The imaging system is comprised of color and monochrome CMOS imagers
built around chips from Agilent Technologies. Both communicate with the
On-Board Computer (OBC) and are used for ground-controlled horizon
sensing and star-tracking experiments.
Active Three-Axis Magnetic
Three custom magnetorquer coils and a Honeywell three-axis digital
magnetometer are used in conjunction with a B-dot control algorithm for
spacecraft detumbling and coarse pointing experiments.
Accurate position determination is accomplished using a low-cost
commercial Global Positioning System (GPS) receiver that has been
modified to work in low Earth orbit.
ARM7 On-Board Computer
Housekeeping and payload application routines run on a powerful ARM7
On-Board Computer. The computer also implements B-dot detumbling and
error-detection and correction algorithms. The Atmel ARM7 OBC operates
at 3.3 V, consumes 0.4 W at a speed of 40 MHz, and is equipped with 512
KB of Static-RAM and 32 MB of Flash-RAM.
All software is custom-written in C. To reduce CanX-1 mission
complexity, no operating system is used. The OBC is capable of running
a real-time operating system, however, such as eCos. This feature will
enable more complex missions in the future.
Telemetry and Command
Telemetry and command is handled by a half-duplex transceiver operating
on fixed frequencies in the 430 MHz amateur satellite band in accordance
with IARU guidelines and ITU regulations. The 500 mW transmitter
downlinks data and telemetry at 1200 bps using a MSK over FM signal (it
appears as two tones, 1.2 kHz and 1.8 kHz at baseband, alternating
rapidly). The antenna system consists of two quarter-wave monopole
antennas oriented at 90° and combined in phase to produce a linearly
polarized signal. The amateur call sign used by CanX-1 is VA3SFL.
Triple-Junction Solar Cells and Lithium-Ion
The satellite and its payloads are powered by Emcore triple-junction cells (26% maximum efficiency). Energy is stored in a Polystor 3.7 V, 3600 mAh lithium-ion battery pack to handle peak loads and provide power during eclipse periods. In addition, the power system incorporates peak-power tracking, over-current protection, power shunting, and an emergency load shed system.
7075 & 6061-T6 Structure
The total mass of the satellite structure including the frame, all
exterior surfaces, and internal mounting hardware is 373 g, or 37% of
the total satellite mass. Simulations with 12 G loads showed a 30%
margin to the maximum allowable stress, while thermal analysis predicted
a -20 to +40°C temperature range using passive thermal control.
Vibration testing was performed on the satellite at MDRobotics. The
"heavy structure" design resulted in a first natural frequency of
approximately 800 Hz.