Earth and Sun Location Sensors
The Elaboration of High Precision Measurement System on the Basic of the CCD-Sensors.
Tech Area / Field
- SAT-STM/Spacecraft Trajectories and Mechanics/Space, Aircraft and Surface Transportation
- INF-SIG/Sensors and Signal Processing/Information and Communications
8 Project completed
Senior Project Manager
Scientifics Industrial Association "ELAS", Russia, Moscow, Zelenograd
- SPC Astrosystems, Russia, Moscow, Zelenograd
- DaimlerChrysler Aerospace (Satellites), Germany, Friedrichshafen\nJena Optronik GmbH, Germany, Jena
Project summaryRecently, a number of space firms, such as Scientific and Industrial Association (S.I.A.) "Energia", Applied Mechanics S.I.A., Design Bureau "Salut" et al., have started development of low-weight spacecraft that can be delivered to the orbit by missiles or by multimission space vehicles. These investigations have been carried out as part of conversion and commercial programs.
Scientific and commercial problems to be solved require the spacecraft itself as well as astronomical., astrophysical and communication apparatus to be very accurately oriented with respect to celestial bodies ( Earth., stars, Sun, Moon ). Earth surface sounding experiments further require that the spacecraft be put at a predetermined point with high precision. Astrosensors are used to address problems of determining spacecraft attitude and position.
There are no Russian astrosensors accurate and low-weight enough to meet modem requirements at present. Star sensor "OZD" developed in German Democratic Republic for the Soviet spacecraft is too heavy for low-weight spacecraft. Its optical unit alone weighs about 20 kg. Besides, its development has not reached serial production stage. Sun sensors such as "POS-251", "145-K1", insure too short mission lifetime and include movable parts.
Our project's objective is to develop asfrosensors, including star and Sun sensors, that will meet modem requirements for use in low-weight scientific and commercial spacecraft orientation and navigation systems.
The Star sensor is composed of an optical unit, and an electronic unit or onboard computers. The optical unit includes lens sistem, a two-dimensional CCD chip, Peltier cooler attached to the rear side of the CCD, a part of electronics, and a videoprocessor. The videoprocessor's chip, which includes more than 100 one-bit processors, allows for onboard real-time compression of registered observations. The star sensor uses unique CCD, which provides a matrix of 1000 x 1000 pixels in its image area wilh pixel size 9x9 mm. Recent testing of breadboard find computer simulation has shown the sensor is accurate to 2-8 arcsec for 6.5 mean star magnitude. Jt is possible to improve this accuracy to provide future mission requirements. This star sensor is the next generation instrument with respect to such star sensors as ASTROS - USA, ROSAT.Star Tracker, Matra Sodem, although many useful idea and approaches from these experiments were taken into account This sensor is a light weight (3.5 kg ) and compact system ( a sensor head 120 mm x 20 mm x 440 mm ) with low power consumption ( 12 Watts ), but realizes the required accuracy (5 angle seconds ls) and stability in the entire field of view of 3.6 degrees by 3.6 degrees. The expected weight of the electronic unit is 4 kg.
The Sum sensor consist of an optical slit system, a linear CCD, and electronics, including microprocessor. The modular conception of this sensor will provide, numerous alternative design possibilities which make it compliant with new missions of various kind in either low or high altitude orbits. Further the upgraded versions of this sensor may also be able to aim at other targets than the Sun (for example, Moon). At the- same time, there exist some types of a sun sensor, such as Digital Sun Sensor - MATRA, Fine Sun Sensor JAPAN. Our Sun sensor will be similar to those sensors, but our sensor is planned to be more universal and practical
This sensor is a light weight (2. kg ) and compact system ( a sensor head plus electronics package 120 mm x 120 mm x 140 mm ) with low power consumption ( 5 - Walls) but realizes the required accuracy ( I angle minute 3s) and stability in the entire field of view of 48 degrees by 96 degrees.
Our enterprises have wide experience in spacecraft devices development. S.I.A. "ELAS" and its subpisions have been creating optico-electronic devices to be used in space for 20 years. Progressive methods, techniques and unique equipment have been used A space, satellite with experimental star sensors on board has been launched, and a Sun sensor has been developed and manufactured. Astrosensor image processing software has also been developed for those sensors. S..E.C. "Astrosphere" and S.I.C. "OPTEX" are currently involved in the production of astrodevices for a number of leading Russian space enterprises ( S.I.A."Energia", Applied Mechanics S.I.A., Design Bureau "Salut" ). This work is part of the programs "MIR-NASA" Station Modernization and International Usage Program" and "Yamal" satellite communication system program for Russian gas industry.
The proposed project can contribute to cooperation between scientists of varios nations.At present we cooperate with AMPRO firm (USA) in the field microcomputers development for star and Sun sensors. A microcomputer developed by this firm is intended to be used, the one based upon PC-104. It is planne to test these modules under radiation influence, thermal and shock impacts. Some efforts to start, cooperation with RETTCON firm ( USA ) that produce CCD-detectors are also being made.
Other foreign paitners or collaborators on this project in the areas of astrodevices development or marketing would be welcom.
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