A computer system executes hierarchical MK splines approximation for lunar brightness temperature (TB) data approximation. The computer system constructs a TB model map by generating a final approximation function for constructing an interpolated surface that approximates the TB data set obtained by lunar probe. The method includes executing MK splines approximation to the TB data set with a hierarchy of control lattice from coarsest lattice to densest lattice to iteratively obtain approximation functions. The TB model map is constructed by generating a final approximation function to construct the interpolated surface.