It must be ammended such that any sentient race or being from any planet, or source of existance have the same equal and unalienable rights as man (such representing both male and female humanity).
Now here is my reasoning, stick with me for a moment.
Lets assume that there is life on other planets. Lets assume some have become advanced enough for interstellar travel and have thus been in the vacinity of our planet. Lets also assume that they would posses some kind of computer like technology, and even wireless functionality. We therefor also can assume that this technology would be far more advanced and efficient then our own, seeing as they have perfected space venture afterall. Now, with that in mind we should consider that they would be able to wirelessly access most if not all of our digital data storage (read the internet!). Having pilfered through all the data and information, they have certainly come to the conclusion that no protection in the shape of equal rights would be garanteed them should they make their presance/existance public. In fact I think thats the only reason they arn't landing at superbowls and other high populated events. They are affraid of disection, I mean lets face it wouldn't you be?
So I say, we ammend the constitution even though we dont have FACTUAL proof sentient life exists anywhere else in the galaxy, just incase they do but are too affraid to stop by and visit.