An autonomous wireless sensor network for space applications

The importance of wireless sensor networks for space missions is shown in multiple applications, such as assembly, equipment integration, thermal and vibrations test phases in order to monitor the satellite. The high number of sensors required in space applications underscores the need for wireless sensors that save time during integration due to their simpler links and connections.

ASTRAL, which stands for Autonomous System and TRAnsmission wireLess sensor network for space applications, is designed to develop a demonstrator to validate the concept of adapting wireless technology for space missions. The result was a demonstrator for monitoring vibration in satellites on the ground and during the launch over approximately 30 minutes.

The project is financed by the French Research Foundation for Aeronautics and Space (FNRAE). The partners of this project are EADS-ASTRIUM, a wholly owned subsidiary of EADS, a global leader in aerospace, defense and related services; 3D Plus, a worldwide supplier of advanced high-density 3D microelectronic products, and the CEA, a French government-funded technological research organization.

The architecture
Arranged in a topology of a star network (Figure 1), the sensor network is composed of a single master node and multiple slave nodes. It employs two strategies of data transmission: a direct transmission of rough data with sample rate up to 2 KHz, using 5 slaves, and local calculation and authorizing high sample rates up to 20 kHz.



A flexible architecture has been designed allowing master/slave reversibility. The basic architecture is the same for the master and the slaves (Figure 2). The nature of the node is defined by simple programming. The low optimized consumption was taken into account in the architecture design.


Figure 2: Architecture

The system is implemented on a single printed circuit board (PCB) designed either to be cut off and stacked using the 3D Plus technology in the case of slave nodes, or kept in one board for the master node. Three parts are visible on this PCB (Figure 3). The left part shows the analog part with the sensor associated with its electronic components, the antenna, the RF transceiver and the power-supply monitoring. The central part shows the numerical part with the processor and the analog-to-digital ADC converter, and the right part is dedicated to the master node with serial links and contacts for testing.



Figure 3: Printed circuit board (PCB)

Information is shared by www.irvs.info