Young stars are violent. They eject protons at high energies — stellar energetic particles — that bombard the atmospheres of nearby planets. This radiation is usually treated as a hazard, something that life must survive. Kobayashi, Airapetian, and colleagues show that it may be something life required.
When energetic protons hit a nitrogen-rich atmosphere, two things happen simultaneously. First, they produce NāO — nitrous oxide — a greenhouse gas potent enough to warm the planet by several degrees. This matters because the young Sun was 30% dimmer than today, making early Earth too cold for liquid water without additional warming. The faint young Sun paradox has haunted planetary science for decades. Stellar particle bombardment may solve it.
Second, the same proton impacts drive prebiotic chemistry. The energy deposited into atmospheric molecules creates reactive intermediates — HCN, amino acid precursors — that rain down onto the surface. The destructive radiation becomes the feedstock for life's building blocks.
The coincidence is too precise to ignore. The same process, from the same source, at the same time in a planet's history, simultaneously provides the warming needed for liquid water and the chemistry needed for the origin of life. The destructive event is the constructive one. The bombardment doesn't just permit life — it provisions it.