As I said before, science has already begun explaining the mechanism behind many of the phenomena of consciousness: cognition, memory, emotions, deja vu, etc...
What science cannot do (and I suspect, this is what a lot of people expect it to do, as a consequence of being able to explain it) is predict which way is a given fom of consciousness going to behave with 100% accuracy. But because of its intricate complexity, a given form of consciousness will not follow any predictive rules. It has a life of its own, so to speak.
I think of it as, say a sport, like soccer. You can explain soccer to someone. You can describe how the game works in detail, what are the rules of the game, etc... But as soon as a soccer match starts, any infinite number of interactions can happen, and you're always up for a surprise. It's a living entity with its own random behavior. That's what makes it impossible to predict (and that's what makes the sports fun)
Likewise, with consciousness. I think no matter how good science gets at explaining every part of its internal mechanism, there will never come a point where we can explain its function so well, that we can predict exactly how an individual is going to behave at any given time, or what processes is his mind going to go through, etc.
That said, science can make a lot of predictions about consciousness, in terms of its mechanism. We know that if we deprive the brain of certain chemicals or connections, it won't be able to perform specific functions. For instance, Capgras Delusion is a "circuit break" between the temporal cortex and the lymbic system in the brain, depriving the individual from a specific "cable" that send the "emotional signal" to the brain when they see a subject such as their mother, creating the illusion in their brain that the person they are observing is not their real mother, but rather an impostor. Many similar experiments have been made, such in cases like the Capgras Syndrome, proving that every single time such "circuit break" happens, the symptom pops up automatically.
These kind of experiments are the ones that have shown us that the brain, magnificent as it is, is no different from a computer. A much much complex computer, but still, subject to changes in functionality based on lack of proper connections, just like a computer. Science has made an amazing amount of progress explaining the brain's circuitry (and consequntially, the consciousness that arises from its connectivity) and will continue to do so. How far it will get in accuracy is something that only time will tell. But I doubt we will ever be able to entirely predict every single behaviour from any given form of consciousness, even if it's a form of consciousness we ourselves create (Artificial Intelligence) The whole "point" of consciousness is that it is unpredictable. It has a life of its own.