Project Hail Mary

Lore & Background

In the near future, scientists observe the Sun dimming at an exponential rate, coinciding with the formation of a dim infrared line from the Sun to Earth, dubbed the Petrova line. The dimming will cause a catastrophic ice age within thirty years. World governments appoint former European Space Agency administrator Eva Stratt to lead a task force with almost unilateral authority. A space probe sent to Venus reveals the Petrova line is made of single-celled organisms that consume and release electromagnetic radiation, named Astrophage. Astrophage breeds by absorbing energy from the Sun and carbon dioxide from Venus. One star, Tau Ceti, has resisted the infection. A starship, the Hail Mary, is created to travel to Tau Ceti, using a special engine fueled by Astrophage. The mission is one-way; findings will be returned via unmanned mini-ships called beetles. Two science experts are recruited and trained for the mission, but they are killed in an accident shortly before launch. Stratt forces Grace to join the suicide mission against his will; he is sedated and placed aboard the ship. The sedation process causes a coma and brain damage, resulting in amnesia.

In Their Own Story

Four years and eight months later, Grace emerges from his coma aboard the Hail Mary as it approaches Tau Ceti. He has no memory of his identity or situation and finds the rest of the crew has died en route. Over weeks, he gradually recovers his memory. The Hail Mary is approached by an alien starship, which Grace names the Blip-A after its default radar display name. The ships dock, and Grace develops a system to communicate with the eyeless, spider-like, five-legged, rock-like alien he names Rocky. Rocky has been in the Tau Ceti system for 46 Earth-years and is the last survivor of his crew, the rest having died of radiation sickness. Grace and Rocky cooperate to find a predator microbe on Tau Ceti's connected planet, dubbed Adrian, which they name Taumoeba. During collection, a hull breach occurs, and they risk their lives to save each other. Some Taumoeba get into the Hail Mary's fuel lines and eat most of the Astrophage. Grace and Rocky jettison the infected tank and sterilize the ship. They use selective breeding to produce Taumoeba that can survive the atmospheres of Venus and the planet around 40 Eridani. Rocky repairs and refuels the Hail Mary before parting ways. En route to Earth, Grace discovers he accidentally bred Taumoeba to penetrate xenonite containers. He sends beetles back to Earth with Taumoeba farms and instructions, then rescues Rocky. Sixteen years later, Grace is living on Erid, now rid of Astrophage, and learns Earth's Sun has returned to its original luminance.

Reader's Guide

The crisis began when Astrophage appeared near Earth, consuming stellar energy and dimming the sun. Unlike known biology, these microbes feed on photons rather than chemical bonds, threatening to extinguish all photosynthesis-based life within decades. Scientists discovered that a specific strain could be modified to consume itself, but finding it required traveling far beyond the solar system. Ryland Grace was selected for his physics expertise and ability to solve complex problems under pressure. To ensure he did not panic over the near-certain odds of failure, the mission controllers induced amnesia regarding the true stakes upon launch. He wakes up on the ship with no memory of Earth's desperation, only a drive to complete his objective. The turning point occurs when Grace discovers he is not alone. An alien crewmate named Rocky shares a similar mission objective from their own civilization. This interspecies cooperation highlights the universal threat of the Astrophage and sets the stage for a joint scientific breakthrough involving modified algae to restore solar output.

Did You Know?

• The audiobook, narrated by Ray Porter, uses melodic sound effects in the background whenever Rocky speaks.
• Weir wrote 75,000 words of an abandoned space opera called Zhek before writing Project Hail Mary, and several elements from Zhek were brought over, including a ruthless bureaucrat character and an energy-absorbing substance used as starship fuel.
• Bill Gates and Barack Obama each added Project Hail Mary to their respective 2021 book recommendations.
• The film adaptation rights were sold to Metro-Goldwyn-Mayer in early 2020 for $3 million, with Ryan Gosling starring and producing.
• The book debuted at number three on The New York Times Best Seller list for Combined Print & E-Book Fiction in May 2021.