The number of 3U CubeSats corresponds to the space (volume) occupied by the platform within the 3U CubeSat system.
To determine the platform size, the research team analyzed 25 3U CubeSats in the development or operational phase. The figure shows the number of satellites corresponding to different platform spaces (volumes) in the 3U CubeSat system. The platform includes subsystems such as SMS, ADCS, EPS, TCS, and CS, and its size varies according to satellite missions. The most common platform sizes are 1.5U or 2U, with corresponding payload sizes mostly ranging from 1.5U to 1U.
Based on the above data, the 3U standard platform developed in this research is defined as follows: 1.5U is allocated to the platform, and the remaining 1.5U is reserved for the payload, ADCS actuators, and sensors.
To clarify the specifications and functions of the standard platform, the main performance parameters are determined with reference to the specifications of currently operational CubeSats based on commercial off-the-shelf (COTS) CubeSat kits. Benefiting from the development of microtechnology, the performance of C&DHS and ADCS has been significantly improved: early ADCS and C&DHS adopted 8-bit, 8MHz MCUs, while current data processing uses high-performance MCUs with 32-bit or higher architecture and 200MHz clock speed; ADCS previously relied on manual control with permanent magnets, and now achieves active control using control moment gyros or reaction wheels.
Most CubeSats are classified as amateur satellites and have used amateur radio frequency bands since the early development stage, with uplink/downlink data rates remaining stable for a long time. However, for high-capacity mission data transmission, additional downlink transmitters of different frequency bands can be installed.
Referring to the performance, system power consumption, solar panel configuration, and deployment status of previous 3U CubeSats, the estimated power generation capacity ranges from 3W to 30W, and the power system can be independently determined by users. The MPPT (Maximum Power Point Tracking) and BCR (Battery Charge Regulator) are designed to support 30W operation, which can be easily adjusted by users in future development. The structure subsystem is designed in accordance with the CubeSat Design Specification (CDS) Version 2. The baseline specifications of the 3U standard platform are shown in the following table:
