This page contains information regarding Star Trek: Discovery, and thus may contain spoilers.
While on a mission to investigate a dilithium nursery in the Verubin Nebula, the Khi'eth crashed on Theta Zeta. Several crewmembers, including Issa, survived and sent a distress call which was picked up by the USS Hiraga Gennai. Six months after the Hiraga failed to rescue the crew, presumably because it had been destroyed by the nebula, Issa sent a second distress call. In the call, Issa bore the signs of pregnancy – red mottling on her forehead. Her message became the basis for the melody heard throughout the galaxy.
Shortly afterwards, Issa gave birth to her son who she named Su'Kal. Sickened by radiation poisoning and with death approaching, Issa created a world for her infant child in a holodeck. In this holographic environment, Su'Kal would be raised and protected by holographic programs until he could be saved. (DIS: "Terra Firma, Part 1", "Su'Kal")