The crashed saucer Excalibur can only take you as far as the Pewter Moon in orbit around the planet Poptropica. The coordinates are X-56 Y-52 and they were found on the missing page from Mordred's Journal.
(see related question)
Once you get your new spaceship, you have to go to the three planets at the coordinates the Queen gave you. You have to defeat all three planets before you can find the Princess.
The Jungle Planet (X-15 Y-15) - up and far to the left
The Ice Planet (X-73, Y-83) - down and to the right
The Fire Planet (X-82 Y-20) - up and to the right
You can go to space on Astro Knights
What you do is when you go up into space you click on the coordinates and you follow tem
you go to the top of the castle and there it is :D just found out;)
Your spaceship parks on top of the castle. You can come and go from Main Street.
If you land on earth with your space ship, it will be on top of the castle waiting for you!
To return to space on Astro Knights Island after completing the mission there, you can head back to the rocket ship in the observatory and select the option to launch it again. This will take you back to space where you can explore further or complete any remaining tasks.
Go to Mordred's tunnel and you'll see the robot. Get the fuel rod and then go to the ship. From then on, you'll be in SPACE!
To see the solar system on Astro Knights island, go to the Planetarium. (not part of the game, but an interesting view)
Go on youtube
go to the secret door
The rocket is on top of the castle of Arturus.
go to the mud with that ting like a hower board over the mud and you will find it in the mud