SMOS Orbit SelectionSMOS Orbit Selection

Berthyl DuesmannBerthyl DuesmannESTEC, EOP-PESESTEC, EOP-PES

System Analysis OfficeSystem Analysis Office

SMOS SAG, ESTEC, 1&2 Oct 2003 SMOS SAG, ESTEC, 1&2 Oct 2003

Current SRD BaselineCurrent SRD Baseline

Repeat Cycle: 59 days / 851 orbitsRepeat Cycle: 59 days / 851 orbits Characteristics:Characteristics:

Track Spacing: 47 kmTrack Spacing: 47 km(Requested 20 km spacing between tracks)(Requested 20 km spacing between tracks)

Nominal Swath: No full coverage in 3 days Nominal Swath: No full coverage in 3 days Narrow Swath: Full coverage in 7 daysNarrow Swath: Full coverage in 7 days Changing Geometry 3 days: -752 kmChanging Geometry 3 days: -752 km Changing Geometry 7 days: 94 kmChanging Geometry 7 days: 94 km Altitude Range: 749.9 km / 759.8 km / 777.0 Altitude Range: 749.9 km / 759.8 km / 777.0

kmkm(SAG adviced: 755 km)(SAG adviced: 755 km)

Target Characteristics Target Characteristics OrbitOrbit

Track Spacing: 20 km Track Spacing: 20 km Repeat Cycle ~ Repeat Cycle ~ 150 days150 days

Full Coverage Nominal Swath within 3 Full Coverage Nominal Swath within 3 days sub-cycledays sub-cycle

Full Coverage Narrow Swath within 7 days Full Coverage Narrow Swath within 7 days sub-cyclesub-cycle

Changing Geometry after subcycle Changing Geometry after subcycle between 15% and 85% of relevant swath between 15% and 85% of relevant swath (1050 km resp. 630 km (1050 km resp. 630 km 157/892 km resp 94/535 157/892 km resp 94/535 km )km )

Nominal Swath 59/851Nominal Swath 59/851

Hole!

Narrow Swath 59/851Narrow Swath 59/851

ResultsResultsR

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Min

Alti

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Max

Alti

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59 851 47.004 3 43 Hole -752.056 7 101 Full 94.007 749.9 759.8 777.0149 2147 18.631 3 43 Hole -633.442 5 72 Full -130.415 754.6 764.6 781.8149 2146 18.639 3 43 Hole -577.819 5 72 Full -37.279 756.8 766.8 784.0149 2145 18.648 3 43 Hole -522.145 5 72 Full 55.944 759.1 769.0 786.2149 2144 18.657 3 43 Full -466.418 5 72 Full 149.254 761.3 771.2 788.4149 2143 18.665 3 43 Full -410.639 5 72 Hole 242.650 763.5 773.4 790.7

Nominal Swath Nominal Swath 149/2144149/2144

Narrow Swath Narrow Swath 149/2144149/2144

Question to SAGQuestion to SAG

Are the SMOS performances met, Are the SMOS performances met, when increasing the orbit height by when increasing the orbit height by 11km11km

Other orbit constraints / considerationsOther orbit constraints / considerations

ConclusionConclusion Under the condition that the SMOS Under the condition that the SMOS

performances are met, when increasing performances are met, when increasing the orbit height by 11kmthe orbit height by 11km

A minimum orbital height of 761 – 762 km A minimum orbital height of 761 – 762 km will satisfy the following requirementswill satisfy the following requirements Full Coverage Nominal Swath in 3 daysFull Coverage Nominal Swath in 3 days Full Coverage Narrow Swath in Full Coverage Narrow Swath in 55 days days Sufficient Geometry Change after 3 and 5 Sufficient Geometry Change after 3 and 5

daysdays A minimum repeat cycle of 140 days will A minimum repeat cycle of 140 days will

satisfy the track separation requirementsatisfy the track separation requirement Possible Repeat: 149 days / 2144 orbitsPossible Repeat: 149 days / 2144 orbits