Near-Earth asteroids are not uniform: Using thermal models of multiple observations to reveal inhomogeneities

小行星可以通过它们反射的光和它们发出的红外热辐射（热）来研究。研究人员已经开发出一种复杂的技术来研究接近地球的小行星（称为近地小行星，或NEAs）。他们将使用他们的热物理模型（TPM），结合近地天体的可见光和雷达观测来研究小行星的表面特性。虽然一些小行星表面光滑，但其他小行星表面覆盖着厚厚的尘埃，还有一些小行星的表面各有不同的区域。这些不同的区域发射和反射的辐射不同，因此在解释观测结果时，了解NEA表面的性质是很重要的。研究人员将使用他们的热物理模型来解释来自近地天体的反射和发射光，并将确定未来任务的可能目标。应该指出的是，如果在与地球相撞的轨道上发现近地天体，那么了解近地天体的性质对保卫国家至关重要。调查人员将让一名博士后和一名研究生参与外展活动，其中包括为K-12教师举办的四个讲习班。小行星的热模拟揭示了它们的表面特性。简单的热模型往往不能自我一致地适应同一颗小行星的多次观测。要充分了解一颗小行星，非球形性和表面非均质性都是必需的。研究人员将使用多历元观测，利用光学光曲线和雷达数据的详细形状，利用多个观测几何图形更真实地模拟热发射，并更好地约束近地天体的表面特性。他们将研究小行星表面的异质性等特性；每个表面的粗糙度程度，热惯性的重要性以及它如何随尺寸，光谱类型或旋转速率变化；以及使用雷达导出形状的热参数与使用光学光曲线导出形状的热参数的比较。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Asteroids can be studied both by the light they reflect and by the infrared thermal radiation (heat) they emit. The investigators have developed a sophisticated technique for studying asteroids that make close approaches to the Earth (known as Near-Earth Asteroids, or NEAs). They will use their thermophysical model (TPM), together with visible and radar observations of NEAs to investigate the surface properties of the asteroids. While some asteroids are known to have smooth surfaces, others are covered with a thick layer of dust, and still others have regions of each type of surface. These different regions emit and reflect radiation differently, and thus it is important to know the nature of an NEA's surface when interpreting observations. The investigators will use their thermophysical model to interpret reflected and emitted light from NEAs and will identify possible targets for future missions. It should be noted that an understanding of the nature of NEAs would be vital to the defense of the nation should one be discovered on a collision course with Earth. The investigators will involve a postdoctoral student and a graduate student in outreach activities, which will include four workshops for K-12 teachers. Thermal modeling of asteroids reveals much about their surface properties. Simple thermal models often do not fit multiple observations of the same asteroid self-consistently. Both non-sphericity and surface heterogeneity are required to fully understand an asteroid. The investigators will use multi-epoch observations, with detailed shapes from optical lightcurves and radar data to leverage multiple observation geometries to model the thermal emission more realistically and better constrain the surface properties of NEAs. They will investigate such properties as the heterogeneity of the asteroid surfaces; the degree of roughness on each surface, the importance of thermal inertia and how it varies with size, spectral type, or rotation rate; and how derived thermal parameters using radar-derived shapes compare to those using optical lightcurve-derived shapes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.