# An Overview of CubeSat Missions and Applications
## 3 CubeSats as Earth Observation and Earth Science Platforms
### The Role of CubeSats in Earth Observation Missions
It was capable of measuring critical atmospheric cloud ice properties at altitudes between 5 km and 15 km. IceCube was deployed from the ISS on 16 May 2017 and during its operation, provided the world's first global map regarding the distribution of atmospheric ice [100]. As of 2025, other novel atmospheric/weather monitoring technologies are also in the process of being incorporated into CubeSat platforms, with one notable upcoming atmospheric monitoring and research CubeSat mission being CloudCT. The main objective of this mission is to perform cloud tomography, revealing their external as well as internal 3D structures using equipment and techniques inspired by medical Computed Tomography (CT), and in this way, supplement existing remote sensing technologies and infrastructure used in the field of atmospheric modeling and climate prediction. More specifically, the satellites of the CloudCT constellation will be equipped with multi-spectral, polarizedcameras that will be used to detect and measure the backscattered sunlight from a cloud of interest from different angles simultaneously. The data collected by the constellation will then be transmitted to Earth where they will be post-processed using computed tomography methodologies to characterize the cloud and reveal its internal structure. Initially, one precursor 3U satellite will be placed in orbit to test and demonstrate the mission concept. Should this precursor satellite successfully demonstrate its capabilities, the launch of a constellation of ten more 3U CubeSats is expected to follow. These ten CubeSats will fly in the same orbit, following each other in an Along-Track Formation (ATF) with a separation distance of 100 km between each two satellites, thus being able to simultaneously observe the target clouds from different angles. The ten CubeSats will fly in ATF using technologies that were successfully demonstrated by the NetSat mission, which was launched in 2020 [101; 102]. Traditionally, Earth observation CubeSats have relied on passive sensors as their mission payloads. As mentioned before, this can mainly be attributed to the low electrical power generation capacity which stems from their small size, as there is less area available for the installation of solar cells. However, in recent years, several attempts for the incorporation of active sensors by CubeSats in the form of radars have been undertaken, with a notable example being the Radar in a CubeSat (RaInCube) mission, a 6U CubeSat developed by NASA's Jet Propulsion Laboratory (JPL) and Tyvak Nano-Satellite Systems Inc. (Irvine, CA, USA) under the mission of demonstrating the concept of rain precipitation measurements via radar. For this reason, RaInCube was equipped with a 0.5 m deployable Ka-band parabolic antenna which is presented in Figure 8[103]. When stowed, the antenna would be able to fit inside a 1.5U volume. Furthermore, certain attempts at the integration of SAR arrays in CubeSat platforms have also been underway in recent years. SAR arrays emit microwave energy and capture the reflected backscatter to synthesize a picture of the target. Compared to optical imaging, SAR imaging offers certain advantages. The most notable of these advantages is SAR's ability to operate effectively regardless of light and weather conditions due to the long wavelength of microwave radiation. However, it should be noted that SAR imaging does not match the spectral and spatial information that is provided by optical imaging payloads [104; 105]. Figure 8: An illustration of the Radar in a CubeSat (RaInCube) satellite with its parabolic radar antenna and solar panels in deployed configuration. Photo by NASA/Jet Propulsion Laboratory (JPL)-Caltech [106]. Regarding the efforts for the integration of SAR imaging instruments on CubeSat platforms, the Italian space agency has selected and funded the development of the SAT-URN program which is developed by OHB Italia S.p.A. (Milan, Italy).