Detecting tides and gravity at Europa from multiple close flybys

Abstract

[1] This paper presents the expected accuracy of the tides and gravity of Europa that can be measured by tracking a spacecraft during close flybys of Europa. A reference trajectory was designed for flyby science observations and consists of a total of 36 flybys of Europa at 100 km altitude. Earth-based Doppler measurements were created during ±2 hours of each periapsis passage and were simulated with realistic dynamical and measurement assumptions. The result shows that the degree 2 tidal Love number,k2, can be estimated to σk2 = 0.045 and σk2= 0.009 (1-sigma formal uncertainty) assuming X-band and Ka-band tracking capabilities, respectively, which is sufficient to confirm the existence of a global subsurface ocean.