the 14 th annual improving space operations workshop april 15-16 2008
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
The 14th Annual
Improving Space Operations WorkshopApril 15-16 2008
Brasilsat Goes
Longitude Sharing
Evandro Paiva de Andrade
Celestial Mechanics Team
Engineering Division - Star One S/A
• Star One’s Fleet
• Brasilsat B1 (BSat1) and Goes12 Co-location
• Future Co-locations
Star One’s Satellite Types
• Four BSS376-W spinners: BSat1 (1994), BSat2 (1995), BSat3 (1998) and BSat4 (2000)
• Two SpaceBus 3000B3: StarOne-C1 SOC1 (2007) and SOC2 (2008)
00
Star One’s Fleet and Trends
107.5
Anik F1
AMC12
/SOC12
37.5
8470
92
BSat3BSat2 (inc’d)
65
SOC2
68
Launch(Apr
2008)
75
SOC1
55.5
89
G-28
IS 805
BSat1(inc’d)
BSat4
Goes12
Mid-2008
inc’d: inclined orbit
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
BSat1 – Inclined Orbit
5 °
10 °
15°
Aries
Ecliptic Pole
=90°
Geosynchronous Orbit Normal
Evolution
Inc Vector Secular Perturbation
inc naturally defined
Ecc/Inc Co-location
BSat1 one year ecc evolution
ecc // inc
Eccentricity strategy
Strategy Set Up
sma*ecc
sma*inc
R
N
• Comfortable minimum distance 10 Km
ecc // inc
sma:semi-major axis of the orbit
min(sma*ecc, sma*inc) ecc > 23.7E-
05 inc >
0.0136°
Deviation from Nominal Set-up
Relative Motion
-30
-20
-10
0
10
20
30
-30 -20 -10 0 10 20 30
R (Km)
-30
-20
-10
0
10
20
30
-30 -20 -10 0 10 20 30
R (Km)
N (
Km
)
-30
-20
-10
0
10
20
30
-30 -20 -10 0 10 20 30
R (Km)
= 30° min dist = 8.3 Km = 60° min dist = 4.5 Km
= 75° min dist = 2.3 Km
N (
Km
)
N (
Km
)
Intermediate angles between ecc and inc
Actual Data
ecc
inc
Good alignment !!!
Collision Avoidance Maneuver
• 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 more frequent 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
W Flybys and Minimum Distance
GOES-12
Current strategy has guaranteed a minimum of 14 km between the satellites
Goes12 north-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
Furthering Closeness
• BSat3 (orbit not-inclined) will be brought to 75 W by June 2008
• Ecc/inc co-location strategy fails when 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.
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
Box Demarcation
+0.1°-0.1°
Incl
inati
on
Longitude
+0.5°
0.5°
lssz0.1°
Equator
75° W Meridian
ecc/inc separation strategy
zone
lssz: longitude separation strategy zone
-0.5°
Next Steps
• 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
Evandro Paiva de Andrade
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!!!