Our goal is to understand the surface history and characterization of the asteroid 25143 itokawa by study of returned samples from the hayabusa mission. We investigate and utilize radionuclides (10BE,…

This is a grant award from the National Aeronautics and Space Administration (NASA) to the University of California, Berkeley (UC Berkeley) for research related to the Hayabusa asteroid sample return mission. The goal is to study the surface history and characterization of the asteroid 25143 Itokawa by analyzing the returned samples. The research involves measuring cosmogenic radionuclides (such as 10Be, 26Al, 36Cl, and 53Mn) in microgram-sized samples using advanced techniques like accelerator mass spectrometry. The $578,999.97 grant will fund this work over a period ending on December 10, 2021. The research is relevant to NASA's Laboratory Analysis of Returned Samples (LARS) program and aligns with goals in the agency's strategic and science plans. The award is not a set-aside contract.

Our goal is to understand the surface history and characterization of the asteroid 25143 itokawa by study of returned samples from the hayabusa mission. We investigate and utilize radionuclides (10BE, 26AL, 36CL, and 53MN) produced by cosmic rays (both solar and galactic cosmic rays). Expected maximum cosmogenic nuclide concentrations in a microgram (100 m in diameter) of hayabusa sample are a few times 10 4 10 5 atoms or lower. These values are close to or lower than the present best detection limits of highly sensitive accelerator mass spectrometry (AMS). Although we have performed the most sensitive measurements of 10BE and 26AL in the smallest extraterrestrial (hayabusa) sample ever done, we encountered issues that require further development of both chemical laboratory techniques and improvements in AMS measurements. Our work for the next three years includes: (1) measurements of cosmogenic nuclide in samples even smaller than those recently measured facilitated by the successful development of clean chemical separation procedures, including making new ultra pure chemical carriers; (2) measurements of cosmogenic radionuclides and major elements in a set of microgram sized hayabusa samples using AMS and ICP MS; and (3) measurements of cosmogenic radionuclides in a microgram level of lunar grains to enable interpretation of the measured cosmogenic nuclides in the hayabusa samples, most notably the already noted wide scatter of cosmogenic noble gas concentrations in individual hayabusa grains, which correspond to surface exposure ages of 1 20 MYR. The development techniques and methods will be applied not only for hayabusa samples but also for future sample return missions such as hayabusa 2, osiris-REX, or mars sample return and for measurements of cosmogenic nuclides in IDP s. The described research is directly relevant to NASA laboratory analysis of returned samples (lars) program in roses 2015. These include maximize the scientific return from the samples provided by missions such as hayabusa, through development of advanced analytical techniques required for the complete analyses of the samples they return, and analytical work on samples returned by hayabusa. The proposed research to undertake detailed and quantitative studies of the cosmic RAY exposure record and evolution history of solar system materials is highly relevant to several goals of the most recent NASA strategic plan 2014 and the science plan 2014 for NASA's science mission directorate (SMD).