Are there 57 alien species known to government, or is Sargeant Clifford Stone's 57 species a figment of his imagination? As part of The Disclosure Project, Sergeant Stone revealed in 2001 that he had catalogued that many as part of top-secret government projects and described what was known about the physical appearance of some of them. However, as part of such security level projects the public access to such documents is limited or non-existent which therefore leads to there being no factual proof, merely the word of this man. You can watch a clip of this presentation on YouTube at http://www.youtube.com/watch?v=rpAPxdjXLCQ.
It would be simple to dismiss his assertions were it not for number of government around the world that have been conducting investigations into UFOs and aliens, the number of former government members who are revealing what they can and, like Canada's Paul Hellyer - the former Defence Minister who is calling upon governments to release what they know (http://www.thestar.com/News/article/270984 is a link to a Toronto Star article about this) - you have to think they can't all be crazy. Why would such high ranking people be divulging what they can and calling on more information to be released if such information didn't exist? The government of France released to the public a database of investigations into UFOs at their website GEIPAN. Here's a link to the English introduction page: www.cnes.fr/web/CNES-en/5038-geipan.php - access to the database is found on this page but you will need to read French to study the research done.
Add to this the thousands of personal accounts and sitings given by people in the news, the most famous of which is the Area 51 supposed crash of an alien space craft in Roswell, New Mexico in 1947. The following Wikipedia article gives a description of this and cites links to the affidavits of those present at the time http://en.wikipedia.org/wiki/Witness_accounts_of_the_Roswell_UFO_incident.
The question most people have is if they are out there why don't we have real proof? Maybe we do. That's what the Disclosure Project is about. If Sargeant Stone is to be believed, he stated that many of the known aliens don't look like the typical movie description of a grey being with big eyes - they look like us. That they may not want to be found but instead are here for their own purposes is an important consideration. Why they are here if they are here is probably the most fearsome thing for governments. There is no reason to believe that their motives may be for the good; add to that is the fact these aliens are obviously far more advanced technologically than we are and while meeting them might enable them to give us knowledge we could find of great use to us, it could also be used against us.
Governments are privy to information that could be downright dangerous if brought out into the open, such is the nature of government. Governments are also about control, and staying in power to further the party agenda. I would say that for leaders of the various governments, knowing that there may be civilizations far more advanced than we are leaves us open to control by alien leaders. Are they trying to protect us or protect the status quo? To be fair I'd say it's probably a bit of both, but the key players in governments are the ones that aren't elected, those of big business who fund political parties and pay for elections. Yes, having the technology to create vehicles that generate their own power would be a wonderful thing (and end wars over oil) but to those whose wealth and power come from oil, this cannot be a good thing in their minds. They would be trying to suppress technology that would put them out of business, and yes, the various governments fed by this would also not be overly interested in furthering this technology.
So, are there 57 species of aliens? I'd have to say, why not? As Carl Sagan used to say there are billions and billions of planets out there, and while he believed the possibility of alien contact was quite small he was a key player in SETI, the search for intelligent life project. Sergeant Stone's assertion that many of these aliens look like to me is valid explanation for not having simple proof of their existence, especially if their interest in us is merely as observers, not wanting to be seen.