05-13-2018, 08:58 PM
Perhaps you don't really need a reason for going in space! 
The characters find a space/spelljammer ship fallen to the ground who knows when, clear it from an array of Blackmoorian monsters that crawled into the ship, some offshoot of whatever off-world mosnters they carried and perhaps some original crewman (undead?), start studying the ship and, suddenly, they find that the landscape has plenty of stars and planets...
In alternative you coould make up a plot linked to the Sahuagin: perhaps something is getting wrong with the black stone of Blackmoor and the race that knows more than anybody about it are the Sahuagin. Unfortunately, in Blackmoor there are no more Sahuagin and the only ones known surviving are on the moon...
The characters find a space/spelljammer ship fallen to the ground who knows when, clear it from an array of Blackmoorian monsters that crawled into the ship, some offshoot of whatever off-world mosnters they carried and perhaps some original crewman (undead?), start studying the ship and, suddenly, they find that the landscape has plenty of stars and planets...
In alternative you coould make up a plot linked to the Sahuagin: perhaps something is getting wrong with the black stone of Blackmoor and the race that knows more than anybody about it are the Sahuagin. Unfortunately, in Blackmoor there are no more Sahuagin and the only ones known surviving are on the moon...
He's a real Nowhere man, sitting in his Nowhere land,
making all his Nowhere plans for Nobody.
making all his Nowhere plans for Nobody.