Mini-EUSO is a telescope observing the Earth in the ultraviolet band from the International Space Station. It is a part of the JEM-EUSO program, paving the way to future larger missions, such as K-EUSO and POEMMA, devoted primarily to the observation of ultrahigh-energy cosmic rays from space. Mini-EUSO is capable of observing extensive air showers generated by ultrahigh-energy cosmic rays with an energy above 10²¹ eV and to detect artificial showers generated with lasers from the ground. Other main scientific objectives of the mission are the search for nuclearites and strange quark matter, the study of atmospheric phenomena such as transient luminous events, meteors, and meteoroids, the observation of sea bioluminescence and of artificial satellites and man-made space debris. Mini-EUSO will map the nighttime Earth in the UV range (290–430 nm), with a spatial resolution of about 6.3 km and a temporal resolution of 2.5 μs, through a nadir-facing UV-transparent window in the Russian Zvezda module. The instrument, launched on 2019 August 22, from the Baikonur Cosmodrome, is based on an optical system employing two Fresnel lenses and a focal surface composed of 36 multianode photomultiplier tubes, 64 channels each, for a total of 2304 channels with single-photon counting sensitivity and an overall field of view of 44. Mini-EUSO also contains two ancillary cameras to complement measurements in the near-infrared and visible ranges. In this paper, we describe the detector and present the various phenomena observed in the first months of operations.

Mini-EUSO 是一台在国际空间站的紫外波段观测地球的望远镜。它是 JEM-EUSO 计划的一部分，为未来更大的任务铺平了道路，如 K-EUSO 和 POEMMA，主要致力于从太空观测超高能宇宙射线。Mini-EUSO 能够观测到能量超过 10 ^{21 的}超高能宇宙射线所产生的大范围空气簇射eV 并检测由地面激光产生的人造淋浴。该任务的其他主要科学目标是寻找核子和奇怪的夸克物质，研究大气现象，如瞬态发光事件、流星和流星体，观察海洋生物发光以及人造卫星和人造空间碎片。Mini-EUSO 将在紫外线范围（290-430 nm）内绘制夜间地球图，空间分辨率约为 6.3 公里，时间分辨率为 2.5 μs，通过俄罗斯 Zvezda 模块中面向天底的紫外线透明窗口。该仪器于 2019 年 8 月 22 日从拜科努尔航天发射场发射，基于采用两个菲涅尔透镜的光学系统和由 36 个多阳极光电倍增管组成的焦面，每个光电倍增管 64 个通道，总共 2304 个通道，单光子计数灵敏度和 44 的整体视野。 Mini-EUSO 还包含两个辅助相机，以补充近红外和可见光范围内的测量。在本文中，我们描述了探测器并介绍了在运行的前几个月观察到的各种现象。