A CubeSat (U-class spacecraft) is a type of miniaturized satellite for space research that is made up of multiple cubic modules of 10 cm × 10 cm × 10 cm size. CubeSats have a mass of no more than 1.33 kilograms (2.9 lb) per unit, and often use commercial off-the-shelf (COTS) components for their electronics and structure. CubeSats are put into orbit by deployers on the International Space Station, or launched as secondary payloads on a launch vehicle. As of 1 January 2021, more than 1350 CubeSats have been launched. More than 1200 have been successfully deployed in orbit and more than 90 have been destroyed in launch failures.
In 1999, California Polytechnic State University (Cal Poly) and Stanford University developed the CubeSat specifications to promote and develop the skills necessary for the design, manufacture, and testing of small satellites intended for low Earth orbit (LEO) that perform a number of scientific research functions and explore new space technologies. Academia accounted for the majority of CubeSat launches until 2013, when more than half of launches were for non-academic purposes, and by 2014 most newly deployed CubeSats were for commercial or amateur projects.
Uses typically involve experiments that can be miniaturized or serve purposes such as Earth observation or amateur radio. CubeSats are employed to demonstrate spacecraft technologies intended for small satellites or that present questionable feasibility and are unlikely to justify the cost of a larger satellite. Scientific experiments with unproven underlying theory may also find themselves aboard CubeSats because their low cost can justify higher risks. Biological research payloads have been flown on several missions, with more planned. Several missions to the Moon and Mars are planning to use CubeSats. In May 2018, the two MarCO CubeSats became the first CubeSats to leave Earth orbit, on their way to Mars alongside the successful InSight mission.
Some CubeSats have become the first ever satellite of a country, being launched by universities, state-owned, or private companies. The searchable Nanosatellite and CubeSat Database lists over 2,900 CubeSats that have been and are planned to be launched since 1998.