W. Thomas Vestrand, Los Alamos National Laboratory; Yancey H. Sechrest, Los Alamos National Laboratory; Robert J. Hill Jr., Los Alamos National Laboratory; David M. Palmer, Los Alamos National Laboratory; Lucas P. Parker, Los Alamos National Laboratory; Marion W. Vance, Los Alamos National Laboratory; Przemek R. Wozniak, Los Alamos National Laboratory
Keywords: Ultra-fast glints, stereoscopic cislunar optical ranging
Abstract:
The recent discovery of sub-second, bright, optical flashes in the night sky has generated questions about their origin. Are they a class of previously unknown ultra-fast glints from satellites? Or are the flashes of astrophysical origin? Preliminary studies suggest that most of the sub-second flashes are probably a previously unknown class of ultra-fast glints from Resident Space Objects (RSOs; i.e., earth orbiting satellites and debris). But the sub-second flashes still have not been linked to known RSOs. The “point-like” nature of flashes suggest that the glinting surfaces are located at Geostationary (GEO) or higher altitudes. The angular size of the Sun means that the narrowest glint beam pattern (generated by a flat mirror surface) is ~1/2 degree across. A glinting surface at GEO generates a ground footprint of at least 330 km in diameter. If the glinting surface is on a stable GEO platform; that beam pattern takes about two minutes to sweep by the ground observer. So, the existence of large population of sub-second glints that are nearly three orders of a magnitude shorter than the known class of bright GEO satellite glints is a surprise. The simplest explanation is that there is a significant population of RSOs, with glinting (specular) surfaces, spinning or tumbling at high angular rates (> 1 rpm) that, until now, were largely unknown. The key to understanding the origin of these ultra-fast glints is to associate the individual glints with known RSOs, or, if they are associated with an unknown RSO, establish the object’s orbit for subsequent tracking. However, the extremely short duration of the flash (~0.2 seconds or shorter) and point-like nature of the detection presents a challenge for traditional optical orbit determination techniques.
We describe a new, wide-field (4.5 sq-deg), stereoscopic imaging system employing high frame rate cameras that can detect a sub-second flash and derive the distance of the glinting object. The 38-km separation of the imaging telescopes and the arc-second spatial resolution of the images enables measurement of the distance to the glinting RSOs out to cislunar ranges. The system is being built to identify sub-second flashes events in real time, estimate the flash distance, and then rapidly follow-up with more powerful autonomous telescopes that have multi-color capability and greater sensitivity. This will enable a search for and characterization of sub-second astrophysical optical flashes. And, for the case of glinting RSOs, provide an initial orbit determination that will enable a search for a fainter Lambertian (diffuse) base component that, once identified, can be tracked. That, in turn, will enable a systematic exploration of the properties of the ultra-fast glint generating RSO population.
Date of Conference: September 27-20, 2022
Track: Optical Systems & Instrumentation