Wireless ad hoc networks in space
Hundreds or even thousands of small sensors could be dropped from a satellite orbiting a planet and deployed as a distributed instrument for the exploration and study of its surface. In particular, the ability to observe the planet's atmosphere would help ensure that there are no hazardous conditions at the location where landing is planned. The EU-funded project SWIPE (Space wireless sensor networks for planetary exploration) was launched to develop such a planet exploration scenario. The proposed mission was based on adaptive wireless technology. This state-of-the-art technology has already found applications in emergency rescue in remote areas, where connectivity with the outside world is limited. The sensors designed and manufactured during SWIPE are micro-meteorological stations, capable of measuring environmental parameters such as temperature, dust deposition, radiation and light in different wavelengths. Each station is autonomously powered with solar energy and has data processing as well as networking capabilities. Some of the SWIPE stations, equipped with satellite communication capabilities, can establish a link with a satellite in orbit around the planet. All together, they create their own ad hoc network. Data gathered from the set of four sensors would be first processed and then sent to the orbiter. Measurements collected on the environmental conditions found on the planet can be handled by stations using dedicated data fusion algorithms. The data are then passed through the network and collated and organised before they are sent to the orbiter and later transmitted to Earth. SWIPE partners have defined this mission scenario on the surface of Moon. They also developed fully functional network nodes with the sensor payload to evaluate three different communication levels: within the wireless sensor network, between the sensor network and the relay satellite, and between the satellite and Earth. The whole system was tested in the laboratory as well as at an Earth analogue in Svalbard, Norway – especially chosen to match the mission scenario. Although the work focused on Mare Ingenii on the far side of the Moon, the results can be extrapolated for other planetary exploration missions, including a Mars mission. SWIPE has successfully taken hybrid network technologies developed for terrestrial applications and implemented them to solve problems in planetary exploration. Compared to solitary planetary probes, wireless sensor networks allow mapping larger surfaces over longer periods.
Keywords
Space, SWIPE, wireless sensor networks, planet exploration, orbiter
