It is the fact that spy satellites of super powers cover every major movements in the air around the glob. There is no doubt that all super powers know what exactly happened to Malaysian Flight 370. Regarding invisibility to radar, theoretically you can make any plane invisible to radar. Radar beams made up of negative electrons, which reflect back when hit some thing like a plane. To prevent reflection, charge outer surface of the plane positively. The positively charged surface should absorb all electron beams of the radar. In this way no electrons should remain to reflect and go back. If there is no reflection nothing will be visible on the screen. But this is very simplistic explanation. Anyway, thanks to the posts of TLEasley, now we know exactly what happened to this plane and I was right when I stated that all passengers, I meant also crews, could be alive and kicking. What ever has happened to the passengers and crews, if anything has happened, it wouldn't have happened because of mechanical failures of the plane.