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Asteroids are closely related to meteorites. The kinds of meteorites that fall to the earth are said to be very similar to certain types of asteroids. However, how can we say they are "similar"if nobody has ever been to an asteroid? The similarity is assumed by the"spectrum."
You may remember an experiment using a prism to decompose light into seven colors during a science class at school. Natural light is composed of many colors. On the other hand, substances are also made up of various colors. They look like certain colors like those that make up human eyes because each substance absorbs specific wave lengths of light (color). Therefore, we can check what kind of substances exist in an asteroid even though we have never visited it by studying which substance absorbs what type of light wave lengths. Despite this, we can learn only about a spectrum surface. In the case of a small asteroid, the spectrum tells us only that the whole surface of the asteroid is one substance. Thus it is difficult to obtain more details from only the spectrum. In that sense, bringing back samples is very important for us to examine them more closely in a laboratory. The Hayabusa is about to take samples for that purpose. On the earth, there have already been some meteorites that are believed to have originated from Mars and other asteroids. However, to date, the only substance from space whose origin is clearly known is "a rock from the Moon." Hence this mission by Japanese engineers and scientists is the first attempt in the world to bring back substances from an asteroid. » Story 5: The role of the whiteboard in the Hayabusa operation room and concern about the weather |
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Story 3