Editing Albedo (section)

====Relationship to surface [[bulk density]]====
In the event that most of the echo is from first surface reflections (<math>\hat{\sigma}_\text{OC} < 0.1</math> or so), the OC radar albedo is a first-order approximation of the Fresnel reflection coefficient (aka reflectivity)<ref name="Ostro_Asteroid_Radar" /> and can be used to estimate the bulk density of a planetary surface to a depth of a meter or so (a few wavelengths of the radar wavelength which is typically at the decimeter scale) using the following empirical relationships:<ref name="Shepard_M2">{{cite journal |last1=Shepard |first1=M. K. |display-authors=etal |title=A radar survey of M- and X-class asteroids II. Summary and synthesis |journal=Icarus |date=2010 |volume=208 |issue=1 |pages=221–237 |doi=10.1016/j.icarus.2010.01.017|bibcode=2010Icar..208..221S }}</ref>

:<math>\rho = \begin{cases}
   3.20 \text{ g cm}^{-3} \ln \left( \frac{1 + \sqrt{0.83 \hat{\sigma}_\text{OC}}}{1 - \sqrt{0.83 \hat{\sigma}_\text{OC}}} \right) & \text{for } \hat{\sigma}_\text{OC} \le 0.07 \\
  (6.944 \hat{\sigma}_\text{OC} + 1.083) \text{ g cm}^{-3} & \text{for } \hat{\sigma}_\text{OC} > 0.07
\end{cases}</math>.