Satellite Gravity and the Geosphere Contributions to the Study of the Solid Earth and Its Fluid Envelopes (1997) / Chapter Skim
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2 MISSION SCENARIOS AND MEASUREMENT TECHNIQUES
2 MISSION SCENARIOS AND MEASUREMENT TECHNIQUES
Pages 15-28
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From page 15... ...
We estimate the ability of each of our generic missions to resolve the gravity field using standard techniques in spherical hannonic analysis. Spherical harmonic analysis of functions defined at points on a sphere is analogous to Fourier analysis of functions defined at points on the real line.
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From page 16... ...
A dedicated spac~ome avid moping mission bag long been seen as Me mews 10 improve We occupy Id ~soludon of ED Dip geld model Such a mission would provide data of global extent Id homogeneous quaff, You He geog~bic or geopolitical limitations of altimc~ Id sure g~mvi~ anomaly surveys. \1~i of ~ man ^ sc ~ describe ~ tab by using various Yes of satellite^~^s~ellite making.
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From page 17... ...
Bottom panel: The time required to acquire a ground-track pattern that will resolve a given across-track wavelength. Curves are drawn for the same orbital altitudes as in the top panel.
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From page 18... ...
Tbc density of we ~osphe~ incomes ~one~i~ly aim defaming wide, so ~ ~ eat of ~e dissipative ~mospberic ~ accelerations becomes very si~iCc~1 ~ log altim~s This ~ wiI1 cause 1be omit ~ti~de to dead ad evenm~ly we satellite ail} -ever Me lower ~ospbe~, unless ~ is plods ~ ^~d ~ a baa ~ ~ ~ ~ coed oxbow The duration beam -end, or We sillily mission lifetime, is depended Won We initial Wade of Beckon, He bdILdc c~edsUcs of ~ sillily Be oxbow Bellowing ohmic, ad Be .
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From page 19... ...
It now appears preferable that a satellite mission be placed at a higher altitude, where it would stay in orbit for several years, while resolving the longer wavelength components of the geopotential over that time scale, after which the natural decay of its orbit would allow it to resolve the shorter wavelengths over the last few months. As a further example, if the observing instrument must be cooled to superconducting temperatures, the current state of the technology limits the liquid helium dewar life, and hence the mission lifetime, to approximately 9 months.
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From page 20... ...
Be shies of SST missions ~ aped ~ He lit_ in ~ Ail he various pal Deposals fir such spore missions. Easy silo Housed on He Asocial sew fission scow Cueing e1 a., 1986)
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From page 21... ...
ERROR ESTIMATES FOR MISSION SCENARIOS OF THIS REPORT All He mission concepts discussed here will yield observations win some limited precision. To determine definitive error estimates for a specific mission, it would be necessary to have a detailed engineering summary of the mission, including the spectra of all He errors, and to combine these win full numerical simulations of the estimation of the gravity field.
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From page 22... ...
also oboe ~ ~ ~ Alias Or ~ ~ s~oF~e~= ~ Geld golly EO~96 |
From page 23... ...
Figures 2.3-2.6 show that at high degree, the errors in the gra~rity-field coefficients determined from all the missions exceed the expected gravity-field signal and the error estimates of the current gravity-field model EGM96. At these high degrees, the satellite missions do not usefully constrain the gravity-field model.
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From page 24... ...
s'= o - ~ of (s =W ~ ) ~S 19~H plooo Is s ~ - ~ _ 5 an' Sop ''a S - t as.
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From page 25... ...
~lo ef It f T 1 1,1471 ~f 111~ ~ f i 1 1 1 ~f ~1 1 11111 l 1 1 ~I .
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From page 27... ...
Although we have not simulated the error effects of non-gravitational or rotational influences, we do not think these will bias our results as SST and SSI missions are expected to be flown with high-precision accelerometers onboard, and the SGG missions are expected to reject these influences with careful commonmode rejection and precise alignment of the accelerometers. In addition, rigorous numerical simulations reported by Bettadpur and Tapley (1996a)
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From page 28... ...
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