A linear formation-flying astronomical interferometer in low Earth orbit

Space interferometry is the inevitable end point of high angular resolution astrophysics, and a key technology that can be leveraged to analyse exoplanet formation and atmospheres with exceptional detail. However, the anticipated cost of large missions, such as Darwin and TPF-I, and inadequate technology readiness levels have resulted in limited developments since the late 2000s. Here, we present a feasibility study into a small-scale formation-flying interferometric array in low Earth orbit, which will aim to prove the technical concepts involved with space interferometry while still making unique astrophysical measurements. We will detail the proposed system architecture and metrology system, as well as present orbital simulations that show that the array should be stable enough to perform interferometry with <50 m s–1 yr–1 delta-v and one thruster per spacecraft. We also conduct observability simulations to identify which parts of the sky are visible for a given orbital configuration. We conclude with optimism that this design is achievable, but a more detailed control simulation factoring in a demonstrated metrology system is the next step to demonstrate full mission feasibility.