Nyota means 'star' in Swahili and in Lingala.
Uhura was inspired by uhuru, the Swahili word for freedom. Nichols was reading the book Uhuru by Robert Ruark on the day she auditioned for Star Trek. When the meaning of the word was explained to Gene Roddenberry, he changed it to Uhura and used it for the character.
Neither name appears in the Social Security Administration's database. I believe Nyota is the more usable of the two, as Uhura has become closely associated with the character.