A CubeSat is a small-satellite form factor built around standardised units, written as U. Under the CubeSat Design Specification Revision 14.1, a 1U spacecraft is based on a ten-centimetre cube and may have a mass up to two kilograms; larger configurations combine units into forms such as 2U, 3U, 6U or 12U.1 The standardised spacecraft-to-deployer interface is the defining feature. CubeSat is therefore not a synonym for every nanosatellite.
Standard interface
The CubeSat specification controls the external envelope, rails or tabs that contact the deployer, mass properties, prohibited protrusions, deployment switches and launch-safety features. It also requires environmental testing and constrains when radio transmitters, stored energy and deployable items may activate. ISO 17770 covers CubeSat physical and functional interfaces and the associated verification.2
These rules allow a launch provider to treat compliant spacecraft as repeatable secondary payloads rather than redesigning an interface for every mission. They reduce integration work, but do not waive licensing, radio authorisation, debris mitigation or launch-provider acceptance.
Spacecraft design
A CubeSat still contains the main subsystems of a larger spacecraft: structure, electrical power, command and data handling, communications, attitude determination and control, thermal management and a payload. Commercial modules and deployers can shorten development, while the fixed envelope forces tight trades among them.
Power and communications are persistent constraints. Small solar-array area limits generation, and a small antenna limits gain. Payload data can accumulate faster than a low-Earth-orbit spacecraft can transmit it during short ground contacts. Deployable arrays and antennas improve performance but add mechanisms and risk. On-board processing can reduce the data that must cross the downlink.
Thermal design is also demanding. CubeSats have little room for radiators, insulation and component separation, yet they cycle between sunlight and eclipse. Their low thermal mass can produce rapid temperature changes, and dense packaging can create local hot spots.
Uses and limitations
CubeSats support education, technology demonstration, Earth observation, communications, space-weather measurements and distributed science. Their standard interface can reduce cost and development time, but this is a design opportunity rather than a guarantee. Mission assurance, radiation tolerance, propulsion, communications licensing and operations can still dominate the programme.
Expanded CubeSat configurations now span more than one mass category. NASA places them in both its nano- and microsatellite classes.3 Any mass statement should name the configuration and classification scheme.
UK experience
UKube-1 was the UK Space Agency’s first CubeSat mission. Clyde Space, now AAC Clyde Space, built the 3U spacecraft, and organisations across UK industry and academia supplied four main payloads, flight software and ground support. Launched in 2014, it demonstrated deployment, communications, payload commissioning and the use of a CubeSat as a national technology programme.4
UKube-1 showed that a CubeSat can carry several useful payloads and the principal subsystems found on larger spacecraft. Its result does not establish equal capability, lifetime or reliability for every CubeSat.
References
Footnotes
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Cal Poly CubeSat Program, CubeSat Design Specification Revision 14.1. ↩
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International Organization for Standardization, ISO 17770:2017: Space systems, Cube satellites. ISO marked this edition for revision at the time of research. ↩
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NASA Small Spacecraft Systems Virtual Institute, State-of-the-Art of Small Spacecraft Technology: Introduction. ↩