2016 Fiscal Year Research-status Report
高精度長時間シミュレーションによる初期地球への小天体衝突率の推定
| Project/Area Number |
16K17662
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
ブラサー ラモン 東京工業大学, 地球生命研究所, 特任准教授 (30747142)
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| Project Period (FY) |
2016-04-01 – 2018-03-31
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| Keywords | bombardment / Asteroid belt / Kuiper belt / geochronology / Late accretion |
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| Outline of Annual Research Achievements |
-Published a paper in Earth and Planetary Science Letters on the nature of late accretion on Earth, Moon and Mars. Late accretion is bombardment after the planets are almost fully formed. On Earth it consisted of a single, lunar-sized impactor rather than a rain of small bodies. This is contrary to conventional wisdom but it agrees with the geochronology.
-A paper in review in Geophysical Research Letters regarding late accretion on Mars. We conclude that Mars was struck by a Ceres sized body early in its history because of its mantle highly siderophile element abundances.
-Currently investigating the role of comets and asteroids in the late heavy bombardment. Our team are the first to combine the effects of three populations simultaneously.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
It turns out that the project has more requirements than anticipated. For example, it was necessary to constrain the role of remnant planetesimals from terrestrial planet accretion in the bombardment of the terrestrial planets during the first billion years. However, we have dealt with these at a reasonable pace, having published two first-author papers within the first year, all of them dealing with the nature of late accretion from remnant planetesimals. Thus we consider phase one to be completed.
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| Strategy for Future Research Activity |
The project is delayed because of a shortage of computing power. Investigation into the role of comets and asteroids on the late heavy bombardment requires many high-accuracy long-duration simulations of the first billion years of the solar system. These simulations take months and require many runs because of chaotic dynamics. Due to an increase of cluster-CPU users, the number of CPUs that can be used for this project has decreased . A lack of other free-for-use supercomputer facilities within Japan with enough capacity has caused a delay in the simulations. The PI is looking for computing power outside of Japan.
We expect to submit a long, detailed paper about the nature of the late heavy bombardment in the summer or early autumn of 2017.
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