1. Figure 5: a) Reflectance (I/F) as a function of phase angle (g) for the BZs. b) BZ reflectance, normalized to background values. c) Reduced reflectance (IoF/LS), showing compositional differences between landing sites. d) Apollo 12 reflectance versus incidence angle (i), showing the effects of viewing geometry. e) Apollo 12 reflectance versus g. f) Apollo 12 reduced reflectance as a function of g, which masks the effects of viewing geometry and shows increased separation between BZ and background I/F values at higher phase. Figure 2: Apollo 11 landing site, with the LR-BZ and HR-BZ outlined. NAC image M150361817R. Mission Avg. I/F for HR- BZ Avg. I/F for LR-BZ Avg. background I/F Avg. normalized I/F b Elliptical Area (m 2 ) Lander mass (kg) Avg. Thrust c (kN) Ap11 0.033 0.016 0.0291.151 25403 1509542.5 Ap12 a 0.053 0.054 0.0481.123 53872 1523542.8 Ap14 0.059 0.046 0.0531.134 21339 1526442.9 Ap15 0.032 0.028 0.0271.185 18725 1660046.7 Ap16 0.074 0.070 0.0691.110 34483 1666046.8 Ap17 0.029 0.026 1.153 18888 1665842.5 Apollo avg0.047− 0.0421.143 28785 1591945 L16 0.046 − 0.0431.079 3355 5600 15.9 L17 0.027 − 0.0251.105 1889 5700 16.2 L20 0.082 − 0.0781.071 2166 5600 15.9 L23 0.047 − 0.0421.130 2105 5800 16.4 L24 0.040 − 0.0351.146 987 5800 16.4 Luna avg 0.048 − 0.0451.106 2100 570015-20 S1 0.024 − 0.0221.147 197 292 − S5 0.026 − 0.0221.330 131 303 − S6 0.040 − 0.0381.141 252 299.6 − S7 0.052 − 0.0511.008 279 305.7 − Surv. avg 0.035 − 0.0331.156 215 300.10.133-0.472 a Apollo 12 measurements include Surveyor Crater b Normalized I/F = IoF_bz/IoF_background (for HR-BZs) c Calculated from average Apollo, Luna, and Surveyor thrust values a Apollo 12 measurements include Surveyor Crater b Normalized I/F = IoF_bz/IoF_background (for HR-BZs) c Calculated from average Apollo, Luna, and Surveyor thrust values Table 1: Average blast zone measurements and reflectance values for each landing site. Average I/F values are for phase angles of ~30°. Figure 1: NAC images of the Apollo, Surveyor, and Luna landing sites, cropped to the region around the landers. Dashed lines outline the outer extent of each blast zone (HR-BZ). Insets are zoomed in on the lander. a) Apollo 14, image M11406206L. b) Luna 23, image M174868307R. c) Surveyor 1, image M122495769L. (a) Apollo (b) Luna (c) Surveyor Photometric Functions Hapke’s Bidirectional Reflectance Equation (from [6]) Double Henyey-Greenstein Function: Lommel-Seeliger Function (LS): Hapke’s Bidirectional Reflectance Equation (from [6]) Double Henyey-Greenstein Function: Lommel-Seeliger Function (LS): Parameters w = single scattering albedo p(g) = single particle phase function B co = amplitude of Coherent Backscatter Opposition Effect (CBOE) B c = angular shape function of CBOE h c = CBOE angular width parameter S = shadowing parameter b = angular width of forward or backscattering lobe c = magnitude of forward or backscattering lobe i = incidence angle e = emission angle g = phase angle *Bold variables are key parameters Parameters w = single scattering albedo p(g) = single particle phase function B co = amplitude of Coherent Backscatter Opposition Effect (CBOE) B c = angular shape function of CBOE h c = CBOE angular width parameter S = shadowing parameter b = angular width of forward or backscattering lobe c = magnitude of forward or backscattering lobe i = incidence angle e = emission angle g = phase angle *Bold variables are key parameters Figure 6: Preliminary photometric model fitted to BZ reflectance for Apollo 12 (top) and Apollo 16 (bottom). Acknowledgments We thank NASA for support of the LRO mission and the LROC Operations Team for making available the data used in this research. Acknowledgments We thank NASA for support of the LRO mission and the LROC Operations Team for making available the data used in this research. (b) (a) backward (d) wB co hchc bcS Ap120.350.400.1070.24-0.200.40 Ap160.480.400.1070.24-0.200.48 Table 2: Parameter values used for modeling in Fig. 6 feldspathic basaltic forward (e) (f) ID: 1495593 P43B-1931