from Hacker News

Could a Paper Plane Thrown from the ISS Survive the Flight?

by dxs on 7/10/25, 1:51 PM with 36 comments

• by nickparker on 7/10/25, 2:33 PM

  Bad popularizing article, doesn't cover the actual conclusion:

  The main points emerging from the combined simulation and experimental study on atmospheric entry of the paper plane are: • Orbit: The paper space plane de-orbits from LEO extremely quickly due to its very low ballistic coefficient. Atmospheric entry from a 400 km circular orbit occurs within a few days. • Attitude: In the free-molecular portion of atmospheric entry, above ∼120 km altitude, the paper space plane maintains a stable flow-pointing attitude. Small-amplitude oscillations occur in pitch and yaw. Although the coupled simulator is not designed for application at lower altitudes, the results suggest the onset of uncontrollable tumbling at ∼120 km altitude. • Heating: Based on the hypersonic wind tunnel test results and simulation, surface forces acting on the space plane during atmospheric entry are not expected to cause significant deformation. However, the paper space plane experiences severe aerodynamic heating in the order of 105 W/m2 (or 10 W/cm2 ) for several minutes. Accordingly, combustion or pyrolysis is expected during atmospheric entry

• by peterlk on 7/10/25, 2:22 PM

  Answer: it would most likely burn up

  Original paper: https://www.sciencedirect.com/science/article/pii/S009457652...

• by ngriffiths on 7/10/25, 3:00 PM

  I feel like the news article doesn't emphasize that you aren't "launching" the plane any more than you would by setting it on the roof. So it's really surprising that it all happens in <4 days.

  I thought atmospheric effects were much lower at that altitude, but apparently even the ISS loses about 3km every month (enough to deorbit in ~15 months).[1]

  The ballistic coefficient of the ISS is a whopping >500 times greater than the plane so the plane drops really fast.

  [1]: https://space.stackexchange.com/questions/9482/how-long-woul...

• by fainpul on 7/10/25, 2:52 PM

  Isn't the windtunnel test completely different from actual conditions? Mach 7 at 1 bar is wildy different than Mach 7 at very low pressure, isn't it?

  My gut feeling tells me the paper plane doesn't have enough mass to "power through" the thickening atmosphere with enough force to substantially heat up.

  Also, if it starts tumbling or not is not very relevant, it's still flying. Surely it could recover at some point, maybe at low altitude with higher air pressure and random turbulences.

• by deadbabe on 7/10/25, 4:05 PM

  If you had 250 miles of wire (only about 400 pounds), could you unroll it all the way down to the surface of earth and drag it across the world? I guess at some point it would melt from friction with air. But what if the source was geostationary??

• by K0balt on 7/10/25, 2:47 PM

  I wonder if there is a paper treatment or paper like substance that could manage those temperatures without issues? Certainly a little “styrofoam” glider carved out of foam heatshield material, which would be cool enough, but lacks the “I found a paper airplane and it was signed by an astronaut “ appeal.

• by FiatLuxDave on 7/10/25, 4:32 PM

  Hmm... the paper plane has an initial kinetic energy of (0.004 kg) * (7800 m/s)^2 / 2 = 121.6 kJ. But it is supposed to experience 10^5 W of heating for several minutes? The atmospheric heating comes from converting the kinetic energy to thermal energy. What am I missing?

• by nodesocket on 7/10/25, 4:27 PM

  Asking some follows up to ChatGPT it was interesting to hear that if the plane was made out of copper it would orbit significantly longer than the paper airplane because it has a lower surface-area-to-mass ratio. Estimated to orbit months, before mostly being burned up due to coppers melting point.

  It’s getting even more interesting if the plane was made out of titanium. It would orbit for years potentially before having a 30-40% of surviving reentry. It’s fascinating sometimes physics is the opposite of what you think intuitively. You’d think heavier metals would orbit for less time than a paper airplane. Ballistic coefficients are the key.

• by wrp on 7/10/25, 3:17 PM

  > Combustion or pyrolysis is expected due to aerodynamic heating.

  My naive impression is that this would not be possible. I would expect that a very light object with large sail area would be driven so easily by air flow that it would experience negligible heating from friction. What is the physical reasoning behind thinking it could burn up?

• by mcphage on 7/10/25, 3:18 PM

  Rather than an airplane, what about a paper helicopter? Paper airplanes can get into an unrecoverable dive, but the helicopters start rotating on their own (one of these: https://www.wikihow.com/Create-a-Paper-Helicopter)

• by chris_va on 7/10/25, 2:55 PM

  A black surface can re-radiate 1E5W/m^2 at ~1100C (assuming I calculated correctly).

  So, paper is out, but maybe glass would work ok :)