Samples returned by Hayabusa2: Expecting the unexpected
What kind of results came out of the initial analysis of the original Hayabusa samples?
Noguchi It was my job to conduct observation and analysis of samples using an electron microscope to determine what was inside the particles and how their surface gradually changes. We call this “space weathering,” the process by which rocks and minerals are altered after being exposed to space for long periods of time, which we were able to see at the material level. Also, in March this year, in collaboration with JSPS Postdoctoral Fellow Dr. Toru Matsumoto, we discovered a single iron crystal with a whisker-like growth on the surface of dust particles brought back by Itokawa, something still unknown in extraterrestrial materials. I believe that it will be an important insight into the history of the surface of asteroids like Ryugu. Professor Naraoka, what did you think?
Photo taken just after the first Itokawa particles were discovered at the Sample Curation Facility of JAXA. Front, from left: Dr. Tomoki Nakamura, Tohoku University; Professor Takaaki Noguchi, Kyushu University. Back, from left: Associate Professor Takashi Okazaki, Kyushu University; Masanao Abe, JAXA; and Akio Fujimura, then Director of the JAXA Extraterrestrial Sample Curation Center.
Naraoka Well, my specialty is organics, and Itokawa was an S-type asteroid with no organic matter. Nevertheless, there was meaning in the very process of checking for the presence of organic matter. Despite the analysis we conducted, so far, no organic matter has been found.
Hayabusa2’s target body, Ryugu, is a C-type asteroid that contains organic matter, which must be very exciting.
Naraoka That’s right. When a meteor enters the atmosphere, the material on the surface gets peeled away, but the samples brought back by Hayabusa2 will still have that surface material intact, so I am hoping that we will be able to find something that we have never seen before.
There are reports that you were able to collect samples, not only from Ryugu’s surface, but also from the bottom of an artificial crater.
Naraoka Asteroids are exposed to cosmic rays, which are high-energy particles, so I think the organic matter on an asteroid’s surface is in a rather precarious position. If we are able to collect material from areas not affected by cosmic rays, we may find something unexpected—the original organic material of the asteroid
The samples brought back by Hayabusa2 will be analyzed at this cleanroom, which was recently installed in the Faculty of Science at Kyushu University. Professor Naraoka at center.
Professor Noguchi, what are your expectations for the samples?
Noguchi There are hydrous minerals on Ryugu, but it will depend on whether they are merely minerals that contain water, water-containing minerals that have been dehydrated, or minerals that have not yet reacted with water.
Naraoka It would be great to find material that has never reacted with water.
Noguchi It would. The samples should contain primordial organic matter, and I think that we will see some rather unexpected results. Some people say that we shouldn’t expect much because an asteroid’s surface is warmed by solar radiation, but the results of rock samples from Ryugu observed by the French-German MASCOT lander ended up defying expectations. So I still think that we should expect the unexpected.
Valuing curiosity and finding your calling
It is said that people are shaped by their environment. In what ways is Kyushu University equipped to excel in space exploration?
Noguchi Well, Kyushu University has a number of electron microscopes on par with those used by leading international researchers. For more than ten years now, the university has been lending these high-performance electron microscopes to researchers across the country, and in a sense, this is quite a state-of-the-art environment. We also have new processing equipment scheduled to be installed at the Faculty of Engineering Sciences this year. If we can take full advantage of this equipment, it will allow us to receive Hayabusa2 samples and look at them under an electron microscope without them ever being exposed to the atmosphere. I think that the unique environment here at Kyushu University will allow us to achieve better results.
Trajectories of Hayabusa and Hayabusa2
Launch of the original Hayabusa spacecraft
Curation team begins preparing for analysis
Original Hayabusa mission returns to Earth and dust particles are collected
Collected dust particles are announced to indeed be from Itokawa
Particles for initial analysis are provided to researchers in Japan and initial analysis begins
Presentation of the initial analysis results at the 42nd Lunar and Planetary Science Conference
Launch from Tanegashima Space Center
Arrival near asteroid Ryugu
Separation, landing, and operation of the small asteroid lander MASCOT
Departure from Ryugu and start of journey home
Re-entry capsule returns to Earth
Initial analysis scheduled to begin
Naraoka Although he could not join us today, Associate Professor Takashi Okazaki of the Kyushu University Faculty of Science is also leading one of the teams handling the initial analysis of Hayabusa2 samples. Four faculty members from Kyushu University, including Associate Professor Okazaki, are involved in the analysis of Hayabusa2 samples, and several graduate students are also participating in the research. A number of JAXA researchers and technicians are also Kyushu University graduates. I believe that these professionals and what they have accomplished are one of Kyushu University’s advantages.
Lastly, do you have a message to all of the students here at Kyushu University?
Naraoka In addition to Hayabusa2, there are many other space programs currently underway, so we have a lot to look forward to. But that kind of progress relies on the hard work of researchers focused on what is in front of them. If you don’t enjoy your work, you won’t make progress in your research. I hope that students will stay curious to keep their research going.
Noguchi Whatever your specialty, I think it is essential, as a scientific researcher, to be able to focus on one thing. While you are still a student, I hope you will find your calling—the one thing you want to become an expert in—and make it your life’s work. I encourage you to find it while you’re a student at Kyushu University before you head out into the world.
This interview was conducted on October 7, 2020, in the Exhibition and Observation Room of the Ishigahara Tumulus, located on the 9th floor of East Zone 1 on Kyushu University’s Ito Campus. Associate Professor Takashi Okazaki of the Kyushu University Faculty of Science is also leading one of the teams in charge of the initial analysis of the Hayabusa2 samples but could not join us as he was busy preparing for the recovery of the Hayabusa2 capsule.
This article first appeared in the Dec. 2020 issue of Kyushu University Campus Magazine
), the university's quarterly Japanese-language magazine. View the full issue online
for more information in Japanese about the recent happenings at Kyushu University.