The surfaces of most atmosphereless solar system objects are referred to as regolith, layers of loosely connected fragmentary debris, produced by meteorite impacts. Measurements of light scattered from such surfaces provides information about the composition and structure of the surface. A suitable way to characterize the scattering properties is to consider how the intensity and polarization of scattered light depends on the particle size, composition, porosity, roughness, wavelength of incident light and the geometry of observation. In the present work, the effect of porosity on bidirectional re ectance as a function of phase angle is studied for alumina powder with grain size of 0.3 μm and olivine powder with grain size of 49 μm at 543.5 nm. The optical constants of the alumina sample for each porosity were calculated with Maxwell Garnett eective medium theory. On using each of the optical constants of alumina sample in Mie theory with the Hapke model the variation of bidirectional re ectance is obtained as a function of phase angle with porosity as a parameter. Experimental re ectance data are in good agreement the model. For the olivine sample the effect of porosity is studied using Hapke (2008).

ABSTRACT
1. INTRODUCTION
2. INSTRUMENTAL DETAILS
3. MODELLING OF EXPERIMENTAL DATA
4. CONCLUSIONS
REFERENCES

• Amritaksha Kar(Department of Physics, Assam University)
• Sanjib Deb(Department of Physics, Assam University)
• A. K. Sen(Department of Physics, Assam University)
• Ranjan Gupta(Inter-University Centre for Astronomy and Astrophysics)