I don't know exactly if there are "aliens" but I do think there is some other life up there that we humans are unaware of. From what I here, they found water on Mars, so there's a hint that something or someone might be there. Who know's? Only God can answer this question.
I have a feeling that there are other forms of life out there. Earth isn't the only planet so other planets like Mars may have living things on it. Maybe the satelites were really close to finding evidence of life on Mars, but weren't close enough. Just my opinion, but wouldn't it be selfish of us to think that the organisms and plants on Earth were the only things alive in the entire Universe?