Either found on a derelict leviathan of a now extinct ancient race - or taken from a research lab as a prototype. This forcefield shielding for a ship affects both cannons and missiles. However it was only fully tested on missiles (if a prototype) - if from a derelict it isn't fully functional and only partially absorbs cannon energy.
It can only be installed in a cargo bay, and takes up the entire bay. It replaces the normal shielding on a ship and requires that there be energy in shields to function.
It has the same affect on missiles as the “Throwing out the trash” power of the special ability “Tricky”. Each point of power in shields is the amount of missiles it can affect that phase. Like normal shields, the use of it does not drain the shield energy. The effect it has on cannons is a bit more Farscapian, however. When hit by a cannon, ignore the damage and just look at the energy level used to power the cannon. That's how many minds are swapped. For each point of energy in the cannon - roll randomly, twice, amongst the sentient lifeforms on board (including NPCs if boarded and Allies - but not Bots). These two people swap minds. Exchange character sheets. If the second roll is the same as the first, reroll (a mind never stays put).
I'll leave it up to individual GMs as to how players can get back into their own characters. But solutions could include lots of science and engineering - or just getting shot with a cannon many times and spacewalking when in your own body.
Again, this is a completely un-playtested mission (like Alien Bushwack), so use at your own discretion :)