The main interest of working on the nano-satellite scale is that of increasing the opportunities for scientific applications at a hugely reduced cost and without the tight constraints of traditional space exploration missions. At this scale it is possible to demonstrate new concepts in preparation for larger future missions.

The CubeSat format is an optimal format from a financial and operational view point. It has changed the paradigm of space missions, forcing a different approach.

Within the CENSUS framework researchers and engineers acquire new original know-how both in terms of space observation platforms and in terms of shorter and more flexible cycles of development.

3 CubeSats 1U lancés depuis l’ISS

Expedition 38 Crew, NASA,@ APOD 6-jan-2014

Family - SmallSat, NanoSat, CubeSat

Within the nano satellite family the "CubeSat" corresponds to a standard defined in the USA in 1999 in order to facilitate access to space for students. The size of a CubeSat basic unit (1U) is normalised, 1U being a cube of 10x10x10 cm weighing 1.3 kg. The standard was further increased to 2U and 3U, meaning 2 or 3 superposed cubes. Today formats of 4U or N x 3U are available. Yet the idea behind ​​the standard remains intact: to simplify as much as possible the realisation of a CubeSat by imposing its external shape, which makes it possible to adopt a standard deployment system, which in turn interfaces in a standard way with the launch vehicle according to the requirements of space qualification and safety.

This standard greatly simplifies the construction and launching of satellites. In 15 years it has led to the realisation of hundreds of CubeSats projects, the first French project being "Robusta" in 2012 designed by a team from the University of Montpellier.

Illustration : CubeSat

The CubeSat is placed in the off position in a sealed deployer (P-POD or equivalent), attached to launch vehicle. The CubeSat remains in this position until it is released into space by opening the deployer. The release triggers the power-up of the CubeSat and the beginning of its mission.

Three applications for nano satellites

Generally three types of applications for CubeSats, or any satellite with a mass smaller than 50 kg, scale can be defined.

Educational Nanosat: to train students in a number of engineering disciplines needed to develop a satellite. It is for this purpose that the CubeSat standard was created in the first place. In this application the mission of the satellite itself is not in the main goal.

Technology Nanosat: to demonstrate a particular technology in a space environment using a satellite that is much cheaper than a traditional mission. In this way nano satellites can help us prepare the instrumentation of tomorrow. If such a nano satellite mission is successful the technology will have a higher TRL (Technology Readiness Level, see below), making it possible to propose it later for more ambitious scientific space mission that can be of any format.

Scientific Nanosat: to acquire scientific data with an instrument mounted on a nano satellite. Scientific applications are gradually emerging with a large variety of concepts. An example is a CubeSat to accompany a mother mission to recognize the terrain before approaching an asteroid, or a fleet of nanosatellites to perform simultaneous measurements. To distinguish between these and the educational and technological nano satellites, the term "research" satellite is sometimes used.

CENSUS addresses all universe sciences because nanosatellites, and in particular CubeSats, have demonstrated their flexibility to acquire good data from space, for Earth observation, for space weather in Earth’s vicinity or in interplanetary medium, as an auxiliary probe in a space exploration mission, to observe other stars and maybe their own planets, and maybe even the dark ages.

CENSUS also prepares the future instruments for all universe sciences, as soon as a technology demonstration is required for space measurements as a single probe, as a constellation or as a swarm.

The total cost of a CubeSat 3U student mission, with much lower salary costs, is estimated at 1 million euros, including launch to a Low Earth Orbit. Several hundred CubeSats have been launched already, and CubeSats constellation projects are emerging. The rapid expansion of this format makes it an economic sector in its own right, where subsystems as well as services are commercially provided, from engineering to operations to piggy back launches, that is as a passenger on a traditional satellite launch.

The CubeSats thus represent a promising market and an opportunity to create a diversity of startups.

A reference used in the space industry is the Technology Readiness Level (TRL). It indicates in one figure the degree of technological maturity of a new instrument or of any component that it contains.

TRL 0 indicates a simple concept, for example pin pointing a satellite’s position in its orbit around the Earth by listening to GPS signals. For an instrument in a traditional space mission TRL 5 level is required before transition to phase B, the Detailed Definition Phase. TRL 9 refers to a perfectly mastered technology that has been flown, for example a subsystem that uses GPS signals to accurately determine the position of a satellite on-board without any assistance from the ground.