Secrets of the Dark Side

Three months ago, Lunar Explorer Six landed on The Dark Side of the moon.
No one knew it was a secret manned lunar mission.
The astronauts stayed on The Dark Side for 8 minutes and 23 seconds, uttering only one sentence:
'There's something here.'
After returning, the astronauts left a final message before dying:
'The legend is true! Stop exploring the moon, don't let her return home!'