The Extraterrestrial Sample Curation Center (ESCuC) manages the particles that the spacecraft "HAYABUSA" brought back from the asteroid Itokawa.

Preparation for Acceptance of the "HAYABUSA" Return Sample

The Extraterrestrial Samples Curation Center was established in 2007 for the purpose of acceptance of the "HAYABUSA" return sample. In the last one year before the return, the Astromaterials Science Research Group (ASRG) have had a thorough rehearsal for the acceptance. In June 2010, the re-entry capsule from "HAYABUSA" had been delivered to Earth, and carried to ESCuC. In the clean room of ESCuC, the sample container was removed from the re-entry capsule. The sample container is a vacuum sealed container that contains a sample catcher. After thoroughly cleaning the surface of the sample container, it was set in an opening device and introduced into the first room of the clean chamber. After that, the container was opened under the vacuum atmosphere of the first room of the clean chamber, and the sample catcher was retrieved safely. We, ASRG, monitored gas released at the time of opening and performed isotope analysis of noble gas, but unfortunately, we could not detect any components derived from Itokawa.

Sample Recovery

When a cover of the sample catcher was opened in a nitrogen atmosphere and the inside of the catcher was observed with an optical microscope, particles of a size that could be seen with the naked eye were not found. After that, the sample catcher was moved to the second room, and as a result of scratching inside the catcher with a Teflon spatula, fine particles adhered. Electron microscopy (SEM) and energy dispersive X-ray analysis (EDS) showed that about half of the particles were aluminum fragments that had peeled off from the inside of the catcher. The rest were confirmed to be mineral particles such as olivine, pyroxene, plagioclase, etc., and were found to be derived from Itokawa.

Teflon spatula observation by SEM.

Initial Analysis and Collaboration

A portion of the samples collected from the catchers are provided to universities and research institutes that are collaborating with ASRG. A variety of analyses, called initial analyses, have been conducted to gain insight into the existence of Itokawa's parent body, the history of Itokawa formation, and the evolution of surface materials. JAXA has also exchanged a memorandum of understanding (MOU) with NASA and has provided part of the sample to NASA's curation group.

Current Status

The sample catcher has Room B in addition to Room A which was opened just after returning. In addition, there was also a mechanism called as a rotating cylinder, and particles believed to be from Itokawa were also attached to those parts. ASRG are still retrieving these materials.

Initial Description

Particles collected from the sample catcher are preliminary identified by SEM and EDS analysis. This process is called as the Initial Description. After the Initial Description, the particles are returned to the clean chamber, and the samples identified as Itokawa origin are sorted and stored on a slide glass (quartz glass). An ID is assigned to stored samples, and the ID, initial information, and storage location are registered in the database and managed.

Sample Catalogs and Sample Distribution

Particles' information registered in the database are arranged annually in a catalog and published. In addition, the latest sample list is available on the Internet at all times, and users can request to use sample within the framework of the International Announcement of Opportunity (AO).

Curation Techniques and Tools

  • It is a device that is prepared to receive the "HAYABUSA" return sample. It is mainly consisting of a vacuum chamber and a nitrogen-atmosphere glove box.

  • The maximum sample size collected from the sample catcher is about 300 micrometers. Most of them are fine particles of about 50 micrometers. In order to handle these samples, an electrostatic control manipulator was developed at ESCuC. The tip of the manipulator is a quartz needle with a platinum core wire. By applying voltage to the core wire, static electricity is generated on the surface of the quartz needle, and the sample can be attached and carried.

  • At first, ASRG recovered samples from the sample catcher with a specially developed Teflon spatula. After that, in order to recover as much as possible, the sample in the catcher room, the catcher was dropped upside down on a quartz plate. An aluminum or stainless-steel plate whose surface has been polished also were used. This method is called free fall or tapping out.

  • The slide glass for storing samples is made of quartz. The squares and address numbers are engraved on the glass surface, and a hollow is made in the center of each square to place the sample. The slide glass is thoroughly cleaned by ultrasonic cleaning with organic solvents and ultrapure water, and boiling cleaning with strong alkali and strong acid. After confirming by visual observation that no material larger than 15 micrometers is attached, it is used for sample storage.

  • When the sample is removed from the clean chamber, we need a special container to avoid samples to touch the atmosphere. To meet this purpose, we, ASRG exclusively developed sample containers.

  • A container used when carrying from a clean chamber to an electron microscope for initial description. The sample exchange chamber on the electron microscope side is also improved and has a mechanism to open the container by introducing pure nitrogen.

  • For international research applications, we use sealed sample containers when transporting samples both in Japan and overseas and strive to provide high-quality samples to researchers.

  • ID such as RA-QD02-0056 or RC-MD01-0001 is given to each sample. RA indicates that the sample catcher was collected from Room A, RB indicates Room B, and RC indicates that the sample was collected from the rotating cylinder. QD02 and MD01 represent the 2nd quartz plate and the 1st stainless plate to be collected (tapping) from the sample catcher, respectively. RA-QD02-0056 is the 56th particle of the quartz plate from which the particles in Room A were collected. RC-MD01-0001 means the first particle of the stainless-steel plate recovered from the rotating cylinder.

  • Based on the results of the Initial Description, samples are classified into four categories. Category 1 consists mainly of silicate minerals such as olivine, pyroxene and plagioclase. Category 2 includes opaque minerals such as iron sulfide, iron-nickel metals, and chromite in addition to silicate minerals. Initial analysis and international public research have revealed that they are derived from Itokawa. Category 3 consists primarily of carbon and its origin is currently unknown. Category 4 is obvious artifacts such as aluminum and stainless-steel debris. There are samples of unknown origin that cannot be classified in these categories.

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