long-term NASA exposure mission and performed well. We performed test patterns using the CerMark material on scrap material to validate the application process and unfortunately determined that we do not have a sufficiently fine laser cutter to apply this product. As such, we are laser etching the pattern on.