# HYPSO-1 CubeSat: First Images and In-Orbit Characterization
## 1 Introduction
The _observational pyramid_, illustrated in Figure 1, consists of multiple platforms with different capabilities of spectral, temporal and spatial resolution measuring within the same region, as described in greater detail in [5; 15]. In addition to the autonomous assets developed at NTNU AMOS, these campaign will also rely on the globally available satellite infrastructure intended to continuously cover the entire earth, e.g., the upcoming PACE mission. The HYPSO satellites are essential elements in the pyramid because they collect data over larger areas with a relatively short revisit time. The revisit time will depend on the given position of the satellite relative to the target and the target's latitude. The data collected by the satellites will be used to detect features of interest that other autonomous agents can investigate further and in greater detail with optical sensors on UAVs or in-situ measurements [15]. The pyramid will provide decision support to improve water quality monitoring and to detect oceanographic events such as phytoplankton blooms in the Arctic or even HABs, contributing to the environmental sciences studying marine food chain dynamics. Detection of HABs at an early stage would enable a warning system for both the aquaculture and fishing industries. An HAB warning system requires short revisit times and low latency since HAB dynamics can be fast and complex. The HYPSO-1 satellite is a 6U CubeSat equipped with a Hyperspectral Imager (HSI) as its payload. The satellite was launched on 13 January 2022 into a 540 km altitude Sun-synchronous orbit, with an orbital period of about 96 min. The payload commissioning phase began at the end of February 2022, and has been ongoing in parallel with the development and advances in the satellite operations scheme, imaging campaigns and gathering data to be used for the calibration and validation of the instrument. The details about the operational schemes used for HYPSO-1 are included as an aid to other universities and institutions seeking to do satellite-based remote sensing. Satellite operations are run by students and researchers in an academic environment, providing both limitations and flexibility to the operations of the satellite [16]. For instance, exploring new operational scenarios is more attainable at the cost of limited routines and transparent procedures for satellite operations. Many different satellites and imaging spectrometers have been developed to observe the Earth and ocean color [1; 2; 4; 6; 7; 8; 17; 18], including several cubesats [19; 20; 21]. Leveraging the combination of low revisit time, i.e., the period between two possible consecutive observations of a specific target, and fine spectral resolution, is still an active area of research for ocean color remote sensing. This paper presents images from the first months of operations and describes selected technical specifications such as spatial and spectral resolution and SNR estimated from the in-orbit data. First, in Section 2, the payload operations' procedures, and their justifications are described. In particular, it demonstrates that the satellite can capture images within 1.5 h after an area of interest has been identified and that the low revisit time allows for  
Figure 1: The observational pyramid with all the different autonomous data-collecting robotic agents developed at NTNU AMOS together with third-party satellite infrastructure. The right-hand side of the figure gives typical values for speeds, area coverage and data collection method. consecutive captures of the same location. Finally, a series of images over Ny-Alesund, Svalbard demonstrates how a fjord system, an area of interest, can be monitored over an extended time period. Various parameters to indicate the hyperspectral instrument's in-orbit performance are given in Section 3. The spatial resolution is approximated based on scenes with distinct spatial patterns, while the spectral resolution is estimated by comparing radiometrically normalized measurements of the moon with solar irradiance.