- Second Pole mission - Eric and Charlie round trip to the Pole, with Randy and Allen observing. - Leak(s) found around rack filter and possibly also around MPV. Closed up covers to minimize breath influence. Subsequently on the ground could not reproduce, but using Picarro pressure testing identified leak at inlet filter o-ring. O-ring was smaller than those in labelled bag, replacing helped. Also added teflon tape to threads. - High H2O at Pole - cause? - Did a dip maneuver on the NB return segment.