What is a CubeSat?
A CubeSat is a miniaturised satellite built to a standardised form factor defined by the CubeSat Design Specification (CDS), originally developed by professors Jordi Puig-Suari (Cal Poly SLO) and Bob Twiggs (Stanford) in 1999. The basic unit, 1U, is a 10×10×10 cm cube with a maximum mass of 2.0 kg. Larger formats stack units linearly: 3U (30×10×10 cm, 4 kg), 6U (30×20×10 cm, 8 kg), and 12U (30×20×20 cm, 12 kg).
Why standardisation matters
The CubeSat standard defines not just size, but also mechanical interfaces with the launch vehicle deployer (typically a PPOD — Poly-Picosatellite Orbital Deployer). This allows multiple CubeSats to share a single launch slot as secondary payloads, dramatically reducing per-satellite launch cost. Commercial off-the-shelf (COTS) components — solar panels, attitude control modules, on-board computers, radios — have proliferated in CubeSat-compatible form factors, creating a commodity supply chain.
From university tool to commercial platform
Initially conceived as an educational platform, CubeSats have evolved into serious commercial instruments. Planet Labs built a 200+ satellite Earth observation constellation (Dove) based on 3U CubeSats. Spire Global uses 6U CubeSats for AIS vessel tracking, ADS-B aircraft tracking, and GNSS radio occultation weather data. Kepler Communications is building an IoT and data relay constellation from 6U CubeSats.
Limitations
CubeSat power budgets (a 3U panel generates ~10W), limited propulsion options, and small antenna apertures constrain performance for communications and high-resolution imaging applications. Larger SmallSat formats (50–150 kg microsat class) are often preferred for commercial constellations requiring higher capability.