# Orbit design and thruster requirement for various constant-arm space mission concepts for gravitational-wave observation

## TL;DR

This paper evaluates orbit design and thruster needs for various gravitational-wave space missions, highlighting fuel requirements and proposing solutions for maintaining constant arm lengths in different orbital configurations.

## Contribution

It extends previous work by applying orbit and thruster analysis to B-DECIGO and DECIGO missions, assessing fuel needs and proposing alternatives for proof mass actuation.

## Key findings

- Heliocentric orbits require manageable fuel for constant arm maintenance.
- Geocentric orbits pose significant fuel mass challenges.
- Alternative proof mass solutions are necessary for adequate dynamical range.

## Abstract

In previous papers, we have addressed the issues of orbit design and thruster requirement for the constant arm versions of AMIGO (Astrodynamical Middle-frequency Interferometric Gravitational-wave Observatory) mission concept and for the constant arm GW (gravitational wave) mission concept of AIGSO (Atom Interferometric Gravitational-wave Space Observatory). In this paper, we apply similar methods to the orbit design and thruster requirement for the constant arm GW missions B-DECIGO and DECIGO, and estimate the yearly propellant requirements at the specific impulse Isp = 300 sec and Isp = 1000 sec. For the geocentric orbit options of B-DECIGO which we have explored, the fuel mass requirement is a concern. For the heliocentric orbit options of B-DECIGO and DECIGO, the fuel requirement to keep the arm equal and constant should be easily satisfied. Furthermore, we explore the thruster and propellant requirements for constant arm versions of LISA and TAIJI missions and find the fuel mass requirement is not a show stopper either. The proof mass actuation noise is a concern. To have enough dynamical range, an alternate proof mass is required. Detailed laboratory study is warranted