Acoustic Imaging of Geosynchronous Satellites via a Newly Upgraded Hyper-Temporal Imaging Instrument

Abstract

Presented here are investigations into acoustic imaging techniques designed to identify geosynchronous (GEO) satellites by their polarization signatures. In order to conduct these observations, a hyper-temporal imaging (HTI) instrument has been developed. This new instrument has been designed to operate on the 61” Kuiper telescope, located on Mount Bigelow, Arizona. At the core of HTI is a polarizing beam splitter and two identical cameras which record s and p linear polarized channels simultaneously. These two channels are then used to calculate degree of linear polarization of the signal over time. The latest upgraded cameras are each Andor Zyla 4.2+sCMOS. These cameras are capable of recording data at speeds greater than 1000fps with a Field of View of 5 arcminutes. Typical site conditions at the telescope give an estimated 1 arcsecond of seeing (on good nights), thus the optical aberrations in HTI have been designed to be far less than this limit. Observations with the HTI instrument were conducted over 10 nights and data were collected on 22 different GEO satellites plus several stars for comparison. Here three of these target satellites are analyzed in detail for their unique signatures. StarOne/Brasilsat B4 (HS-376W bus) is a known spin-stabilized satellite. It showed clear peaks in the signal of: 0.53Hz, 1.06Hz, 1.59Hz, 2.1Hz, 2.65Hz, 3.18Hz, and 3.71Hz. Ciel-2 (Spacebus-4000C4 bus) is one of the larger of these GEO satellites and showed a signal which may be consistent with a satellite maneuver. This signal showed peaks in the power spectrum of DOLP at: 0.028, 0.043, 0.08, 0.26Hz. The third satellite, DirecTV-15 (Eurostar-3000 bus) also contained a signal which appears to be a satellite maneuver taking place. Peak frequencies of 0.069Hz and ~0.05Hz were observed in this signal.