chunk: Gordon develops an apparatus which can permanently destroy a replica but Kelvin objects to using it on Rheya. Driven by his own grief and guilt over the 'real' Rheya's death on Earth, he begins ingesting a chemical stimulant to stay awake in order to monitor Rheya, trying to avoid repeating the past and essentially abandoning her to suicide. Kelvin eventually falls asleep and Rheya successfully petitions Gordon to destroy her with the apparatus as she has done for her own replica(s). Traumatized, Kelvin confronts Dr. Gordon who maintains she merely facilitated in assisted suicide and only strives for the preservation of the humans on the station.