TY - JOUR

T1 - Comparing seven candidate mission configurations for temporal gravity field retrieval through full-scale numerical simulation

AU - Elsaka, Basem

AU - Raimondo, Jean Claude

AU - Brieden, Phillip

AU - Reubelt, Tilo

AU - Kusche, Jürgen

AU - Flechtner, Frank

AU - Iran Pour, Siavash

AU - Sneeuw, Nico

AU - Müller, Jürgen

N1 - Funding information: In 2009, the project “Concepts for future gravity field satellite missions”, funded by the ‘Geotechnologies Program’ of the German Federal Ministry of Education and Research (BMBF) and the German Research Foundation (DFG), was established in a partnership between various German scientific and industry partners. One of the main project goals was to define stable formation configurations to optimize time-variable gravity field recovery. To this end, in the first step a catalog of suitable orbit and formation parameters was defined while potential future developments (aim: year 2020) of metrology and system design are considered. Eight satellite formation designs have been investigated in detail including the GRACE mission as reference: a modified version (with a small cross-track component and a lower orbit) of the currently implemented GRACE Follow-on (GRACE-FO) mission (Flechtner et al. ), a moderate Pendulum (with a small cross-track angle , abbreviated as “mod. Pend.”), a Cartwheel, a Helix (cf. LISA-type in Elsaka et al. ) and an in-line Bender configuration (Bender et al. ) (see Fig. ) in addition to two advanced Pendulum configurations (with a larger cross-track angle of , labeled “adv. Pend. 1” and “adv. Pend. 2”). All mission scenarios have been assumed as drag-free except for the GRACE and GRACE-FO missions. The authors would like to thank the reviewers for their valuable comments. We gratefully acknowledge Dr. Pavel Ditmar, the Editor, for his valuable comments and corrections to improve this manuscript. Additionally, the financial support of the German Federal Ministry for Education and Research (BMBF) and the German Research Foundation (DFG) within the frame work of the German joint research project “Concepts for future gravity field satellite missions” as part of the Geotechnologies Program (grant 03G0729) is acknowledged.

PY - 2013/11/9

Y1 - 2013/11/9

N2 - The goal of this contribution is to focus on improving the quality of gravity field models in the form of spherical harmonic representation via alternative configuration scenarios applied in future gravimetric satellite missions. We performed full-scale simulations of various mission scenarios within the frame work of the German joint research project "Concepts for future gravity field satellite missions" as part of the Geotechnologies Program, funded by the German Federal Ministry of Education and Research and the German Research Foundation. In contrast to most previous simulation studies including our own previous work, we extended the simulated time span from one to three consecutive months to improve the robustness of the assessed performance. New is that we performed simulations for seven dedicated satellite configurations in addition to the GRACE scenario, serving as a reference baseline. These scenarios include a "GRACE Follow-on" mission (with some modifications to the currently implemented GRACE-FO mission), and an in-line "Bender" mission, in addition to five mission scenarios that include additional cross-track and radial information. Our results clearly confirm the benefit of radial and cross-track measurement information compared to the GRACE along-track observable: the gravity fields recovered from the related alternative mission scenarios are superior in terms of error level and error isotropy. In fact, one of our main findings is that although the noise levels achievable with the particular configurations do vary between the simulated months, their order of performance remains the same. Our findings show also that the advanced pendulums provide the best performance of the investigated single formations, however an accuracy reduced by about 2-4 times in the important long-wavelength part of the spectrum (for spherical harmonic degrees <50, compared to the Bender mission, can be observed. Concerning state-of-the-art mission constraints, in particular the severe restriction of heterodyne lasers on maximum range-rates, only the moderate Pendulum and the Bender-mission are beneficial options, of course in addition to GRACE and GRACE-FO. Furthermore, a Bender-type constellation would result in the most accurate gravity field solution by a factor of about 12 at long wavelengths (up to degree/order 40) and by a factor of about 200 at short wavelengths (up to degree/order 120) compared to the present GRACE solution. Finally, we suggest the Pendulum and the Bender missions as candidate mission configurations depending on the available budget and technological progress.

AB - The goal of this contribution is to focus on improving the quality of gravity field models in the form of spherical harmonic representation via alternative configuration scenarios applied in future gravimetric satellite missions. We performed full-scale simulations of various mission scenarios within the frame work of the German joint research project "Concepts for future gravity field satellite missions" as part of the Geotechnologies Program, funded by the German Federal Ministry of Education and Research and the German Research Foundation. In contrast to most previous simulation studies including our own previous work, we extended the simulated time span from one to three consecutive months to improve the robustness of the assessed performance. New is that we performed simulations for seven dedicated satellite configurations in addition to the GRACE scenario, serving as a reference baseline. These scenarios include a "GRACE Follow-on" mission (with some modifications to the currently implemented GRACE-FO mission), and an in-line "Bender" mission, in addition to five mission scenarios that include additional cross-track and radial information. Our results clearly confirm the benefit of radial and cross-track measurement information compared to the GRACE along-track observable: the gravity fields recovered from the related alternative mission scenarios are superior in terms of error level and error isotropy. In fact, one of our main findings is that although the noise levels achievable with the particular configurations do vary between the simulated months, their order of performance remains the same. Our findings show also that the advanced pendulums provide the best performance of the investigated single formations, however an accuracy reduced by about 2-4 times in the important long-wavelength part of the spectrum (for spherical harmonic degrees <50, compared to the Bender mission, can be observed. Concerning state-of-the-art mission constraints, in particular the severe restriction of heterodyne lasers on maximum range-rates, only the moderate Pendulum and the Bender-mission are beneficial options, of course in addition to GRACE and GRACE-FO. Furthermore, a Bender-type constellation would result in the most accurate gravity field solution by a factor of about 12 at long wavelengths (up to degree/order 40) and by a factor of about 200 at short wavelengths (up to degree/order 120) compared to the present GRACE solution. Finally, we suggest the Pendulum and the Bender missions as candidate mission configurations depending on the available budget and technological progress.

KW - Future gravity missions

KW - Numerical simulation

KW - Temporal gravity field

UR - http://www.scopus.com/inward/record.url?scp=84892511993&partnerID=8YFLogxK

U2 - 10.1007/s00190-013-0665-9

DO - 10.1007/s00190-013-0665-9

M3 - Article

AN - SCOPUS:84892511993

VL - 88

SP - 31

EP - 43

JO - Journal of geodesy

JF - Journal of geodesy

SN - 0949-7714

IS - 1

ER -