the dung
You need a new green fuel rod and space coordinates to use the saucer Excalibur. (see the two related questions)
Use the UFO. (The saucer Excalibur in the mud swamp past the mill.) To use it you need to find a fuel rod and the coordinates. Once you get to the Pewter Moon you can make a new spaceship. (see related questions)
You will use the saucer Excalibur to reach space, then build a spaceship on the Pewter Moon. (see related questions for how)
go to the mill and get the ship
Once you have replaced the fuel rod for the saucer Excalibur, you can go to the moon at X-56 Y-52. There you can get a new spaceship. Use it to go to the three planets and find the knights, who can help you battle the robot creatures.
You use the manure that the man gives you
When you have recovered a fuel rod for the saucer, the instrument will let you use the X and Y dials to set the coordinates. But the planet coordinates the Queen gave you are too far away. You will need to use the coordinates from Mordred's missing journal page, which are X-56 Y-52. (see related question)
You do not get or use a bucket on Astro Knights Island.
in the swamp mud you need the manure the guy gives you so you enter the windmill on top then use the manure on the fly step.
In Astro Knights Island on Poptropica, the fuel for the hovercraft can be found in the fuel canisters located next to the dock where you first arrive on the island. You need to collect the fuel canister and use it to power the hovercraft to cross the toxic swamp.
When you are in the spaceship (solar system) view, click on the moon or planet you want to land on. To leave again, use the "launch" lever.
After you get the fuel rod in the dungeon, go to the spaceship in the swamp. When you reach the ship, the rod will be in the bottom left corner. Click it and drag it to the broken one. To reach the crashed saucer Excalibur in the mud swamp, get the hovercraft from the attic of the mill. (see related question)