She had been communicating with Lieutenant Commander Data through an RF transmitter for eight weeks in 2365. He became aware that her planet was tearing itself apart due to geological shifts caused by an unusually high concentration of dilithium lattices in the planet's crust.
Initially, Captain Picard ordered Data to cease contact with Sarjenka to prevent any further violations of the Prime Directive. However, Data urged intervention and the captain eventually allowed the crew of the USS Enterprise-D to stop the geological shifts by destroying the crystals with modified probes.
To lessen the contamination that the crew of the Enterprise-D had caused, Picard ordered Doctor Pulaski to erase Sarjenka's short-term memory. But in the process of returning her to Drema IV, Data left her with the Elanin singer stone she had seen in sickbay so that she could keep a small part of her experience with her. (TNG: "Pen Pals")
Sarjenka was played by actress Nikki Cox.
According to the script, Sarjenka was a child between ten and twelve years of age, placing her birth in the 2350s. Her description from the script: "Her skin has a luminous gold color; her eyebrows have a metallic quality as if gemstones and precious metals had been crushed and brushed across the hairs. From above each brow spring delicate antennae which curve back over the top of her head. The hair which hangs to her waist is of the same metallic multicolored strands as the brows. The quality is as if a dragonfly developed bipedally. Eyes can be faceted or not. She is coughing."
In the Corps of Engineers eBook series, Drema IV was invaded by a species known as the Exiles, and then became a Federation protectorate after they cast out the invaders. The now-grown Sarjenka became the first Dreman in Starfleet, enrolling in Starfleet Medical Academy, and became deputy chief medical officer of the USS da Vinci, ultimately succeeding Elizabeth Lense as chief. She eventually regained her memory of the events of "Pen Pals".