Survey Design for Small Autonomous Ground-Based Telescopes To Detect Uncontrolled/Debris GEO Objects
Abstract
In this paper innovative surveys of uncontrolled GEO debris objects are designed for a small autonomous ground-based telescope. The key innovation is that the survey designs are based on the known astrodynamics of uncontrolled GEO objects (e.g. due lunar/solar perturbations) combined with the current concentration of catalogued uncontrolled/debris GEO objects. This innovation also applies to the more practical matters of solar phase angle, lunar/galactic center proximity, and telescope slew rate, to develop surveys that maximize the number of observed catalogued and uncatalogued near-GEO uncontrolled/debris objects and enhance the Space Situational Awareness (SSA) of uncontrolled, near-GEO, orbital debris objects.
The objectives of this research are threefold: 1) develop an efficient ground-based optical survey strategy that utilizes the astrodynamics of the GEO environment and the known concentrations of current GEO uncontrolled objects to maximize the coverage of GEO space debris while ensuring good visibility/lighting and good information content; 2) test and assess the merit of the new survey strategy through simulation using metrics which include visibility, information content, and coverage measures; and 3) test and assess the merit of the new survey strategy by utilizing USU's Space Situational Awareness Telescope for Astrodynamics Research (USU-STAR) to validate simulation results. It known that when a space object first becomes a debris object (i.e., uncontrolled), the orbital inclination of the GEO debris object increases from 0 degrees to 15 degrees and then decreases back to 0 degrees over a 54 year period (Vaughan and Mullikin, 1995) as a result of lunar-solar and geopotential perturbations. A consequence of this phenomena is that GEO space objects that were incapacitated 27 years ago are currently in a near 15 degree inclination orbit. Over the subsequent 27 years these objects return to a near 0 degree inclination orbit, the same orbit where our most valuable GEO assets reside.This will be the first key element in the survey design. This research will use the information from current TLE catalog and the a priori system information of USU-STAR telescope (e.g. slew rates) to design surveys. Four other key factors are taken into account including (1) the concentration/distribution of catalogued uncontrolled GEO objects, (2) solar phase angle, (3) proximity of the moon, and (4) the proximity of the galactic center to the observed GEO object. Because of the nature of the GEO orbit, uncatalogued/uncorrelated debris will mimic the behavior of the cataloged uncontrolled objects and thus will also be observed. Further, ensuring a good solar phase angle will ensure object detection, and sufficient angular distance from the moon, as well as the galactic center, will ensure a saturation-free and star-crowd-free image. The impetus for this work was based on the idea of a "pinch point" survey (Sharma et al., 2002) for space-based observatories which is in turn based on GEO object concentrations in RADEC space over a 24 hour period. In this work, multiple survey designs will be presented based on the concentration of known uncontrolled GEO debris. Further, the surveys are designed based on a performance index consisting of the four key factors stated above. The highest performance index at each time step will select the viewing direction of the EO sensor, and this technique will confirm the maximum utilization of the observation time. Comparison of the surveys will be made on the number of unique objects detected, the angle between two consecutive slewing directions of the telescope, and the state information gathered from the survey.- Publication:
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Advanced Maui Optical and Space Surveillance Technologies Conference
- Pub Date:
- September 2019
- Bibcode:
- 2019amos.confE..68N
- Keywords:
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- Astrodynamics;
- Debris;
- Space Situational Awareness;
- Small Autonomous Telescope Systems