Earth Horizon Sensor
Basic Set of the Earth Horizon Sensor
Tech Area / Field
- INS-MEA/Measuring Instruments/Instrumentation
3 Approved without Funding
RDC Astrosfera, Russia, Moscow reg., Zelenograd
- VTT Automation, Finland, Espoo\nInstitut National de Recherche en Informatique et en Automatique (INRIA), France, Rocquencourt\nNASA / Jet Propulsion Laboratory, USA, CA, Pasadena
Project summaryThe purpose of the project is to develop the base set of main mechanical, optical and electronic modules to create the advanced Earth horizon sensor* (* Earth Horizon Sensor is essential element of Attitude Control and Determination System of any spacecraft. The sensor provides digital signals in accordance with deviation between the direction to Earth center and optical axis of the sensor. These signals are used to correct pitch and rool errors of a three-axis stabilized spacecraft).
. This set will be a base for a new generation of Earth horizon sensors for spacecraft operating in round orbits with fixed altitudes in the range from 400 to 45000 km.
It is planned to create the geostationary satellites' Earth horizon sensor with following features: weight 1.5-2 kg, accuracy < 2 arcmin, field of measurement ± 2 degrees, field of view ± 14 degrees, power consumption 2-3 W, life time 12-15 years, cost $120,000.
The device will be static, two-coordinate, totally redundant, and will exceed all known analogues in totality of its features.
The appearance of space satellites 40 years ago opened vast perspectives to the development and improvement of all information interchange systems. Space communications, television and navigation form a quickly growing market segment at present. The majority of the world's population uses space services and they are so deeply rooted in everyday life that it is now impossible to imagine the nearest future without them.
Spacecraft the number of which is about several thousands and is still growing at high rate serves this market. The well-known specialist professor Yuri Zubarev noted at the 2nd International Conference "Satellite Communications" (Moscow, 1996) that, according to International Telecommunication Union, more than 400 communication satellites are to be launched in geostationary orbit at present.
Each spacecraft is equipped with attitude determination and navigation sensors the purpose of which is to determine the spacecraft's attitude relative to the Sun, Earth and stars. This information is needed to control the spacecraft. The Earth horizon sensor is indispensable part of attitude determination and navigation system and is used to determine the spacecraft's attitude relative to the Earth. The quality of communication, TV, and navigation depends on the stability of the satellite's location in the orbit, which cannot be achieved without the Earth horizon sensor.
The growing competition makes the satellites' manufacturers to increase the quality of services, to decrease the cost of spacecraft, to increase their lifetime, to decrease their size and weight.
So, the growth of space services market stimulates the development of new Earth horizon sensors which would make it possible to create the spacecraft meeting all modern market requirements.
Astrosphere Ltd. specialists using their knowledge and experience gained during the development of spacecraft attitude determination and navigation systems developed an original technical concept based on high technologies and latest scientific advances which makes it possible to start the development of static infrared range two-coordinate Earth horizon sensor of new generation.
Earth horizon sensors created with the aid of the base set of mechanical, optical and electronic modules will have low weight, high reliability, long life time and low cost.
The main features of the Earth horizon sensors created with the aid of the base set of mechanical, optical and electronic modules are as follows:
- the use of non-cooled scanning infrared radiation detector;
- manufacturing of the case from ceramic materials;
- hardware implementation of algorithm of computation of Earth image center of gravity.
Expected project results:
- hardware implemented algorithms of computation of angular coordinates;
- algorithms and programs for mathematical simulation of Earth radiation in visible and infrared ranges at various Sun-Satellite-Earth angles and seasons;
- methods of ground tests of the devices' stability at the influence of space agents;
- design documents for the Earth horizon sensor;
- manufacturing technology for the following parts:
- non-cooled scanning infrared radiation detectors;
- semiconductor microchips with implanted oxide layer;
- aspheric one-component optical parts forming the infrared images;
- ceramic case parts and ceramic materials.
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