Both of those are impossible at our current level of technology - when it would take an emergency priority plan to get to Mars any time in, say, the next twenty years, there IS no neutral site in the Solar System.

We have nothing like a cloaking system that would work - I don't even know how well stealth bombers work against both instruments and plain ol' eyeballs. (Then again, I've never seen a stealth aircraft, so...)

The only possibility I can think of in the next 50 years is still a long shot. If we detected an alien exploratory race before they detected us, we might be developed enough to send non-humanoid robots to, say, Titan or Ganymede. As communications would obviously take eight hours back and forth, we'd want to lie about that - say a communications burst every 12 hours. And rather than return them to Earth, we'd want to be able to self-destruct them once discussions were done (or more reasonably, set them on a 24 hour self-destruct that must be deactivated every 12 hours... or after a day, they deactivate and blow up.)

Sure it sounds crazy. But it's at least a margin of safety. And in any case, I suspect that, while aliens could land tomorrow, we won't have extra-terrestrial visitors anytime soon.

Ah well.

...We are talking about HUGE distances ...

Space is so vast and yet we haven't found anything about alien life !

This does't mean that is impossible to be in existense...but is more likely impossible to come in contact with them!

First we haven't a mapped the universe yet! Also the area that is mapped and the signals we have received from that area indicates no alien life!( fun factor : every once in a while we all here those big mouth announcements from NASA of that  new planet that can suctain life , only to find out that is some hundreds lightyears away!( 300000 km/sec for a whole year/ whole decade!)

And above this there is the other parameter...that we should co-exist at the same time-period!I mean that galaxies are born and die!And we are no exception! We don't know if alien civilisations are born , or will be born, who says that is the most propable to exist at the same time period!It is something very very unlikely to happen!

and in the case that something is found and we decide to send a mission (in cryo-stasis ect ect) the rest of us won't be alive to see it.

And for any other possibility there are other difficulties that reach the point of no executable! And so on and so on.....