CubeSat: the microsatellites that changed everything

 

 


 

 

It is a name that has become almost generic for a whole generation of satellites, and for their designers. The CubeSat architecture, in just over a decade, has established itself for its ease of use, standards and innovations. But what is a CubeSat?

A success that can be counted in U ...

 

 

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Little but strong


The real story of the CubeSat starts at the end of the 90s. With the rise of microelectronics, and at the same time as the advent of the PC in homes as well as in universities, several researchers are working on small satellite platforms. The objective is multiple: carry out ambitious projects with students, while developing a platform that is inexpensive and reliable. There were already a few mini-formats at the time, such as TUBSAT or PICOSAT, which had promising results.

But the game will be played in California, at CalPoly University and Stanford, where Bob Twiggs seeks to define a 'minimum size to have a practical satellite to use', with a simple and standard ejection system. He would have been inspired by the design of the packaging of small plush toys 'Beanie Babies' for its cubic format of 10 x 10 x 10cm of useful volume. With Jordi Puig-Suari, they put in place a specification document for the academic community. They don't know it, and the term won't emerge until a little later, but the CubeSat was born.

 

 


 

 

Moreover, at its beginnings, it does not interest NASA, which does not judge its value for education sufficient to have the label (and the subsidies) of the agency. In 2014, B. Twiggs will declare 'I am glad that the agency did not help us, otherwise we would probably never have succeeded'. Critics are not lacking, however, when they present their idea in 1998 and 1999 during several consortia and academic meetings. An industrialist even explains to them that 'it is the silliest idea that I have ever seen, no one will use your toy'. But among academics, the idea is gaining ground. Several groups of students have already started working with the specifications. The first CubeSats flew on March 30, 2003: 6 American, Canadian, Danish and Japanese satellites, all from research and universities.

They take off on a Russian launcher. When they went to see the giants of the American launchers, B. Twiggs and J. Puig-Suari failed to convince the latter that their system could take the place of the ballasts used during the lightest launches ...

 

 


 

 

 

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Small format, large standard


A CubeSat can have multiple sizes, which are described by Units (U). A Unit is the smallest format, with a maximum mass of 1.33 kg and a size of 10 x 10 x 10 cm (one of the sides is actually 11.35 cm, to have one liter, or 1000 cm3 interior volume). Many CubeSats have flown in 1U format, but there is often a need for more space on the satellite. We therefore find 2U versions (two 'cubes' attached), the very numerous and very successful 3U formats (10 x 10 x 30 cm) and the 6U satellites that we usually describe as 'shoe boxes' in the press in relation to their size (10 x 20 x 30 cm). There are even bigger ones, but the larger formats are less used and therefore less standard: 8U (20 x 20 x 20 cm), 12U (20 x 20 x 30 cm) and even 24U, in which the starting philosophy got a little lost ...

The great advantage of this standardized format is obviously the components that go with it. In more than 20 years of creation, students, startups and even well-established companies today have developed hundreds of pieces suitable for the CubeSat format, so much so that it is possible to buy almost anything today, and even online, for a 'reasonable' price (generally count a few hundred thousand euros depending on what you plan to order). Today we consider that the essential, whatever the size of your CubeSat, is a set of small solar panels (with management cards and the small battery), a motherboard, processing cards and a communication module with UHF or S-band antenna.

 

 


 

 

Beyond that of course, it is possible to find on-board payloads such as cameras, deployable panels, deployable antennas, thrusters (cold gas, ion, iodine ...), GPS receivers, armored components to radiations, solar sails, and a whole Prévert-style inventory since with more than 1,300 CubeSats sent into low orbit, a large number of ideas have materialized and are on sale today.

And this is not limited to the satellite itself. There are now more than a dozen solutions (and about as many companies) to eject CubeSats into orbit, all implemented from the same standard. Single ejector, in groups of 8, ejector adapted to the robotic arm of the ISS, or even autonomous satellite which releases the CubeSat at the customer's request… There is something for everyone.

 

 

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From interplanetary CubeSat to student CubeSat


The CubeSats have conquered the world in less than 20 years. In February 2017, more than a hundred of them were ejected during a single orbital flight of the Indian rocket PSLV. Space agencies love it, whether it's for testing new technologies in orbit at a lower cost, for stimulating a particular commercial sector or for the miniaturization of existing technologies. NASA, which now strongly supports the CubeSat format, has its powerful ELaNa grant program. But she is not the only one.

In France for example, CNES subsidizes the JANUS project, which aims to help students, universities united in “University Space Centers” and young French companies to assemble innovative CubeSats. The Von Karman Institute, which launched the “QB50” project in 2012 to help European students create around fifty CubeSats to study the upper atmosphere and atmospheric re-entry, has also generated many vocations ...

 


 

 

However, be careful not to do anything. At the altitude of the ISS, a 1U CubeSat will take on average about 18 months to enter the atmosphere (sometimes up to 3 years). Above 500 km altitude, these very small satellites which most of the time have no propulsion can constitute debris for a long time, much longer than a quarter of a century than the French “Law on Space Objects”. asks our companies. So be careful not to generate more debris than we can track or manage, otherwise we will have to quickly find a model for cleaning CubeSats (and curiously, these do not yet exist today).

By their low cost, these satellites are also known to be sometimes capricious, some equipment being subject to mechanical breakdown (for those who have moving parts) or electronic… What to learn to do better the next time!

 

 


 

 

Today, from the armies who test their latest sensors there to the agencies which use them for interplanetary missions (we remember the two MarCOs, who relayed the signals of InSight during its landing on Mars) by the way by companies that deploy them by the dozen to observe the Earth (Planet or Spire for example), CubeSats have become very common models.

The costs have fallen dramatically and continue to democratize. Which, for the initial objective of developing an academic learning tool, is a big victory!


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