Uhura will try her best to make sure everything goes well. If it doesn't she will let Major take Gault out of the chamber and use any kind of first aid knowledge to help him even at risk of being contaminated herself.
Artemis will help remove Gault's body from the chamber, trying to do so in as reverent way as possible. Not knowing the customs of Gault's people, she settles for laying his corpse out on the floor or whatever other flat surface that's available.
She whispers a prayer for his soul, then turns back to the chamber and climbs into it.
Major steps back allowing Uhura to do her thing. Major checks around the room to see if there is something that he might have missed.
Uhura will attempt to get the chamber to do its thing differently so it does not produce the same effect as what happened to Gault.