Gotana-Retz was an astronaut from Kelemane's planet, a planet with a tachyon core which caused a differential in space-time such that each second that passed on the orbiting USS Voyager was the equivalent of an entire day on his planet.
Retz was part of a mission, Orbital 1, sent to investigate the ancient "Sky Ship" which was revered by the people of his planet. He managed to survive the time shift after entering Voyager. When Captain Janeway explained the situation he agreed to help to find a solution to Voyager's problems.
A short time later Voyager came under attack from the surface. Janeway asked him to return to the planet to explain the situation, ensure the attack stops and enlist the help of his people. Retz agreed.
Retz returned to his planet with specifications of Voyager and convinced his people to help Voyager break orbit. Two ships from the planet surface returned and used a tractor beam to break Voyager free. Retz used a temporal compensator to travel to Voyager and say goodbye. As an old man, he witnessed Voyager finally leave from a hilltop. (VOY: "Blink of an Eye")