During the days of nuclear research before the first detonation of the atom bomb, people thought that it would start a chain reaction that would destroy the planet. Nothing but mass destruction was expected of this research at that time, yet now we have power stations, various medical treatments, ships that run for years on a tankfull. Who is to know what spinoffs may result from this latest venture?
As for the UFO thing, I am a firm believer in anything is possible. We have developed stealth aircraft enough to suit our immediate purpose, if I were to visit a planet such as this one with it's distrusting, fragmented population, constant wars, total belief in "power is wealth" etc, I would develop the most sophisticated system of concealment I could before I came near this place. They could be thousands or millions of yrs ahead of us. There may be one or two of these guys standing right next to us right now having a laugh as they watch our guess work. The idea of some alien landing in a field with "Take me to your leader" is an utter ludicrousity, "You got this far without my help, find him your bloody self!!"
As far as space travel is concerned we have, in my opinion, only reached the stage that Wilbur & Orville were at in 1903 or was it 4? At the increasing rate of acceleration of technology we should be on Antares 4 in about 100yrs maybe less if we stop fighting in the playground among ourselves.
However with the current Government / Dictatorship type of rule very little will happen, unless someone parks a UFO the size of Belgium over Washington & says "This is the way you will behave!"