## 3 Adaptation of COTS for space applications
In some of the small platforms passive thermal control can achieve and maintain a moderate temperature environment of around 50 \({}^{\circ}\)C. In other cases, a temperature cycling at the operating and storage temperatures is developed for the COTS. In this cycling test the speed of the variation of the temperature needs to be representative but fast enough so as to simulate the total life of the mission. Other temperature tests are the thermal shock resistance test and a working test when sensors need a driving excitation. For instance in the case of fluxgates it is convenient to cycle during a long time the driving current and in the AMR sensors the Set/Reset current pulses to guarantee the repeatability and maximum sensitivity and because in the range of temperature the variation of the electrical resistance of the coils can be considerable. The temperature can also affect the mechanics of the device leading to cracks and movements of the lithographed parts. Often materials with compensated thermal expansion coefficients have to be used for the assembly to avoid stresses or changes of shape of the elements that eventually can influence the behaviour of the sensors or break them. But attention needs to be paid too when using metallic surfaces because thermal gradients can generate thermoelectric currents that disturb the measurement. Another problem with in-orbit missions is the radiation. The sources of radiation are diverse. Apart from other missions to the giant planets, perhaps the most harmful for in-orbit missions and mostly in LEO-Low Earth Orbit, are the Van-Allen belts, where electrons and protons are trapped around the lines of the Earth magnetic field. These belts approach the surface of the Earth in the South Atlantic anomaly. But there is also radiation, which comes from the outer space, cosmic radiation, and solar flares associated to the maximums of activity in the solar cycles. The effects of radiation on the components can be divided into three main groups: TID - Total Ionizing Dose, DD - Displacement Damage and SEE - Single Event Effects. The TID effect consists of the damage inflicted by the charging process caused by the accumulated dose in semiconductors and other components. Normally to simulate or study the influence of this kind of effect on the components, \(\gamma\)-ray irradiation campaigns are developed covering the expected total dose during the life of the missions. A reference for a three year mission in a polar LEO (700 km) can be 10 krad (with the typical aluminum shield of 1 mm-spherical). DD is characterized by changes in the crystalline structure of a device produced when a high energy particle passes through it. This effect, mostly produced by protons, can be equivalent to TID and some times more significant than TID, like in some semiconductors. The SEE consists of the damage caused generally by high energy particles when they pass through a material. These effects can be temporary or permanent. The way of testing components for SEE effects is through irradiation with high energy atomic nuclei and particles. Regarding magnetic technologies, Hall sensors seem to be more sensitive to radiation damage than AMR sensors, for instance [55]. INTA, the Spanish National Institute of Aerospace Technology has tested both AMR and GMR COTS sensors with \(\gamma\)-ray with total doses higher than 10 krad and with 52 MeV protons with a flux of 2.5 x 10\({}^{8}\) protons/cm\({}^{2}\)s achieving a fluence of 2 x 10\({}^{12}\) p/cm\({}^{2}\). The COTS sensors (AMR sensors of the family HMCxxxx by Honeywell and AAL002-02 GMR sensors by NVE) did not experience substantial damage [54]. In the case of magnetic devices, both electrical and magnetic properties have to be checked in the end of each test. This last part of the testing has to be done very carefully (using shielding chambers) as most of the thermal and vacuum chambers have ferromagnetic composition, which seriously influence the magnetic measurements [3].