So I'm slowly working on a Spelljammer 5e campaign setting/idea and I'm not a big Sci Fi consumer, so I'm here asking for some suggestions and ideas for adventures or concepts that could be interesting to incorporate into this eventual game!

Some concepts I've already got include space pirates, space vampires, space fey, a search for a replacement helm for one going bad, fetching a piece of a dead star for someone who wants it for mysterious purposes, and, of course, a good good ol crash landing which results in needing to do some quests for locals in order to acquire necessary parts (as the introductory mission, naturally). Further ideas or expansions upon these existing ones would be much appreciated.

Thank you guys! (:

One idea is how the players would react when they go into the different world, especially if they grew up in space.

Don't forget about mind flayers, they have a strong presence in space.

Also, come up with problems between clerics and their gods when they go to space.

Other ideas could be: An evil necromancer with and ship of death, A destoryed world (Death star like weopon), Space mutants. 

Sorry that I only have some ideas.

Do you have access to any of the old Spelljammer materials? There are some real gems in there, though some require a bit of polishing to really shine.

And my single best suggestion is, stop thinking of SJ as sci-fi. The original setting began with the sentence "Everything you think you know about space is wrong." Double down on that.

Unfortunately not, unless it's available as free PDFs somewhere. I have read through a 5e Spelljammer conversion for the basics on Spelljammer though.

No apologies needed, these are great, thank you!

Wow, Spelljammer's getting a lot of press right now.

I'm planning a Spelljammer campaign centered on an elder brain known as the Messiah. The first few levels will be set on Toril with the players taking care of normally unintelligent monsters, such as Ogres, who have been using clever tactics. In reality, they're slaves of the Prophet, the Messiah's agent on Toril. Soon, the players should take the fight to the Messiah, who has conquered several Crystal Spheres already with his personal ship the Parable. I can link in the stats I'm using if you want. What I'm trying to say, is that Illithids are cool.

I'm a first-time DM and I began my current campaign with a little one-off quest with a few encounters for the party (mostly first-timers as well) to give them a feel for how the game mechanics work. I introduced spelljamming early on by having them being hired by a privateer captain of a spelljammer ship who then whisks them off the planet they started on, and landing on Faerun, with which I then had them start the Dragon of Icespire Peak campaign. I've adjusted some of the story to fit the narrative surrounding my privateer captain and his crew (Corsair and the Starjammers, stolen from the X-Men Comics/Animated Series) and plan to have the group stay on Faerun for all of the follow-up campaigns, which will bring them to level 13, while I work on the remainder of the campaign. I was thinking of having the ship's wizard/pilot come to the group at lvl 13 to tell them the captain and crew were captured off-planet and he needs their help to rescue them, but I'm unsure of where to go from there.  Currently trying to build up a list of monsters I would like to throw at them in the future and then plan out the settings around them (i.e. is the planet desolate or full of fauna? will there be lots of ruins/dungeons or mostly open-field encounters?). Definitely going to be using Illithids at some point, but recently thought about making the planet they go to based on Greek Mythology so I can incorporate Minotaurs, Medusa, Hydras, etc. Might even build a planet that's just full of demons and enemies of that nature as well.

My spelljammer game took a lot of inspiration from planet of the week scifi.  The pcs (all from Krynn) found an ancient ship called the Hornet.  It was the map to the key to waking an armada of superships who could take over the galaxy.  A warrior race wanted it and was working really hard to catch them while casually killing and enslaving lots of people ali g the way.  Pcs have to go to world and find pieces of the grand mcguffin find someone who could put it together find someone who knew how to make it work.  All while staying one step ahead of the warrior race.  It was a grand adventure.  The advantage is the Mcguffin could be added to essentially any adventure you wanted to putting the adventures hunting it while others just wanted that darn cut anything sword that the lady insiide that pond was holding.  Its probably in my top 3 campaigns ever

im prepping a campaign where the PCs grew-up on The Rock of Bral and get caught-up in a full-on attack by skeleton pirates. They flee in a skiff and end-up commandeering a huge dragon-skull ship. The ship is ill-kept and not all of it has air. The plan is to end-up adrift and fighting for survival (with some undead still on the ship). They'll crash-land on an uncharted asteroid lost in space style, eventually finding a crashed spelljammer ship with what they need to get the dragon skull ship up and running. 

How on this green earth do I make Atropus for Spelljammer? I get that it's a Pathfinder/older DND abomination but my gods do I want to put that in this game soooo much, as well as the Angels he comes with. I don't want it to be an impossible fight but I don't want it to be easy, this would be my first time making such a big boss for a campaign.