³Cat-2

The ³Cat-2 (pronounced “cube-cat-two”) is the second satellite in the ³Cat series and the second satellite developed in Catalonia at UPC’s NanoSat Lab. It carries the PYCARO GNSS-R payload, a novel dual-band, dual-polarization GNSS Reflectometer, and integrates additional experimental payloads.

Mission Overview

Primary Objectives:

• Technology Demonstration: Validates GNSS-Reflectometry (GNSS-R) for Earth observation.
• Scientific Research: Supports atmospheric and surface monitoring using GNSS-R.
• Educational: Developed by students and researchers at UPC’s NanoSat Lab.

Mission Details

Subsystem Overview

On-Board Computer (OBC) & Flight Software

• Processor: ARM7 microcontroller (40 MHz, 2MB RAM)
• Operating System: FreeRTOS
• Storage: 2GB microSD card (FAT16 file system)
• Functions: Sensor readings, communications, attitude determination, control, and payload management.

Electrical Power Subsystem (EPS)

• Energy Source: Triple Junction Gallium Arsenide solar cells (30% efficiency)
• Battery: 7.4V Lithium-Ion (7000mAh)

Communication Subsystem

• Uplink: UHF link (1200 bps, AFSK Bell 202 standard)
• Downlink:
  • VHF (9600 bps, BPSK)
  • S-Band (115200 bps, BPSK, LDPC-Staircase coding)
• Beacon: Periodic VHF telemetry transmission

Attitude Determination and Control Subsystem (ADCS)

• Actuators: Three orthogonal magnetic torquers (0.24 Am² each)
• Sensors:
  • Two 3-axis magnetometers
  • 3-axis MEMS gyroscope
  • Six photodiodes for sun positioning
  • Experimental star tracker (Mirabilis)

Payloads

1. PYCARO GNSS-R: Dual-band, dual-polarization GNSS Reflectometer
2. Mirabilis Star Tracker: Experimental star tracker for attitude determination
3. IEEC AMR eLISA Magnetometer: Future ESA LISA mission technology validation
4. FAPEC Compression Algorithm: Developed by DAPCOM, first in-space implementation