Near-Earth object 2024 MK was discovered on 2024 June 16, less than 2 weeks before it made a sub-lunar-distance close approach. This close approach provided an ideal opportunity to determine how planetary encounters affect asteroid surfaces in preparation for the numerous missions to (99942) Apophis during its close approach in 2029. We collected spectroscopic data before and after its close approach to determine if planetary encounters induce spectral changes due to surface refreshing. We used NASA’s Infrared Telescope Facility’s (IRTF) near-infrared spectrometer SpeX prism mode (0.7–2.5 μm) to observe 2024 MK pre and postapproach. We also observed the asteroid before its close approach using Las Cumbres Observatory’s FLOYDS visible spectrometer and after its close approach using IRTF’s SpeX long-wavelength cross-dispersed short grating mode, resulting in full spectral coverage from 0.32 to 4.2 μm. 2024 MK is an S-type asteroid that is compositionally most analogous to an L-ordinary chondrite. Spectral analysis of the 3 μm region indicates no surficial water or hydroxide within the level of noise. Band parameter analysis of the pre and postapproach data shows the planetary encounter did not induce any significant spectral changes, suggesting that surface refreshing did not occur on a measurable scale. Similar studies of other targets at smaller encounter distances are required to determine if the lack of spectral changes on 2024 MK indicates it was not close enough to Earth to affect its surface or if the spectral similarity pre and postapproach instead indicates planetary encounters do not cause surface refreshing.

中文翻译：

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近地小行星 2024 MK 的综合研究：测试行星相遇作为表面刷新的来源


近地天体 2024 MK 于 2024 年 6 月 16 日被发现，距离它在月球以下距离近距离接近不到 2 周。这种近距离接近提供了一个理想的机会，可以确定行星相遇如何影响小行星表面，以便为 2029 年阿波菲斯近距离接近 （99942） 阿波菲斯的众多任务做准备。我们收集了它接近前后的光谱数据，以确定行星相遇是否会因表面刷新而引起光谱变化。我们使用 NASA 的红外望远镜设施 （IRTF） 的近红外光谱仪 SpeX 棱镜模式 （0.7–2.5 μm） 来观察 2024 MK 接近前后的 2024 MK。我们还使用 Las Cumbres 天文台的 FLOYDS 可见光谱仪在小行星近距离接近之前以及近距离接近后使用 IRTF 的 SpeX 长波长交叉分散短光栅模式对其进行了观察，从而实现了 0.32 至 4.2 μm 的全光谱覆盖。2024 MK 是一颗 S 型小行星，在成分上与 L 型普通球粒陨石最相似。3 μm 区域的光谱分析表明，在噪声水平内没有表面水或氢氧化物。接近前后数据的波段参数分析表明，行星相遇没有引起任何显着的光谱变化，这表明表面刷新没有发生在可测量的尺度上。需要对较小相遇距离的其他目标进行类似的研究，以确定 2024 MK 上缺乏光谱变化是否表明它离地球不够近而无法影响其表面，或者接近前后的光谱相似性是否表明行星相遇不会导致表面刷新。