People picture a dead satellite “burning up” on reentry — a clean disappearance. It isn’t. A metal satellite vaporizes, and that metal doesn’t leave: it becomes a haze of aluminum oxide (alumina) suspended in the stratosphere, where it scatters sunlight, nibbles at ozone, and lingers for years. The biggest chunks don’t even vaporize — they reach the ground.
There’s another way to build one. Launch a satellite, pick its material, and let it fall. Watch the wooden one return the way everyone assumed satellites already did — and watch the metal one write its name across the sky.
🐧 NULL watched the wooden one turn to ash and the metal one turn to haze, and marked the difference: the sky keeps the receipt either way.
Reentry isn’t a clean delete. When a metal satellite reenters, friction vaporizes its aluminum into alumina (Al₂O₃) — particles that are not naturally present in the stratosphere in any quantity. They sit up there for years, scatter sunlight, and can erode ozone. As of recent sampling, roughly 10% of stratospheric aerosol particles already carry metals from spacecraft, and that number is projected to climb toward ~50% as the megaconstellations scale up — tens of thousands of satellites, every one of which eventually comes down.
And the big pieces don’t burn up at all. Dense components — tanks, reaction wheels, hardened alloys — survive reentry and reach the surface. That’s the debris hazard the dial in this lab counts.
The wooden satellite is a real answer. Wood incinerates to fine ash on reentry — no alumina, no surviving chunk. It disappears the way people always thought satellites did. It isn’t science fiction: a magnolia-wood satellite has already flown.
The lesson points downward from the rest of the Space Node: the same orbit, the same mission — the material choice decides whether the sky heals or scars.
The stratospheric-metals finding is real. A 2023 NOAA/PNAS study (Murphy et al.) detected metals from spacecraft reentry — aluminum, lithium, copper, lead, niobium and more — in about 10% of stratospheric sulfuric-acid aerosol particles, and projected that fraction could reach ~50% as satellite launch and reentry rates climb. Alumina from reentry is not naturally present in the stratosphere.
The wooden satellite is real. LignoSat — built by Kyoto University and Sumitomo Forestry with JAXA/NASA, from honoki magnolia wood assembled with traditional Japanese joinery — launched in November 2024 and deployed from the ISS. Wood incinerates to ash on reentry instead of shedding alumina.
Surviving debris is real. Dense satellite components routinely survive reentry and reach the ground or ocean; orbital-debris and reentry-casualty risk is tracked by NASA and the FCC.
Stylized here: the launch, the orbit, the descent arc, and the “metal load” dial are an illustrative teaching model tuned for legibility — not an orbital-decay solver or an atmospheric-chemistry simulation. The 10%→50% figures are the real published range; the per-reentry increments on the dial are chosen to make the trend visible, not to predict a specific year. Built to teach, not to scare.
Pairs with the live Sky Sentinel (what’s up there now) and SpacePulse. Sister labs: The Wing, The Space Weather Lab.