Yesterday NASA announced that we had found flowing water on Mars. It immediately elevated the four sites where the salts indicative of liquid water were located to some of the best candidates in the search for life on the red planet. But even though one of the sites — a central mound in Mars’ Gale crater — shows the same, previously identified dark streaks that dribble downslope in the summer and disappear in the winter, we won’t be sending any rovers to check for life. The Mars Curiosity rover is within 50 kilometers (31 miles) of the mound, and it won’t be making a detour.

Though flowing water on Mars is one of the best places to look for life, we won’t be sending spacecraft there for years. Why? The Prime Directive.

In Star Trek lore, the Prime Directive is a complicated order with dozens of sub-orders, but the general interpretation is that no advanced civilization should interfere in the development of a less-advanced civilization. And though it was violated many times in many different Star Trek iterations, going against the Prime Directive was a very serious offense. NASA has a similar order for spacecraft.

The real reason that we won’t send our robots to trickling Martian water anytime soon is that they simply aren’t sterilized to the degree where contamination would be impossible. Speaking in a Reddit AMA, Rich Zurek, the Project Scientist for the Mars Reconnaissance Orbiter, put it simply:

These [dark streaks] are on steep slopes, so our present rovers would not be able to climb up to them. Because liquid water appears to be present, these regions are considered special regions where we have to take extra precautions to prevent contamination by earth life. Our current rovers have not been sterilized to the degree needed to go to an area where liquid water may be present.

In other words, though it’s unlikely, microbes from Earth might still be living in the nooks and crannies of Curiosity, ready to infect the waters of Mars. If any microbes were living on Mars, they may be out-competed or eradicated by invaders from Earth. If that happened, the biosphere would be irrecoverably changed, and the Prime Directive violated.

So for now, a possible violation is unacceptable. With the discovery of these leaking faucet-like seeps on the Martian slopes, it could be that the next generation of NASA rovers, beginning with the Mars 2020 rover (to be launched in, you guessed it, 2020), will be sterilized to the point where they could explore the liquid water. Then even Picard would be proud.

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IMAGE: CBS