Orbital and thermal evolutions of four potential targets for a sample return space mission to a primitive near-Earth asteroid
Orbital and thermal evolutions of four potential targets for a sample return space mission to a primitive near-Earth asteroid
复制标题
原始近地小行星样本返回太空任务的四个潜在目标的轨道和热演化
DOI：
10.1016/j.icarus.2010.05.013
复制
发表时间：
2010
期刊：
影响因子：
3.2
通讯作者：
M. Delbo’
中科院分区：
文献类型：
--
作者：
P. Michel;M. Delbo’
本文研究了四颗近地小行星(NEA)由于太阳辐射加热而产生的轨道和热演化，这些小行星被认为是原始小行星样本返回空间飞行任务的潜在目标。我们使用了NEA群体的动力学模型来估计这些天体最有可能的源区和轨道历史。然后，对于每一颗小行星，我们在其整个生命周期内对14个最初无法区分的轨道(克隆)进行了数值积分，这些轨道(克隆)是通过名义初始条件的微小变化获得的。使用一个热模型，然后我们计算了这些物体在其动力学历史过程中的表面和亚表面温度。我们的目标是确定这些天体是否可能经历了高温，以及由于轨道变化以及它们的最大和最小值是否可以预期巨大的温度变化。这些信息在以带回原始材料为目标的样品返回空间飞行任务的框架内很重要。对潜在目标轨道演变过程中不同深度的材料温度范围的了解，可以帮助确定抽样战略，以确保将未改变的材料带回地球的可能性。我们的结果表明，对于所有考虑的潜在目标，表面经历了一段时间的温度高于400K，最高500K的可能性为50%。这一概率随着温度的升高而迅速下降。只有3厘米深的地下材料更容易受到高温的保护，通常不会达到超过450K的温度(概率为50%)。因此，至少从太阳驱动的加热角度来看，它们在这个深度应该是不变的。另一方面，一些被考虑物体的表面材料可能具有一定的温度范围，这可能会使它们作为原始材料变得不那么可靠。然而，这里假设相同的材料不断地暴露在太阳热下，同时可能发生风化层周转。后者可能由不同的过程引起，例如地震震动和/或撞击陨石坑。这将减少材料暴露在一定温度下的总时间。因此，从四个被考虑的目标中的任何一个收集的样本，或者任何具有类似动力学性质的原始NEA，都很可能具有热不变的成分，只要其中一些来自只有3到5厘米深的地方。目前的一些采样设备设计并不认为很难达到这样的深度。
In this paper, we present our study of the orbital and thermal evolutions, due to solar radiative heating, of four near-Earth asteroids (NEAs) considered as potential target candidates for sample return space missions to primitive asteroids. We used a dynamical model of the NEA population to estimate the most likely source region and orbital history of these objects. Then, for each asteroid, we integrated numerically over their entire lifetime a set of 14 initially indistinguishable orbit (clones), obtained by small variations of the nominal initial conditions. Using a thermal model, we then computed surface and sub-surface temperatures of these bodies during their dynamical history. Our aim is to determine whether these bodies are likely to have experienced high temperature level, and whether great temperature changes can be expected due to the orbital changes as well as their maximum and minimum values. Such information is important in the framework of sample return space missions whose goal is to bring back pristine materials. The knowledge of the temperature range of materials at different depth over the orbital evolution of potential targets can help defining sampling strategies that ensure the likelihood that unaltered material will be brought back. Our results suggest that for all the considered potential targets, the surface has experienced for some time temperatures greater than 400K and at most 500K with 50% probability. This probability drops rapidly with increasing temperature. Sub-surface materials at a depth of only 3cm are much more protected from high temperature and generally do not reach temperatures exceeding 450K (with 50% probability). They should thus be unaltered at this depth at least from a Sun-driven heating point of view. On the other hand, surface material for some of the considered objects can have a range of temperature which can make them less reliable as pristine materials. However, it is assumed here that the same material is constantly exposed to solar heat, while regolith turnover may occur. The latter can be caused by different processes such as seismic shaking and/or impact cratering. This would reduce the total time that materials are exposed to a certain temperature. Thus, it is very likely that a sample collected from any of the four considered targets, or any primitive NEA with similar dynamical properties, will have components that will be thermally unaltered as long as some of it comes from only 3 to 5cm depth. Such a depth is not considered difficult to reach with some of the current designs of sampling devices.