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Simulation of multiangular remote sensing products using small satellite formations

Simulation of multiangular remote sensing products using small satellite formations
Simulation of multiangular remote sensing products using small satellite formations
To completely capture the multiangular reflectance of an opaque surface, one must estimate the bidirectional reflectance distribution function (BRDF), which seeks to represent variations in surface reflectance as a function of measurement and illumination angles at any time instant. The gap in angular sampling abilities of existing single satellites in Earth observation missions can be complemented by small satellites in formation flight. The formation would have intercalibrated spectrometer payloads making reflectance measurements, at many zenith and azimuthal angles simultaneously. We use a systems engineering tool coupled with a science evaluation tool to demonstrate the performance impact and mission feasibility. Formation designs are generated and compared to each other and multisensor single spacecraft, in terms of estimation error of BRDF and its dependent products such as albedo, light use efficiency (LUE), and normalized difference vegetation index (NDVI). Performance is benchmarked with respect to data from previous airborne campaigns (NASA's Cloud Absorption Radiometer), and tower measurements (AMSPEC II), and assuming known BRDF models. Simulations show that a formation of six small satellites produces lesser average error (21.82%) than larger single spacecraft (23.2%), purely in terms of angular sampling benefits. The average monolithic albedo error of 3.6% is outperformed by a formation of three satellites (1.86%), when arranged optimally and by a formation of seven to eight satellites when arranged in any way. An eight-satellite formation reduces albedo errors to 0.67% and LUE errors from 89.77% (monolithic) to 78.69%. The average NDVI for an eight satellite, nominally maintained formation is better than the monolithic 0.038.
BRDF, Clouds, CubeSat, Earth, Estimation, Extraterrestrial measurements, NDVI, Satellite broadcasting, Satellites, Space vehicles, constellations, multi-view measurements
1939-1404
638 - 653
Nag, Sreeja
f3488c2c-58f4-427d-a6d0-ee98c9eac54d
Gatebe, Charles K.
2ddab2d3-ec09-4f89-a652-4fb58a3c77bf
Hilker, Thomas
c7fb75b8-320d-49df-84ba-96c9ee523d40
Nag, Sreeja
f3488c2c-58f4-427d-a6d0-ee98c9eac54d
Gatebe, Charles K.
2ddab2d3-ec09-4f89-a652-4fb58a3c77bf
Hilker, Thomas
c7fb75b8-320d-49df-84ba-96c9ee523d40

Nag, Sreeja, Gatebe, Charles K. and Hilker, Thomas (2017) Simulation of multiangular remote sensing products using small satellite formations. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 10 (2), 638 - 653. (doi:10.1109/JSTARS.2016.2570683).

Record type: Article

Abstract

To completely capture the multiangular reflectance of an opaque surface, one must estimate the bidirectional reflectance distribution function (BRDF), which seeks to represent variations in surface reflectance as a function of measurement and illumination angles at any time instant. The gap in angular sampling abilities of existing single satellites in Earth observation missions can be complemented by small satellites in formation flight. The formation would have intercalibrated spectrometer payloads making reflectance measurements, at many zenith and azimuthal angles simultaneously. We use a systems engineering tool coupled with a science evaluation tool to demonstrate the performance impact and mission feasibility. Formation designs are generated and compared to each other and multisensor single spacecraft, in terms of estimation error of BRDF and its dependent products such as albedo, light use efficiency (LUE), and normalized difference vegetation index (NDVI). Performance is benchmarked with respect to data from previous airborne campaigns (NASA's Cloud Absorption Radiometer), and tower measurements (AMSPEC II), and assuming known BRDF models. Simulations show that a formation of six small satellites produces lesser average error (21.82%) than larger single spacecraft (23.2%), purely in terms of angular sampling benefits. The average monolithic albedo error of 3.6% is outperformed by a formation of three satellites (1.86%), when arranged optimally and by a formation of seven to eight satellites when arranged in any way. An eight-satellite formation reduces albedo errors to 0.67% and LUE errors from 89.77% (monolithic) to 78.69%. The average NDVI for an eight satellite, nominally maintained formation is better than the monolithic 0.038.

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More information

Accepted/In Press date: 13 May 2016
e-pub ahead of print date: 24 June 2016
Published date: February 2017
Keywords: BRDF, Clouds, CubeSat, Earth, Estimation, Extraterrestrial measurements, NDVI, Satellite broadcasting, Satellites, Space vehicles, constellations, multi-view measurements
Organisations: Geography & Environment

Identifiers

Local EPrints ID: 397763
URI: http://eprints.soton.ac.uk/id/eprint/397763
ISSN: 1939-1404
PURE UUID: 539f3752-dffb-474a-92f2-93051884095b

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Date deposited: 06 Jul 2016 13:40
Last modified: 15 Mar 2024 01:22

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Contributors

Author: Sreeja Nag
Author: Charles K. Gatebe
Author: Thomas Hilker

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