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The Forefront of Space Science

Micro-Sized Handyman
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Small is better

Small mobile phones, game machines, portable music players, etc., are popular and preferred today. Looking to space, small satellites and explorers are also a hot topic. This is because the launch cost falls as the launched object becomes smaller. Small spacecraft are also generally cheaper to build.

Recently, small satellites called cansat or cubesat are often in the news. Since such satellites can be built and launched inexpensively, even students at technology colleges and universities, or engineers at small- and medium-sized enterprises can develop and launch them.

In addition, by making spacecraft much smaller and lighter, we can send them to more distant places. For the same reason a baseball can be thrown further than a softball. When sending satellites or explorers to distant celestial bodies, making them smaller and lighter is very important.

But is making small always best?

So is it better to simply make everything small? What if downsizing diminishes performance? In fact, if we simply miniaturize devices just like the “Small LightEof Doraemon, a popular children's cartoon character, performance diminishes and sometimes they no longer function.

Just as there is a difference between how fish swim using fins and how microbes move with flagella, various ideas and techniques are needed for downsizing, not simple miniaturization. MEMS is a technology that, even in being made smaller, allows equipment to operate properly without functional deterioration and, further, to add new functions after size reduction.

What is MEMS?

Have you heard the acronym MEMS? Or perhaps “micro-machineEis more familiar? Even if you have never heard the words, there are many MEMS or micro-machines in your daily life.

For example, the function to detect inclination of mobile phones or shaking/inclination of digital cameras is supported by MEMS technology. It is also adopted in a variety of applications such as game-machine controllers, inkjet printers, projection displays, medical devices and automobiles.

MEMS stands for “Micro Electro Mechanical Systems,Edevices combining small machines and electronic circuits.

We are able to produce very small mechanical components by applying the manufacturing technology of semiconductor integrated circuits. Mobile phones, digital cameras, and game machines contain “acceleration sensorsEto detect inclination/acceleration and “gyrosEto sense inclination/movement. MEMS technology shrinks these components to a size where they fit on top of your little finger. Since MEMS technology is used for a variety of purposes as above, we can call it the “micro-sized handyman.E

Making satellites and explorers smaller with MEMS

Using MEMS technology, we are trying to shrink the conventional components and equipment used for satellites and explorers. The concept of MEMS is not my idea, but was proposed decades ago and R&D has been conducted across the world.

Downsizing devices called “inertial sensors,Esuch as acceleration sensors or gyros, has already been realized using MEMS technology. They have been used in launchers and experimental vehicles, and are about to be introduced to satellites and explorers. The devices, however, are inferior in performance and reliability compared to traditional “largeEsensors. The devices cannot yet be used for critical purposes, specifically, where their malfunction would cause the breakdown of the entire spacecraft. Nonetheless, small MEMS acceleration sensors and gyros are sometimes used in small rovers and explorers. In addition, R&D for other devices is actively being performed.

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