Orbital Stability Study of the Taiji Space Gravitational Wave Detector

TL;DR

This study investigates the orbital stability of the Taiji space gravitational wave detector, emphasizing the impact of planetary gravitational perturbations, especially Earth's, on spacecraft formation and armlength variations through numerical simulations.

Contribution

It provides a detailed analysis of planetary gravitational effects on Taiji's spacecraft orbits, highlighting the significance of Earth's gravity and the differences caused by various ephemerides.

Findings

Earth's gravity significantly affects spacecraft formation stability.

Including Venus and Jupiter reduces armlength and velocity variations.

Initial orbit entry time influences formation motion amplitude.

Abstract

Space-based gravitational wave detection is extremely sensitive to disturbances. The Keplerian configuration cannot accurately reflect the variations in spacecraft configuration. Planetary gravitational disturbances are one of the main sources. Numerical simulation is an effective method to investigate the impact of perturbation on spacecraft orbits. This study shows that, in the context of the Taiji project, Earth's gravity is an essential factor in the change in heliocentric formation configuration, contributing to the relative acceleration between spacecrafts in the order of $\mathcal O(10^{-6})\,{\rm m\cdot s^{-2}}$. Considering 00:00:00 on 27 October 2032 as the initial orbiting moment, under the influence of Earth's gravitational perturbation, the maximum relative change in armlengths and variation rates of armlengths for Taiji is $1.6\times 10^{5}\,{\rm km}$, $32\,{\rm m\cdot s^{-1}}$, respectively, compared with the unperturbed Keplerian orbit. Additionally, by considering the gravitational perturbations of Venus and Jupiter, the armlength and relative velocity for Taiji are reduced by $16.01\%$ and $17.45\%$, respectively, compared with when only considering that of Earth. The maximum amplitude of the formation motion indicator changes with the orbit entry time. Results show that the relative velocity increase between the spacecrafts is minimal when the initial orbital moment occurs in July. Moreover, the numerical simulation results are inconsistent when using different ephemerides. The differences between ephemerides DE440 and DE430 are smaller than those between DE440 and DE421.