The EnVision Gravity Experiment
Abstract
The EnVision mission, which is ongoing selection at ESA, is a spacecraft in near-polar and low-altitude orbit around Venus. A regular tracking of the spacecraft in such an orbit will allow to uniformize the spatial resolution of the gravity field solution and to improve the accuracy of its tidal component (k2 Love number). This improvement of Venus' gravity field will allow to detect possible lateral variations of the lithospheric and crust thicknesses and the better constrain the size and state of the core. Precise Doppler tracking data of the EnVision spacecraft are foreseen to be performed during telemetry slots of the payload instrument data, providing at least 3 hours of effective tracking per day over the mission science duration. This tracking will use the Ka-band carrier frequency, which allows less noisy Doppler data than in X-band (Magellan data). In this study, simulations are performed to assess the expected improvement of the gravity field solution, taking into account a realistic Doppler noise budget and the misleading of the knowledge of the full dynamics of the spacecraft motion (especially the atmospheric drag at low-altitude and the inertial wheel off-loading maneuvers). Simulation results show that a spatial resolution better than 200 km can be reached over at least 40% of the planetary surface when the spacecraft altitude is lower than 350 km, allowing to fill the major gaps in the resolution of the current solution. The precision on the potential tidal Love number k2 is predicted to be better than 3%, allowing to better constrain the size and state of the core. The improvement would also allow to investigate smaller gravity variations due to the mass transfer in the atmosphere related to the thermal tides in the atmosphere.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMP048.0005R
- Keywords:
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- 6297 Instruments and techniques;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 6964 Radio wave propagation;
- RADIO SCIENCE;
- 6979 Space and satellite communication;
- RADIO SCIENCE;
- 6994 Instruments and techniques;
- RADIO SCIENCE