Apollo 14 astronaut Edgar Mitchell has long been involved in the investigation of paranormal phenomena. Unfortunately, claims like this don't exactly buttress his credibility.
If there's any truth to Mitchell's assertions, he should be able to back them up with specifics. As it stands, his statements (assuming they have been reported accurately) sound like off-the-wall conspiracy-theory ramblings. Note that at one point he says he has "sources" at NASA who've had contact with aliens, but at another point he implies that he himself was "briefed" on the issue. So which is it? Is he relying on anonymous back-channel sources or on official NASA briefings? There's a big difference.
The article also notes that Mitchell has endorsed the very questionable and much debunked Roswell case. From everything I know about Roswell, there's no there there.
And if there is a vast decades-long government conspiracy aimed at stifling this information, how can Mitchell casually break the story in a radio interview, apparently without fear of repercussions?
Stuff like this does nothing but make all psi researchers look bad.
Earth to Edgar: phone home!