Grace and Rocky do their Taumoeba breeding in containers made of Xenonite. But there’s a huge problem — the nitrogen-resistant Taumoeba can burrow through the Xenonite and escape. That starts killing Grace’s astrophage, and he starts to realize that Rocky is doomed, because his whole ship is made of Xenonite.
Could microbes really burrow through a solid container? Well, they can’t get through Earth metals, but some microbes can eat through plastic containers. And Xenonite is made up, so who knows how it works. Microbes do find a way to get just about everywhere on Earth. They even exist deep in the Earth’s crust, where there’s no sunlight or oxygen! In fact, this may be the world’s largest ecosystem. We’ve even found surviving microbes in NASA clean rooms and on the outside of the Space Station.
Artificial gravity
Let’s talk about artificial gravity. If you drop a ball, it accelerates to the ground because of gravity. We call that 1 g, which is 9.8 meters per second per second. But if you’re in a spaceship accelerating at 1g, it feels like gravity.
The Hail Mary is accelerating at 1.5g, so Grace feels a force 50% stronger than Earth’s gravity. But what about when the Hail Mary is in orbit around Tau Ceti? Astronauts are weightless while they’re in orbit, because they’re effectively in free-fall around the planet. So in that case, in the book, the upper capsule on the Hail Mary can flip around and move away at a distance while being attached by wires to the main ship. Then the whole thing rotates, creating an acceleration that acts like gravity. It is a lot like spinning a bucket over your head to keep the water in.
For the movie redesign, the crew compartment is much bigger, but it still detaches, turns sideways, and the whole ship rotates to simulate gravity. This led to some cool interiors that have to function in two orientations.
“The Hail Mary is accelerating at 1.5g, so Grace feels a force 50% stronger than Earth’s gravity.”
In the airlock tunnels, Grace ought to be weightless. But in the movie, they wanted to minimize weightless scenes, because they are very hard to show convincingly, and they’re expensive to film. So when the Hail Mary and Rocky’s ship, the Blip-A, are connected, they rotate around the connecting tunnel as if to simulate gravity. This is only notionally correct — it wouldn’t actually work in practice. First, you need a fast rotation to get the gravity correct at your feet. Second, if the curvature of the circle you’re rotating in isn’t huge, you’ll have gravity at your feet but almost no gravity at your head. But at least the movie gets points for trying, even though the math doesn’t quite work out.
Ship physics
We’re used to seeing ships fly like airplanes in science fiction movies, but of course, in space, without air resistance, a ship would just keep going forever unless acted on by an outside force. The ship physics is mostly done well, but there are a couple of scenes where they fly around in an unrealistic way, and kind of move and change direction a little too quickly. I know they are trying to keep the movie fast-paced, but to me it looks like inserting a scene from Benny Hill into 2001.
Summary
Project Hail Mary is an incredible film adaptation of one of the greatest science fiction novels of all time. And it isn’t just great entertainment, it shows Hollywood that there’s a market for hard science fiction. It shows a scientist as a real human being, not just a nerd in a lab coat. Science can underpin the plot, but also connect with real emotion. But most of all, it shows it is possible to push the boundaries of what we can show as aliens on screen. We can think bigger than we’ve ever dared to before. Rocky is one of my favorite science fiction characters of all time. Project Hail Mary doesn’t just entertain, it will inspire future generations of scientists, and remind everyone that the universe is a place filled with awe and wonder. It shows us that even when our problems seem insurmountable, we can solve them with science and empathy.
