Galactic Altruism follows two parallel lives that eventually merge. Randy grows up on an Iowa farm, discovers astronomy, and becomes fixated on the Andromeda galaxy, later pursuing cosmology and joining NASA's Von Neumann Probe project. Thal grows up on Fox Island in Puget Sound, builds a homemade Arduino-powered submarine called MARSHI with help from her science teacher, and develops a deep love of the ocean, eventually studying oceanography. The two meet in graduate school at the University of Washington, bond over a mycology class, and marry. Years later, aboard a research vessel, Thal finally gets the chance to launch MARSHI into the Aleutian Trench. There, at a hydrothermal vent, the little submarine encounters what appears to be an alien seeding probe manufacturing new life forms. The probe etches an image of the Andromeda galaxy onto MARSHI's shell before releasing it, suggesting that life on Earth itself may once have been planted the same way.

Galactic Altruism by Larry Carlson is a gentle, science-forward tale, and the title sums up its whole point rather neatly: that scattering life across the galaxy with no reward in sight is the purest kind of generosity. The world-building is where the book earns its stripes, with real Arduino electronics, telescope mechanics, and deep-sea vent biology in the story without turning it into a lecture. The moment a father calmly agrees to source a pressure-rated plexiglass sphere for his daughter's homemade submarine is a small delight that captures the book's easygoing charm. Thal and Randy come across as sincere, curious characters whose shared love of discovery drives the story forward nicely, and their playful early exchange over mycology samples in the lab shows real chemistry. The "lights out" launch ceremony aboard the research vessel is another standout, turning a simple submarine drop into a moving, cinematic moment. Overall, this suits younger readers or science enthusiasts who enjoy fiction with an educational backbone; a heartfelt, inventive read.

Galactic Altruism is a science fiction novella by Larry G. Carlson. Thalassa (Thal) grew up on Fox Island in Washington State's Puget Sound. As a child, she took an avid interest in oceanography. She successfully achieved her dream of creating a small autonomous research submarine named MARSHI. Randy came from a farm in Plainfield, Iowa. After receiving a telescope from his high school science teacher, Randy went on to study cosmology and met his future wife, Thal, in an upper-level mycology class. Thal's and Randy's career paths collided when MARSHI went missing on one of its research missions. Randy was working at NASA's VNP project when his team stumbled upon MARSHI. MARSHI's findings, however, would soon change the course of scientific research and human space exploration.

Galactic Altruism is one of those sci-fi stories that get people interested in fields like cosmology and oceanography. I felt author Larry G. Carlson deliberately paced the narrative as a slow burn to develop the characters organically so readers can follow every step of their career trajectories. I'm sure readers involved in scientific research will resonate with the story arcs of Thal and Randy. Another impressive aspect of Carlson's writing is his incorporation of real-world research agencies and their work into the narrative in a way that felt authentic. I also enjoyed Thal and Randy's underlying romance. These two came from different environments but found their way to each other in the pursuit of their dreams. Sci-fi fans will also love the lore of the Courier. Overall, it's a fantastic book for anyone who loves first contact tales.