"Juvenile" or "juvie" SF is the usual term for SF that's aimed at kids and teenagers. One of the nice things about science fiction authors is that many of them write very good juvie fiction, which talks at a kid's level without talking down to the reader. Juvie SF is generally (relatively) simple stories with simple characters. There's little violence, and what there is is understated.
Alan Dean Fosters "Humanx Commonwealth" universe includes a pretty good juvie series known as the "Adventures of Flinx and Pip." He started with a set of three, then added Flinx and Pip as secondary characters in a fourth novel.
THE TAR-AIYM KRANG
c.1972, Ballantine Books
ISBN: 0-345-29232-4
The first novel that Foster wrote with Flinx as the main character. It's also the first in the whole Commonwealth milieu. 'Flinx' is an orphan boy in his late teens who lives with his foster-mother Mother Mastiff in the city of Drallar on the colony world of Moth. Flinx is rather unusual in a number of ways, with his substantial (although unreliable) telepathic powers not least among them. 'Pip' is his pet: a "minidrag" from the world called Alaspin, basically a snake with wings, limited empathic powers of its own, and extremely lethal venom. In this first of Flinx's adventures, two wealthy offworlders hire Flinx to escort them on a tour of Drallar. But the offworlders aren't really interested in touring the city. In fact they're looking for the home of a certain powerful merchant, one Maxim Malaika, whom they hope will back an expensive research project of theirs. Before he quite knows what's happening, Flinx finds himself in the middle of a hunt for a near-legendary weapon built by the long-dead warrior species called the Tar-Aiym. Besides the two researchers and Malaika, the hunt also involves one of Malaika's rivals and the Commonwealth's long-time enemies, the reptilian species called the AAnn. This is a fun, simple, pretty straightforward story of adventure and discovery, sort of a juvie variant on space opera. The tone of the first few pages is extremely unconventional, but that's largely because when he wrote this Foster was still a beginner at writing.
ORPHAN STAR
c.1972, Ballantine Books
ISBN: 0-345-32449-8
A direct sequel to THE TAR-AIYM KRANG, this novel starts a few months after the end of the earlier book. A wealthy and corrupt merchant named Conda Challis tries to kidnap Flinx for purposes of his own. Flinx is rescued by his minidrag Pip and a local friend. In the course of the rescue, Challis makes a chance remark that leads Flinx to think Challis knows something about his biological parents. There's nothing Flinx wants to know more than who his real parents were, so he sets off in pursuit of Challis. From Moth, he travels to the Thranx homeworld of Drallar, then to Earth, and finally to a remote world called Ulru-Ujurr. Along the way he makes some powerful enemies, and some even more powerful friends, discovers a secret plot by the AAnn against the Commonwealth, and gets tangled up with an alien species whose potential for advancement is beytond belief. He also learns something of his past, including a few things he'd rather not have known.
THE END OF THE MATTER
c.1977, Del Rey
ISBN: 0-345-25861-4
Following his adventures on Ulru-Ujurr, Flinx returns home depressed from the failure of his search for his parents. But Mother Mastiff, his foster-mother, gives him a new lead: the slave trader from whom she originally bought him. On his way to talk to the trader, Flinx stumbles into the middle of an operation by the Qwarm, an outlawed guild of assassins. He also acquires a new possession: a weird four-eyed, four-armed, intelligent but apparently insane creature called Ab. The trader gives Flinx a new clue that takes him to Pip's homeworld Alaspin. On Alaspin, Flinx runs into Skua September, the iconoclastic strongman from the Icerigger series, who may or may not have some of the answers Flinx seeks about his parents. Unfortunately, the Qwarm are now after him, as are other, unknown forces. The "others" turn out to be two old friends, Bran Tse-Mallory and Truzenzuzex, who believe the creature Ab holds the key to saving three Commonwealth worlds from destruction by a wandering black hole.
BLOODHYPE
c.1973, Del Rey
ISBN: 0-345-25845-2
An unusual entry in the series, because Flinx is only a secondary character in it. An AAnn patrol has found a mysterious creature on an otherwise lifeless world. The AAnn don't know it, but the mystery creature is an intelligent entity called the Vom which lives by draining life-force from other living things. It was imprisoned on the dead world by the ancient race called the Tar-Aiym, who hoped that if the Vom was kept there, unable to feed, it would eventually die. The AAnn transport the Vom to an outpost of theirs on the Commonwealth sea-world of Repler. The Guardian left behind by the Tar-Aiym to watch the Vom follows it to Repler.
At the same time, a Commonwealth undercover team is on Repler investigating the source for a new, very nasty, very illegal drug called Bloodhype. And freighter-captain Mal Hammurabi has found that his ship was being used to smuggle bloodhype, which he doesn't like a bit. Eventually they all wind up joining forces to defeat both threats, the Vom and the drugrunners. Flinx plays a peripheral role in the drugrunning storyline and a major one in the fight against the Vom.
After writing The End of the Matter, Foster left the Flinx character alone for several years. Eventually he returned to the character with a new series of novels that follow Flinx as he matures. Unfortunately, the Flinx of these new stories is not the same character as in the first four. He's a darker, moodier character moving through a darker universe full of many enemies and few friends. The writing of these stories isn't nearly as good, either. They're still worthwhile to read, but don't make the mistake of thinking they're the same quality as the first four.
Robert A. Heinlein is considered one of the best SF writers of all time, and rightly so. He has a huge number of SF novels and short stories to his credit. Among these are a series of juveniles, such as:
SPACE CADET
c.1975, Del Rey
ISBN: 0-345-35311-0
Set in Heinlein's "solar System future history" timeline, when the Space Patrol is the primary peacekeeping force among the various worlds of the Solar System. Matt Dodson is a typical teenager, out to join the Space Patrol. The story follows Matt through his experiences as a cadet at the Patrol's academy and his first deployment, which includes a search for a vessel lost in the asteroid belt and a mission to Venus to rescue a stranded spacer.
THE ROLLING STONES
Heinlein, Robert
c.1952, Del Rey
ISBN: 0-345-30332-6
One of Heinlein's best juvies. The seven members of the Stone Family -- grandmother Hazel, mother and dad Roger and Elizabeth, daughter Meade, twins Castor and Pollux, and kid brother Lowell -- buy their own spaceship and go touring the Solar System, from the Moon to Mars to the Asteroid Belt. A fine, fun romp, which just happens to include some very good factual material on space dynamics and astrogation.
