A little over a week ago, Paul Stefko published an eight page campaign frame for Fate Accelerated Edition called Interstellar Patrol. The first review to appear on DriveThru is rather harsh. The product is Pay What You Want, so if you like space opera, I'd encourage you to give it a look.
Interstellar Patrol bills itself as offering players the opportunity to play a campaign of relatively optimistic SF, such as the original Star Trek. This isn't a fully realized retro SF RPG setting though, such as Cosmic Patrol and Rocket Age. Instead, Interstellar Patrol offers the barebones tools for creating a space opera game. If you needed to run a pick-up game in an hour, you could download this (provided you have downloaded and read Fate Accelerated Edition already), read this eight page guide, and offer your players a game.
The PDF offers quick suggestions for making PCs, primarily focusing on selection of two strong Approaches for each character type. The examples are perfect for the bridge crew/core cast for a show like Star Trek. I don't agree with all the recommendations but the examples are fine.
This is followed by some great examples of Stunts that are perfect for a space opera game. Here's an example:
Because I know every inch of the engine room like the back of my hand, once per session I can "give all she's got" and automatically succeed with style on one action using the ship's systems.Next come quick 4DF tables for creating worlds and adventures. Again, these are perfect for a pick-up game.
Finally we get quick rules for creating spacecraft. Ships have four systems that are represented as Aspects with three possible damage conditions. Those systems are: Propulsion, Tactical (which includes both Attack and Defense), Sensors (which includes communications), and Amenities (which includes life support).
It would be easy enough to embellish these Aspects to make them specific to the vessel. For example, the shuttlecraft Galileo might have Impulse Engines (Propulsion), Harmless (Tactical), Planetary Range Sensors, and Barely Any Amenities. Note that the last Aspect will work equally well for any D7 Battlecruiser your players run into during a game.
Players take action with the ship using their own Approaches but only one player may operate a particular ship system at any given time. So you can't have three PCs each running Tactical and taking shots at the enemy.
Each system has three damage states (Disrupted, Damaged, and Disabled) which must be taken in order, and which absorb 1,2, and 4 shifts of shit-to-ship combat stress, respectively. Alternatively, a PC can take a number of shifts directly as a personal Consequence on their own character sheet, rather than the ship's. This simulates all the being tossed around we see during space combat in shows like Star Trek.
Again, this looks pretty sufficient for a pick-up game, but maybe less so if you enjoy the tactical complexity of Diaspora or the broader range of design selections possible in a game like Starblazer Adventures.
There's no aliens offered in the game, although it's straightforward to make an alien character. Just take an appropriate Aspect.
I should mention that the FATE Bestiary at here FATE SF is mostly written for Fate Accelerated Edition - so most entries there are 100% compatible with Interstellar Patrol.