Ultrasonic Wireless Sensor Network for Human Habitation in Deep Space Mission

Abstract

In this work we show the design and measurement of ultrasonic wireless sensor network in on-earth Columbus Module. The module is a copy of the original module attached on International Space Station (ISS) and it is usually used for testing any new hardware before launching them to the ISS. An analog mixed signal 350 nm technology Application-Specific Integrated Circuit (ASIC) was designed to handle ultrasonic modulation and signal conditioning. The sensor node comprises three pairs of ultrasonic transmitters and receivers. Smart sensors such as humidity/temperature sensor, air pressure sensor and visible/infrared light sensor are utilized to minimize power consumption, computational time and save weight. A low power micro controller ATMega238 is added to interface the smart sensors and ultrasonic ASIC. In order to achieve simple installation procedure for the astronauts, an innovative sensor node casing was designed to allow easy mounting and easy signal directing when attached to the wall. One access point and two sensor nodes were built for testing the signal range on various location in the module. During the test, the ultrasonic signal managed to propagate and received within the entire module. A constant speech signal was added (e.g. human conversation in the background) in order to simulate real mission condition. The power consumption of the sensor node in active/communication mode is less than 60 mW that ensures high durability. The total weight of the sensor node including 400 mAh battery, casing and sensor node holder is less than 50 g.