The cheese is in the castle dungeon. Recover it and feed the mouse in the Maid's room.
To get into the dungeon :
After you get the cheese you put it in the princesses dressing room and capture the mouse to feed it to the owl.
the mouse is in the princesses room in the hole in her wall but you have to get the cheese to get him/her.
In the Maid's room (castle first floor left), feed the cheese to the robot mouse.
To catch the mechanical mouse, in the Princess's Maid's room (castle first floor left).
In the Maid's room (castle first floor left) you will find a mechanical mouse.
you put it in the room with the mouse in the astro knights castle and the mouse will eat it
Find the old cheese. . Give the cheese to the mouse and give the mouse to the owl.
get the moldy cheese from the basement of the castle and lay it out in the bed room
The only place is in the castle dungeon, below the library. (see related question)
Use the cheese from the dungeon (under the library in the castle). (*To get to the dungeon, see the related question.)
you need the hovercraft,mouse,moldy cheese, owl,green glowy thing,coordinates, and find the broken paceship.
go to the princesses maid's room and use it you will get the robot mouse