The hideout of the Binary Bard is in the asteroid belt, near X-11 Y-82. You must have defeated all three planets and have all three knights with you. You can draw the Golden Key from the crystal and enter the portal to the castle of the Binary Bard, who is shortly revealed as Mordred.
(see related question)
you push through
One common glitch in Poptropica's Astro Knights Island involves getting stuck at Mordred's castle door. To bypass this issue, try resetting the quest by leaving the castle and re-entering, or restarting the island entirely. If the glitch persists, consider contacting Poptropica's support team for further assistance.
It is on tp of the castle roof in astro knight island
You go into Mordreds lab and grab a paper and turn it into her.
The castle is the second area on the island, to the right of the Village.
Once you have built a new spaceship on Astro Knights Island, it will park on top of the castle whenever you leave the island.
Walk to the right.
its on top of the castle
There is no jail on Astro Knights Island. There is a castle dungeon, where an attacking alien robot is being held after his capture. (see the related question)
There is a castle on Astro Knights Island, in the kingdom of Arturus.
On the top of the castle
it is to the right of the castle, just keep going right.