MAIN CHARACTERISTICS Link range • 45000 Km worst case of SPOT4/ARTEM1S space configuration Link capacity ♦ Forward link : unmodulated, but 2 Mbps modulation capability on GEO • Return link : 50 Mbps, SPOT 4 useful data rate Wavelength range • 800-850 nm Key components • laser diodes. CCD detectors. APD sensor Optical power • 60 mWatts maximum average power (Communication laser diodes) » 500 mWatts CW power (Beacon laser diodes) Beams divergence ♦ Communication beam : 8 prad ♦ Beacon (GEO): 750 grad Link performances • Routine acquisition : 150 seconds maximum duration 0.95 probability of success 10° (EOL) achievable Sun Aspect Angle ♦ Data transmission: long term quality : BER better than IO-6 short term quality : limited occurrence of errors • Availability: better than 95 % of the LEO-GEO annual visibility Operations • Autonomy w.r.t. ground : 24 hours operation without ground command • Autonomy w.r.t. satellite : On-Board processor and software, integrated thermal control, safe configuration ♦ GEO multi-user capability (operation of 2 LEO's in an interleaved way) • LEO multi-relay capability (operation of 2 GEO's, 1 per communication session) Terminal • Mobile aerial, blocked with lockins devices during launch and configuration located on the anti-earth panel of STOT4 (LEO) or on the earth panel of ARTEMIS (GEO) • Fixed part electronics on the spacecraft LEO terminal ’Mass: 123 Kg (current status) • Power consumption : 160 Watts (Communication mode) • Aerial volume : 1605 x 890 x 807 mm3 GEO terminal • Mass: 113 kg (current status) • Power consumption : 180 Watts (Communication mode) • Aerial volume : 1600 x 900 x 850 mm3 LEO terminal • Angular mobility : quasi hemispherical pointing • Initial uncertainty on GEO angular position : 0 8500 grad • Communication pointing accuracy : probability less than IO 5 to exceed 2 grad error. Delivery'dates • January 1994 (LEO) • December 1994 (GEO)
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