Rigidizable

Kinescope Recording of Big Shot-2 Satellite Balloon Suborbital Inflation
Back in the early 60's, NASA's Project Echo put a couple of very large balloons into orbit. Echo 1 was 100 feet in diameter and Echo 2 was 135 feet in diameter. I remember looking up at the night sky when I was a little kid and seeing them sail by. Dots of light is all they were. Or maybe that was Sputnik. Whatever.

Before they launched these giant mylar balloons into orbit, the launched a couple of balloons 250 miles into space to test their inflation scheme. Low earth orbit, which is where the International Space Station is, is about 100 miles, so they were well up there. This was back in the 60's, so putting something into orbit was a real stretch. Launching something straight up was much easier. Putting something in orbit requires accelerating to around five miles per second. Sending something 250 miles straight up only required reaching a velocity of around two miles per second. Much, much easier.

The first one (Big Shot 1) failed when "the balloon was torn apart due to rapid inflation". The second one (shown in the video above) was a success. This video comes to us through a Rube Goldberg combination of technology:

A Kinescope is a film recording of a television screen. It really is that simple: a film camera aimed at a TV. But why? Primarily because early videotape was unreliable, expensive, and low quality. Many early television broadcasts were recorded via Kinescope before videotapes became available. NASA used Kinescope to record live feeds from space off of video monitors. - The Unwritten Record

The balloons themselves were pretty amazing.

Unlike Echo 1, Echo 2's skin was rigidizable, and the balloon was capable of maintaining its shape without a constant internal pressure. This removed the requirement for a long term supply of inflation gas, and meant that the balloon could easily survive strikes from micrometeoroids. The balloon was constructed from "a 0.35 mil (9 µm) thick mylar film sandwiched between two layers of 0.18 mil (4.5 µm) thick aluminum foil and bonded together." The balloon was inflated to such a level as required to slightly plastically deform the metal layers of the laminate, while leaving the polymer in the elastic range. This resulted in a rigid and very smooth spherical shell. - Wikipedia

I think what this means is that they used enough pressure to slightly stretch the balloon material. For a big balloon like this, you would need a great deal of pressure to stretch the whole thing. On the other hand, you have an enormous volume of gas doing the pressing, and the material is very thin (.0007 inches, less than a sheet of typing paper), so maybe they only needed a small amount of pressure. In any case they used enough pressure to stretch the aluminum so it stayed stretched (kind of like stretching a slug of aluminum into a beer can), but not so much that it ripped the mylar film.

Morse Code Decoder

I tried decoding the beeps in the video. They sound like they could be Morse Code, but I couldn't make much sense of it. Seems to be something like N-R-F-R-E-0 repeated over and over again.

Via Indy Tom