## 1 Introduction  
Acid mine drainage (AMD) is the product of a series of reactions involving the oxidation of sulphide-bearing minerals, such as pyrite (FeS2), pyrrhotite (FeS), and arsenopyrite (FeAsS), with oxygen, water, and bacteria [1]. These reactions result in the release of protons, sulphate, and metal(loids) to waters, and ultimately, produce low pH and metal(oid)-rich sulfuric acid (AMD), which can severely contaminate receiving surface and groundwaters, soils and sediments [1, 2, 3, 4]. Acid drainage may form naturally (acid rock drainage) [5] or by mining (acid mine drainage), with a continual need to monitor both. Above-ground mines cover more than 57 thousand km\({}^{2}\) globally [6]. The costs of detecting AMD at mine sites using traditional methods, with a view to remediating or managing it, are significant, and thus, can be a substantial burden upon taxpayers and mining companies [7]. The scale of the problem is truly colossal: total worldwide liability associated with the current and future remediation of AMD is of the order of USD 100 B [8]. The breakdown of the Fe-bearing sulphides generates Fe\({}^{2+}\), which is oxidized and used by chemotrophic microorganisms for energy generation. This, in turn, produces even more sulfuric acid through the production of Fe\({}^{3+}\), which can act as an oxidant of the sulphides [2; 3]. The solubility of Fe\({}^{3+}\) at near-neutral pH is low, and thus, Fe(III) iron oxyhydroxide solids form rapidly. Fe(III) iron oxyhydroxides can be regarded as proxies for AMD because they are formed from it. They are also characterised by high concentrations of potentially toxic metal(loids) that they incorporate from the AMD. Fe\({}^{2+}\) alteration can create a suite of secondary minerals (oxides, sulfates, carbonates, and more), such as goethite, hematite, and jarosite, which often exhibit similar colours [9]. pH plays a crucial role of secondary mineral precipitation and control, where goethite forms between pH 2 and12, and hematite at pH 7-9 [9; 10; 11]. Jarosite forms a magnitude lower in comparison (pH 1-3) [12]. As a known set of secondary mineral products exhibit an orange to red colour (with high concentrations of Fe (III)), they are distinguishable via remote sensing methods and have previously been used as proxies of AMD and iron ore deposits [13; 14; 15; 16]. Band ratio operations are a well-established method that has been used as an effective geological surveying tool for decades, targeting and isolating geological material through their unique spectral signatures [17]. It is both low in cost as well as computational demand and covers vast areas in a short timeframe. Remote sensing and band operations are useful tools, but band ratio products do not guarantee mineral presence with absolute certainty due to environmental interference [18]. Therefore, ground truthing is crucial and, in combination with the remote-based surveillance of AMD-impacted landscapes, has been successfully used to help identify mine waste by using band ratios for specific iron absorption features [15]. Ref. [19] successfully used ground-based reflectance spectroscopy to identify a suite of secondary iron oxide minerals indicative of the subaerial oxidation of pyrite. Multiple satellites can be used to increase the accuracy of AMD detection in mining environments by using a multi-sensor process chain alongside ground verification. A prerequisite is identifying a series of instruments with spectral sensitivities that overlap and cover Fe(III) iron signatures (Table 1). Using an interoperable set of wavelength bands is an effective method to link multispectral and hyperspectral observations using ground-based spectroscopy [16]. Environments containing AMD are prone to morphological change. It is, therefore, important that the capture of spectra is carried out in the shortest time window possible, preferably on the same day. This has not previously been attempted.