The best way is to get buy-in from your players. One way of doing that is giving them a selection of games that you would enjoy and asking them to decide amongst themselves which to play. This leverages a bit of human psychology where we will invest in something more if we have a hand in choosing it, especially if, in the process of choosing it, we ever argue for its merits to a peer. Giving your players a choice of sci-fi games means that the one they pick will have at least a little bit of support from at least some of your players already built-in.
Pick three or four games and present them to your players. Say you're running one of these, but which is up to them. Don't defend the games if they disparage them, just ask them to pick the one they think they'll enjoy the most. (By not allowing them to make you a target of arguments, you prevent them from digging in their heels and deciding preemptively they'll hate it.) If they hate it, well, they chose it. Which specific games you present them is up to you, but if I were doing this and trying hard to keep them all as appealing to dedicated Pathfinder players as possible, I would include at least one of these three if not all of them:
Stars Without Number is based on an older edition of D&D, so it's as close as you will come to the feel of Pathfinder, mechanically, as a science-fiction system can get. As a bonus, it's free, and if your players like it, it's very well supported with for-pay supplements and print books.
As a fan of Traveller, you should find the GM's side of SWN to be pleasantly familiar too. It's built to accommodate a system-hopping game or a campaign that stays on one world, and the "tags" system for setting development means you have a constant supply of new ideas at the roll of a die. It will work for a one-shot as well as Pathfinder would – possibly better, because new characters are not quite as complicated, and it gives you tools for quickly "statting up" a world.
Thousand Suns is exactly aimed at re-creating the genre of Isaac Aasimov, Niven, Pournelle, and their kindred in classic science fiction. Written by a luminary of classic D&D blogging, James Maliszewski of Grognardia, it's a straightforward system that still has its roots in D&D, so it doesn't ask players coming from a d20 background to make a paradigm shift in "how RPGs work" like Fate does, and it doesn't have the explosion of complexity (compared to d20) that GURPS or BRP does. It has stats with unfamiliar names but familiar function, and a skill system that should feel familiar enough to them.
d20 Future is going to be very familiar to your players. It's a bit more generic in that it's aimed at creating all kinds of sci-fi, not just the sort written by the authors you mention, but it will do the job. Being a supplement to d20 Modern it does require more books, but the breadth of character options will probably be welcome to your players, since lots of "chunky" character build options (as opposed to the fine-grained ones of GURPS, et. al.) is one of the big draws of d20 for its dedicated fans. d20 Future and Modern both have SRDs online, which somewhat makes up for the extra materials you need by making them free.
I strongly suggestion one of those, but the most important part is to give them a shortlist of games you're willing to run and then make the decision theirs. They've already agreed to a change of game, and it's only for a short time, so they should at least be able to agree on one they think they won't hate.
And if they do hate it, all is not lost: you've played a bit of a game you want to play, and you've burned only one of thousands of games that you could try. Really, you could keep trying one-shots of strange new games regularly, and it would take you decades to go through even a fraction of the RPGs currently published, and there are more every year; so don't worry too much if they hate it. Enjoy it yourself, and give them some agency in the choice, and it will all turn out in the end.