The Centrifuge and Xenonite
Artificial gravity, spin drives, and an impossible material
The Hail Mary has an engineering secret: it can split in two and spin like a centrifuge to generate gravity. Dimitri's spin drive demonstrates astrophages' brute power. And the alien cylinder reveals an impossible material: xenonite, made of solid xenon.
The Hail Mary as centrifuge: artificial gravity
Dr. Lokken convinced Stratt to split the ship in two with Zylon cables and spin it. At 104 m from axis and 20.71°/s, exactly 1 g is generated.
The science behind it
In a spinning ship, centrifugal force pushes everything outward, simulating gravity. Formula: g = ω² × r (ω = angular velocity in rad/s, r = radius in meters).
With r = 104 m and g = 9.8 m/s²: ω = √(9.8/104) = 0.307 rad/s ≈ 20.7°/s. The ship takes about 20 seconds per revolution.
Zylon cable (polybenzoxazole) is one of the strongest fibers per unit mass. Used in Martian probe parachutes and high-tech ropes. It withstands the tension of two ship halves spinning.
Design problem: when engines accelerate, "down" points toward engines. When spinning, "down" points outward. Solution: rotate the crew compartment 180° when switching modes, like Apollo rotated its command module.
Key terms
Try it yourself
Centrifuge Simulator
Hail Mary: 104 m, 2.95 rpm → 1g
The spin drive: how the engine works
Dimitri shows the prototype: a triangular revolver with three zones. 20 micrograms of astrophage generate 60,000 N and melt a ton of steel.
The science behind it
Works through radiation pressure: astrophages emit Petrova IR light when excited by heat. That light pushes the ship (Newton's third law: light has momentum).
Three rotating positions: zone 1 (dim light, astrophages adhere), zone 2 (intense light, they "fire" and release all energy as IR), zone 3 (residue cleanup). Continuous process.
20 μg × c² ≈ 1.8 × 10⁹ J = 1,800 MJ released in 100 microseconds. Comparable to a small nuclear bomb in a fraction of a millisecond.
The ship uses 1,009 spin drives in parallel. If one fails, others compensate. Aerospace engineering redundancy principle.
Key terms
Xenonite: the impossible alien material
Grace analyzes the alien cylinder: it's solid xenon. But it's extremely hard, non-conductive, non-magnetic. Impossible with known physics.
The science behind it
Xenon is a noble gas: it normally doesn't form compounds. It has 54 protons and complete electron shells, so it doesn't "want" to react with anything.
Under extreme conditions (high pressure, low temperature, reactions with fluorine), xenon forms rare compounds like XeF₂. Xenonite extrapolates this radically.
The handheld X-ray spectrometer only detects elements above aluminum (Z=13) in the periodic table. Light elements like H, C, N, O are undetectable. So xenonite could be a xenon-carbon-nitrogen compound the spectrometer can't fully see.
Grace names it: "xenonite" (xenon + -ite, mineral suffix). It's extraordinarily strong, able to contain 29 atmospheres in flat panels.
Key terms
The alien star map: 40 Eridani
The cylinder contains 3D models: one of the Petrova line and a star map centered on Tau Ceti, with a thread connecting to 40 Eridani, their home star.
The science behind it
40 Eridani is a real star system 16.5 light-years from Earth. It has three stars (triple system). The primary (40 Eridani A) is an orange dwarf, smaller and cooler than the Sun.
The aliens use physical 3D models to communicate without shared language. Physics is universal: a scale model of a star system is understandable to any intelligent species.
Decoded message: "We come from 40 Eridani. Our star also has the Petrova line. We're here for the same problem as you."
A second cylinder shows models of both ships connected by a tunnel: a proposal for physical meeting.