The Prime Directive In Effect On Mars

"We know that there's life on Mars because we sent it there," said NASA's John Grunsfeld, regarding our Martian probes. Did NASA just admit to life on Mars? Well theoretically yes. NASA's data no doubt points to at least microbial life with all that flowing water there, but specifically what John is referring to is the scenario of an Earth microbe relocated to Mars on a probe.

The U.S. and most countries signed a U.N. pact called the Outer Space Treaty which has very strict rules regarding interaction with alien life.
The treaty is concerned that an Earth stowaway microbe attached to a rover or probe might contaminate Mars and kill off the native organisms. Although the probes are built in a sterile environment, contamination on the journey to Mars is a possibility. That should answer any question as to why the rovers aren't getting up close and personal with the flowing water.

This is a fine example of how the Shadow Government conceals the truth. They investigate flowing water secretly and hide the evidence from the public with a trumped up lie based on the Prime Directive fantasy from Star Trek. General Order 1: "No starship may interfere with the normal development of any alien life or society." - "A starship captain's most solemn oath is that he will give his life, even his entire crew, rather than violate the Prime Directive." – James T. Kirk.

Dr. Michio Kaku explains the significance of flowing water versus frozen water in this video.