Sci-fi movie where a spaceship containing dead aliens is found on Earth

When I was kid saw a movie about a spaceship found on earth containing two dead astronauts. Can only remember parts and my guess is that MAYBE is from the second half of the 70's:

• The dead astronauts were humanoid, in fact -and oddly- human but they didn't have appendix.


• Their eyes were covered by some sort of white? plastic contact lens, the scientist said that maybe was for high speed protection while travelling in space.


• In the spaceship they had recordings with strange characters (sort of Japanese or something)


• The astronauts died when some vessel broke and released poisonous gas (I think).

Thanks a million in advance.