The European Space Agency’s INTErnational Gamma-Ray Astrophysics Laboratory (ESA/INTEGRAL) was launched aboard a Proton-DM2 rocket on 17 October 2002 at 06:41 CEST, from Baikonur in Kazakhstan. Since then, INTEGRAL has been providing long, uninterrupted observations (up to about 47  h, or 170  ksec, per satellite orbit of 2.7 days) with a large field-of-view (FOV, fully coded: 100 deg${}^2$), millisecond time resolution, keV energy resolution, polarization measurements, as well as additional wavelength coverage at optical wavelengths. This is realized by two main instruments in the 15  keV to 10  MeV energy range, the spectrometer SPI (spectral resolution 3 keV at 1.8  MeV) and the imager IBIS (angular resolution: 12 arcmin FWHM), complemented by X-ray (JEM-X; 3–35  keV) and optical (OMC; Johnson V-band) monitor instruments. All instruments are co-aligned to simultaneously observe the target region. A particle radiation monitor (IREM) measures charged particle fluxes near the spacecraft. The Anti-coincidence subsystems of the main instruments, built to reduce the background, are also very efficient all-sky $\gamma$-ray detectors, which provide virtually omni-directional monitoring above $\sim$75  keV. Besides the long, scheduled observations, INTEGRAL can rapidly (within a couple of hours) re-point and conduct Target of Opportunity (ToO) observations on a large variety of sources.

INTEGRAL observations and their scientific results have been building an impressive legacy: The discovery of currently more than 600 new high-energy sources; the first-ever direct detection of ⁵⁶Ni and ⁵⁶Co radio-active decay lines from a Type Ia supernova; spectroscopy of isotopes from galactic nucleo-synthesis sources; new insights on enigmatic positron annihilation in the Galactic bulge and disk; and pioneering gamma-ray polarization studies. INTEGRAL is also a successful actor in the new multi-messenger astronomy introduced by non-electromagnetic signals from gravitational waves and from neutrinos: INTEGRAL found the first prompt electromagnetic radiation in coincidence with a binary neutron star merger.

Up to now more than 1750 scientific papers based on INTEGRAL data have been published in refereed journals. In this paper, we will give a comprehensive update of the satellite status after more than 18 years of operations in a harsh space environment, and an account of the successful Ground Segment.

欧洲航天局的国际伽马射线天体物理实验室（ESA/INTEGRAL）于 2002 年 10 月 17 日欧洲中部时间 06:41 从哈萨克斯坦拜科努尔乘坐质子 DM2 火箭发射升空。从那时起，INTEGRAL 一直在提供大视场（FOV，完全编码：100 度）的长时间不间断观测（最多约 47  小时或 170   ksec，每个卫星轨道 2.7 天）${}^2$)、毫秒时间分辨率、keV 能量分辨率、偏振测量以及光波长的额外波长覆盖范围。这是通过 15   keV 至 10   MeV 能量范围内的两个主要仪器实现的，光谱仪 SPI（光谱分辨率为 3  keV，1.8   MeV）和成像仪 IBIS（角分辨率：12  arcmin FWHM），辅以 X 射线（JEM- X；3-35   keV）和光学（OMC；约翰逊 V 波段）监测仪器。所有仪器都对齐以同时观察目标区域。粒子辐射监测器 (IREM) 测量航天器附近的带电粒子通量。主要仪器的反重合子系统，为减少背景而构建，也非常高效全天$\gamma$-射线探测器，提供几乎全方位的监测 $～$75   keV。除了长时间的预定观测外，INTEGRAL 还可以快速（在几个小时内）重新指向并针对各种来源进行机会目标 (ToO) 观测。

INTEGRAL 观测及其科学成果创造了令人印象深刻的遗产：目前发现了 600 多种新的高能源；首次直接探测到来自 Ia 型超新星的⁵⁶ Ni 和⁵⁶ Co 放射性衰变线；来自星系核合成源的同位素光谱；关于银河隆起和盘中神秘正电子湮灭的新见解；和开创性的伽马射线偏振研究。INTEGRAL 在由引力波和中微子的非电磁信号引入的新型多信使天文学中也是成功的参与者：INTEGRAL 在双中子星合并的同时发现了第一个瞬发电磁辐射。

迄今为止，已有超过 1750 篇基于 INTEGRAL 数据的科学论文发表在相关期刊上。在本文中，我们将全面更新卫星在恶劣空间环境中运行 18 多年后的状态，并说明地面段的成功。