Sun sensor on a chip is the high accurate version of a sun sensor for small satellites (SSOC)

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Technology abstract

The size and the weight are key factors that determine the final cost of the launch and the mission. The Spanish company applied to the manufacture of sun sensors, which involves the development of electronic and optical devices on a very small scale, can reduce size, weight and consumption of these devices.

Technology Description

The strong trend to miniaturization during the last years has allowed significant cost savings in the nanosatellite market. Now the presence of the commercial sector in nanosatellite missions has significantly increased, providing much of the performance of a conventional satellite for a fraction of the cost. As the nanosatellite technology capabilities increase, their requirements do as well. New applications demands higher accurate in orbit detecting and positioning systems for which the sun is used as a reference to support other systems. This is where sun sensors play a fundamental role, and in many cases they are very expensive devices, with high volume and low accuracy. The size and the weight are key factors that determine the final cost of the launch and the mission. MEMS applied to the manufacture of sun sensors, which involves the development of electronic and optical devices on a very small scale, can reduce the size, weight and consumption of these devices.
The company commercializes four different sun sensor models, which are based on MEMS fabrication processes to achieve high integrated sensing structures. They have minimum size, weight and power consumption to be the perfect AOCS (Attitude and Orbit Control System) solution for nanosatellite platforms.
These devices are two-axis, low cost sun sensors for high accurate sun-tracking and attitude determination. The devices measure the incident angle of a sun ray in both azimuth and elevation, providing a high sensitivity based on the geometrical dimensions of the design. The sun sensor uses four silicon photodiodes monolithically integrated, including a transparent glass on the same silicon die to act as a shield to prevent space radiation damage. The device fabrication combines MEMS technology with a high efficiency solar cell fabrication process, leading to small area and low weight device. All materials used in the silicon sensor fabrication process are compatible with space requirements in terms of radiation, thermal and vibration resistance, and low degasification.
The applications of the sun sensors are summarized as follows:
·         Low cost satellite attitude determination
·         Accurate Sun position determination
·         Satellite solar panel positioning
·         Attitude Failure alarm
·         Satellite positioning in specific trajectory points
·         Balloons and UAVs control 

Innovations & Advantages

The application of MEMS (Micro Electro Mechanical Systems technology) technology to the development of sun sensors provides remarkable benefits compared to other options in the market. The main competitive advantages are summarized as follows:
·         High miniaturization and low weight.
·         Very low power consumption
·         High reliability
·         High accuracy
·         High operation range and sensitivity
·         Easier integration in the satellite platform
·         Low cost
 
These advantages allow SSOC (Sun Sensor on a Chip) sun sensors to be a suitable and affordable solution for the new pico and nanosatellites, especially Cubesats. These characteristics fulfil the recent requirements of the space industry, which tends to produce smaller satellites which require the use of high integrated systems with lower power consumption levels, but without losing the benefits of traditional macroscale devices. MEMS technology also allows the industrialization and provides a mass production approach, achieving reduced lead times. 

Current and Potential Domains of Application

-          Low cost satellite attitude determination
-          Accurate Sun position determination
-          Satellite solar panel positioning
-          Attitude Failure alarm
-          Satellite positioning in specific trajectory points
-          Balloons and UAVs control