Every reaction in the Saturn economy, animated bond by bond, each with the energy it moves.
Each card plays one reaction from start to finish: the molecules or nuclei approach, a flash marks the moment they react, and the products leave. The same script drives the deep zooms in the tour, so the species, the sequence and the energy are the ones the tour shows. Press Play, or drag the slider to stop on any step.
The picture is a drawing, and the card says so. What is measured is the energy: it comes from tabulated enthalpies of formation for the chemistry and from the mass the products lose for the nuclear reactions, and every figure is in the science register. Under each card, a second graph plots that energy against the progress of the reaction. Only its two levels are data. The hump between them marks a barrier that heat or a catalyst has to carry the molecules over.
D + D → ³He + n. When two deuterium nuclei meet, this is one of the two ways it can end. The neutron carries 2.45 MeV of the 3.27 MeV released, and no magnet can touch it.
10⁻¹⁵ m Two deuterons, one neutron
10⁻¹⁵ m Two deuterons, one proton
10⁻¹⁵ m Tritium meets deuterium
Two deuterons, one neutron: the products sit 3.3 MeV lower than the reactants, so the reaction gives energy out. The hump between them is a barrier that the heat of the flame, a catalyst or a hot reactor lets the molecules climb. physicsillustrative
Two deuterons, one protonillustrative
2 D → T + p
Products leave
mass 4.0239 u
energy released 4.0 MeV
Bonds broken: none. Bonds formed: none.
D + D → T + p. The other way makes tritium and a proton, 4.03 MeV in all. Both products are charged, but the tritium is fresh fuel for a third reaction.
10⁻¹⁵ m Two deuterons, one neutron
10⁻¹⁵ m Two deuterons, one proton
10⁻¹⁵ m Tritium meets deuterium
Two deuterons, one proton: the products sit 4.0 MeV lower than the reactants, so the reaction gives energy out. The hump between them is a barrier that the heat of the flame, a catalyst or a hot reactor lets the molecules climb. physicsillustrative
Tritium meets deuteriumillustrative
D + T → ⁴He + n
Products leave
mass 5.0113 u
energy released 17.6 MeV
Bonds broken: none. Bonds formed: none.
D + T → ⁴He + n. The tritium made a moment ago burns with a deuteron and releases 17.59 MeV, 14.05 MeV of it in a neutron. This is the most energetic neutron in the plasma.
10⁻¹⁵ m Two deuterons, one neutron
10⁻¹⁵ m Two deuterons, one proton
10⁻¹⁵ m Tritium meets deuterium
Tritium meets deuterium: the products sit 17.6 MeV lower than the reactants, so the reaction gives energy out. The hump between them is a barrier that the heat of the flame, a catalyst or a hot reactor lets the molecules climb. physicsillustrative
D + ³He → ⁴He (3.7 MeV) + p (14.7 MeV). The products weigh 0.4% less than the fuel; that missing mass is the 18.35 MeV released (E = mc²). Both products are charged, so magnets can turn them into thrust.
Deep zoom 3: deuterium meets helium-3: the products sit 18.4 MeV lower than the reactants, so the reaction gives energy out. The hump between them is a barrier that the heat of the flame, a catalyst or a hot reactor lets the molecules climb. physicsillustrative
Uranium-235 fission: one neutron in, two fragments and more neutrons out
Uranium-235 fission: one neutron in, two fragments and more neutrons outillustrative
n + ²³⁵U → ¹⁴¹Ba + ⁹²Kr + 3 n
Products leave
energy released 200.0 MeV
Bonds broken: none. Bonds formed: none.
A neutron has no charge, so nothing repels it from a uranium-235 nucleus and it does not need to be fast. The nucleus takes it in, shakes and pinches in two. One textbook branch leaves barium-141, krypton-92 and three neutrons. The fragments slow in the fuel and turn about 200 MeV per fission into heat. The neutrons go on to split more nuclei.
10⁻¹⁴ m A neutron splits a nucleus
Uranium-235 fission: one neutron in, two fragments and more neutrons out: the products sit 200.0 MeV lower than the reactants, so the reaction gives energy out. The hump between them is a barrier that the heat of the flame, a catalyst or a hot reactor lets the molecules climb. physicsillustrative
CH₄ + 2 O₂ → CO₂ + 2 H₂O. Stronger bonds form than break, releasing about 800 kJ per mole of methane. Hot, light molecules leave the nozzle at about 3.4 km/s.
Deep zoom 1: methane burning: the products sit 802.3 kJ per mole lower than the reactants, so the reaction gives energy out. The hump between them is a barrier that the heat of the flame, a catalyst or a hot reactor lets the molecules climb. physicsillustrative
energy absorbed 571.7 kJ for two moles of water split
Bonds broken: 4 O–H. Bonds formed: 2 H–H, 1 O=O.
2 H₂O → 2 H₂ + O₂. Four O–H bonds break and three bonds form, two H–H and one O=O. Splitting two moles of water takes at least 571.7 kJ, which the reactors supply as electricity.
10⁰ m The electrolyser stack
10⁻⁶ m At the electrodes
10⁻⁹ m Bonds break and re-form
Splitting water: the products sit 571.7 kJ per mole higher than the reactants, so the reaction has to be fed that energy. The hump between them is a barrier that the heat of the flame, a catalyst or a hot reactor lets the molecules climb. physicsillustrative
N₂ + 3 H₂ → 2 NH₃. Nitrogen's triple bond and three H–H bonds break, and six N–H bonds form. The reaction gives off 91.9 kJ per mole of nitrogen, heat the plant keeps.
10⁰ m The synthesis loop
10⁻⁹ m Bonds break and re-form
Nitrogen into ammonia: the products sit 91.9 kJ per mole lower than the reactants, so the reaction gives energy out. The hump between them is a barrier that the heat of the flame, a catalyst or a hot reactor lets the molecules climb. physicsillustrative
CH₄ → C + 2 H₂. Four C–H bonds break and two H–H bonds form, and the carbon is left as a solid. It takes 74.6 kJ per mole of methane, 37.3 kJ per mole of hydrogen against 285.8 kJ to get the same hydrogen from water.
10⁰ m The hot reactor
10⁻⁹ m Bonds break and re-form
Hydrogen from methane, without oxygen: the products sit 74.6 kJ per mole higher than the reactants, so the reaction has to be fed that energy. The hump between them is a barrier that the heat of the flame, a catalyst or a hot reactor lets the molecules climb. physicsillustrative