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SARA, S.A.R.A (Satellite Amateur de Radio- Astronomie) stands for radio astronomy amateur satellite, and measures the radio-waves transmitted by the largest planet in our solar system, Jupiter, at frequencies between 2-15 MHz. These frequencies can not be observed from the Earth, as they are blocked by the ionosphere. These measurements are of great scientific interest, and reflect phenomena occurring deep in Jupiter's magnetosphere. An earth orbiting satellite beyond the ionosphere is ideally suited to receive and study these signals. The waves are expected to be strong enough to be received by omni-directional antenna, thus no attitude control was required. Radio astronomers were to use a duplicated earth station to be used to make a solar cycle survey to correct the in-orbit measurements, as SARA is an isotropic receiver. The groundstation receives decametric waves above 20 MHz, and this information will be used to distinguish the emissions from Jupiter from the numerous natural and artificial emissions from the Earth and the Sun. SARA is the first satellite designed by ESIEESPACE (aerospace association of the groupe ESIEE's school in Paris). The study team of SARA was aware that it was important to make a very simple satellite to have a good chance both to succeed and overall to be credible. Electronic subsystem: Uplink: A 436.5 MHz receiver. This device has been developed by ESIEESPACE. It used a quartz based modulation recovery system, and has a sensitivity of 110 dBm with a 2KHz bandpass channel. It is used with the transmitter switched off. Downlink: A 145.955 MHz 0.5 W transmitter. This part has been designed to provide a good reliability to the telemetry which is essential to the mission. This has been achieved by providing a good thermal environment to the power devices included in this card. Power system: This part is used to collect the energy from the solar panels. Furthermore it provides the charge for the battery taking into account the thermal condition. Computer: is a 8031 based microcontroller. The system controls the payload and format the telemetry which is composed with space qualified components. This was possible mainly because these devices were on the shelf and also because they have a better resistance to total dose radiation effects. Thermal and voltage technological experiments: Shortly before launch it was decided to add two other technological experiments on board. The hardware provides a real time telemetry of the temperature of SARA plus the battery's voltage. Budget SARA has been completed with very low funding. The total cost of this project is 3,244 Kf (about 0.6 M$) launch included. It has been done thanks to the CNES, Matra, Dassault, SAT, CCIP, etc. Launch During the launch, the ARIANE telemetry indicated that SARA had separated prematurely, but this was later found to be a fault of the separation switch. contact: ESIEESPACE; groupe ESIEE; 2 Bd Blaise Pascale; BP 99; 93162 Noisy le Grand Cedex; France. phone (33) 45 92 65 00 fax (33) 45 92 66 99 References
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Made by:
ESIEESPACE (France) 