Daniel Kucharski, Space Environment Research Centre and University of Texas at Austin; James Bennett, EOS Space Systems and Space Environment Research Centre; Georg Kirchner, Space Research Institute, Satellite Geodesy Department, Austrian Academy of Sciences; Moriba Jah, The University of Texas at Austin; James Webb, EOS Space Systems Pty Ltd; Justin Spurbeck, The University of Texas at Austin
Keywords: High sampling rate photometry, spin dynamics
Abstract:
Passive space debris objects can gain spin energy from the interaction with external forces with the dominant effects arising from the Earths magnetic and gravity fields, solar radiation pressure, residual atmosphere pressure and the electrostatic effects. The torques exerted on an orbiting object affect its attitude dynamics and cause changes in the spin rate and a drift of the spin axis. The observed spin parameters combined with the physical models help to identify the source and the magnitude of the torques perturbing the orbital motion of the satellites [1].
The spin parameters of the passive objects can be determined from light curve measurements. The accuracy of the spin determination depends on the sensitivity and the sampling rate of the photometric system. In order to detect the perturbing torques on the nano-Nm scale we have developed a photometric system that performs satellite brightness measurements at the rate of 100 thousand samples-per-second. The sunlight reflected from the spinning object is collected by a robotic telescope (0.7-metre) and measured by the photomultiplier tube with a high sensitivity over the entire visible spectrum. The 100 kHz light curves are collected and processed by the dedicated software that allows for the spin rate determination at an accuracy level of 1 part-per-million.
The highly accurate spin measurements are used to detect and analyze the tiny forces and torques that perturb the dynamics of the space debris objects, including the nano-perturbations caused by laser photon pressure force delivered by the system being developed in the Space Environment Research Centre.
This presentation will show the design characteristics of the developed 100 kHz photometric system as well as the details of the post-processing and spin parameters determination methods. We will also present results on the torque analysis based on the spin observations of the selected passive satellites and space debris objects.
REFERENCES
Kucharski, D. et al., Photon pressure force on space debris TOPEX/Poseidon measured by Satellite Laser Ranging, AGU Earth and Space Science, Vol. 4, 661-668, 2017, doi:10.1002/2017EA000329
Date of Conference: September 11-14, 2018
Track: Optical Systems Instrumentation