In 2369, she was assigned to the USS Enterprise-D as a transporter operator. Palmer was on duty when the Enterprise-D discovered Thomas Riker, the transporter duplicate of Commander William T. Riker, on Nervala IV. (TNG: "Second Chances")
Background information Edit
Her name comes from the script for Second Chances. The script describes Palmer as being a transporter technician holding the rank of ensign as does the reference work Star Trek: The Next Generation - The Continuing Mission. However, in her on-screen appearance, she wore the rank insignia of a lieutenant junior grade and is referred to as "Lieutenant Palmer" on StarTrek.com.  
Jemison was approached by LeVar Burton in 1993 who asked her if she would mind appearing in an episode he was directing.
A huge Star Trek fan, she jumped at the chance and immediately accepted. "Being on Star Trek was really cool because the first thing is you don't really understand that the sets are very substantial," Jemison enthused. "I got to hang out with Worf. I got to meet Riker, and all these kinds of things. It was a very cool experience, because in many ways it was coming full circle. As a little girl, I watched Star Trek. I knew that looking at Nichelle Nichols as Lieutenant Uhura, someone was connecting my idea of space, and now I got to come back around and help to verify that 'yes this happened'." (Star Trek: The Next Generation Companion, pp. 249-250;   )
Indeed, during her time on-set, Jemison got to meet her idol Nichelle Nichols who had visited especially to meet with her.