What would happen if you threw a paper airplane from the International Space Station? It’s the sort of idea that might emerge from a curious child — or a physicist with a flair for wonder. Maximilien Berthet and Kojiro Suzuki, researchers at the University of Tokyo, decided to find out.

Their answer is part serious engineering analysis, part scientific whimsy, and wholly captivating.

Their experiment didn’t involve astronauts flinging paper darts out of airlocks (wouldn’t that be something?). Instead, the researchers combined high-fidelity computer simulations with blistering wind tunnel tests to explore how a folded A4 sheet of paper might behave if launched from low Earth orbit.

A Descent Like No Other

From the moment the simulated origami plane leaves the ISS (some 400 kilometers above Earth), it begins its doomed descent. Unlike a spacecraft designed to slice through the atmosphere with shielding and engines, this tiny paper glider weighs just four grams. Its surface is cellulose and kaolinite, not titanium or carbon fiber. And yet, for a time, it soars.

Thanks to its airplane-shaped folding, the paper plane is statically stable in the vacuum-like upper reaches of space. It points nose-first into the airstream, guided by the subtle aerodynamic forces acting on its paper form.

This initial phase of descent, researchers found, is surprisingly calm. The plane passively maintains orientation for several days as it spirals downward, shedding altitude rapidly. “Atmospheric entry from a 400 km circular orbit occurs within a few days,” the authors write.

But then after around four days and at around 120 kilometers — just above the region where satellites begin to burn — gentle descent gives way to chaos.

Controlled Flight Gives Way to Tumbling Fire

The thin air thickens. Drag surges. The plane begins to tumble. The simulations, based on equations tracking orbital mechanics, rotation, and aerodynamic drag, show the once-stable dart now spins uncontrollably.

This can only mean one thing — heat. The paper would begin to burn.

To verify their models, the researchers turned to hardware. They folded a scaled-down version of the origami plane and placed it into the Kashiwa Hypersonic and High Enthalpy Wind Tunnel in Tokyo. Then they blasted it with Mach 7 winds — over 1,000 meters per second — for seven seconds straight.

The plane’s paper nose began to bend backward under the force, forming a 3 mm ridge. The tip darkened and wing edges charred. Despite the onslaught, the plane held together — but barely.

“Combustion or pyrolysis is expected during atmospheric entry,” the authors concluded. It was, for all intents and purposes, a one-way trip.

Why Launch a Paper Plane From Space?

The idea may sound whimsical, but this tiny experiment carries weightier implications.

First, there’s sustainability. In an era where space debris crowds low Earth orbit and satellite mega-constellations are multiplying, the researchers note a growing interest in using organic, biodegradable materials for space missions. Paper, largely plant-based, could offer a cleaner way to dispose of lightweight objects or components through passive atmospheric reentry. Japan, for instance, launched a working wooden satellite in space that operated for 116 days. It’s launching a second, improved version soon.

More practically, a paper plane’s rapid descent makes it a sensitive probe for studying the upper atmosphere if it were equipped with tiny sensors. Because of its low mass and large surface area, its trajectory is highly responsive to small changes in air density—information that’s still difficult to collect at altitudes between 200 and 300 kilometers.

“The paper space plane’s strong sensitivity to aerodynamic drag . . . suggests it could be used as a passive probe for atmospheric density measurement,” the authors write.

In the end, the origami space plane does exactly what you’d expect of something made from office supplies hurled into Earth’s atmosphere: it burns up.

But along the way, it teaches us something new. Not just about aerodynamics or orbital decay, but about creativity, sustainability, and the spirit of scientific curiosity.

The study was published in the journal Acta Astronautica.