VST-SMASH: VST Survey of Mass Assembly and Structural Hierarchy. I. Survey presentation and deep photometry of IC 5332: Tracing the mass assembly in the challenging faintest-end regime

Understanding the formation and evolution of late-type galaxies requires deep imaging for tracing the faintest stellar components in their outskirts (i.e. accreted material, diffuse halos, and tidal streams). Despite their crucial role in the build-up of stellar mass, these low-surface-brightness features remain largely unexplored due to observational limitations. The VST Survey of Mass Assembly and Structural Hierarchy (VST-SMASH) is designed to fill this gap, providing deep, wide-field optical imaging for a volume-limited sample of nearby spiral galaxies (D<11 Mpc), overlapping with the Euclid Wide Survey in the southern hemisphere. This paper aims to introduce the VST-SMASH survey and showcase its scientific potential through the analysis of a late-type spiral galaxy observed in the g, r, and i bands. The main goal is to demonstrate the depth, quality, and diagnostic power of the dataset in tracing low-surface-brightness features and structural components in galactic outskirts. We carried out detailed surface photometry of . We performed multi-component Sérsic decompositions in each band and constructed stellar mass surface density profiles. Furthermore, we identified and characterized faint stellar streams visible in the very deep and smoothed images, estimating their colours and comparing them with adjacent galactic regions. using elliptical isophotal fitting and growth curve analysis to extract radial surface brightness and colour profiles down to μ_r ∼ 30 mag arcsec -2 While the internal ($<$ 1 effective radius) negative colour gradients can be explained by dissipative (monolithic) collapses and supernovae outflows, the colour profiles at larger radii reveal a significant gradient towards redder g-r and g-i, spatially consistent with the presence of accreted populations in the outskirts. Nevertheless, we also find bluer r-i, which , together with the behaviour of g-r and g-i, could be explained by strong emission. Single-component Sérsic fits fail to reproduce the observed light distribution, especially in the outer regions, requiring a two-component model. In the outskirts, multiple faint stellar streams are detected, with integrated g - r colours consistent with disrupted dwarf and/or low-surface-brightness satellites. However, spectroscopic follow-ups would be needed to detect possible strong emission lines, which could affect the r-band photometry. These findings support a scenario of ongoing stellar mass assembly through accretion and highlight the capability of VST-SMASH to uncover faint structures in nearby galaxies.