<blockquote><font class="small">In reply to:</font><hr /><p>same instruments, used to find oil, also delivered weird results hard to interprete until we actually learned to interprete them<p><hr /></p></p></blockquote><br />Yeah, based on existing first-hand knowledge of earths geology, i.e. acquired data patterns were fit to existing knowledge. With mars, you simply dont have any existing knowledge and data received from the instrument could be interpreted in many ways.<br />With all instruments, you are observing some physical phenomena, like radio waves bouncing back from hard surfaces. The instrument data will only give you this info, that the waves bounced back from something, possibly with many echoes i.e. from subsequent hard layers in crust, everything else is pure interpretation based on other existing knowledge.<br />With mars, there's just that little of existing data on subsurface geology. Until that first hole will be drilled, everything will remain just hypotheses and guesses.