We all know from experience that there is a big difference between a teaspoon of salt and a tablespoon of salt. A little too much pepper might be ok. But a little too much salt is going to be bad. Really salty! And since one tablespoon equals three teaspoons, getting those measurements wrong will definitely ruin your meal. Everyone gets the units wrong once in a while. But what’s the worst that could happen with incorrect units?
Well, in 1998 NASA launched the Mars Climate Orbiter to study the red planet from orbit. As the satellite approached Mars it was found to be off course and ended up disintegrating as it unintentionally entered the Martian atmosphere. Unfortunately, a ‘simple’ error resulted in a catastrophic failure. Software commands had been sent from Earth to the satellite using English units (pound-seconds) instead of metric units (Newton-seconds). Metric measurements are used in space navigation to determine the position of a spacecraft relative to moving planets in order to keep it on course. The use of wrong units resulted in a disaster that costed the space agency $125 million.
In the Nanoworld, scales are really important as well. Nanomaterials are typically designed to be less than 100 nanometers because at that scale, materials exhibit unique physical, chemical, mechanical, and optical properties.
One typical example is the difference between magnetite and ferrofluids. I love using this example because I fondly remember the days my mother and I would play with a magnet at the beach to extract the magnetite mineral out from the black streaks in the sand. Little did I know then that I would be studying nanomaterials like ferrofluids as an adult.
The naturally occurring magnetite and the synthetic ferrofluid material are both made of iron oxide, but they exhibit dissimilar behavior due to their different sizes. Now, if you could grind the magnetite (micrometer size) to make tiny little particles (around 10 nanometers in size) and then disperse them in a fluid, you would end up with a ferrofluid. In the absence of a magnet, ferrofluids behave like a liquid. In the presence of a magnet, the tiny particles become magnetized and start acting more like a solid. Ferrofluids have been used in loudspeakers, in rotary seals for computer hard drives, and to make amazing art!
Another fun fact about ferrofluids is that they were first invented for space travel in the 1960s. Stephen Papell, an engineer from NASA Glenn Research Center came up with the idea of magnetizing rocket fuel to find a way to move the fuel from the storage tank into the combustion chamber in conditions of microgravity. An unfeasible idea with down-to-Earth applications!
If you are a teacher, you can find educational resources (both in English and Spanish) about this fantastic material here.
The following video will help you visualize the scales from the Nanoworld to Space and back!
Please follow me along on this amazing journey through our Universe!
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