Regolith behavior under asteroid-level gravity conditions: low-velocity impact experiments
Regolith behavior under asteroid-level gravity conditions: low-velocity impact experiments
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DOI：
10.1186/s40645-018-0222-5
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发表时间：
2018-11-13
影响因子：
3.9
通讯作者：
Mohammed, Nadia
中科院分区：
文献类型：
--
作者：
Brisset, Julie;Colwell, Joshua;Mohammed, Nadia
覆盖在小行星和行星卫星表面的尘土在大小、形状和组成上与地球上的土壤颗粒不同，并受到与地球上发现的非常不同的环境条件的影响。这种风化层是在低环境压力和低重力环境中演化的。它对低速撞击的反应，例如可能伴随人类和机器人探索活动的撞击，可能与地球上遇到的完全不同。因此，有必要对行星浮冰在相关环境条件下的响应进行实验研究，以便于将来的太阳系探测活动。我们利用两个实验装置和一系列微重力平台，将这些结果结合在一起，为一系列撞击实验提供了新的数据分析元素，从而模拟了低重力条件下的行星浮沉。微重力实验中的浮尘撞击物理(PRIME)在几次抛物线飞行中飞行，能够以大约4-230厘米/S的速度记录撞击颗粒物质的速度。碰撞成尘埃实验(COLLID)在概念上与PRIME设置接近。它曾于1998年和2001年在航天飞机上飞行，最近又在蓝色起源新谢泼德火箭上飞行，记录了以1至120厘米/秒的速度撞击模拟风化层的过程。这些实验活动的结果发现，随着重力环境的变化，风化层的行为发生了显著变化。在10(-2)g的环境中(g是地球表面的重力加速度)，只观察到冲击器的嵌入，在>；20 cm/S的大多数撞击下产生抛射物。有一次是在微重力水平(10 cm/S)。测得的抛射物速度略低于在失重水平下测得的速度，但抛射物质量较高。一般情况下，喷出物的平均速度与撞击能量呈幂函数关系，指数约为0.5。当弹丸发生回弹时，我们观察到其在模拟风化层上的恢复系数随着撞击速度从大约5增加到100 cm/S而减小10倍，我们还观察到与石英砂靶材相比，JSC-1颗粒之间的粘聚力增加。
The dusty regolith covering the surfaces of asteroids and planetary satellites differs in size, shape, and composition from terrestrial soil particles and is subject to environmental conditions very different from those found on Earth. This regolith evolves in a low ambient pressure and low-gravity environment. Its response to low-velocity impacts, such as those that may accompany human and robotic exploration activities, may be completely different than what is encountered on Earth. Experimental studies of the response of planetary regolith in the relevant environmental conditions are thus necessary to facilitate future Solar System exploration activities.We combined the results and provided new data analysis elements for a series of impact experiments into simulated planetary regolith in low-gravity conditions using two experimental setups and a range of microgravity platforms. The Physics of Regolith Impacts in Microgravity Experiment (PRIME) flew on several parabolic aircraft flights, enabling the recording of impacts into granular materials at speeds of approximate to 4-230 cm/s. The COLLisions Into Dust Experiment (COLLIDE) is conceptually close to the PRIME setup. It flew on the Space Shuttle in 1998 and 2001 and more recently on the Blue Origin New Shepard rocket, recording impacts into simulated regolith at speeds between 1 and 120 cm/s.Results of these experimental campaigns found that there is a significant change in the regolith behavior with the gravity environment. In a 10 (-2)g environment (with g being the gravity acceleration at the surface of the Earth), only embedding of the impactor was observed and ejecta production was produced for most impacts at >20 cm/s. Once at microgravity levels (10 cm/s. The measured ejecta speeds were somewhat lower than the ones measured at reduced-gravity levels, but the ejected masses were higher. In general, the mean ejecta velocity shows a power-law dependence on the impact energy with an index of approximate to 0.5. When projectile rebound occurred, we observed that its coefficients of restitution on the bed of regolith simulant decrease by a factor of 10 with increasing impact speeds from approximate to 5 up to 100 cm/s. We could also observe an increased cohesion between the JSC-1 grains compared to the quartz sand targets.