Project Hail Mary: review

[Warning: spoilers.]

Project Hail Mary is a 2021 novel written by Andy Weir, who wrote The Martian in 2011 (that novel was subsequently made into a 2015 film). Once again, a smart and capable loner must figure his way through a seemingly intractable problem, although in Project Hail Mary, the loner ends up having help in the form of an alien whom our human protagonist, Ryland Grace, names Rocky. But let's not get ahead of ourselves. 

The story begins with Grace waking up to a computer voice and a set of intelligent robot arms. He quickly discovers he's been intubated in almost every bodily opening, and he can't remember how he got here. Barely conscious at first, and unable to speak, Ryland initially can't even remember his own name. As the story progresses, however, Grace is subject to flashbacks that give him clues as to who he is, where he is, and what his mission is.

Turns out Grace is on a ship called the Hail Mary, built to make the long trip out to a relatively nearby star called Tau Ceti. Earth's sun has been losing its luminosity, and it won't be long before extreme climatic changes cause the collapse of the environment and of civilization. Grace, a Ph.D. who used to ponder problems of xenobiology (the biology of alien life), has left higher academe to become a middle-school science teacher. He loves his kids, and they love him. Grace is known to the US government, however, and he is tapped as a potential authority on the question of what might be causing the sun to fade. Shanghaied by the government and given his own lab (by a mysterious, powerful Dutchwoman named Eva Stratt), Grace discovers that a creature he dubs Astrophage ("star-eater") has come to our solar system and established a link between the sun and Venus. Astrophage can live on the surface of the sun, but it goes to CO₂-rich Venus to breed. Astrophage, though microscopic on the order of microns, has evolved to perform almost perfect mass-energy conversion, and when it senses starlight that contains the appropriate wavelengths, it can propel itself at almost the speed of light toward that light source, feed off its energy, then turn to a planet with carbon dioxide in its atmosphere in order to breed.

Grace and an international team next discover that a star, Tau Ceti, seems not to be as affected as other local stars by Astrophage, so the various scientific teams across the world now working on the problem of the sun's luminosity conclude that a mission must be sent out to Tau Ceti to find out what makes it impervious. So it is that the Hail Mary project is born, "hail Mary" being the term used in American football to describe a desperate throw of the ball in an improbable attempt to score a final few points.

A ship is built, and when scientists are able to harvest and breed Astrophage on Earth, they realize they have the potential to create Astrophage-powered spacecraft engines that will allow a human to reach Tau Ceti in about four years of subjective time (on Earth, because of relativity, thirteen years will pass). Ryland Grace assumes an advisory position directly under Stratt, who seems to have the world's resources at her fingertips (this power is never explained).  A team is chosen to go to Tau Ceti with the knowledge that not enough Astrophage has been bred to bring the team home—a suicide mission. Because the trip will last four subjective years, the crew is to be placed in a coma. Thanks to a chemical developed by French scientists, the crew will experience a retrograde amnesia that will keep a person from remembering much of the recent past, with the assumption that the amnesia will fade as memory returns. Whatever the team eventually discovers about Tau Ceti will be recorded and sent back to Earth via Astrophage-powered Beetles, small probes designed to travel fast.

So how does Grace end up on the Hail Mary if he is merely an advisor and not a team member? One of the other team members is killed in an explosion during an Astrophage-related experiment, and Ryland Grace turns out to be the only other qualified person to go on the mission, in part because he is genetically predisposed to be tolerant of long comas (1 in 7000 people have this tolerance, according to the story). Grace, as he recovers his memory, is ashamed to recall that he didn't go willingly: he was forced onto the mission by Stratt, who accused him of being a coward unwilling to save the billions of human lives on Earth.

In space now, awake and aware of why he is aboard (his two teammates didn't survive their comas, and when Grace wakes up from his, he sees their desiccated corpses in their hibernation hammocks), Grace approaches Tau Ceti and discovers, to his shock, that another vessel is already in that region, and thus Ryland Grace makes the acquaintance of the alien he calls Rocky. Now, it should be noted that Grace caused academic controversy, back in his professor days, when he proposed that alien life would not need to have water to evolve, an idea that other scientists found inconceivable. When Grace first discovers Astrophage, he thinks he has vindication for his thesis, but it turns out that Astrophage does indeed need water to survive. Grace is crushed, but not defeated.

Then along comes Rocky. Grace comes to call Rocky's race "Eridians" because they come from the 40 Eridani system. Rocky and Grace have to figure out ways to communicate with each other; Rocky's homeworld is extremely hot, with an atmospheric pressure 29 times that of Earth's. Rocky himself is a spider-like alien who "sees" the world through sound and has a rocky carapace (hence the moniker); he is also his ship's equivalent of an engineer, and he communicates through a series of musical tones. Eventually, Grace and Rocky are able—thanks to Grace's computer resources—to build an extensive vocabulary, and while they learn each other's languages, they also learn to interpret more subtle cues like body language, gestures, and facial expressions (although Rocky doesn't seem to have an identifiable "face," per se). Grace also learns that Rocky's blood is essentially mercury, and Eridian life evolved without the need for water. Vindication at last!

Eridians have perfect memories and can do math instantly in their heads, but their reliance on sound has made them woefully inadequate when it comes to dealing with the electromagnetic spectrum, so strangely enough, Earth technology proves superior to Eridian technology in many respects. Rocky, once he's made aware of radiation, comes to understand why his twenty-some crewmates all died on the way to Tau Ceti (via their very own Project Hail Mary): radiation had killed them because they never knew they'd have to build a ship that shielded them from it out in deep space. Rocky, as the ship's engineer, lived in a space that just happened to have the right sort of shielding to protect him from ambient radiation. While Earth's technology proves superior to Eridian in many ways, the Eridians do have some aces up their sleeve, one of them being a material that Grace calls "xenonite," a solidified form of xenon gas that functions the way metals function on Earth. As a builder, Rocky is able to use xenonite to make modifications to the Hail Mary, and Rocky's huge ship has millions of kilograms of Astrophage that Grace can use to steer the Hail Mary back home if he wishes.

Do the scientist and the engineer solve the problem of why Tau Ceti isn't affected by Astrophage? Does Grace make it back to Earth? These are plot points I don't wish to spoil, so I'll stop my summary here and let you read the story for yourself.

As with The Martian, Weir writes in a humorous, engaging, page-turning style. The book went by fast for me, and I was a bit sad when the adventure was finally over. Like any good science-fiction story, Project Hail Mary traffics in big ideas, including the notion that even extraterrestrial life will have DNA and mitochondria, essentially relying on a panspermia theory of life's origins. Near the end of the story, Rocky asks Grace about the possibility of other life existing, and Grace finds the idea highly probable, given his encounter with both Astrophage and Rocky. Issues like environmentalism are also folded into the story, although in this case, what threatens Earth is an ice age caused by the sun's dimming, a disaster that will take a generation to unfold. (One subplot, back on Earth, has to do with slowing the coming disaster by creating further global warming to stave off the ice age.)

I haven't read Weir's other novel, Artemis, but I bet that it, too, involves a lone protagonist who must use his or her knowledge to solve hard problems. Project Hail Mary, despite its differences with The Martian, nevertheless had a very The Martian feel about it, and that might be my one lone complaint. But every novelist has a voice and several pet issues; should I really blame Weir for simply writing what he knows and likes? Seems petty. A deeper complaint is that Grace never thinks to record evidence that he has encountered an intelligent alien—a bit of data that might be useful to send back to Earth. The entire plot of the book plays out with Earth none the wiser that Eridians exist. But maybe Grace has his reasons for not letting Earth know about the Eridians.

So, complaints aside, read Project Hail Mary with my hearty recommendation if you're into science fiction. I'm not sure whether this qualifies as "hard" SF (which is based entirely on a realistic knowledge of physics, chemistry, etc.), but there's enough hard science in the story to satisfy most people, I think. Weir has proven himself, at least twice for me, to be a reliably interesting writer, so I suppose I'll be picking up Artemis next.

ADDENDUM: Wikipedia notes that Project Hail Mary's movie rights have already been sold to MGM, making Andy Weir 3 million dollars richer, and the film version will star Ryan Gosling as Ryland Grace. So get ready for "First Man to Tau Ceti."