A LONE ASTRONAUT.
AN IMPOSSIBLE MISSION.
AN ALLY HE NEVER IMAGINED.

RYLAND GRACE is the sole survivor on a desperate, last-chance mission—and if he fails, humanity and Earth itself will perish.

Except that right now, he doesn’t know that. He can’t even remember his own name, let alone the nature of his assignment or how to complete it.

All he knows is that he’s been asleep for a very, very long time. And he’s just been awakened to find himself millions of miles from home, with nothing but two corpses for company.

His crewmates dead, his memories fuzzily returning, Ryland realizes that an impossible task now confronts him. Hurtling through space on this tiny ship, it’s up to him to puzzle out an impossible scientific mystery—and conquer an extinction-level threat to our species.

And with the clock ticking down and the nearest human being light-years away, he’s got to do it all alone.

Or does he?

An irresistible interstellar adventure as only Andy Weir could imagine it, Project Hail Mary is a tale of discovery, speculation, and survival to rival The Martian—while taking us to places it never dreamed of going.

I read Andy Weir’s The Martian in an enthralled 24 hour rush back in 2019. Ten years after that book’s 2011 debut, Weir put out another accolade gathering science fiction master work with Project Hail Mary.

My brief Goodreads executive summary of The Martian was “Bought on Saturday finished less than 24 hours later. A well told gripping read – believable science fiction that makes you wish more people believed science.” I waxed more lyrical in a full Fantasy Hive review about the book and the film here.

I had been slow to pick up Project Hail Mary since – obviously – it could not be a sequel to the very solar system centred drama of The Martian and I was unsure how Weir could recapture the intoxicating pace and science of that book. However, eventually the weight of friends’ recommendations, the comparators that were mentioned (Embassytown, Arrival), and the themes that naturally intrigue me (first contact, completely alien species, linguistic challenges), prompted me to pick the book up and dive in over a leisurely start to the 2025 festive season.

When I reviewed The Martian in 2019 the book had been out long enough for me to have seen the Matt Damon film shortly after reading the book and it was interesting to compare the two, although the film was a fairly faithful adaptation. At this point the Ryan Gosling vehicle for Project Hail Mary has not yet hit the cinemas, so I can’t do the same comparison. However, I do think that Project Hail Mary will present more challenges for the film maker’s art.

As in The Martian – where Mark Watney opening line to the reader declared  “I’m pretty much fucked” – Andy Weir kicks off Project Hail Mary with a similar in media res moment of crisis for his initially unnamed first person protagonist, waking from a coma in a sealed hospital room where robots have cared for him and (less successfully) two corpses.

Like Watney, our amnesiac hero has to “science the shit” out of his predicament – while waiting for memories of little details like his own name to resurface. As a former physics A’level student and teacher, I enjoyed how he used a simple pendulum to work out the strength of gravity in his hospital room and so deduce that not only that “he wasn’t in Kansas anymore, Toto” but that he wasn’t even still on Earth, with its comfortable 9.81 N of force on every kg of mass.

As sporadic memories (including his own name) return and Ryland Grace is able to explore his own environment some more, he discovers he is the sole surviving crew member of a space ship mission that is approaching a star which (based on its observed period of orbital rotation measured from watching sunspots) is not the Sun.

Two timelines are then braided together. There is the back story of what happened on a contemporary Earth to place Grace in this predicament teased out in fragmentary half-memories, and there is the current time of Grace’s activities in this non-solar star system.

The Martian was about one man’s survival against the odds – and the immense investment of effort and resources that would go into saving him. The spine of Project Hail Mary is the survival of the entire human race, and indeed life on Earth – so the stakes are certainly raised. Grace has been instrumental in discovering that the accelerating dimming of the Sun (which will lead to a life extinguishing global cooling) is being caused essentially by a bacterial infection of Astrophage. Astrophage leech off the Sun’s energy and arc over to Venus where the carbon dioxide rich atmosphere is essential in their reproduction cycle. The key to Astrophage’s interstellar survival is its ability to transmute matter entirely into energy according to that good old Einstein relationship E=mc² .  I did once point out to the sixth form Physics students that one could satisfy the Earth’s whole annual energy needs if one could only convert 100% of the mass of the entire sixth form into energy. For contrast those well-known nuclear processes of Fission and Fusion convert only between 0.1% and 0.4% of the mass into energy.

This is where the concrete feasibility of the science of The Martian spins off into the reason defying science-fantasy of an organism able, within the confines of a cellular membrane, to outdo the wildest dreams of cold fusion fanatics and their CERN scale magnetic tori. But it is the engine of the plot (and also of the space ship The Hail Mary) so one must let Weir’s inventiveness take us where he wills.

A desperate Earth science community scours the heavens for a solution to their dying star and discover that several local stars have the same optical signature of Astrophage presence. (Another interesting bit of physics adaptation using the idea of emission spectrum and the very narrow bands of wavelengths that Astrophage emit – a bit like the narrow pure yellow light from sodium streetlamps which presents as just two lines in a spectroscope). These stars all exhibit the same slow dimming from the infestation of cosmic bacteria as the greedy bastards sap the stars’ energy, except for one – the star Tau which is stably bright despite the astrophage presence. Revealed through the backstory the reader now understands Grace and the Hail Mary’s mission (“Hail Mary, full of Grace” – geddit?! I only just did) is to find out what makes Tau special and can it be used to save the Earth.

As with The Martian the earth-based element of the story naturally enjoys a larger cast with a range of interesting characters, particularly science supremo Eva Stratt who co-ordinates the earth wide science mission to save the Earth, utilizing the resources of every nation including China, Russia and the USA. To be fair I am perhaps unkind in suggesting that a space bacteria able to convert mass entirely into energy is the most unlikely element of Weir’s plot; far less plausible is the whole world coming together to accept the reality of a threat based on hard scientific fact and subordinating national interests and rivalries to scientific led pragmatism. I mean come on, we can’t even do that with the Climate Crisis and are still stuttering through the aftermath of Covid.

Although the narrative interleaves Grace’s space experiences and the Earth back story, the two elements are sequential rather than simultaneous as in The Martian.

Gradual memory recovery leads the Earth side of Grace’s story through some interesting scientific and political challenges and dangers to reveal how he came to be on the spaceship at all. This includes the means by which he was kept in a coma but healthy for the duration of the four- year journey at near light speed. (Say what you like about Astrophage, but they make great rocket fuel with a device that reminds me of the very bizarre Wankel engine for petrol driven cars).

The present time of the space side of Grace’s story initially has him alone – as Mark Watney was. However, he discovers another spaceship is already in the Tau system on exactly the same mission as he is but from a different Astrophage afflicted system.

This gives Weir the chance to imagine an alien life form and he goes all out for alien. In the early Dr Who story Galaxy Four the Doctor finds himself caught between two rival stranded spaceships on an alien planet that is on the brink of self-destruction. One side have reassuringly familiar and attractive golden haired human shaped crew. The other – the Krill – have a murkier existence sealed within the ammonia-based atmosphere of their space ship while using robots to explore the – to them – unsurvivable atmosphere of an M-class planet.

Weir takes a similar motif of an ammonia breathing alien living in an incredibly hot environment with whom Grace must find some way to communicate and interact so as to solve the problem of Astrophage for both their worlds.  Weir also eschews the convention of bipedal aliens so beloved of Star Trek The Original Series with a pentacly symmetrical alien that Grace christens Rocky.

I am curious how the 2026 film will render that alienness. The halting efforts to communicate and work together come across as interesting problem solving in the page but, would I suspect, be less easy to condense into the shorty pithy visual images that film favours. I’m also unsure how the remarkably bipedal James Ortiz will represent the differently symmetrical Rocky unless through even more CGI than Andy Serkis’s Gollum.

I have a couple more science grips to get off my chest. There is the Xenonite material from which Rocky’s spaceship and artefacts are made, such an incredibly strong alloy that flat sheets of it can withstand multiple atmospheres of pressure yet, at one key point in the plot, dangerously permeable to determined organisms.  It reminds me a bit of the material Cavorite that H.G.Wells invented for The First Men in the Moon – a material that conveniently blocks the effects of gravity and so helps propel a spaceship into orbit. The device intensely and understandably annoyed Jules Verne whose own From the Earth to the Moon drew on scientific calculations so rigorous and detailed that they correctly predicted Cape Canaveral as the best site to launch a moon probe from. I share Verne’s frustration at such materials of sci-fi legerdemain.

The other quibble I had is with the Hail Mary’s system for artificial gravity – once it has finished decelerating (which gives the sensation of gravity that Grace originally experienced). I mean I have no objection to spinning a stationary object so it acts like a centrifuge, or one of those wall of death fairground rides. The absence of a centripetal force gives the appearance of gravity as people feel pressed into the floor (or walls). I just doubt the Hail Mary’s ability to spin harmoniously in a flat plane without some central stabilising central axis rather than wobbling about like a toddler’s bike wheel.

To be fair though, I did appreciate Weir’s reference to the cane toad infestation in Australia, where a foreign species was brought to a place with no natural predators and quickly multiplied to overwhelm local flora and fauna. Astrophage presents a similar problem in the afflicted systems of Weir’s story and the solution he and Rocky discover is at once elegant and dangerous.

Ultimately, this is a fun story of first contact, found friends, and – in true Flash Gordon style, saving not just the Earth but another world too. While some of the hard science elements grated for me in how unlikely they were, I can’t say they outright broke laws of physics (eg short sighted Piggy’s glasses in Lord of the Flies focussing sunlight or the green glasses of Oz’s Emerald city making other colours appear green.)  It is still, like The Martian a story of a man (and alien) against the environment and Rocky deserves admission to the hall of imaginatively ultra-alien aliens, along with Dr Who’s Krill from Galaxy 4, China Mieville’s Ariekei from Embassytown, and Ted Chiang’s heptapods from Story of your Life/Arrival. It will be exciting to see if the film adaptation is as successful as The Martian was.

Project Hail Mary is available now, you can order your copy on Bookshop.org