The H.G. Wells short story The Country of the Blind tells of an explorer named Nuñez who falls down the side of a mountain and finds himself in an isolated valley whose residents have been born blind for generations. They have no idea what sight is, and Nuñez doesn’t have much luck describing it, or convincing them of its value. Ultimately, the joke’s on him; though he thinks someone sighted will have no trouble running the place, the locals are entirely unimpressed. The point is, be careful when making presumptions of cultural superiority. Carolyn Ives Gilman’s Dark Orbit begins as a sci-fi spin on that old story, but quickly spins off of those familiar ideas in new directions.

Saraswati Callicott is an interstellar explorer and cultural expert who travels on lightbeams (think Star Trek’s transporter, but with limitless range). The beam is bound by the speed of light, so she typically spends years (even decades) of objective time traveling from place to place, aging only seconds in the process. Naturally, she has few attachments. Arriving from her most recent job, she barely has time to process the years she’s skipped over when she’s given a new assignment: a trip to a Questship, launched centuries prior to seek out new worlds. Automated systems have discovered Iris, an intriguing planet on the edges of human exploration, a journey that will take her almost 120 years round trip. Officially, she’s lending her cross-cultural expertise to a team of scientists studying the planet. Unofficially, she’s there to keep an eye on Thora Lassiter, a high-born young diplomat whose last job as emissary went awry, owing to what’s described as a serious mental breakdown.

It’s not long before Thora, lost on an away mission, finds herself among the native (after a fashion) inhabitants of Iris: approximately human, and entirely blind. This is where the novel, heretofore an engaging scenic journey to a strange world of razor grass and fractal trees, truly comes to life: the locals live in complete darkness, so Thora is left to adapt to a world where she’s entirely cut off from one of her primary senses. Even given a shared language (for reasons left vague), words are inadequate to describe the experience of sight. Eventually, a young woman from Isis winds up aboard the Questship with the situation reversed. It’s a subtle, convincing take on the challenges and opportunities of cross-cultural engagement. When it becomes clear that there’s more to the seemingly simple people of Iris than meets the, er, eye, the mission’s corporate masters want merely to exploit their abilities, while others take an almost maternalistic view, aware of the danger that a pristine culture will become contaminated.

That’s the core of the narrative, but the book is packed with ideas. There’s quite a bit to mull over, about science and faith, and the real-world applications of the observer effect in physics: can you really ever study something without that very act changing it forever? And lest we forget this is splashy SF, there’s also a murder mystery, plenty of intriguing tech, a way-cool trip through that fractal forest, and a looming planetary catastrophe to tie everything together. The real heart, though, is in the interactions between the genuinely strong, thoughtful lead characters, almost all of them women. And there’s not a love triangle in sight, nor any of the other structures we’ve been trained to expect in books starring lady types. In some ways it’s incidental, but in other ways it’s essential: as Thora reclaims the memories of her previous, ill-fated excursion, it becomes clear why her actions were dismissed as mental breakdown. Even in the future, for women who speak too loudly and challenge the orthodoxy, the traditional, well-worn diagnosis stands.

There are almost too many ideas here: scientific, spiritual, and cultural questions are raised and occasionally dismissed before they really have a chance to develop. I’d rather have too many ideas than too few, though, and Gilman digs deep into realms of culture and human relationships that sci-fi rarely deals in outside of the strongest works by Ursula K. LeGuin (who, incidentally, gave this one a glowing cover blurb). Aside from being a pretty cool mystery on a spaceship, Dark Orbit explores the overlap between two contradictory ideas: the impossibility of ever truly understanding each other, and the need to keep trying. I don’t come to the end of many books hoping for a sequel, but I’d love to spend more time with these characters.