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The 14 th Annual Improving Space Operations Workshop April 15-16 2008

Longitude Sharing. The 14 th Annual Improving Space Operations Workshop April 15-16 2008. Goes. Brasilsat. Evandro Paiva de Andrade Celestial Mechanics Team Engineering Division - Star One S/A. Star One’s Fleet Brasilsat B1 (B Sat 1) and Goes12 Co-location Future Co-locations.

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The 14 th Annual Improving Space Operations Workshop April 15-16 2008

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  1. LongitudeSharing The 14th Annual Improving Space Operations WorkshopApril 15-16 2008 Goes Brasilsat Evandro Paiva de Andrade Celestial MechanicsTeam Engineering Division - Star One S/A

  2. Star One’s Fleet Brasilsat B1 (BSat1) and Goes12 Co-location Future Co-locations

  3. Star One’s Satellite Types • Four BSS376-Wspinners: BSat1(1994), BSat2(1995), BSat3(1998) and BSat4 (2000) • Two SpaceBus 3000B3: StarOne-C1 SOC1(2007) and SOC2(2008) 00

  4. Star One’s Fleet and Trends Mid-2008 SOC2 Launch (Apr 2008) BSat3 BSat1(inc’d) BSat2 (inc’d) BSat4 SOC1 AMC12 /SOC12 92 107.5 89 84 75 70 68 Goes12 65 G-28 55.5 Anik F1 37.5 IS 805 inc’d: inclined orbit

  5. BSat1 and Goes12 Co-location • BSat1 arrived at 75° W in March 24, 2007 • NOAA switched eccentricity (ecc) control strategy from • one thruster firing near perigee • to • one thruster firing sun-synchronous, • which allowed eccentricity vectors synchronization and, • therefore, eccentricity/inclination (ecc/inc) co-location • Weekly orbit data exchange

  6. Inc Vector Secular Perturbation  =90° Aries 5 ° Geosynchronous Orbit Normal Evolution 10 ° 15° inc naturally defined Ecliptic Pole BSat1 – Inclined Orbit

  7. Ecc/Inc Co-location Eccentricity strategy BSat1 one year ecc evolution ecc // inc

  8. Strategy Set Up • Comfortable minimum distance 10 Km min(sma*ecc, sma*inc) ecc > 23.7E-05 inc > 0.0136°  N sma*inc ecc // inc  R sma*ecc sma:semi-major axis of the orbit

  9. Deviation from Nominal Set-up Intermediate angles between ecc and inc Relative Motion N (Km) 30 30 N (Km) 30 N (Km) 20 20 20 10 10 10 0 0 0 -30 -20 -10 0 10 20 30 -30 -20 -10 0 10 20 30 -30 -20 -10 0 10 20 30 -10 -10 -10 -20 -20 -20 -30 -30 -30 R (Km) R (Km) R (Km) a = 30°  min dist = 8.3 Km a = 60°  min dist = 4.5 Km a = 75°  min dist = 2.3 Km

  10. ecc inc Actual Data Good alignment !!!

  11. Acceptable minimum close approach margin between GOES12 and BSat1   2 km Close approach prediction between 2 km and 5 km   alert for a potential issue  trigger morefrequent communication between Star One and NOAA Close approach prediction of anything less than 2 Km  trigger collision avoidance maneuver to be performed by Star One Collision Avoidance Maneuver

  12. W Flybys and Minimum Distance Goes12north-south maneuvers done outside box of 75°±0.1 W and timed in such a way that any in-plane coupling will not make Goes12 enter BSat1 box before the following E-W maneuver GOES-12 Current strategy has guaranteed a minimum of 14 km between the satellites

  13. BSat3 (orbit not-inclined) will be brought to 75 W by June 2008 Ecc/inc co-location strategy failswhen Goes inc < 0.1 One alternative is to combine ecc/inc and longitude separation co-location strategies. Star One agrees to continue with the responsibility of performing collision avoidance maneuvers if the minimum close approach margin is outranged. Furthering Closeness

  14. Longitude Separation Strategy Goes12 enters ±0.1° inclination box outside of the eclipse season, what favors an adequate planning of Goes12 West maneuvers aiming at the co-location by longitude separation strategy during this phase. This would minimize need for coordination between Star One and NOAA

  15. Box Demarcation 75° WMeridian Inclination 0.5° ecc/inc separation strategy zone 0.1° lssz Longitude Equator -0.5° +0.1° -0.1° +0.5° lssz: longitude separation strategy zone

  16. Finalize discussions that include satellites in standard geostationary orbit Develop any required longitude sharing procedures or memoranda Formalize agreement through the exchange of technical letters Next Steps

  17. Evandro Paiva de Andrade evandro.andrade@starone.com.br Tel.: (55) (21) 2121-7003 Celestial Mechanics Team - Engineering Division - Star One Rio de Janeiro - RJ – Brazil Helpful contributions from: DSc Cintia Quireza, MSc Mauricio Bottino, Lincoln Oliveira, Reinaldo Pinto and PhD Annelisie Aiex THANKS!!!

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