I don't really get the default assumption you all make that NASA would want to hide evidence of aliens. It seems that the conspiracy crowd too often confuse rigor and skepticism for a coverup. If anything, NASA wants to find hard evidence of extraterrestrial life, it would be a boon to their funding, and those who work there want to make that kind of discovery. At the same time, they're also keenly aware that jumping to that conclusion without solid evidence is a quick way to end your career in the eyes of the broader scientific community. Getting involved with NASA scientists has been eye opening and some of them are much more open minded than any of you would give them credit for.