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Optimal trajectories and orbit design for separated spacecraft interferometry

IP.com Disclosure Number: IPCOM000128066D
Original Publication Date: 1998-Dec-31
Included in the Prior Art Database: 2005-Sep-14
Document File: 3 page(s) / 17K

Publishing Venue

Software Patent Institute

Related People

Edmund Mun Choong Kong: AUTHOR [+3]

Related Documents

http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1998-227: URL

Abstract

Imaging of inter-stellar objects at angular resolutions that are beyond the capability of single aperture systems is made possible with the advent of the interferometer. Since the angular resolution of an interferometer is inversely proportional to the separation of its apertures, angularly fine objects can only be detected using a separated spacecraft interferometer (SSI). In order to maximize the return from such a system, this study addresses the optimal trajectories for a SSI operating both outside and within a gravity-well. In the case of imaging from outside the gravity-well, the sequence of physical locations, where measurements are made to best mimic the point spread function of an equivalent filed aperture system, is determined by optimizing an image quality metric, known as the Mean Square Error. Then, the minimum effort trajectory for maneuvering these apertures to these locations is found. While sub-optimal, since the optimization problem is broken into two independent parts, it is shown that substantial efficiencies are realized over other proposed methods. Furthermore, the military and intelligence community is seriously considering the use of a SSI for Earth imaging purposes. Since the size of the apertures contribute towards the total mass of the system, the minimum aperture size required for a Fizeau interferometer which allows instantaneous imaging of a terrestrial target is determined. The orbits in which these spacecraft should be placed, to minimize the propellant required to maintain their positions in the cluster, are then determined. In particular, an innovative orbit design is presented which employs all four conic sections to meet the interferometric requirements while minimizing propellant expenditure. Thesis Supervisor: Prof. David W. Miller Dept. of Aeronautics and Astronautics 3

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OPTIMAL TRAJECTORIES AND ORBIT DESIGN FOR SEPARATED SPACECRAFT INTERFEROMETRY

by (Edmund) Mun Choong Kong
B.E., Mechanical and Space Engineering (Hons) University of Queensland 1995 Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE at the Massachusetts Institute of Technology February 1999
SIGNATURE OF author: [[signature omitted]]

Department of Aeronautics and Astronautics

November 05 1998

CERTIFIED BY: [[SIGNATURE OMITTED]]

David W. Miller

Assistant Professor Thesis Supervisor

ACCEPTED BY: [[SIGNATURE OMITTED]]

Jaime Peraire Associate Professor Chairman, Department Graduate Committee ARCHIVES MASSACHUSETTS INSTITUTE OF TECHNOLOGY LIBRARIES MAY 17 1999

Massachusetts Institute of Technology Page 1 Dec 31, 1998

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Optimal trajectories and orbit design for separated spacecraft interferometry

Optimal Trajectories and Orbit Design for Separated Spacecraft Interferometry

by

(Edmund) Mun C. KONG

Submitted to the Department of Aeronautics and Astronautics on November 05, 1998 in Partial Fulfillment of the Requirements for the Degree of Master of Science at the Massachusetts institute of Technology

ABSTRACT

Imaging of inter-stellar objects at angular resolutions that are beyond the capability of single aperture systems is made possible with the advent of the interferometer. Since the angular resolution of an interferometer is inversely proportional to the separation of its apertures, angularly fine objects can only be detected using a separated spacecraft interferometer (SSI). In order to maximize the return from such a system, this study addresses the optimal trajectories for a SSI operating both outside and within a gravity-well. In the case of imaging from outside the gravity-well, the sequence of physical locations, where measurements are made to best mimic the point spread function of an equivalent filed aperture system, is determined by optimizing an image quality metric, known as the Mean Square Error. Then, the minimum effort trajectory for maneuvering these apertures to these locations is found. While sub-optimal, since the optimization problem is broken into two independent parts, it is shown that substantial efficiencies are realized over other proposed methods. Furthermore, the military and intelligence community is seriously considering the use of a SSI for Earth imaging purposes. Since the size of the apertures contribute towards the total mass of the system, the minimum aperture size required for a Fizeau interferometer which allows instantaneous imaging of a terrestrial target is determined. The orbits in which these spacecraft should be placed, to minimize the propellant required to maintain their positions in the clus...