Disappointment and self doubt

Having failed to collect the data I was seeking during the recent trip to my field site, my mind has been dwelling of thoughts of failure.  Doubting wether I have the skill to complete the research, fear of the disappointment I will see in my professors face tomorrow.  The idea of managing a field site and collecting data on the plant species seems simple when planned from the safety of my desk, but the ideas once applied to the real situation never come to fruition.  It's incredibly frustrating to have so little control over the experimental variables at this field site.