## 1 Introduction  
The collection and archiving of Earth observation data has historically been led by government agencies, spurring a range of benefits including continuity in data processing algorithms and more open and public access to the data [1, 2]. A drawback to this model has been the extremely long delays, sometimes a decade or more, for developing and launching satellite systems as agencies work to secure funding and advocacy [3]. When issues arise, such as the failed launch of Landsat-6 or the scan line corrector malfunction of Landsat-7, coverage gaps can persist for months or years while another platform is authorized and built, diminishing the opportunity for scientific returns. Commercial satellite programs such as Digital Globe, QuickBird, and RapidEye reduced platform production times, but the build-and-launch process still took several years [3]. Companies such as Planet (Planet Labs, Inc., San Francisco, CA, USA) have been innovating Earth observation by developing miniature satellites, called smallsats or cubesats, that can be produced and launched much faster than traditional satellites. Their small size (approximately the dimensions of a loaf of bread) allows them to be built rapidly, and they do not require a dedicated launch vehicle but instead can be delivered into orbit onboard other deployments as secondary payload [4]. This flexibility means that Earth observation capabilities can be rapidly improved as new technologies progress, and satellite constellations can quickly be updated or bolstered by additional platforms in the event of malfunctions. As a result, commercial smallsats, specifically Planet's PlanetScope (PS) satellites, are emerging as a key resource for Earth imaging. The PS constellation offers a means to augment the suite of Earth observational data acquired by government and commercial agencies [4; 5] and fill key spatio-temporal Earth observing needs. However, there are several technical and processing hurdles that need to be overcome before the data can be leveraged to their full potential by the remote sensing community. Since PS imagery is captured via a constellation of many smallsats rather than a single large platform like Landsat, a patchwork of images must be stitched together into wall-to-wall mosaics for analyses in most cases. Adjacent scenes captured by different platforms and sensors, at different times of day, and under different illumination conditions create substantial scene-to-scene variations in reflectance [6] (Figure 1). Since PS scenes cover relatively small areas comparatively, many adjacent scenes are often needed to canvas a study area. The geometric and radiometric accuracy of these products does not always match the quality the remote sensing community has come to expect [7; 8]. While Planet continues to improve the radiometric calibration of individual sensors [9], scene-to-scene radiometric and geometric differences often require substantial user preprocessing before the data are 'analysis ready' and can be integrated into analytical processing pipelines. A second issue for the remote sensing community is that different PS sensor generations reflect evolving technology [10]. Planet has upgraded their sensor instrumentation several times, which means images captured from different generations are not always radiometrically or geometrically compatible. At this time, there are 180+ Planet platforms in orbit comprising three generations of PS sensors. Because Planet is constantly innovating its data collection and processing procedures, it can be difficult for researchers to remain current in terms of data quality and standards across the multiple platforms and sensors. These technical hurdles coupled with discrepancies in image access and licensing agree  
Figure 1: Example of scene-to-scene differences for two PlanetScope images captured on the same day (8 October 2020) by different smallsats in the constellation. Image captured near Crested Butte, CO, USA.