TEMPERATURE HISTORY AND DYNAMICAL EVOLUTION OF (101955) 1999 RQ 36: A POTENTIAL TARGET FOR SAMPLE RETURN FROM A PRIMITIVE ASTEROID
TEMPERATURE HISTORY AND DYNAMICAL EVOLUTION OF (101955) 1999 RQ 36: A POTENTIAL TARGET FOR SAMPLE RETURN FROM A PRIMITIVE ASTEROID
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(101955) 1999 RQ 36 的温度历史和动力学演化：从原始小行星返回样本的潜在目标
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
P. Michel
中科院分区：
文献类型：
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作者：
M. Delbo’;P. Michel
最近的研究表明，由于太阳的辐射加热，近地天体（NEO）的温度历史与其当前轨道密切相关。这是因为近地天体的近日点距离会因动力学机制（例如共振和与行星的近距离接触）而变化。因此，值得研究近地天体的温度历史，这些近地天体是致力于返回生命前有机化合物样本的太空任务的潜在目标。其中一些化合物预计会在具有原始成分的近地天体上发现，会在中等温度（例如 300-670 K）下分解。利用近地天体轨道演化模型和热模型，我们研究了 (101955) 1999 RQ36（OSIRIS-REx 任务的主要目标，在 NASA 新前沿计划中提出的）的温度历史。假设相同的材料总是位于表面（即没有风化层周转），我们的结果表明，其过去演化过程中达到的温度影响了表面某些有机化合物的稳定性（例如，1999 RQ36 的表面有 50% 的可能性在温度⩾500 K 下被加热）。然而，温度随着深度的增加而迅速下降：3-5 cm 深度的风化层，在当前采样装置的设计中并不被认为难以到达，但其温度却比地表温度低约 100 K。这足以保护一些地下有机物免受热分解。
It has been recently shown that near-Earth objects (NEOs) have a temperature history—due to the radiative heating by the Sun—non-trivially correlated to their present orbits. This is because the perihelion distance of NEOs varies as a consequence of dynamical mechanisms, such as resonances and close encounters with planets. Thus, it is worth investigating the temperature history of NEOs that are potential targets of space missions devoted to return samples of prebiotic organic compounds. Some of these compounds, expected to be found on NEOs of primitive composition, break up at moderate temperatures, e.g., 300–670 K. Using a model of the orbital evolution of NEOs and thermal models, we studied the temperature history of (101955) 1999 RQ36 (the primary target of the mission OSIRIS-REx, proposed in the program New Frontiers of NASA). Assuming that the same material always lies on the surface (i.e., there is no regolith turnover), our results suggest that the temperatures reached during its past evolution affected the stability of some organic compounds at the surface (e.g., there is 50% probability that the surface of 1999 RQ36 was heated at temperatures ⩾500 K). However, the temperature drops rapidly with depth: the regolith at a depth of 3–5 cm, which is not considered difficult to reach with the current designs of sampling devices, has experienced temperatures about 100 K below those at the surface. This is sufficient to protect some subsurface organics from thermal breakup.