What is a 3U CubeSat and when would you use one?

CubeSats are named for the units in which they exist. Though the shape of the satellite itself can form a cube, it can also exist in arrangements of smaller cubes, called units.

Units are a shorthand way of describing the approximate size, or at least the mass, of a CubeSat.

So, what is a 3U CubeSat?

What is a 3U satellite?

A 3U satellite is one composed of three units, the cubes that make up CubeSat proper. One unit measures 10cm x 10cm x 10cm and has a maximum mass of 2kg.

The ability to have an uneven number of units making up a CubeSat—indeed, some CubeSats consist of only one unit—is why the name is derived from the units themselves rather than the overall shape, since a 3U CubeSat does not actually form the shape of a cube once their units are held together to create the cohesive satellite proper.

Being nanosatellites, a CubeSat typically comprises of commercial off-the-shelf (COTS) components, further reducing the cost of their development alongside their small stature.

How big is a 3U CubeSat?

3U CubeSat structure will typically measure around 10cm x 30cm x 10cm with the units arranged in a straight linear framework.

This makes the satellite simpler to develop, because it gives the most uncomplicated surface area for the payload and in turn makes the spacecraft itself a simpler payload for the rocket that will launch it into orbit.

This somewhat uniform arrangement also aids in satellite research, allowing calculations in terms of mass and shape to take place with the safe assumption that a 3U satellite will form a rectangular prism.

Relative to other spacecrafts, a 3U CubeSat is on the smaller end. Though there are numerous smaller classifications of satellites, a 3U satellite is still scarcely longer than a ruler.

How much does a 3U CubeSat cost?

CubeSat costs can vary, though they are steadily reducing and becoming more and more accessible.

Not too long ago, the cost of a 1U CubeSat was around $50,000 (roughly £43,000), while a 3U CubeSat can now be developed for approximately €25,000 (roughly £21,500).

Thanks to the COTS basis of CubeSat construction, there is a wide market for components. Since many COTS satellite components are identical to those used in other electronics and machinery, there is no single ‘satellite market’ for those looking to build a CubeSat. This means a certain degree of variance in component price and ultimately encourages competition.

There are some rough price ranges that can be inferred for essential CubeSat parts:

  • A 3U CubeSat structure can be bought for around £2,600 to £3,100. This provides the linear shape of the CubeSat as a whole, giving developers a concrete area to work within and keep their satellite to guidelines.
  • Power systems can vary widely in cost. An electric power system can cost from around £2,500 to £7,500, but a battery array can require significantly more and a battery matrix even more than that.
  • Solar panels naturally differ in price due to their differing specifications. Solar cell equipment can be bought as single panels for around £1,200, or as deployable solar arrays for around £4,000 upwards. These can come to suit CubeSats of one, three, six, or more units. Costs will naturally be higher the larger and more powerful you want your array to be.
  • Communications systems can again vary widely in cost, depending on the strength and capability of the system. For instance, a half-duplex transceiver will cost less than a full-duplex. Costs can start around £3,500 and climb to around £20,000 for more complex transmitters and transceivers.
  • Though not a tangible component, flight software is an integral part of a CubeSat and what essentially holds it together. Flight Software Development Kit can be available as COTS options too just like physical components, and pricing reflects the accessibility and ease of setting this software up to work with a CubeSat using a library of pre-validated components.

Developers who set their budget and ensure they have a firm grasp of the price ranges of COTS CubeSat components will find that a CubeSat, whilst not something that can be built on pocket money, is still an affordable and accessible entry into space missions.

Examples of recent 3U missions

Recently deployed 3U CubeSats have proven their ability to fulfil missions despite their compact size.

The IDEASSat (Ionospheric Dynamics Explorer and Attitude Subsystem Satellite) is a CubeSat launched in January 2021, developed by the National Central University of the Republic of China (Taiwan).

IDEASSat’s mission is to measure ionospheric activity and its effects on satellite communications. The reason this satellite needed three units is due to its payload of the Compact Ionosphere Probe (CIP), a plasma sensing device whose size would take up the majority of space in a single unit CubeSat.

Another 3U CubeSat launched in January 2021 is the CACTUS-1, which serves as a demonstration of new satellite technologies. One major component of CACTUS-1 is Project TRAPSat, which traps debris and micrometeorites in an aerogel medium. The size of the unit demands extra space on the CubeSat, as CACTUS-1 also needs to telecommunications technology.

Another recent CubeSat is the ExoCube-2, which was launched with the task of measuring the upper exosphere using a spectrometer. ExoCube-2, like the previous two satellites mentioned, requires its 3U mass due to the size of its payload. The first ExoCube satellite’s spectrometer took up 1.5U of the satellite’s available room, a full half of the satellite itself.

Software for 3U CubeSats

CubeSats need reliable software that will ensure their missions go off without a hitch. Bright Ascension offer simple, easy-to-use software development kits to ensure your spacecraft flies right for the entire duration of its mission.



To support future skill-building within the academic community we offer to affordable (in some instances free) licences for our flight and ground software products.

Bright Start Academic Programme

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We’ve been evolving our technology over the past 12 years through extensive development work. During this time, our software has powered more than 50 spacecraft in orbit, helping them to maximise their mission potential. 

Contact us today to see our products in action and arrange a one-to-one demo of our software, tailored to your unique mission needs and requirements.