Assessment of constellation designs for earth observation: Application to the TROPICS mission

Abstract

The orbit and constellation design process for Earth observation missions is complex and it involves trades between different metrics such as mission lifetime, instrument performance, coverage, cost, and risk among others. In this work, these figures of merit were utilized to support the orbit selection process used during Pre-Phase A and Phase A studies for the NASA-funded Time-Resolved Observations of Precipitation structure and storm Intensity (TROP-ICS) mission. Thousands of potential constellations were defined, simulated and compared with each other according to different mission coverage requirements. The sensitivity and robustness of figures of merit to various hypothetical operational failures (e.g., loss of one satellite or one launch) was systematically measured. A deployment strategy based on differential drag was described and analyzed. Finally, the orbital lifetime of various architectures was also studied with respect to NASA's 25 years de-orbiting recommendation. The contributions of this work include: (1) an exhaustive analysis of figures of merit commonly used in Earth observation orbit design, including a new metric called Continuous High-Revisit Coverage, which captures the long coverage gaps left by string-of-pearls constellations. (2) A methodology to assess robustness of constellations based on a brute-force disjoint scenario simulation approach (3) Results and recommendations from the mission analysis process for the TROP-ICS mission. BIOGRAPHICAL SKETCH Pau Garcia Buzzi is a second-year aerospace engineering student at the Sibley School of Mechanical and Aerospace Engineering from Cornell University. He received a double Bachelor's degree in industrial and telecommunications engineering from Universitat Politecnica de Catalunya (BarcelonaTech) in Barcelona, Spain. In August 2018, he will graduate with an Master's of Science degree in aerospace engineering. He is particularly interested in the coverage analysis and constellation design for Earth observation missions. During the past two years, Pau worked under the supervision of his advisor, Dr. Daniel Selva, as part of the orbit and constellation design team of the NASA-funded Time-Resolved Observations of Precipitation Structure and Storm Intensity (TROPICS) mission. This experience provided him with valuable experience and insight into the orbit analysis and design of large constellations of Earth observing satellites. Pau was initially a doctorate student at Cornell University but will transfer to Texas A&M together with his advisor in the Fall 2018 semester, after obtaining his Master's degree from Cornell University. In the short term, he looks forward to continuing his investigation and applying machine learning techniques to the orbit and constellation design of future space missions. In 3 years, Pau wishes to obtain his doctorate degree at Texas A&M university. Outside of academics, Pau enjoys outside activities including fitness and running, and he has a lifelong passion for soccer. iii This document is dedicated to all my friend...

Fast Methods of Coverage Evaluation for Tradespace Analysis of Constellations

“…Ref. [18] introduces a similar aggregate metric called Continuous High Revisit Coverage which is the percentage of time where a GP is either in an access, or in a gap shorter than a threshold gap duration. The normalized number of useful revisits metric, on the other hand, considers the number of imaging opportunities, and not the time available for any opportunity.…”

“…For applications where the primary purpose of multiple satellites is to improve temporal resolution of the observations made over regions of interest, metrics commonly selected are temporal in nature, e.g., percentage of area of interest covered (maximize) in a given time span, and revisit time (minimize) of a region of interest. Examples of DSMs where it was important to optimize the temporal resolution of observations are the NASA-funded CYGNSS mission [16] which has demonstrated wind speed measurements taken from eight simultaneous vantage points in the same orbital plane, and thereby reduction of model uncertainties and the TROPICS constellation of microwave radiometers [17], [18], also funded by NASA, which is looking to increase science value of temperature/pressure profiles especially for tropical cyclones with six spacecraft in three orbital planes.…”

Preference-based Evolutionary Many-objective Optimization for Regional Coverage Satellite Constellation Design

“…In this paper, each small satellite is assumed to have no propulsion capability for out-of-plane maneuvering. And the total cost of propellant required to put spacecraft to the desired mission orbit is utilized to approximate the total cost [14]. The launch process is described as an out-of-plane Hohmann transfer.…”

Image Interpretability of nSight-1 Nanosatellite Imagery for Remote Sensing Applications

“…The use of miniaturized satellite platforms such as microsatellite and nanosatellites for earth imaging has been gaining momentum globally over the last decade [1][2][3][4][5][6]. Trends in miniaturization of low earth orbit earth observation satellites witnessed over the last few decades have been driven by universities, commercial satellite operators and space agencies that aim to reduce development cost, reduce launch overheads and scale down development time associated with large satellites such as Landsat, ENVISAT, and Sentinel missions.…”