History Literature / ProjectHailMary

* DrinkBasedCharacterization: During the celebration of the ''Hail Mary'' being launched and assembled Yáo has a German beer, Ilyukhin has a large thermos full of vodka, and Dubois has a red wine (perfectly aerated).

* TheEngineer: Ilyukhin in the flashbacks, though she dies during the transit to Tau Ceti. Rocky takes over the role in the main plot.

* TwoGuysAndAGirl: Discussed, the original mission plan involves sending two men and a woman, all heterosexual, which Stratt hates due the gender setup having few benefits and mostly [[BelligerentSexualTension down]][[{{Cockfight}} sides]]. If Ilyukhin hadn't been the best candidate for engineer and Shapiro the alternate candidate for biologist, she'd have sent all heterosexual men to minimize the odds of messy conflict.

** Grace comes to a sudden and horrifying realization: [[spoiler: He had just discovered that the specially-bred taumoeba can now travel through Xenonite, which isn't a problem for him since he can make a container of something that the taumoeba can't penetrate. But Rocky's ship is ''made up of taumoeba-permeable Xenonite'', meaning there's nothing stopping the evolved microbes from eating all of Rocky's fuel, stranding his ship, and dooming the Eridians.]] A glance at his telescope only supports his fears.

* StarCrossedLovers: Dubois and Shapiro are aware that their fling will only end in heartbreak (either one will go on the SuicideMission or the other one will), which doesn't stop them from. [[spoiler:Unexpectedly, they both die together in an accident right before the mission.]]

** Because the boiling point of water changes with atmospheric pressure, at 29 atm the boiling point of water is 230 C (not 100 C like at Earth's 1 atm). Thus Eridians are most comfortable at a temperature of around 210 C. Air pressure of under 19 atm is fatal to them, because the boiling point of water would correspondingly drop, so their own internal temperature of 210 C would literally boil them own cells alive.
** While their ammonia-based atmosphere blocks out all sunlight from their surface, the Eridians themselves actually don't "breathe" at all, ammonia or oxygen. That is, they don't use "cellular respiration" for gaseous exchange: they do cycle air through tubes, which is also how they make noises audible to humans, but this is purely used to regulate internal temperature. Thus the pressure differential, not difference in chemical composition, is what makes them unable to live in an Earth-like atmosphere.
** Eridians are covered in heavy carapaces to survive the high atmospheric pressure, giving them the appearance of rocky spiders: this takes up over 90% of their mass and is made of inorganic metals and ceramics (i.e. how human bone is made of calcium, except it's ''almost all'' of their body). Despite this, Eridians ''are not'' silicon-based lifeforms, but carbon-based. Indeed, the basic sugars and proteins of their biosphere are essentially compatible with Earth's (they even have [[MirrorChemistry matching chirality]]), leading Grace and Rocky to speculate that both of our biospheres share a common origin through microbial panspermia. Eridian bio-matter is ''not'' edible to humans, however, due to being saturated with a large number of additional heavy metal toxins.

* AlmightyJanitor: Grace isn't just MoreThanJustATeacher, he's an expert microbiologist with a groundbreaking paper that's eventually proven right and competent in several other fields of science- and this is before all the training he goes through. [[spoiler: Stratt calls him out on why this is, he's a coward that couldn't handle academia or any field where he could make a difference and preferred the safety of being "the cool science teacher." He doesn't deny it.]]

** While the very nature of the ''Hail Mary'' and it propulsion is new technology, all machinery and lab equipment ''aboard'' it is existing off-the-shelf technology with many thousands of hours of consumer testing, save for the coma apparatus and medical droids. Microsoft Office may not be flashy, but it works reliably.

* ComicallyMissingThePoint: The FirstContact with Rocky goes remarkably well, until Grace tries teaching Earth units of distance with a tape measurer. Rocky has no idea what to do with the device and just pulls and releases the tape repeatedly like a child playing with a toy. This is what leads Grace to figure out that Eridians can't see like he can.

* StarFishAliens: Examined in realistic detail: while Eridians are very different from humans, on the cosmic scale of things Grace and Rocky are astonished that they're still reasonably close enough in terms of biology and technology levels that they're able to work out how to communicate with each other relatively well. The comparable technology levels are explained by Rocky pointing out that a pre-spaceflight civilization couldn't even try to stop the astrophages, and anything more advanced than they are could have solved the problem without launching an expedition to the astrophage homeworld in the Tau Ceti system. In terms of interaction, Eridians evolved in total darkness so they have no eyes, but their "sight" is a highly developed form of echolocation. Grace is thankful to discover that Eridian language is based on sound in the audible spectrum for humans, and vice versa, after which it's just a matter of learning (they don't have the mouthparts to make the sounds of each others' languages, but they can understand them). Weir published [[https://www.reddit.com/r/SpeculativeEvolution/comments/s5ixcv/eridian_biology_from_project_hail_mary_canon/ extensive notes]] about the Eridians biology:

* StarFishAliens: Examined in realistic detail: while Eridians are very different from humans, on the cosmic scale of things Grace and Rocky are astonished that they're still reasonably close enough in terms of biology and technology levels that they're able to work out how to communicate with each other relatively well. The comparable technology levels are explained by Rocky pointing out that a pre-spaceflight civilization couldn't even try to stop the astrophages, and anything more advanced than they are could have solved the problem without launching an expedition to the astrophage homeworld in the Tau Ceti system. In terms of interaction, Eridians evolved in total darkness so they have no eyes, but their "sight" is a highly developed form of echolocation. Grace is thankful to discover that Eridiann language is based on sound in the audible spectrum for humans, and vice versa, after which it's just a matter of learning (they don't have the mouthparts to make the sounds of each others' languages, but they can understand them). Weir published [[https://www.reddit.com/r/SpeculativeEvolution/comments/s5ixcv/eridian_biology_from_project_hail_mary_canon/ extensive notes]] about the Eridians biology:

* StarFishAliens: Examined in realistic detail: while Eridians are very different from humans, on the cosmic scale of things Grace and Rocky are astonished that they're still reasonably close enough in terms of biology and technology levels that they're able to work out how to communicate with each other relatively well. The comparable technology levels are explained by Rocky pointing out that a pre-spaceflight civilization couldn't even try to stop the astrophages, and anything more advanced than they are could have solved the problem without launching an expedition to the astrophage homeworld in the Tau Ceti system. In terms of interaction, Eridians evolved in total darkness so they have no eyes, but their "sight" is a highly developed form of echolocation. Grace is thankful to discover that Eridiann language is based on sound in the audible spectrum for humans, and vice versa, after which it's just a matter of learning (they don't have the mouthparts to make the sounds of each others' languages, but they can understand them). Weir published [https://www.reddit.com/r/SpeculativeEvolution/comments/s5ixcv/eridian_biology_from_project_hail_mary_canon/ extensive notes] about the Eridians biology:

* BittersweetEnding: [[spoiler:Grace has to use what fuel he has left to save not only Rocky, but the Eridian race itself, by carrying Rocky home, leaving the Beetles to bring info back to Earth. Fortunately, the Eridians treat him very well, doing everything they can to make his new home pleasant. It also turns out that he succeeded in his own mission, as Sol is observed to be brightening. And he is doing the thing he loved most, teaching again (to Eridian children, who are as excited as Earth children would be to be in a class taught by an actual alien!) But he is still basically stuck in a small domed habitat on an alien world that he can never really explore, and Erid's high gravity is starting to take its toll on his body.]]

* CunningLinguist: Stratt showed no difficulty working through paperwork in six languages and four alphabets.

* FiveSecondForeshadowing: Some of Grace's returning memories serve as this.
** The flashback about Stratt dismissing a copyright lawsuit for putting copies of all of Earth's software aboard the ''Hail Mary'' without paying royalties appears right before Grace starts looking for a way to translate Rocky's speech. Thanks to Stratt, he has a plethora of sound-analysis programs to choose from.

* DrinkOrderCharacterization: During the celebration of the ''Hail Mary'' being launched and assembled Yáo has a German beer, Ilyukhin has a large thermos full of vodka, and Dubois has a red wine (perfectly aerated).

* YouNeedToGetLaid: Grace is horrified to hear that ''everyone'' thinks Stratt are sleeping together, given their closeness on the project. When he denies it, someone tells him maybe it'd do them both some good.

* {{Heavyworlder}}: Erid has roughly double Earth’s gravity with twenty-nine times its surface air pressure.

* InterfaceSpoiler: Averted in the ebook version. The table of contents shows the chapter titles as regular numbers ("Chapter 1", "Chapter 2", etc.), while in the book itself, [[spoiler:the very last chapter number is Eridian numerals ("Chapter ∀ℓ") to show Grace's long time on Erid]].

* WhamLine: Grace tries to measure the distance from the sun by calculating how fast a sunspot is growing bigger. Then he sees it's moving far too quickly, does a few more calculations, and realizes that he's orbiting ''Tau Ceti'', not Sol.

* AppliedPhlebotinum: Xenonite, a super-strong xenon-based material that can be used to build pretty much anything [[spoiler:except taumoeba-82.5 containment]].

* ImAHumanitarian: [[spoiler:At the end of the book, Grace is living on Erid, which has a biosphere never meant for humans or their nutritional needs. Luckily they had an example of earth-evolved biota on hand and eventually worked out how to clone muscle tissue in-vitro. (You see where this is going.) By the time of the DistantFinale, a large part of Grace's diet is made up of what he likes to call "me-burgers". He is fully aware of how disturbing it is objectively, but you try living off of taumeba slurry and vaguely sweet protein shakes for a few years and see how gross you find it then.]]

** "He lead me through a maze of [[VideoGame/ColossalCave twisty little passages, all alike.]]"

* ChekhovsSkill: Grace being a science teacher greatly comes in handy for explaining things like relativity and radiation to Rocky, and later [[spoiler: gives him a purpose when he's living on Erid]].
* {{Cincinnatus}}: Stratt's job in a nutshell. And for all her hard work she has a [[PromotedToScapeGoat dismal future to look forward to]].

* SchizoTech: Vice versa –- one race has incredibly advanced materials science, the other has incredibly advanced computation.

** The Eridians managed to brute-force an interstellar mission despite having no experience with space travel, but this has a myriad of unintended consequences -- some good (having a huge surplus of fuel thanks to now knowing that TimeDilation was a thing) and some bad (radiation killing most of the crew because they didn't know ''that'' was a thing either).

* StarCrossedLovers: Dubois and Shapiro are aware that their fling will only end in heartbreak (either one will go on the SuicideMission or the other one will), which doesn't stop them from. [[spoiler: In the end, they both die together right before the mission.]]

* SurprisinglyRealisticOutcome: [[spoiler:No, Grace, you can't decline going on the SuicideMission, not while [[NecessarilyEvil Stratt]] is in charge.]]

* TheseQuestionsThree: Grace is awakened from his coma with three questions to test his recovering cognition, two rudimentary math problems and asking for his name. [[OnlyTheSmartMayPass The last one is needed to progress to the next room of the ship.]]

** The reverse is also true. Earth's environment is almost a vacuum as far as Eridians are concerned, and its high oxygen content causes their lung-equivalent to spontaneously combust just from their natural body heat.