Astronomer Zehn has a pass that open that door.
More hintsWhen he’s on Bio-Bi watching Mars, you’ll have the chance to get the pass from his things.
More hintsYou must distract him with something that won’t make him notice you’re touching his things.
More hintsHe’s trying to watch Mars.
Ok, tell me everything!Take a picture pf Mars from the spyglass at Sirey’s house, reveal it and place it in front of the astronomer’s telescope.