Originally Posted by Swift

Let me try another spin on this.

Can governments and government agencies keep secrets, at least for some period of time? - sure

Is it possible that NASA could be keeping secrets on alien life? - maybe

But the problem is, the fact that it is possible, even if highly improbable, doesn't make it true. And if they are so good at keeping their secrets, we'll never uncover it.

So you are asking us to prove that NASA is not keeping secrets about alien life forms and that is not possible to do so.

But, on the flip side, the fact that we can't prove it wrong, doesn't make it right. And, given that there is no evidence supporting the discovery of alien life, the simplest explanation is that it hasn't been discovered.