ARGOS testbed: study of multidisciplinary challenges of future spaceborne interferometric arrays

Abstract

Abstract. Future spaceborne interferometric arrays must meet stringent optical performance and tolerance requirements while exhibiting modularity and acceptable manufacture and integration cost levels. The Massachusetts Institute of Technology (MIT) Adaptive Reconnaissance Golay-3 Optical Satellite (ARGOS) is a wide-angle Fizeau interferometer spacecraft testbed designed to address these research challenges. Designing a space-based stellar interferometer, which requires tight tolerances on pointing and alignment for its apertures, presents unique multidisciplinary challenges in the areas of structural dynamics, controls, and multiaperture phasing active optics. In meeting these challenges, emphasis is placed on modularity in spacecraft subsystems and optics as a means of enabling expandability and upgradeability. A rigorous theory of beam-combining errors for sparse optical arrays is derived and flown down to the design of various subsystems. A detailed elaboration on the optics system and control system is presented based on the performance requirements and beam-combining error tolerances. The space environment is simulated by floating ARGOS on a frictionless airbearing that enables it to track both fast and slow moving targets.

Far Infrared Astronomy After Spica

“…In the first, which we might term a Fizeau interferometer, the light from an arrangement of apertures is brought together at a combined focal plane. The distributed aperture may be as shown in Figure 3a (Lester et al, 2005), may a be a ring like aperture (the TALC proposal, see Ivison et al 2013) or could be arranged as separate telescopes with some form of phase correction system between them (Chung et al, 2004). The second possibility is essentially to place an ALMA or SMA type heterodyne interferometer in space.…”

Nonlinear Model Reduction and Decentralized Control of Tethered Formation Flight

“…Additionally, the array is assumed to always rotate at a certain angular rate so the tether is taut and straight at all times. A nonzero angular rotation [29] is a realistic assumption because tethered interferometers will attempt to fill a full u-v coverage [1] by rotation. For simplicity, the speed of the tether motor can be easily predefined in the control code and does not constitute the system states.…”

“…One such example includes stellar interferometers in which multiple apertures in controlled formation collect light for coherent interferometric beam combination, thereby achieving a fine angular resolution comparable to a large monolithic aperture telescope [1]. The possible architectures of spaceborne interferometers include a structurally connected interferometer (SCI), which allows for very limited baseline changes, and a separated spacecraft interferometer (SSI) [2] where the usage of propellant can be prohibitively expensive.…”

Dynamics and Control of Tethered Formation Flight Spacecraft Using the SPHERES Testbed

“…4 to 5 m) as well as the scaling laws of manufacturing cost. 1 In order to overcome this difficulty, break-through technologies such as a Separated Spacecraft Interferometer (SSI) are being studied for NASA's Terrestrial Planet Finder (TPF) mission.…”