The Unique (And Ironic) Way Project Hail Mary Achieves Interstellar Travel

Contains spoilers for "Project Hail Mary"

Traveling through interstellar space is a big element of many sci-fi stories. Whether you're talking about Star Trek's Warp speed or the wormhole jump points in the "Guardians of the Galaxy" franchise, there have been many different takes on how humans could potentially move quickly through space. In the case of the stunning space drama "Project Hail Mary," the means to travel light years away actually comes from the "antagonists" of the film: Astrophage.

Astrophage is the name given to the alien microbe that is causing the sun to dim, threatening the future of humanity. It's essentially an interstellar mold that grows on stars. However, Astrophage also gives humans the tools needed to address the issue — it can travel for several light years from its source. This means that, when harnessed and pointed in the right direction, the microbe can actually power a ship through space at incredible speeds.

How is this possible? At the risk of oversimplifying Weir's fictional but believable scientific explanations, Astrophage "eats" light. It takes massive amounts of energy from light and turns it into mass. Then, it burns that mass to move through space at lightning speed toward other sources of light, flitting from star to star. Earth starts to cool down when the microbe reaches our sun, but humans are able to harness its power to give themselves a fighting chance.

Fairly early on in the book version of "Project Hail Mary," science teacher Ryland Grace (played by Ryan Gosling in the movie) helps discover some of Astrophage's features, including the fact that it moves at very fast speeds toward energy sources it wants to feed on. Grace also figures out how to breed Astrophage on Earth, making him the perfect candidate to help build up the fuel source for the one-way trip. Project leader Eva Stratt (played by Sandra Hüller) puts him to work cooking up two million kilograms of the stuff, using the Sahara as a massive Astrophage Farm.

In comparison, Rocky (voiced by James Ortiz) — the alien friend that Grace meets when he finally arrives at Tau Ceti — and his race, the Eridians, have a relatively easy time making their own Astrophage. Their planet, Erid, is close to their star and has an extremely high pressure atmosphere. That means their water is very hot. As Rocky says in the book, making Astrophage was actually "easy" for them. "Put in metal balls with carbon dioxide. Put in ocean. Wait. Astrophage double, double, double. Much Astrophage."

Whether it's through paving the Sahara or letting an overheated ocean do its thing, both Eridians and humans manage to breed vast quantities of Astrophage for their respective missions to Tau Ceti, where it originates. Ironically, they're able to use it as the power source to push their heroes straight to Astrophage's home star system in search of a solution to the very microbes fueling their ships. It's a fun twist that keeps things interesting as Rocky and Grace work to use Astrophage to defeat itself.