Considered a nano satellite for its weight of less than 20 kg,[1] its main mission was forwarding communications between far reaching points of the Earth such as Juan Carlos I Antarctic Base from mainland Spain.

[6] To keep the dead weight to a minimum, INTA, in cooperation with ESA, developed an experimental replacement for traditional wiring using optical infrared arrays, known as OWLS, to exchange data between the different modules.

[11] It contained two biaxial sensor units, refereed as AMR (Anisotropic Magnetic Resistor), with two redundant PCBs equipped with radiation-hardened proximity electronics and two photoelectric cells.

Although conventional, this solution provided moderate detection sensitivity (around 3 mV/V/G), good resolution (3 μG) and an acceptable operational range for measuring the geomagnetic field (0.1 mT - 1 nT).

To ensure a service life as long as possible, an operational spin rate between 3 and 6 rpm was chosen with corrections to the satellite's position applied non-continuously once a week.

[12] As a prove of concept, INTA designed and developed a magneto-optical compass based on the Faraday effect capable of accurately measure Earth's magnetic field.

The centerpiece of the device was a Sol–Gel Faraday rotor, consisting in several rods of a dispersion of γ-Fe2O3 nanoparticles (less than 15 nm in size) suspended in an amorphous silica lattice.

When the light propagated inside the rods along their axis, the magnetic field created by the austenite nanoparticles would interact with it causing the rotation of the polarizers.

The data collected by the photodetectors would then be processed in the OBDH which was capable of providing accurate readings (up to 10 nT) on both the satellite's attitude and the value of the geomagnetic field.

In addition, it contained several coils designed to compensate possible variations of Verdet constant due to changes in temperature or wavelength inside the sensor.

The cells were strategically allocated in two groups of three along the outermost edges and the signals contrasted to give a precise location for the Sun (up to 5º of nutation angle error).

[14][15] The system was based on commercial components heavily modified to adapt them to the mission, which was centered on two experiments:[16] The first was to provide a reliable link between the OBDH and the ACS, particularly the Honeywell magnetic sensors so it was given the codename OWLS-HNWLL.

It combined infrared communication with a redundant wire connection in order to compare results when the readings were computed by the processing unit allowing, in addition to assess the performance of the OWLS, to measure the occurrence of SETs (Single Event Transients), that's to say momentary glitches in the output voltage of a circuit caused by ions passing through sensitive nodes in the circuit, in the optical detectors due to incidence protons.

An additional line was added to simulate a zero on the sensor, thus giving, by comparison, the number and nature of the pulses resulted from undesired SETs interacting with the system.