So, what’s the connection between contact lenses and rocket engines? The answer, I probably don’t hear you cry, is hydrogen peroxide and cleanliness.
The lens holder includes a small piece of material (I have yet to identify it) that catalyses the decomposition of the peroxide solution. If it didn’t then the peroxide would remain and, having successfully killed the bugs on your lenses, then do its best to kill the cells of your cornea too. And this is where the rocket engine connection comes in.
The reaction that decomposes the peroxide also produces oxygen – you can see it bubbling off the catalytic material. That same type of reaction, albeit using extremely concentrated hydrogen peroxide, was exploited in the engines of Britain’s Black Arrow space rocket to launch the Prospero satellite into orbit in 1971.
The catalyst used was silver metal gauze and it decomposed the peroxide violently into oxygen and steam, which then ignited kerosene fuel, and so provided thrust to lift the rocket. In fact, earlier rocket engines dispensed with fuel altogether and replied on the thrust of the decomposing peroxide alone.
Oh, and the cleanliness connection? Well, peroxide rocket engines are considered ‘clean’ or green as their exhaust, after all, contains little more than oxygen and steam.