Schuerger Andrew C, Borrell Adriana V
Department of Plant Pathology, University of Florida, Space Life Sciences Lab, 505 Odyssey Way, Exploration Park, Merritt Island, FL 32953, USA.
Microorganisms. 2023 Sep 28;11(10):2421. doi: 10.3390/microorganisms11102421.
Mars spacecraft encounter numerous -loads that occur along the launch or landing vectors (called axial vectors) or along lateral off-axes vectors. The goal of this research was to determine if there was a threshold for dislodging spores under brute-force dynamic shock compressional impacts (i.e., henceforth called shock-impacts) or long-term vibrationally induced -loads that might simulate spacecraft launches or landings profiles. Results indicated that spores of 168 and ATCC 9372 were dislodged from ChemFilm-coated aluminum coupons during shock impact events of 60 's or higher. In contrast, the threshold for dislodging SAFR-032 spores was approx. 80 's. Vibrational -loading was conducted at approx. 12-15 's (z-axis) and 77 Hz. All three spp. exhibited very modest spore dislodgement at 1, 4, or 8 min of induced vibrational -loads. However, the numbers of spores released depended on the Earth's -vector relative to the bacterial monolayers. When the experimental hardware was placed in an '' orientation (defined as the spores sat on the upper surface of the coupons and the coupons pointed up and away from Earth's g-vector), zero to only a few spores were dislodged. When the experimental hardware was inverted and the coupon surfaces were in a '' orientation, the number of spores released increased by 20-30 times. Overall, the results of both assays suggest that spores on spacecraft surfaces will not likely be dislodged during nominal launch and landing scenarios, with the exception of jettisoned hardware (e.g., heat shields or backshells) during landing that might hit the Martian terrain at high 's. However, off-nominal landings hitting the Martian surface at >60 's are likely to release low numbers of spores into the atmosphere and regolith.
火星航天器会遇到沿发射或着陆向量（称为轴向向量）或沿横向离轴向量出现的大量载荷。本研究的目的是确定在强力动态冲击压缩撞击（即此后称为冲击撞击）或可能模拟航天器发射或着陆剖面的长期振动诱导载荷作用下，是否存在孢子脱落的阈值。结果表明，在60秒或更高的冲击撞击事件中，168和ATCC 9372的孢子从涂有化学膜的铝试片上脱落。相比之下，SAFR - 032孢子脱落的阈值约为80秒。振动加载在约12 - 15秒（z轴）和77赫兹下进行。所有三种菌株在诱导振动加载1、4或8分钟时，孢子脱落都非常少。然而，释放的孢子数量取决于相对于细菌单层的地球向量。当实验硬件处于“向上”方向（定义为孢子位于试片的上表面，试片向上指向且远离地球重力向量）时，零至仅有少数孢子脱落。当实验硬件倒置且试片表面处于“向下”方向时，释放的孢子数量增加了20 - 30倍。总体而言，两种试验的结果表明，在正常发射和着陆情况下，航天器表面的孢子不太可能脱落，但着陆时抛弃的硬件（如隔热罩或后壳）可能以高速度撞击火星地形的情况除外。然而，以大于60秒的速度非标称着陆撞击火星表面时，可能会有少量孢子释放到大气和风化层中。
