Imagine that some day we willl send some manned mission to the stars because we will discover that there is an Earth-like habitable planet.
At relativistic speeds they will get there after about, say 17 years, and - they would be VERY SURPRISED - that there is an advanced ( I mean as advanced as us or a bit more, not godlike empire) civilization (No folks, we did not recieved any signals because our TV signals are unrecognisable beyond the orbit of Pluto and also that is in case about alien signals).
They will not know their language or even their system of communication.
They would be somewhat warned that they cannot land (for example by warning fire from a defense satelite of the alien civilization shooting into space just near the ship or by some unfriendly sounding or looking signal).
What you will do?
Assuming that there are no 100000 H-bombs on ship prepared to kick the alien asses or basically any defense system on our ship.