Measurement of the photometric and spectral BRDF of small Canadian satellite in a controlled environment

Transcription

1 Measurement of the photometric and spectral BRDF of small Canadian satellite in a controlled environment 15 September 2011 AMOS Conference Major Donald Bédard Royal Military College of Canada, Department of Physics Martin Lévesque Defence Research & Development Canada - Valcartier Brad Wallace Defence Research & Development Canada - Ottawa

2 My thesis supervisors: Acknowledgements Dr. Gregg Wade, RMC Dr. Kira Abercromby, Cal Poly San Luis Obispo Dr. Rob Zee, UTIAS Space Flight Laboratory Microsat Systems Canada, Inc. (MSCI) 2

3 Points of discussion Background: Why are we doing this? CanX-1 EM characterization experiment: Aim Subject Set-up and procedure Some results NEOSSat characterization Future work Conclusion 3

4 Reflectance spectroscopy applied to SSA: A young discipline Consideration of the Sun-object-sensor geometry: Currently limited to phase angle. Most observed objects have been measured a few number of times No detailed characterization of artificial space objects. Limitations of spectrometric measurements: In which situation is this technique appropriate, and most importantly, when is it not? Same phase angle but different Sun-objectsensor geometry n n Reddening effect, described by Abercromby et al. as increase in reflectance at wavelength greater than approximately 700 nm, is still unexplained. Sun-object-sensor geometry. 4

5 Opportunity in the next 12 months Improve the technique of using reflectance spectroscopy for SSA purposes: New methods of acquiring and comparing ground and remote measurements. What makes this possible: Availability of NEOSSat for both ground and remote measurements Full availability of NEOSSat attitude data An example of the variation of the Sunspacecraft-sensor geometry over a 10- second period. 5

6 CanX-1 EM characterization experiment Experimental objectives: z φ l Develop an experimental procedure. ω φ c θ l y Develop the software tools. x θ c Study the spectrometric data. 6

7 Subject: CanX-1 Engineering Model Images of the six faces of the CanX-1 EM. The nomenclature used to identify the six faces corresponds to that used by the CanX-1 mission team. 7

8 Experimental set-up Light source Dummy sensors Dark background Turn table Phase angle pattern ASD Spectrometer Picture of the set-up used for the CanX-1 EM characterization experiment 8

9 Set-up components Halogen lamp at the focal point of a parabolic mirror ASD spectrometer head and Nikon camera Light source seen by the satellite Equivalent solar illumination 9

10 Types of measurements taken Spectrometric and photometric measurements Standard reference: Spectralon Background measurements 10

11 Data analysis: Photometric light curve vs phase angle 11

12 Main observations: Data analysis: Determining material type CanX-1 EM spectra is dominated by solar cell. Shape of the spectra varied with changing light-object-sensor geometry. CanX-1 EM spectral reflectance factor as a function of wavelength. Modeled spectral reflectance of a simplified modeled Emcore TJ solar cell used on the CanX-EM. 12

13 CanX-1 EM: Spectral variations Phase angle = 5 degrees ω sat = 192 degrees Phase angle = 5 degrees ω = 197 degrees Phase angle = 10 degrees ω = 197 degrees Visible variation in the spectral reflectance of the CanX-1 EM solar cells. 13

14 Data analysis: Reddening effect in the lab? CanX-1 EM characterization data seem to show an analogous phenomenon to the one described by Abercromby et al. Not reported to have been observed in a lab environment. Spectral reflectance measurements of the X and +Y faces taken at a 30 degree phase angle illumination. Come and check out my poster!!! 14

15 Data analysis: Determining spacecraft orientation Comparison of principal and perpendicular plane of the +Z panel taken with a 5 degrees illumination phase angle. The left image shows weak diffuse reflectance from the Aluminum 6061 surface, while the right image shows specular reflectance from the solar cells at 95 o. 15

16 Data analysis: Determining material type (2) Weak diffuse reflectance obtained from the +Z panel at a phase angle of 5 deg. Theoretical spectral reflectance from an Al surface with RMS surface roughness of 0 (top) and 50 nm (bottom). 16

17 Ground characterization of NEOSSat Activities: NEOSSat panel characterization at MSCI facilities. NEOSSat spacecraft characterization at DFL. Outcomes: Improved spacecraft ground characterization procedure Ground truth data of NEOSSat material Figure 22. Planned experimental set-up of the ground characterization of the NEOSSat spacecraft. 17

18 Future work NEOSSat CanX-4 and 5 M3MSat Remote observations of NEOSSat: Remote spectrometric observations Simultaneous multi-color observations at RMC Modelling and simulation Ground characterization of other Canadian small satellites Characterization of common spacecraft materials at RMC 18

19 Objective of the work: Improve the technique of using reflectance spectroscopy in the context of surveillance of space Conclusion This will be done through new methods of: Acquiring ground-truth measurements Comparing the above with remote measurements. 19

20 References 1. Remote and Ground Truth Spectral Measurement Comparisons of FORMOSAT III. Abercromby, K.J., et al., et al. Maui, Hawaii : s.n., AMOS Technical Conference. 2. The design and operation of the Canadian advanced nanospace experiment (CanX-1). Strass, L., et al., et al. Toronto, Canada : s.n., Proceedings of the 21st AMSAT Space Symposium. 3. Jorgensen, K. Using Reflectance Spectroscopy to Determine Material Type of Orbital Debris. PhD Dissertation. Boulder, Colorado : University of Colorado, Nicodemus, F.E., et al., et al. Geometrical Considerations and Nomenclature for Reflectance. Washington : National Bureau of Standards, US Department of Commerce, Obtaining material type of orbiting objects through reflectance spectroscopy measurements. Jorgensen, K., et al., et al. Kihei, Maui, Hawaii : s.n., AMOS Technical Conference. 6. Using Space Weathering Models to Match Observed Spectra to Predicted Spectra. Guyote, M., Okada, J. and Abercromby, K.J. Wailea, Maui, Hawaii : s.n., AMOS Technical Conference. 20