Lunar Free State Series by John E. Siers

The scientists and engineers at the Deep Space Research Institute are a pretty smart bunch. So smart, in fact, that they've figured out how gravity works. More importantly, they've figured out how to make it work as a propulsion system. Of course, they are going to tell the world about it. Eventually. But first, they have a few things to do, like build a fleet of gravity-powered spacecraft and establish a permanent settlement on the Moon... assuming they can keep the U.S... moreThe scientists and engineers at the Deep Space Research Institute are a pretty smart bunch. So smart, in fact, that they've figured out how gravity works. More importantly, they've figured out how to make it work as a propulsion system. Of course, they are going to tell the world about it. Eventually. But first, they have a few things to do, like build a fleet of gravity-powered spacecraft and establish a permanent settlement on the Moon... assuming they can keep the U.S. government from figuring out what they are doing, shutting them down, and putting them all under arrest. Welcome to the Lunar Free State... less

It's been ten years since the Lunar Free State established itself as an independent nation on Earth's Moon. Since then, other Earth nations have pushed out into space, competing with the LFS for the untapped resources of the Solar system. But thanks to the advantages provided by its gravity-driven spacecraft, the LFS has grown and prospered... moreIt's been ten years since the Lunar Free State established itself as an independent nation on Earth's Moon. Since then, other Earth nations have pushed out into space, competing with the LFS for the untapped resources of the Solar system. But thanks to the advantages provided by its gravity-driven spacecraft, the LFS has grown and prospered.All is going well for the Moon people until the research ship LFS Stephen Hawking encounters an anomaly while surveying Saturn's rings -- an alien spacecraft that leads the LFS vessel on a merry chase before vanishing into... well, for want of a better term, hyperspace. The alien craft is obviously not from around here, which leaves the LFS facing two undeniable facts: humans of Earth are not the only intelligent life in the universe, and travel between the stars is possible. Now the LFS just has to figure out how to do it, and prepare for the consequences if whoever sent the anomaly should decide to return. less

The alien Akara have a secret. They've discovered the location of a planet that is home to a primitive human civilization, another ancient "seeding" of the legendary Progenitors. But this planet lies in the territory of the Otuka, spacefaring alien predators who consider human flesh to be a delicacy and the planet to be their private hunting preserve. Unwilling to confront the Otuka, the Akara have passed the problem to their human allies, the Lunar Free State... moreThe alien Akara have a secret. They've discovered the location of a planet that is home to a primitive human civilization, another ancient "seeding" of the legendary Progenitors. But this planet lies in the territory of the Otuka, spacefaring alien predators who consider human flesh to be a delicacy and the planet to be their private hunting preserve. Unwilling to confront the Otuka, the Akara have passed the problem to their human allies, the Lunar Free State. Now, the LFS needs to decide what to do about it. Are the "Moonies" willing to take responsibility for an entire planet's population? One thing seems certain: a favorite food of the Otuka is about to get much more expensive, as the LFS Marines teach Otuka hunters a hard lesson in the perils of hunting the most dangerous game in this part of the galaxy. "Valkyrie's Daughter" is the latest installment in the award-winning Lunar Free State series by John E. Siers. less