The space environment is surrounded by different physical phenomena. Depending on the physical nature phenomenon, electronics space systems will be affected in one way or another. For a space mission is of necessity to know this environment very well in order to avoid damages and malfunctions in the onboard electronics. The exact behaviour of such physical phenomena in a specific space mission depends on the satellite’s orbit and it can be simulated with software tools. The simulation results help the satellite developers to design the system accordingly.
In the space environment following kind of physical phenomena can be found:
- Atomic Oxygen; UV light break the O2 molecules in single Oxygen atoms. The atomic Oxygen is very reactive and erodes the surface of the satellite structure. This rust affects the thermal behaviour of the structure and of the satellite. This is a very important issue because the spacecraft thermal control will be impacted.
- Plasma; The ionized gases generate electrostatic charges and load the surface of the satellite electrically. The discharge of such loads can affect the operations of the satellite and of the instruments.
- Radiation environment; a variety of effects belong to this phenomena. Gamma rays degrade the electronic components. Protons and heavy ions can literally destroy the electronics of the satellite or in the best case corrupt digital data.
- Micrometeoroids and space debris; the most dangerous events in the space environment represents small artificial or natural bodies. The impact of micrometeoroid or space debris can damage or destroy the satellite. Such situations have already happened and the consequence was the loss of the spacecraft.
At the beginning of the space era, no space electronics were available at all. Military electronic parts were up-screened for its use in space. In this up-screening process, complementary tests were achieved and the best of them were selected.
In 1973, the Skylab hardware was manufactured using military components. After the qualification test, the hardware has to be improved several times due to encountered malfunctions during the qualification process. These improvements implicated further investments over 3 million dollars for achieving system redundancy; new electronic components and further qualification campaigns were needed.
The electronic systems of the first space shuttle mission (1981) were based also on military elements. In order to increase the reliability of the system most of them were built six fold. Using an elective scheme, the valid data was verified. The inclusion of redundant systems meant also the increase of weight, power consumption and more hardware and software challenges.
Due to the fact that military electronics were not good enough for space applications and that the up-screening does not always improve the parts, in the 60’s the systematic development of space electronics was initiated. The manufacture of space electronics demands a high quality production process. In the USA military components were selected and thereafter qualified running additional tests. This strategy allowed the reduction of production costs. Since the space components demand was and is small, the price of these is still high.
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