저작근 근전도에 관한 정상교합자와 ii급 부정교합자의 비교 연구

Exploring and identifying structure is even more important for multivariate data than univariate data, given the difficulties in graphically presenting multivariate data and the comparative lack of parametric models to represent it. Unfortunately, such exploration is also inherently more difficult.

Multivariate Density Estimation

During its approach to asteroid (101955) Bennu, NASA’s Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft surveyed Bennu’s immediate environment, photometric properties, and rotation state. Discovery of a dusty environment, a natural satellite, or unexpected asteroid characteristics would have had consequences for the mission’s safety and observation strategy. Here we show that spacecraft observations during this period were highly sensitive to satellites (sub-meter scale) but reveal none, although later navigational images indicate that further investigation is needed. We constrain average dust production in September 2018 from Bennu’s surface to an upper limit of 150 g s–1 averaged over 34 min. Bennu’s disk-integrated photometric phase function validates measurements from the pre-encounter astronomical campaign. We demonstrate that Bennu’s rotation rate is accelerating continuously at 3.63 ± 0.52 × 10–6 degrees day–2, likely due to the Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect, with evolutionary implications.

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The operational environment and rotational acceleration of asteroid (101955) Bennu from OSIRIS-REx observations

High-resolution gravity data obtained from the dual Gravity Recovery and Interior Laboratory (GRAIL) spacecraft show that the bulk density of the Moon's highlands crust is 2550 kilograms per cubic meter, substantially lower than generally assumed. When combined with remote sensing and sample data, this density implies an average crustal porosity of 12% to depths of at least a few kilometers. Lateral variations in crustal porosity correlate with the largest impact basins, whereas lateral variations in crustal density correlate with crustal composition. The low-bulk crustal density allows construction of a global crustal thickness model that satisfies the Apollo seismic constraints, and with an average crustal thickness between 34 and 43 kilometers, the bulk refractory element composition of the Moon is not required to be enriched with respect to that of Earth.

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The Crust of the Moon as Seen by GRAIL

Lunar sourcebook. A user's guide to the moon

Using a Discrete Element Method to Investigate Seismic Response and Spin Change of 99942 Apophis During the 2029 Tidal Encounter

Distribution of Cracked Boulders on (101955) Bennu: Searching for Evidence of Solar-Induced Thermal Stress

Images of Ryugu and Bennu by the Hayabusa2 (JAXA) and OSIRIS-REx (NASA) missions show that both asteroids have top shapes, which are usually considered to be formed by YORP spin-up. We perform numerical simulations of asteroid disruption and subsequent fragment reaccumulation to investigate the conditions under which the catastrophic disruption of asteroid parent bodies can lead to such shapes. Considering a range of impact energies, we find that oblate spheroids are commonly formed during the reaccumulation phase following the disruption. In some cases, a ridge can also form directly at the equator of reaccumulated bodies. Such a scenario can explain the old age of the ridges of Ryugu and Bennu based on the presence of large craters covering them.

Olivier S. Barnouin

Papers

Using a Discrete Element Method to Investigate Seismic Response and Spin Change of 99942 Apophis During the 2029 Tidal Encounter

Distribution of Cracked Boulders on (101955) Bennu: Searching for Evidence of Solar-Induced Thermal Stress

Disruption and reaccumulation: Forming the top shaped asteroids Ryugu and Bennu

Exploring the Morphology of Simple Craters that Host Polar Deposits on Mercury: Implications for the Source and Stability of Water Ice

The Role of Target Properties and Projectile Velocity on Final Crater Morphology of Craters on Mercury