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Reading the Dust from Asteroid Itokawa First Analysis of the HAYABUSA Sample

Being the first to know

Q. How is the HAYABUSA sample different from those provided by the Apollo program, Russia's lunar exploration program, and NASA's Stardust mission?

Electron microscope photo of dust from Itokawa
Electron microscope photo of dust from Itokawa

The Moon samples brought to Earth by the United States' and Soviet Union's lunar exploration programs rewrote what we know about the evolution of the Moon and Earth. But the Moon is a different type of celestial body in that it is already evolved, with an inner structure partitioned into a core, mantle and crust. Asteroids, on the other hand, contain material from before inner structure partitioning, preserved in a state dating back to 4.6 billion years ago, when the solar system was formed. This is why the HAYABUSA sample is completely different from the samples we collected from the Moon's crust - it holds a vast store of information from the time of the solar system's birth.

Meanwhile, the Stardust program, which captured comet dust, played a vital role in advancing materials science as it relates to comets. However, the Stardust sample was exposed to the atmosphere when it was returned to Earth, allowing oxygen and water to contaminate it. Also, NASA used a substance called aerogel to capture comet dust particles as they collided with the probe at high speed, so the sample was inconsistent because some of the particles melted or otherwise reacted to the aerogel. In comparison, the HAYABUSA sample was retrieved in a protected return capsule, so it was not exposed to high temperatures or shocks while reentering the atmosphere, and was not contaminated by the Earth's oxygen or water. This allows us to understand when, where and how the sample particles were picked up from Itokawa.

The initial analysis showed us that the HAYABUSA sample has different characteristics from meteorites, and I think this can serve as a clue to help us partially recreate the conditions prior to the creation of planets. We have in our hands material from 4.6 billion years ago, so we should be able to perform unprecedented research. I believe that the challenge set before humanity now is to decide how to use this sample, packed with so much precious information, and find out how much we can learn from it.

Q. What do you think is the appeal of space exploration?

Working with the curation facility
Working with the curation facility

The interesting thing about scientific research is learning new things that nobody has ever known before. It's disappointing when you think you've discovered something and write a research paper, only to have someone say to you, "So-and-so already knows that." But when you make the discovery, you think you're the only one who knows. You get excited because you think, "I'm the first person ever to find this amazing thing about the world!" That's the fun of science.

It's the same with space exploration. It's about sending probes to places no one has ever been and being the first to learn things that nobody else has ever known. It's incredibly exciting. Plus you get to share that with the other people involved in the mission. That's the greatest draw. Then new knowledge is created from this previously unknown thing. And if you create new knowledge, then that becomes the start of even deeper scientific inquiry. Take, for example, the Moon samples. Bringing them to Earth created new fields such as lunar petrology and structural geology. This knowledge was then extended to Mars and Venus, which led to the new field of comparative planetology. I believe that the same sort of thing will gradually happen with the Itokawa sample. That's another attractive part of space exploration.

Looking for the origins of life itself

Q. What kinds of things do you anticipate from future asteroid exploration?

Asteroid probe Hayabusa 2 (courtesy: Akihiro Ikeshita)
Asteroid probe Hayabusa 2 (courtesy: Akihiro Ikeshita)

Putting the experience and knowledge we built up with HAYABUSA to good use, the HAYABUSA 2 mission will collect a carbonaceous sample, which has a high probability of containing organic matter, the fundamental building blocks of life. So, first, I expect HAYABUSA 2 to be a success. Then after that, I'd like us to proceed with an inquiry concerning where we came from and how life came about. It would be great to uncover the origins of the solar system, Earth, the other planets, and life itself by getting information that we can't obtain here on Earth. I'd like us to open up new lines of scientific inquiry that seek to discover these origins.

Q. Will the curation facility be used for HAYABUSA 2 and other missions in the future?

I think it has to be. But the intervals between sample-return missions are long - we don't have one every year - so we'll need to upgrade our analytical devices and various other tools. In addition, this facility was made to handle material from a rocky S-class asteroid like Itokawa, so it's not completely compatible with the material from the carbonaceous C-class asteroid that HAYABUSA 2 will visit. We expect this C-class asteroid to have lots of organic matter among the materials on its surface. And that poses a problem. Humans are, of course, made up of organic matter, and we carry large amounts of all kinds of bacteria. So even if we go through all the trouble of getting carbonaceous material that might contain organic matter, we could easily end up contaminating it with our own bodies. That's why we may have to think of a new way to keep out contaminating organic matter, perhaps, in an extreme case, by working from behind a shield of some sort. I'd like to use the lessons we've learned thus far to enhance our curation facility for HAYABUSA 2, and for other sample return missions to the Moon and Mars.

Akio Fujimura, Ph.D.
Advisor, Research and Development Office, Lunar and Planetary Exploration Program Group, JAXA
Advisor, Basic Technology Group, Space Science Research, JAXA

Dr. Fujimura earned a doctor of science in 1984 at the Nagoya University Graduate School of Science, and became a research associate at the Department of Earth and Planetary Sciences of the Nagoya University School of Science. Starting in 1988, he was involved in lunar exploration as a planetary research associate, associate professor and then professor at the Institute of Space and Astronautical Science (ISAS), which was under the jurisdiction of the education ministry before merging into the newly created JAXA in 2003. Since 2005, Dr. Fujimura has been in charge of JAXA's curation facility - facility used to receive and manage extraterrestrial material. He is a professor emeritus at the Graduate University for Advanced Studies (Sokendai). His research specialty is planetary science.

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