## 1 Introduction  
The CubeSat has been defined by the factor of 1U (unit) on a 1.33 kg scale that can increase up to 12U. Since the first successfully operational CubeSat, XI-IV in 2004 [1; 2], researchers from other universities have actively joined the space sector to develop educational CubeSats [3; 4; 5; 6]. The main reason is that small satellites could be built efficiently by students, as they require a shorter development time and have low costs compared to traditional satellites. A study has outlined the key factors for a successful small satellite project, such as limited timeline, adequate team communications, well-informed utilization of available volume, and state-of-the-art components [7]. A decent communication functioning in a close working space is considerably important. Most traditional aerospace institutions have failed due to the rigidity of management structure and point of view. Since CubeSat subsystems are continuously evolving, objectives could be selected from the most straightforward missions, such as an imaging mission [8; 9; 10] to complex interplanetary missions [11; 12]. Although Earth Observation (EO) is an attractive mission for CubeSats, there are several limitations of having a high resolution (<1 m) using the CubeSat platform [13]. A 1U CubeSat can acquire a high ground spatial distance (_GSD_) with a significantly narrow-angle lens such as one with a length of <100 mm; however, the _GSD_ can be increased by increasing the number of units. Currently, the satellite developers use 3U or 6U CubeSats to implement medium-resolution camera payloads [14]. Theoretically, the camera sensor requires a larger form factor lens to improve focal length. Achieving < 10-m resolution by integrating a high-resolution imaging sensor, including a lens with a fixed focal length, is challenging. For instance, the Schmidt-Cassegrain reflective telephoto lens is used for an EO mission, as it provides a large aperture and field of view due to the limited size of CubeSats [15; 16]. In addition, a thermal control design has a vital role in acquiring high-focus images, which are commonly integrated with the lens in most optical payloads. For instance, [PERSON] et al. [17] explained how the ASTERIA flight model was equipped with a thermal strap in order to capture high-quality images by transferring the heat across the payload. The spectral resolution has an essential parameter in determining the target application for the EO missions from the visible (VIS) to the infrared (IR) range of image sensors. Nevertheless, multispectral and hyperspectral sensors are also available in current technology, which would combine into a single sensor [18; 19]. Furthermore, temporal resolution is another functional specification to achieve a successful EO mission [20]. An EO mission benefits from low altitude and an increased number of satellites in a constellation in order to achieve high temporal resolution, and a daily revisit time is required for an EO satellite to effectively monitor the changes on the ground. For instance, Planet Lab is a company that has leveraged the EO mission by deploying a constellation of 3U CubeSats named Doves [21], which had over 250 CubeSats orbiting Earth with 3-m resolution until 2021. More importantly, Doves can provide worldwide daily images with multispectral bands for a wide range of remote sensing applications, such as monitoring natural disasters. Various sensors have been implemented on remote sensing satellites to detect and monitor natural disasters on Earth. EO CubeSats such as ZaCube-2 can detect fire using a K-line sensor [22] and PhiSat-1 implemented machine learning to screen cloud images onboard [23]. Meanwhile, GOMX-4 has a mission to monitor the Arctic region [24], and MeznSat carried a micro-spectrometer to track greenhouse gases [25]. Natural disasters like wildfires occur in significantly increasing numbers every year around the world [26], and the traditional way to detect and monitor these catastrophes is to employ EO satellites [27].