Sucked out during Jump!

I have plans to put a nasty thing on the ship in the crate being hauled. It escaped during the Jump and slowly menaces the passengers and crew. What would happen to it, if put in the airlock and the outer door was opened? Would the ship be fine?
Like the Mummy Xenomorph. Strong and tough, but only because it's cursed undead. Explosives can kill it, but on the ship. Probably not a great idea.

Cool thing is. I got a week of jump time to slowly strike the passengers and fade away. It drains the victim, like the mummy, slowly gaining its original form back before slinking off to its alien sarcophagus to hibernate for another night. One of the passengers brought it on as crate going to a museum.
Someone quite some time ago, possibly here, posted an after-action report of a game he played with his young son. During the course of the action the boy did an EVA during jump, scrambling around on the ship’s hull where it was closest to the jump bubble, and missed a roll of some sort. Dad ruled that his magnetic boots kept him on the hull but in stumbling he touched the bubble and his hand was lost, cauterized, like Luke Skywalker in ESB. The kids survived and later got a cybernetic replacement (and apparently had the time of his life on that adventure).

Ever since I read I thought it was so cool and from there on out have always played jump bubbles that way - or intend to, if any player ever attempts something like that 😉

So I’d say heck yeah, space that monster and save the day! Doubtful the mass of the creature is anywhere near what would presumably disrupt the bubble.

Of course, it might just be able to cling to the hull…😈
If you can blow something out of an airlock into jump space then it stand to reason that something already in jump space can now get in...
Or would it just bounce around in the bubble until you came out of Jump space? Also, can you choose to prematurely come out of Jump space and if so, does that use all the fuel already calculated for the original jump? Can you be pulled out like when an interdictor star destroyer pulled Lukes X-Wing out of hyperspace? (I think it was a Kevin J. Anderson Novel)
Likely drifts out of the bubble, at sufficient velocity.

Now that you coast, voluntarily cutting short your jump would require destabilizing the jump bubble.
A ship has a grid on it that keeps a bubble of 'reality' around a ship in jump-space. But that bubble is nearly skin-tight to the hull. Living beings cannot survive in jump-space unprotected by a ship's hull. What's more, there is a phenomenon called 'jump sickness' that severely debilitates anyone exposed to it. There is no specific rules mechanic for this, but at my table I treat it like exposure to hard radiation.

So, if you are able the lure the beastie into the air lock and successfully close it and trap the beast in there, you can leave the lock pressurized and open the outer lock. This will project the beast into jump-space and kill it. There shouldn't be any damage to the ship unless you as the referee would like to include some as plot point.
Apparently, not this edition.

The lanthanum grid was not adopted, while the jump bubble is somewhat larger, if you recall that quite a number of starships tend to be rather long.
Apparently, not this edition.

The lanthanum grid was not adopted, while the jump bubble is somewhat larger, if you recall that quite a number of starships tend to be rather long.
Well, there is a good likelihood that that'll change [again, some more, still] after the Starship Operator's Guide comes out. It doesn't really matter, it's just flavor text anyway.
The important points are these:
- Jump space exposure kills
- Jump drives create some kind of bubble effect that protects the ship and crew from those effects
- Throwing the alien off the ship and into jump-space will kill it
Even in MgT there is a network of cables that maintain the normal space "bubble" around the ship, it is just not the lanthanum hull grid made popular by MegaTraveller. In every other edition the lanthanum is used to construct the jump coils which are somewhere deep inside the jump drive machinery.
Differing hull costs for starships and general spacecraft would then differ.

If the grid is inside the jump drive, then the jump bubble would be a force field projection, which wouldn't work for us, since the juice for the jump drive is turned off.