"What I'm going to tell you is of the utmost secrecy, Buck. It has been kept secret, known only to my people for centuries. I am descended from both your people (earthlings) and mine (Galacticans). In 1989, an alien colonist named Dillon married a young earth woman named Gloria Alonzo. She kept his secrets, and some of them were passed down through our people through the centuries. In fact a number of them formed the technological basis for Earth's Defence Directorate, but one had to be kept from official knowledge: the design for incorporating a time travel capacity into a Galactican craft known as a Viper. From the time traveller's perspective, it would be possible to 'undo' every rotation of the earth from present day until some desired time in the past."

"Wouldn't you bump into orbiting craft while you were doing it?" asked Buck.

"No. You go into hyper speed and become relatively immaterial and invisible while you are passing backwards through time. I heard rumours begun by a Dr Hewer that you felt out of place with our climate controlled environments, and there must have been other reasons for you to miss the time you came from."

"There certainly are," said Buck, "not the least of which is the woman I left behind. Do you know, after I met a near doppleganger for her in this century, I looked her up in historical archives. From what information survived, it seems she never married. She's back there, alive, but 500 years across time, missing me too, wondering what happened to me. Are you offering me the chance to go back?"

"Yes, but you should know that most time travel activity was outlawed back when the technology was invented. A Commander Adama, head of the Galactican fleet which discovered earth in 1980, had already seen the potential for its misuse, when a rebel councilman named Xaviar attempted to alter the outcome of World War Two, by taking 1980 technology into the 1940s. The only possible reason for my thinking that you would not disrupt the timeline is this. In a sense, time travel would merely be restoring you to your proper time."

"I don't know what to say."

"You can say two things, or at least promise two things. Firstly, you must never pursue any scientific career. You must forget all the things you've learned about 25th Century technology and turn your mind to a career that will not alter what to us is the past. It would otherwise be the effects of Xaviar's plan multiplied by the passing of centuries instead of decades."

"Then why don't I go and stop my younger self from ever taking Ranger 3 up in the first place? Then I'd never sleep 500 years, and this version of me wouldn't exist with all the acquired knowledge."

"That's the second thing you can't do. You can't interfere with your younger self. That timeline must play out. He must remain in orbit, frozen in space drift for 500 years and have all of the involvements in earth saving adventures that you have had in our time. There will be two Bucks living from 1987 until the time YOU die of old age or misadventure. One will be frozen in orbit. The other will be living his life out on earth. You'll have to say that you 'couldn't return in Ranger 3 and came back down in another ship which was then destroyed.' To make that true, you must press the destruct timer of the time travelling Viper, after you've arrived in 1987. Land away from a city and blow it up. Then tell them it blew up. History records that Ranger 3's orbit was so much larger than intended, that nobody from your time ever found you, no matter how hard they might have looked. So your secret will be safe. Under absolutely no circumstances are you to go up into space looking for your other self. A person cannot meet his younger self in the time stream, not ever."

"Aren't you taking a big risk with me?" asked Buck.

"This planet owes you for all the help you've put into saving it many times," said Lar-Son, "The moment Searcher returned to earth, I knew I had to share this knowledge with you. I won't teach you how to construct a time travelling Viper, only give you the one I have built, and teach you how to pilot it into the past. I will truthfully report that I asked you to test pilot a ship design and that I haven't heard from you since. I will let our century's people think you were lost in space, just as your own century's people once correctly assumed."

That night, as he awaited the opportunity to return to his own time and his true love, Buck Rogers inevitably had … a Dream of Jennifer.

Soon he was trained and ready to launch the time travelling viper. Lar-Son farewelled Buck and watched the ship fly towards the sky. Buck engaged the time warp controls and began to undo the last 502 years of rotations. He would be two years older than when he last saw Jennifer, he realised, unless he stopped time travelling in 1989. No. He could not put her through even two years' grief, not this time.

There were those who weren't fully sure of the authenticity of William Rogers' story, when he returned in 1987. It was decided that he should retire from the space program, with an honourable discharge. It was at least as good as the option he would have chosen himself.

Buck would make no attempts to locate the 1987 Galacticans living on earth, no attempts to learn things that would have betrayed Lar-Son's trust in him, and no attempts to alter the timeline any more than his return to 1987 had already done. However, a woman who had grieved his loss for decades in one timeline would now live out her life in his company.

Once back in Jennifer's arms, he said those two words, which for him he had uttered over 502 years ago in his own personal past, albeit two years ago in real time: "Never again."