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Context. The Galactic centre is hazardous for stellar clusters because of thestrong tidal force. Supposedly, many clusters were destroyed and contributedstars to the crowded stellar field of the bulge and the nuclear stellarcluster. However, it is hard to develop a realistic model to predict thelong-term evolution of the complex inner Galaxy, and observing survivingclusters in the central region would provide crucial insights into destructionprocesses. Aims. Among hitherto-known Galactic globular clusters, VVV CL002 isthe closest to the centre, 0.4 kpc, but has a very high transverse velocity,400 km s$^{-1}$. The nature of this cluster and its impact on Galacticastronomy need to be addressed with spectroscopic follow-up. Methods. Here wereport the first measurements of its radial velocity and chemical abundancebased on near-infrared high-resolution spectroscopy. Results. We found thatthis cluster has a counterrotating orbit constrained within 1.0\,kpc of thecentre, as close as 0.2 kpc at the perigalacticon, confirming that the clusteris not a passerby from the halo but a genuine survivor enduring the harshconditions of the Galactic mill's tidal forces. In addition, its metallicityand $\alpha$ abundance ([$\alpha$/Fe] $\simeq +0.4$ and [Fe/H]$=-0.54$) aresimilar to some globular clusters in the bulge. Recent studies suggest thatstars with such $\alpha$-enhanced stars were more common at 3 - 6 kpc from thecentre around 10 Gyrs ago. Conclusions. We infer that VVV CL002 was formedoutside but is currently falling down to the centre, exhibiting a real-timeevent that must have occurred to many clusters a long time ago.

The globular cluster VVV CL002 falling down to the hazardous Galactic centre