If the surface is rough at the wavelength scale or there is significant penetration into the regolith, there will be a significant SC component in the echo caused by multiple scattering.
ɪf ðə sˈɜːfɪs ɪz ɹˈʌf æt ðə wˈeɪvlɛŋθ skˈeɪl ɔːɹ ðɛɹ ɪz sɪɡnˈɪfɪkənt pˌɛnɪtɹˈeɪʃən ˌɪntʊ ðə ɹᵻɡˈɑːlɪθ, ðɛɹ wɪl biː ɐ sɪɡnˈɪfɪkənt ˌɛssˈiː kəmpˈoʊnənt ɪnðɪ ˈɛkoʊ kˈɔːzd baɪ mˌʌltɪpəl skˈæɾɚɹɪŋ.