Title: Probability moon
First published: September 16, 2002
Description: From back cover:

A Desperate Bid to Save Humanity

Humankind has expanded out into interstellar space using star gates -- technological remnants left behind by an ancient, long-vanished race.  But the technology comes with a price.  Among the stars, humanity encountered the Fallers,a strange alien race bent on nothing short of genocide.  It's all-out war, and humanity is losing.

In this fragile situation, a new planet is discovered, inhabited by a pre-industrial race who experience "shared reality" -- they're literally compelled to share the same worldview.  A team of human scientists is dispatched -- but what they don't know is that their mission of first contact is actually a covert military operation.

For one of the planet's moons is really a huge mysterious artifact of the same origin as the star gates -- and it just may be the key to winning the war.
Subjects: Life on other planets, Fiction, Space warfare, Human-alien encounters, Fiction, science fiction, general