SAX: Major System Data

Dimensions

• 3.6 m height; 2.7 m diameter (stowed arrays)
• deployed arrays overall span: 9m

Mass

• Total mass: 1400 Kg
• Payload mass: 490 Kg

Power

• Voltage regulated main power bus at 29V +- 2%
• Number of solar cells: 8700
• Two non sun-tracking deployable solar arrays
• One Body Mounted Solar Panel
• Energy storage by two Ni-Cd batteries each of 36 cells - 30 Ah with a max depth of discharge of 25%

Attitude Control

• Absolute Pointing Error of 1.5 arcmin over an observation period of 100,000 s.
• Sun Aspect Angle Domain:
  • Full cone angle of 60 degrees (half aperture of 30 degrees)
  • Sun vector laying in the S/L-XY plane in the 30-45 degrees range
• Torques actuation and angular momentum storage through a reaction wheels systems.

Data Handling and Communications

• On-board memory for data storage: 460 Mbit
• Frequency stability of on-board clock: 5 x 10**-9/day
• Hight priority real time ground commands: 64
• Communication bit rate:
  • Telecommand: 2Kbps
  • Telemetry:
    • 131 Kbps real time channel
    • 917 Kbps stored data channel (High Bit Rate normal mode)
    • 2-16 Kbps (Low bit Rate contingency mode)
• Telemetry protocol and data structures based on ESA standard Packet Telemetry Protocol
• Telemetry channel coding Technique using the Reed-Solomon code
• Down link Frequency: 2245.24 MHz
• Uplink RF Frequency: 2067.5 MHz
• Modulation:
  • PCM/BPSK/PM: up link
  • NRZ-M/PPSK/PM: down link - Low Bit Rate
  • UQPSK direct: down link - High Bit Rate
• Power Flux Density:
  • 154.5 dBW/m2 for an inclination angle between 0 and 5 degrees on the horizontal plane
• Coherent and non-coherent ranging operation from Ground, based on the Multi Purpose Tracking System (MPTS).

Pointing Requirements:

• Absolute Pointing Error < 3 arcmin
• relative Pointing < 1 arcmin
• Absolute Pointing Drift < 1 arcmin
• Absolute Measurement Accuracy < 1 arcmin

This file was last modified on Wednesday, 02-Sep-1998 17:28:57 CEST by Mauro Orlandini