The reflectance data is an IDL readable, unix structure file containing 88057 records: http://lasp.colorado.edu/pdr/mariner9/SDR/m9_reflectancedb_nov2011.dat
The label (.lbl) file explains the format and parameter descriptions. (The (.fmt) file is the standardized PDS format file for automated processing.)
For ease of transfer, use the zipped TAR file: http://lasp.colorado.edu/pdr/mariner9/SDR/m9_pds.tar.gz