TMZ's learned Adrianne -- who plays Commander Kelly Grayson on the show -- recently filed divorce docs a second time ... after first doing so in July 2019.

Their split was pretty surprising ... considering they'd only been married a couple months at the time, but then in November ... she dropped the divorce petition. That's the sign of reconciliation.

It's unclear what led to calling it quits on matrimony this time around, but Palicki cited irreconcilable differences for the first break up. She also noted then that the 2 have a prenup -- so the financial side of the split could be relatively easy.