CubeSat

Also known as Cube satellite, U-class spacecraft

Nanosatellite standard built from 10 cm units (U). Cal Poly’s CubeSat Design Specification defines the envelope, mass and centre-of-mass limits, rails and separation switches from 1U to 12U.

Document
SQ-FF-002
Updated
20 Oct 2026
Reading time
9 min
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Definition#

A CubeSat is a nanosatellite built from cubic units of about 10 cm, written "U". The standard says almost nothing about the inside of the spacecraft. It specifies the interface with the launcher: the external envelope, mass and centre-of-mass limits, the rails that touch the deployer, the separation switches and the timers that keep the spacecraft silent and folded until it is clear of the rocket[1]. Because that interface is common, a CubeSat can fly in any compatible deployer of its size without changing the primary payload.

History#

Jordi Puig-Suari of California Polytechnic State University and Robert J. Twiggs of Stanford University proposed the standard in 1999, as a platform on which students could design, build and launch a satellite within a degree programme[2]. Cal Poly developed the Poly Picosatellite Orbital Deployer (), a spring-loaded tube for three 1U units that became the model for every later deployer[3].

The first CubeSats were launched from Plesetsk on a Rockot on 30 June 2003. One of them, the University of Tokyo’s XI-IV, is still listed as operational in the database in 2026[4]. In the following two decades CubeSats became carriers for commercial Earth-observation constellations, science missions and deep-space demonstrations: in 2018 the two 6U MarCO spacecraft relayed InSight’s landing on Mars almost in real time, the first interplanetary CubeSat mission[5], and in 2022 the 12U CAPSTONE became the first spacecraft to enter a near-rectilinear halo orbit around the Moon.

The early years were also a lesson in reliability. A large share of the first hundred CubeSats failed early, many of them in the first days, which showed that cheap and fast development carries its own risks[6]. Statistical studies traced most early failures to the power and communication subsystems and to insufficient system-level testing[7].

Size family#

The base unit is 1U. The 1.5U, 2U and 3U sizes grow along the long axis; 6U and 12U are double-row structures that also widen the cross-section. The CubeSat Design Specification Rev. 14.1 defines mass and centre-of-mass limits from 1U to 12U. Fractional sizes such as 0.25U and 0.5U, and larger structures from 16U up, are outside the document; their interface is set by the deployer provider[1].

CubeSat and PocketQube#

The PocketQube grew out of the same community and keeps the same philosophy at half the edge length[8]:

Attribute1U CubeSat1P PocketQube
Governing documentCubeSat Design Specification Rev. 14.1PocketQube Standard, Issue 1
External envelope100 × 100 × 113.5 mm50 × 50 × 50 mm
Volume / external surface1135 cm³ / 654 cm²125 cm³ / 150 cm²
Maximum mass per unit2.00 kg0.25 kg
Maximum bulk density1.76 g/cm³2.00 g/cm³
Deployer interfaceFour railsSliding backplate
Avionics interconnectPC/104-derived stacks (de facto)PQ9/CS14 proposed; otherwise vendor-specific

References

  1. [1]The CubeSat Program, Cal Poly SLO. (2022). CubeSat Design Specification, Rev. 14.1 (CP-CDS-R14.1). California Polytechnic State University.nasa.gov
  2. [2]Heidt, H., Puig-Suari, J., Moore, A. S., Nakasuka, S., & Twiggs, R. J. (2000). CubeSat: a new generation of picosatellite for education and industry low-cost space experimentation. In: 14th Annual AIAA/USU Conference on Small Satellites (SSC00-V-5).
  3. [3]Puig-Suari, J., Turner, C., & Ahlgren, W. (2001). Development of the standard CubeSat deployer and a CubeSat class PicoSatellite. In: 2001 IEEE Aerospace Conference Proceedings, vol. 1 (347–353).doi:10.1109/AERO.2001.931726
  4. [4]Libre Space Foundation. (2026). SatNOGS DB — satellite and transmitter database.db.satnogs.org(accessed 20 October 2026)
  5. [5]NASA Jet Propulsion Laboratory. (2019). The MarCO mission comes to an end.jpl.nasa.gov
  6. [6]Swartwout, M. (2013). The first one hundred CubeSats: a statistical look. Journal of Small Satellites, 2, 213–233.
  7. [7]Langer, M., & Bouwmeester, J. (2016). Reliability of CubeSats — statistical data, developers’ beliefs and the way forward. In: 30th Annual AIAA/USU Conference on Small Satellites (SSC16-X-2).
  8. [8]nadir lab. (2026). PocketQube picosatellites: A review of standards, mission trends and miniaturization constraints, with lessons learned from Grizu-263A, Türkiye’s first PocketQube [Preprint]. nadir lab.Read on nadir lab.
  9. [9]NASA CubeSat Launch Initiative. (2017). CubeSat 101: Basic Concepts and Processes for First-Time CubeSat Developers. NASA.nasa.gov(accessed 20 October 2026)
  10. [10]NASA Small Spacecraft Systems Virtual Institute. (2026). State-of-the-Art of Small Spacecraft Technology (2026 edition). NASA Ames Research Center.nasa.gov(accessed 20 October 2026)

Cite this SatWiki entry

@misc{nadirlab2026cubesat,
  author       = {{nadir lab.}},
  title        = {{CubeSat}},
  year         = {2026},
  month        = oct,
  howpublished = {nadir lab. SatWiki SQ-FF-002 (Rev. 6)},
  url          = {https://nadirlab.space/en/wiki/cubesat/}
}